Positive side of climate change facts, after two years of action, heading for 3°C with 1.5°C well within reach

Robert Walker

Almost nobody seems to report the positive side of our recent climate change action. As someone who followed the topic before Kyoto, what happened since 2016 was remarkable. The change in attitude, pace of action, at last gives much hope that we can rise to the challenge. I have never in my life seen such a coming together of nations worldwide to solve a problem.

Three years ago it was close to hopeless. Many individual actions, but nothing compared to the scale of the problem. Yet the more we act, the more the publicity seems to focus on what we aren't doing, and almost never on our successes.

That's the key to the Paris agrement, to constantly build on successes. The pace is accelerating. Month on month it may seem glacially slow, but over a few years, extraordinary. We can do this!

The young particularly are driving action, such as Greta Thunberg who started the movement of school striking children in Sweden, by standing outside the Swedish parliament.

Greta Thunberg. August 2018, as she started her school strike for the climate

Here is her emotional speech to EU leaders.

Click to watch in YouTube

Longer video here

She is speaking at a critical time. As part of the Paris agreement, countries are expected to increase the ambitions year on year. The EU is already better than 3 °C compatible but not yet 2 °C compatible, however its ambitions can make it 1.5 C compatible it if goes through on them. Amongst those listening, as you can tell from the questions, many are in support of her. Climate change is likely to play a major role in the next EU elections this May. For a summary of how the EU is doing on climate change, see the EU page on Climate Tracker.

This is surely helping to motivate the governments to do more. However, there is much understandable fear, and even hysteria, in some responses, which doesn’t seem to be strongly based on science, and a tendency to use "Climate slogans" that are not always accurate, or are over simplified. As an example, the Extinction Rebellion are disrupting services throughout London right now, with the aim to get the UK government to commit to zero carbon emissions by 2025.

Government must act now to halt biodiversity loss and reduce greenhouse gas emissions to net zero by 2025. Our Demands - Extinction Rebellion

But where does that figure come from? They don't say, I've looked on their website and there is no explanation of it anywhere. It isn’t in the 2018 IPCC report which says we need to reach that level by 2050 for the 1.5 °C goal.

Click to watch in YouTube

I’d like to focus in this article on what the climate scientists themselves say. Also on what we are already doing, and what they say we need to do in the future.

This is another article I'm writing to support people we help in the Doomsday Debunked group on Facebook , that find us because they get scared, sometimes to the point of considering suicide, by such stories.

You can see this blog post with a table of contents on my website:

Add table of contents to this page (on my website) - blog post on Science 2.0 without the TOC

Need for urgent action - but measured, based on science

There’s a pervasive idea in our society of an almost impossible situation, that we can’t do anything about climate change, or that nobody is doing anything, or that we are headed for a doomsday scenario and it is almost over, already. None of that is true, not remotely so.

Myles Allen, a lead author for the IPCC report in 2018, spoke out about this in : Why protesters should be wary of ‘12 years to climate breakdown’ rhetoric in The Conversation:

Today’s teenagers are absolutely right to be up in arms about climate change, and right that they need powerful images to grab people’s attention. Yet some of the slogans being bandied around are genuinely frightening: a colleague recently told me of her 11-year-old coming home in tears after being told that, because of climate change, human civilisation might not survive for her to have children.

In Doomsday Debunked we encounter young kids like this all the time, scared sometimes to the point of being suicidal that they will not live to adulthood, and young adults who feel they shouldn't have children because they have read that they would be bringing them into a future uninhabitable Earth. A fair few are receiving therapy and drugs to treat PTSD and GAD and other anxiety disorders, and have panic attacks and vomit in fear many times a day out of fear of an uninhabitable Earth as well as other nonsense such as the constant fake NASA asteroid warnings in the sensationalist press. The sad thing is that much of what scares them so much is out and out junk science, exaggerated stories or these over simplified climate slogans.

Myles Allen continues:

The problem is, as soon as scientists speak out against environmental slogans, our words are seized upon by a dwindling band of the usual suspects to dismiss the entire issue.

Even when the climate scientists do speak out, as they do sometimes, their views do not get the publicity - a story is far more likely to be shared on social media or run in the mainstream news if it says that all the insects will die, civilization end or humans become extinct.

There is much that does need climate action, and our situation is indeed serious in many ways. However none of the expert projections of the IPCC and others of a similar high quality are of an uninhabitable Earth or a literal collapse of civilization. Also though many individual species do risk extinction and are going extinct, when it comes to ecosystems, many are actually becoming more species diverse due to human effects, with new habitats and species brought in from other parts of the world. The corals are the only complete ecosystem highlighted as at risk of near extinction (see below).

Myles Allen,continues, in his : Why protesters should be wary of ‘12 years to climate breakdown’ rhetoric

Using the World Meteorological Organisation’s definition of global average surface temperature, and the late 19th century to represent its pre-industrial level (yes, all these definitions matter), we just passed 1°C and are warming at more than 0.2°C per decade, which would take us to 1.5°C around 2040.



That said, these are only best estimates. We might already be at 1.2°C, and warming at 0.25°C per decade – well within the range of uncertainty. That would indeed get us to 1.5°C by 2030: 12 years from 2018. But an additional quarter of a degree of warming, more-or-less what has happened since the 1990s, is not going to feel like Armageddon to the vast majority of today’s striking teenagers (the striving taxpayers of 2030). And what will they think then?

As he says the IPCC projections are the best estimates. They are based on review of the academic literature at the highest level, but they always have a range of uncertainty. He says that it's not impossible that we reach 1.5°C by 2030, that it's within the range of uncertainty, but this is not an uninhabitable Earth, or anything resembling it. If we do hit this level, the world will feel much as it does today to the majority of the population of the Earth. (The expected time to reach 1.5°C is between 2040 and 2050, but there is enough uncertainty so that 2030 is not impossible).

He goes on to say that "the IPCC does not draw a “planetary boundary” at 1.5°C beyond which lie climate dragons."

...

So please stop saying something globally bad is going to happen in 2030. Bad stuff is already happening and every half a degree of warming matters, but the IPCC does not draw a “planetary boundary” at 1.5°C beyond which lie climate dragons. Why protesters should be wary of ‘12 years to climate breakdown’ rhetoric - by Myles Allen

Climate slogans, journalist exaggerations and out and out junk science

How many of you have seen or shared Myles Allen's post Why protesters should be wary of ‘12 years to climate breakdown’ rhetoric ? I expect nobody.

How many of you have seen or shared that study that was on TV saying that we are headed for a world without insects in 40 years? Did you know that that study had only one data point for the whole of China, for the domestic honeybee? It's like using sheep in a study on declines of mammals. Most of the map is blank, and the few studies they do include come from a literature search for "DECLIN*".

This is what the insect ecologist Manu Saunders had to say about it in a tweet:

The key take-home is the amount of white space on this map of available data showing local/regional declines. Most countries have no data. N.B. the single data points in Australia & China are both managed honey bees, not wild insects pic.twitter.com/PNNlZ7yGaR — Dr Manu Saunders (@ManuSaunders) February 3, 2019

Those purple bars in Australia and China are for the domestic honeybee

Yet nobody shared the much more thorough study from the UN released just a week later which concluded that the situation is mixed, some increasing, some decreasing and some stable, and also went into detail about the many measures being taken to protect insect biodiversity (see below).

Or you may heard that humans are going to go extinct in 2026. If so you have probably been duped by one of the "Arctic News" blog posts by Sam Carana. Widely shared on ocial media, they feature graphs that project a sudden increase of temperature by many degrees in a few years. You may have been decieved by the impressive list of "contributors" on his About page. Few bother to click through and discover that he credits every professor whose video he embeds in his daft blog posts. Most likely they don't even know that he has done this, as anyone can embed their videos under YouTube's license!

He uses a quadratic (or other polynomials) to extrapolate. You may see the absurdity if I extend his graph both ways in the blue inset below:.

Such a graph always decreases from an infinite temperature in the past and increases to an infinite temperature in the future - unless they decrease to minus infinity both ways (see below). Or what about Guy McPherson's blog posts and videos. Many are impressed because he used to be a professor, but sometimes professors lose their way, and fall into junk science. He uses Sam Carana's absurd "polynomial extrapolations" as one of his sources for his predictions, 'nuf said!

Or you may have heard of Jem Bendell's "Deep Adaptation", the paper that is "driving people to therapy"? It failed peer review, not for the views expressed, but because it didn't meet academic standards(see below). Or, "Uninhabitable Earth", the sensationalist book by the generalist journalist David Wallace Wells who has only been interested in climate science for two years (see below ), or the often repeated journalistic claim that the IPCC report said that the only way to stop global warming is a tax leading to $240 a gallon for fuel (see below)?

Or the claim of a runaway feedback from a "methane bomb" (see below), or from the Siberian Permafrost (see below), that our agricultural land is going to run out of topsoil in 40 years (see below), that nearly all species will go extinct this century (see below), or that the Amazon jungle will soon burn down and be gone (see below)? Or the 1972 "supercomputer" that predicted an end of civilization in 2040 (see below). Or Adam Frank's model that supposedly showed our civilization will end in one of three horrible ways (see below). Or perhaps you have heard that we are going to run out of oxygen to breathe (see below). Or that we risk a cascade of tipping points leading to a hothouse Earth (see below).

I expect almost everyone with an interest in the topic has come across most of those stories and more. You may be surprised to learn how much of that is based on misunderstandings, exaggerations, sensationalism, climate slogans, and junk science.

If only the journalists and bloggers would heed the warnings about climate slogans by scientists like Myle Allen. Some probably do. However, it would take some major change or initiative for all journalists to stop doing the click bait titles. For as long as some do, those ones get shared and rise in Google results. It would also take some major change to deal with this issue of the junk climate science widely shared in social media. Perhaps social media initiatives to flag fake news may help, but so far they don't do anything, share Sam Carana's blog and there is no indication at all that it is junk science. How can your average reader, with no physics background, know this? Meanwhile, the bloggers have freedom of speech. They are not doing anything illegal by publishing nonsense even if they know that what they say is false.

It is hard to know what to do when faced with what seems an onslaught of fake and exaggerated climate change news. Since the start of 2019 the pace has really heated up. Most weeks we get a virally shared fake or exaggerated climate catastrophism or climate slogan story on social media, and often click bait and exaggerated or mistaken items on the mainstream news or on mainstream TV too.

I do have a petition to Google News and other news aggregates, asking them to stop promoting fake and junk science news stories, and to journalists to be more responsible in their reporting, which you may want to sign and share, and any suggestions do say in the comments!

What can you do? Tell the truth

Meanwhile the main thing one can do is to tell the truth, as clearly and succinctly as one can. If you are a blogger or journalist, please do the same, and anyone - please do more sharing of the posts that present the true situation and less sharing of the junk science. Try checking a climate change story against reliable sources first. Our Doomsday Debunked group may help you, as we now have a fair few members with a decent scientific understanding of climate change.

Also, if you are a climate scientist or expert, you may like to consider joining our group and giving a bit of your time to help the scared people who constantly panic about climate change and other doomsday scenarios.

Anyway, I’d like to focus in this article on what the climate scientists themselves say rather than the climate action slogans. Also I will cover what we are already doing, and what they say we need to do in the future.

Remarkable progress so far

For instance, how many of you know that the EU reduced emissions by 22% from 1994 to 2017? It is on track to meet its 2020 target

20% cut in greenhouse gas emissions (from 1990 levels)

20% of EU energy from renewables

20% improvement in energy efficiency

Progress made in cutting emissions - Climate Action - European Commission

Its long term strategy is zero emissions by 2050, and if it achieves that, it makes it 1.5 °C compatible. The UK has done even better, see Slow burn? The long road to a zero-emissions UK. In the UK, our emissions are now the lowest since 1920. The government says greenhouse gas emissions have fallen by 42% since 1990. Greta Thunberg told MPs in Westminster that the true reduction was more like 10%. The reason is, the UK is using territorial emissions, which is the fairer way to look at a countries own work to tackle climate change. She is using the pattern of consumption, which includes effects from other countries for instance if we import from China, it would depend on their policies not ours, things that we can't do anything about (except by importing from someone else). It can also lead to some double accounting where the same figure is counted twice. The method the UK uses is the method adopted for the Paris agreement. See Climate change: Is Greta Thunberg right about UK carbon emissions?

China and India are often criticized because their emissions are still increasing. But they start off with much lower emissions per person, especially India with only 1.8 tons per capita well below world average of 4.2 tons per capita. They are rapidly industrializing, yes but they aim to achieve this without increasing emissions, indeed, to reduce emissions. It takes a while to turn around the energy use of a population of over a billion people so you can’t expect this to happen in just two years.

India remains on track to overachieve on its 2 C compatible target and 1.5 C is within reach India | Climate Action Tracker, see also Guest post: Why India’s CO2 emissions grew strongly in 2017 | Carbon Brief

China faces the biggest challenge of all, it is expected to meet its commitments which include 20% non fossil fuel by 2030 and to peak emissions before 2030 but it has to increase its commitments for us to have a chance to say within 1.5 C. China | Climate Action Tracker

Important role of sub national entities such as cities and private industry

Although the US has no climate change initiatives at the Federal level after Trump's declaration of his intention to withdraw from the Paris agreement, it has strong suport at a subnational level. Initiatives already taken will bring it nearly halfway to its Paris pledge to reduce emissions by 26-8% by 2025, and subnational commitments and pledges will lead to a reduction of 17%, over two thirds of the way. The report by California governor Jerry Brown and UN’s special envoy for climate action Michael Bloomberg in 2017 outlined a roadmap to reach a 24 percent emission reduction by 2025 and make 26% achievable shortly therafter. prepare for faster emission reductions beyond 2025. See Fulfilling America's Pledge.

Cities and other non state actors also have an important role. In the UN review published ahead of the Global Climate Action summit in September 2018, they found that pledges by non-state actors represent a global reduction of between 1.5 and 2.2 gigatonnes of carbon dioxide equivalent by 2030. But the combined effects can be much larger.. Erik Solheim said:

“Cities, states, civil society and the private sector can be the resource that puts the world over the top in our fight to reduce CO 2 emissions,”

The 2018 Yale study found that there is alot of potential in these subnational initiatives. Indeed they concluded that if they are all fully implemented along with the NDC's (Nationally Determined Contributions at the country .level), and taking account of overlaps, that we can already reach our 1.5°C goal! Not that they necessarily will all be fully implemented, but this shows the vast potential there is at the subnational level.

In summary, Angel Hsu, Director of the Data-driven Yale said:

“What our report shows is many actors are signing up to take actions, but their ambition and ability to move us faster and closer to reach the Paris climate goals in time is limited. What’s needed now is the financing, policies, and support to urgently realize these efforts.”

Key to Paris agreement - countries set policies they can achieve, then constantly step up ambitions

As far as I can see the demands of the Extinction Rebellion are not based on any report by climate scientists. By pushing for nearly impossible demands they risk a future where we commit to things that we can’t achieve, instead of committing to things that are possible.

The thing that has made the Paris agreement such a success is that nations are able to set policies they know they can achieve at every stage, and then increase their pledges year on year as they gain experience and develop new industries to make it all possible. I think we need to continue in the same spirit. Be ambitious, but make sure our goals can be achieved when we commit to them.

The UK government’s plan is to reduce emissions by 80% in 2050. That’s not enough yet, but if it steps up in its pledge to a 100% reduction, it would then be 1.5 °C compatible to save the corals UK steps towards zero-carbon economy. This is something we can pressurize them to do. And then to be even more ambitious once they do that.

According to the IPCC report in 2018, we lose 99% of the corals after just a decade or so at 2 °C, and the reefs probably do not recover. If we don’t go much above 1.5 °C then 10 - 30% of them remain and they can recover, though this may take a long time. They can recover because they can adapt to warmer temperatures, as well as migrate and set up reefs in places that used to be too cold for them, but at 2 °C the warming is too rapid for this to work so well.

They do caution that these projections are not certain and that it’s possible that corals are more resistant than this, or that we can do things to help them adapt. See box 3.4, page 230 of their chapter 3.

They found that no other major ecosystem on Earth is so sensitive, either in the sea or on land. The corals are the only entire ecosystem we risk losing at 2 °C. Humans for sure are not at any risk of extinction under any of the scenarios,

There is a risk of severe impacts on other ecosystems however. In this map the regions marked in red risk severe impact at 2 °C, and the dark red regions, at 1.5 °C.

Figure 3.16 of chapter 3 of the IPCC report in 2018. The coloured regions highlight risks of sever impact. The gray scale regions correspond to moderate impacts at those various temperatures.

This doesn’t mean that the ecosystems vanish. Rather, they change to other ecosystems. For instance the melting permafrost will lead to a radically different ecosystem in northern Canada, Alaska and Siberia, in a 2 °C warmer world, but this warmer world would be more habitable for humans in the far north, with far more vegetation, and letting us grow crops using conventional agriculture that never could grow there before. The pace of the change is the main issue.

It is important to stay within 1.5 °C for these and many other reasons. However, our future is a habitable world for humans in all the scenarios. Indeed it has been greening as a result of the CO 2 fertilization effect so far (Rising CO 2 has 'greened' world's plants and trees | Carbon Brief). This should continue through to 2050 at least, with increasing crop yields, and faster growing trees (see below)

It’s the transition, and the speed of transition that matters, far more than the end state. Even at an increase of 12 °C then the world is still very habitable for humans, as we’ll see. What’s more we have already averted a possible ice age 20,000 years from now, and are headed to a future where there won’t be any ice ages for hundreds of thousands of years. That is good because interglacials are far more stable than ice ages when there are often wild swings in temperature.

The IPCC do project tens or hundreds of millions of climate refugees and other serious effects at 2 °C of warning. At that temperature point, we may get population densities quadrupling in some places in the sub tropics due to the migrants from the tropics.

That is a serious societal impact in anyone’s books. However, there is nothing in the report about collapse of society or an end of civilization. Those “predictions” are all embellishment by journalists, which sadly are often just believed “as is” by their readers, especially young children.

Here is what they say about climate migrants in chapter 3:

Displacement: At 2°C of warming, there is a potential for significant population displacement concentrated in the tropics. Tropical populations may have to move distances greater than 1000 km if global mean temperature rises by 2°C from 2011–2030 to the end of the century. A disproportionately rapid evacuation from the tropics could lead to a concentration of population in tropical margins and the subtropics, where population densities could increase by 300% or more page 245, 3.4.10.2 The changing structure of communities: migration, displacement and conflict from chapter 3 of the IPCC report in 2018.

This summary table shows the numbers affected at various temperature increases. We are currently headed for 3 °C, the last column,

Figure 3.4 page 246 of chapter 3 of the IPCC report in 2018.

Habitat degradation and crop yield change are particularly vulnerable to the difference from 1.5°C to 2°C.

Our achievements in just two years

The situation is undoubtedly serious. However, it is remarkable what we have achieved and are achieving, and can do in the future, especially when you look back to before the Paris Agreement in 2016. Back then admittedly things were dire. The earlier Kyoto protocol agreement based on carbon trading was a flop, leading to only modest commitments.

But then we had this truly major breakthrough.

What you need to know is that the Paris agreement only came into place in 2016. They agreed the rulebook for the first time in December 2018, an essential step before implementing it properly.

When the US decided to leave, this made only a small dent. Indeed Trump may well have galvanized the other countries into more action as well as many cities, companies, states and individuals in the US itself.

In two years, worldwide, we have already implemented policies to knock an entire degree off the temperature projected for 2100 from around 4 °C to around 3 °C.

This shows what we can do if we work together. If we keep up this momentum for the next decade, who knows what we can achieve? Might we not be able to knock another 1.5 °C off the projection for 2100 with our actions in the next twelve years? After all the whole idea of the agreement is that pledges increase year on year.

It is important to keep up the momentum. However, the IPCC made it clear in their report that 1.5 °C is scientifically possible, is affordable and is achievable. The main thing required is the political will to do it.

You so often hear that politicians are not doing anything. This also is not true. Some countries already target below 2 °C. The most populous of those is India, with a population of 1.339 billion, not far off that of China.

It is not far from achieving a 1.5 °C compatible target according to Climate Action Tracker.

Populations of India, China and the World showing how India's population is not far off that of China now. Using World Data via Google.

That is a substantial chunk of the world population that is already well on its way to 1.5 °C. Many of the smaller countries are doing even better and are already below 1.5 °C compatible. For more on this see below.

The journalists just about always hopelessly exaggerate the IPCC reports and add numerous embellishments. Even the mainstream news, such as the New York Times, have their share of exaggerations and misinformation.

A good example here is the mistake the New York Times made about carbon pricing. They confused the future mitigation costs of sea wall defences, of climate migrants, etc with the incentive tax to prevent emissions of that CO 2 , as part of an integrated program. The mitigation costs could rise to $27,000 a ton by 2100, but the aim of a carbon pricing incentive tax is to prevent us getting into this situation at all. This is estimated at various values of $5 upwards, as part of a mixed program of many measures. If this succeeds, then of course we never have to pay the mitigation costs.

They weren’t the only ones to make this mistake. The Hill also ran a story based on this claiming that the IPCC was saying that gas (petrol) would cost $240 a gallon

This is such a major misunderstanding. The passage they got the figure from is crystal clear, if you are used to reading scientific papers. It’s hard to know how the confusion arose. But this is just one of many confusions in even the mainstream press. Instead of going by what the co-chairs said, the journalists went through the report, misread a few passages, and riffed on their misunderstandings without running them past anyone.

Another major misunderstanding was the claim that the IPCC pathways required vast amounts of CO 2 sequestration using technology we don’t have yet. Far from it. The pathway to zero emissions by 2050 only has a practical amount of reafforestation as a carbon negative measure, to offset a small part of the emissions. From the technical summary:

“The overall deployment of CCS varies widely across 1.5°C pathways with no or limited overshoot, with cumulative CO2 stored through 2050 ranging from zero up to 300 gigatons CO2 (minimum–maximum range), of which zero up to 140 gigatons CO2 is stored from biomass”



For more on this see Four ways to get to 1.5 °C (below)

The NY Times title was also click bait: “Major Climate Report Describes a Strong Risk of Crisis as Early as 2040:”. That possible crisis was for coral reefs as early as 2040, not for humanity.

Also, the central message of the report was that this can be averted with policies to stay within 1.5 °C, and that this is scientifically possible, affordable and just needs the political will. That is the positive side of the report which was not highlighted in headlines, and barely mentioned in the articles either.

Try watching the videos by the co-chairs and the press conference for the IPCC report in 2018

Watch the original press conferences and compare with the New York Times report, and others in the mainstream press at the time, and you wonder if they went to the same event.

Yearly CO2 emissions continue to rise for a while on all scenarios

Climate activists and journalists often make a big deal of this, giving the impression that our climate policies can’t be working for as long as we have increasing emissions.

Yes, our yearly CO 2 emissions are still rising, but that’s not surprising. After all China and India are rapidly industrializing, and though they are transitioning to green energy as they do so, and their emissions should peak before 2030, the year on year emissiosn are not likely to come down much before this happens..

All the scenarios project a rise for at least a few more years, even the ones with 1.5 °C targets. If we keep to our current policies and unconditional pledges, this will turn this around to a phase of year on year reduced emissions within a few years.

Also, that's just the start. We should expect CO 2 levels in the atmosphere to keep increasing long after our yearly emissions start to reduce. It is only when the emissions reach zero, that our CO 2 levels and temperature stabilizes. Even with the 1.5 °C compatible paths, this doesn’t happen until the mid century.

With current policies and unconditional pledges we are headed for around 3 °C with a 2/3 chance of staying within 3.2 °C (see summary graphic). That’s just a start. We are bound to get to lower targets than that as they ramp up the pledges.

The bloggers and journalists who share graphs and say “look, we haven’t achieved anything yet” are looking at them with the wrong kind of analysis. This is not a reason to be disheartened.

What is it we have to do by 2030?

Many of the journalists reported that we have a decade to avoid disaster, and the more sensationalist accounts say that we risk human extinction, within a decade.

That’s not what the IPCC said. It was widely misreported and I think the journalists have a lot of the responsibility for the current hysteria, due to the way they mislead the public by not summarizing what they said accurately.

The report actually said that the best way to 1.5 °C is to reduce CO 2 emissions by 45% by 2030.

C.1. In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range). Summary for Policy Makers

Technical summary:

Limiting warming to 1.5°C depends on greenhouse gas (GHG) emissions over the next decades, where lower GHG emissions in 2030 lead to a higher chance of keeping peak warming to 1.5°C (high confidence). Available pathways that aim for no or limited (less than 0.1°C) overshoot of 1.5°C keep GHG emissions in 2030 to 25–30 GtCO2e yr−1 in 2030 (interquartile range). This contrasts with median estimates for current unconditional NDCs of 52–58 GtCO2e yr−1 in 2030.

...

In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range). For limiting global warming to below 2°C with at least 66% probability CO2 emissions are projected to decline by about 25% by 2030 in most pathways (10–30% interquartile range) and reach net zero around 2070 (2065–2080 interquartile range). Technical summary, page 33 of the full report.

So, we have twelve years to reduce emissions by 45%. Nothing much will happen in 2030. But unless we are already down to a 45% reduction by then, it will become increasingly harder to remain within 1.5 °C by the middle of the century.

After that we reduce to zero by 2050.

However if we don’t start those reductions until 2030, we can still stay within 1.5 °C but we have to reduce much more rapidly after that and reach 0 °C by 2045, five years earlier.

That’s for the 1.5 °C pathway. If we want to stay within 2 °C then it’s much easier. For that pathway, we need to reduce 20% by 2030 and reach net zero by 2075.

Also, reaching zero emissions by 2050 (or 2045) was only one of four ways to stay within 1.5 °C. We can also overshoot a little (not all the way to 2 °C), and then use negative emissions to get back again.

But the easiest, the first of these pathways, has no carbon sequestration. The area shown in brown is reafforestation:

Global Warming of 1.5 ºC - chapter 1, figure 1.4

Even if we don’t manage that, and the temperature briefly reaches 2 °C, it is possible to get back down to 1.5 °C if we remove CO 2 for the rest of the century to compensate.

That needs carbon sequestration shown in yellow, starting around 2050 in the other three pathways.

From the IPCC technical summary

“The overall deployment of CCS varies widely across 1.5°C pathways with no or limited overshoot, with cumulative CO2 stored through 2050 ranging from zero up to 300 GtCO2(minimum–maximum range), of which zero up to 140 GtCO2 is stored from biomass” Technical Summary

This is existing technology. The plant in Abu Dhabi pumps 800,000 tons of CO2 a year into old oil reserves, a byproduct of iron and steel production, used for enhanced oil recovery. They plan to expand to capture 2.3 million tonnes per year by 2025 and 5 million tonnes per year before 2030. The one in Petra Nova captures 1.4 million tonnes a year from a coal fired power station - so is an exact analogy of the biofuels carbon capture and storage. Both are used currently for enahnced oil recovery where the injected CO2 is used to

The Sleipner gas fields CO2 injection in Norway alone can store 600 billion tons. That alone is enough to store all the CO2 for even the fourth of their paths, so there is no problem storing it if we can pipe it to suitable reserves, which are also present in many places. For instance the UK also has billions of tons of storage potential (CO2 Storage in the UK-Industry Potential - 2010.).

The mian issue is the amoutn of land would be used to grow al those trees for the powerplants that use biomass.

This shows conceptually the idea of the two approaches. The best approach is the one to the right,

This is a good summary of some of the main points in the agreement:

See also 3.4. Four ways to get to 1.5 °C (below)

Have done so much already

And - this is hardly utopian as a vision. We have done so much already. This graph gives an idea of what we have done already. Our current policies are already well below the “no climate policies” orange region. Remember most of this has been achieved in only two years!

We have another ten years to get onto the 1.5 °C track. First we need to stop our current increase in CO 2 emissions year on year, then we need to do the 45% reduction which is the start of the easier P1 pathway. We can definitely do it. That was the conclusion of the IPCC report. It’s a matter of politics, not science, whether we do this.

Of course the US plan to withdraw. But they are not the largest emitter, China is, and they are the most important of all to reduce quickly. They are responsible for half of the extra emissions that caused emissions to rise again in 2017 after plateauing for a couple of years.

There the bars show the increases or decreases. As you can see half the increase from 2016 to 2017 is from China. Graph from here:

As we’ll see they are fulfilling their pledges under the Paris Agreement - which is not to stop increasing yet - they only committed to peak some time before 2030. But that much is really ambitious for a rapidly industrializing country and they seem on track to do it. We need more ambitious pledges from them to stay within 1.5 °C. But they have fulfilled their pledges so far.

They have a strong incentive as they are amongst the most affected.

With “business as usual” then parts of China would get so hot that farmers can’t work in their rice fields any more during heat waves, and coastal cities are vulnerable to flooding. So, they are very motivated to do something about it. Also, as major contributors to the carbon emissions they are also in a position to be able to make a big impact on climate change just by themselves. See this graph:

Graphs from: CO₂ and other Greenhouse Gas Emissions

Within the US too, then there is strong support for the Paris agreement in many sectors

The United States climate alliance accounts for 16 states, as well as the territory of Puerto Rico committed to upholding the Paris agreement within their borders. Amongst those sixteen, California if they were a separate country would be the fifth largest economy in the entire world.

Cal Facts 2002: Economy

Major cities around the world have committed to build only zero carbon buildings by 2030 and to make existing buildings zero carbon by 2050. In the US that includes New York City and San Francisco:

New York which has 60% of the California economy.

And the US may well return to the Paris agreement in the future at some point before 2030. Trump could change his mind, and the next president in 2022 or 2026 may well return to it, especially with increasingly clear symptoms of climate change and its effects in the US. That is time enough for the US government to join in reducing emissions to zero by 2050.

And remember most of this has happened in the last two years. So how much can we achieve in the next ten years?

What about David Attenborough saying we risk societal collapse?

You can watch it here: Attenborough presents Climate Change - The Facts

It may sound frightening, but the scientific evidence is that if we have not taken dramatic action within the next decade, we could face irreversible damage to the natural world and the collapse of our societies. We are running out of time but there is still hope. I believe that if we better understand the threat we face, the more likely it is that we can avoid such a catastrophic future" Attenborough climate show a 'call to arms'

This is another example of climate change slogans. Strictly speaking it is not literally true. The IPCC report did not say we have to take dramatic action in the next decade. They said that immediate action is the easiest way ahead, scientifically feasible and affordable, and that there are increasingly more dramatic measures needed if we postpone action. The IPCC report also says nothing about societal collapse, at least not large scale collapse.

David Attenborough's program focuses on local communities severely impacted by climate change such as the climate migrants impacted by flooding and those whose houses burnt down in the California fires. In that sense it is a collapse of local communities, which will become much more widespread in a warming world. That may be what he meant. On a larger scale though, we have a lot of climate change resilience. There is also much work being done on increasing that. For more on the research into climate change resilience (see below)

Dealing with some popular misconceptions right away

Before getting to more details about climate change, I’d like to debunk some of the popular misconceptions. There are many stories you may have read and believed that are just false.

Here is a YouTube video of some young women who are so scared that they feel they can't bring a child into the world, and as I said in the intro much of what scares the general public is false or junk science.

Click to watch in YouTube

I will start with one of the most widely shared, a junk sociology paper that failed peer review, that climate scientists say is just "crap" but is widely believed by the general public.

Jem Bendell's Deep adaptation

Many have been scared by Jem Bendell’s “Deep adaptation”. He is a sociologist who relies extensively on Wasdell’s never published non peer reviewed article. This in turn depends on the now disproved Clathrate Gun Hypothesis.

This is the article that is supposedly so depressing it’s driving its readers to therapy. I can well believe that this happens, from the panicked and scared PM’s I get. But the article itself is grounded in junk science. That it makes people depressed doesn’t mean it is correct.

The distinguished climate scientist Michael Mann, director of the Earth System Science Center at Pennsylvania State University had only one word in comment. Just four letters “Crap”. See the other responses to his tweet too. His tweet is here.

Sorry, Hogwash ... — Michael E. Mann (@MichaelEMann) March 6, 2019

I cover this in detail in my article:

Uninhabitable Earth

Others have been scared by this article and then book by David Wallace-Wells. He doesn’t write like a scientist. He says himself that he is a general journalist who has only been interested in climate change for one to two years.

His book is just a scrap book of the scariest stories he has found, not a systematic survey. He misunderstands things, exaggerates, and misses important nuances in the stories he covers.

The evidence that climate change is a serious problem that we must contend with now, is overwhelming on its own. There is no need to overstate the evidence, particularly when it feeds a paralyzing narrative of doom and hopelessness. I'm afraid this latest article does that. That's too bad. The journalist is clearly a talented one, and this is somewhat of a lost opportunity to objectively inform the discourse over human-caused climate change. Michael E. Mann

For more about this see my:

Aren’t humans going to go extinct in 2026 or 2030?

These are fake news stories. One of the worst of the junk blogs is:

Sam Carana and his Arctic news blog

He uses quadratic equations, and other polynomials to project! An utterly bizarre idea to a mathematician.

This image may be enough for you to see how ridiculous his posts are. In the blue inset I have extrapolated his quadratic (or one very close to it) both ways so you can see how it will always predict an increase to infinity in the future and decrease from infinity from the past (unless it’s the other way around, increase from absolute zero and decrease to absolute zero) - it is a RIDICULOUS way to extrapolate.:

Another one here

From: How long do we have?

To back up his nonsense he does stuff like this,

There is no basis for it - it's all make believe. In his diagram on that page he says that between 2025 and 2026 there will be a sudden 8°C increase in temperature due to "cloud feedback". That's not based on any science. Just that he needed some gobbledygook to put in his graph to add a sudden 8 C because that's what his polynomial does.

Presumably it's meant to be about the cloudless skies study, which is based on CO2 levels of 1400 to 2200 ppm, a level we can't reach until the 22nd century even with business as usual. It is not even remotely relevant to the conditions we are in right now in (see below).

If we instantly stopped anthropogenic emissions then it would lead perhaps to a bump by 0.15 C for 20 years.(see below), The "methane bomb" is disproved (see below), and the Siberian Permafrost effect is minute for this century on the path we are on (see below)

This blog sadly impresses readers because the credentials of the “contributors” on his deceptive About page seem impressive

It goes on and on, 33 contributors, professors and emeritus professors.

However, click through to the linked names on his About page, and you realize he will credit as a “contributor” any of the people talking in embedded YouTube videos in any of his blog posts. He surely hasn’t asked permission of any of them and there would be no reason for them to even know that the video is on his blog. He just includes this material under the YouTube license for embedding content. Others are included because he quotes a short paragraph from them, or includes an article they released under a creative commons license.

Sadly many people do believe his blog, at least partly because they believe the About page and think he must have something going for him to attract posts from so many distinguished professors. Just nonsense!

The other junk scientist who scares many people is

Guy McPherson, a retired professor of ecology who has lost contact with the scientific method.

You can tell how far he has gone in the direction of junk science when you discover he uses Sam Carana’s blog with its daft polynomial projections as a source for his own predictions!

Guy McPherson keeps saying the average temperature of Earth is going to increase rapidly by several degrees in a few months. None of it ever happens because it is based on junk science like this.

See my Absurd blog post at Arctic News predicting a ridiculous 10 °C rise in global temperatures by 2026 - using a POLYNOMIAL to EXTRAPOLATE!!!

You are not at risk of extinction in any of the climate scenarios. The worst that happens is that the world gets so hot perhaps you start to grow coconuts in the Mediterranean and oranges in the UK. Not that you have coconuts growing in Canada or that humans can’t survive at all.

Didn’t a 1972 computer model say we would soon be extinct, by 2040? (Limits to Growth)

This is a computer program that simulated the world as five numbers for everything. In 1972 it needed a computer that filled a room. Today it would run in a fraction of a second on your mobile phone.

It is just a coincidence. It predicted the number of children would stop going up because we could no longer find the resources needed to bring up children any more by now. But it's the opposite.

The number of children is almost the same as it was a decade ago, that’s true.

However, it is because we have food and other resources for our children, and have good medicine to prevent children dying and as a result people are having fewer children worldwide. It is in a background of greatly increasing life expectancy. Ten to 20 years in the last 50 years.

See

Here is a graph from that page:

The countries with decreasing populations are places like Japan which have a the highest standards of living.

Japan Population | 1950-2018 | Data | Chart | Calendar | Forecast | News

All this is the opposite of what their model predicted, fewer children because of poverty and not being able to bring them up, and a situation of scarcity and hardship, and short lives.

It is just a coincidence.

We should use the UN population division and other modern well tested and thoroughly researched projections and modern computers and programs not this ancient 1972 program that uses only 5 numbers to represent the entire world!

My article about it is here:

Debunked: No we are not on track for end of world by 1972 computer model

This is another similar one

From appendix D they have a parameter W for wellbeing and they assume that as the well being of a population increases the population growth rate increases, becoming superexponential. That would seem sensible from studies of animal populations. But humans don’t do this.

As our well being increases our population has leveled out. The opposite of what their model suggests. We have already almost reached peak child, we are living a lot longer, and our birth rate has gone right down, to less than replacement in some of the wealthiest countries such as Japan which already has a declining population.

The only major region of our world which still has a high birthrate is the least prosperous, Africa. As it becomes more prosperous with better health care, higher education particularly of women and reduce child mortality its birthrate is expected to fall down to around 2 children per family, as parents become more confident that their children can survive to adulthood and be healthy.The population is expected to level off also. Our final world population depends a lot on how rapidly Africa develops towards these conditions of higher education, reduced child mortality, better health etc.

When will the world reach 'peak child'?

A sociology author has used this simple model, which doesn’t match what is happening to us, to predict that society would collapse. On the science, he says to find out more to read David Waltham's book, which is awful. My debunk of it is here

Quoting from his article:

"The continued growth for much of this period, as well as the very slowly decline in the latter part, is mostly due to the increasing birth rate. Only after a few decades, when the world is approaching global societal collapse, does the death rate overtake the increasing birth rate. … In the present situation, famines tend to be very local problems as much of the planet can import food in case local production is insufficient, but this won’t be the case in a world in which food shortages are no longer local but worldwide (and in which global trade is breaking down)." On the Fragility of Civilization

But the fundamental premise there is flawed, there isn’t an increasing birthrate. It is decreasing rapidly worldwide.

What about Adam Frank's model predicting our civilization will end in one of three horrible ways?

This is a first paper in what they hope to be a long term study. It’s an interesting project, but it should not be used to predict what will happen to Earth in the future.

Their research is at far too early a stage to be relevant to any of that. It makes many simplifying assumptions that do not apply to Earth as it is now. But their aim wasn't to predict what would happen to Earth. It was to try to get a general picture of what can happen to all possible exoplanet civilizations. A huge project that they are just making a start on.

First, let's look at some of its simplifying assumptions - none of which apply to our Earth (no surprise)

One of its assumptions is that populations grow to carrying capacity (via the Logistic equation) - as we've seen the population is going to level off due to prosperity instead. Having plenty of resources is leading to a reduction rather than an increase of population, paradoxically. We reached close to peak child a decade or so ago and the population is now growing mainly because people are living longer with each year.



- as we've seen the population is going to level off due to prosperity instead. Having plenty of resources is leading to a reduction rather than an increase of population, paradoxically. We reached close to peak child a decade or so ago and the population is now growing mainly because people are living longer with each year. They do however assume that renewables can sustain the same population as the non green power supply (e.g. fossil fuels) . That does apply to Earth, However, arguably long term the potential power supply from renewables is vaster than from fossil fuels. A small fraction of the Sahara desert can provide enough solar power to power the entire world at its current levels. Some people object to this idea based on energy return on energy invested (EROEI), well, solar power has proved to be superb as have some other renewables.



. That does apply to Earth, However, arguably long term the potential power supply from renewables is vaster than from fossil fuels. A small fraction of the Sahara desert can provide enough solar power to power the entire world at its current levels. Some people object to this idea based on energy return on energy invested (EROEI), well, solar power has proved to be superb as have some other renewables. It also assumes that the non renewable power source can make the planet uninhabitable in a runaway effect through a "heating term" . Perhaps this is inspired by James Hansen's "Venus hothouse" idea? If so it is disproved (see below).. No amount of degradation of Earth’s environment would make Earth uninhabitable for humans. Indeed, it is becoming more habitable if anything, as we’ll see, it’s the transition that’s the problem. But



I in their model they assume infinite reserves of the non renewable environment damaging resource (this might seem strange but it is a common simplification if you don't want to have to deal with the complexities of a finite item of fixed size - just assume it is infinite and leave the complication of a finite resource to a later study). Of course if there were infinite reserves of oil or coal, eventually as you burn enough then you would get a runaway greenhouse for sure. If extra terrestrials have more fossil fuel than us or a more sensitive environment, it might apply to them.

So, what is actually going to happen to Earth?

As we are now, we are on target to feed everyone by 2100 using conventional agriculture, with the population predicted to level off at 11 billion according to the UN population division. There are challenges but it is well within our capability. With higher standards of living, and better medical care, most families are content to have two children. Once you take account of the childless and single, that leads to populations that drop below replacement through social changes, in a situation of resource abundance rather than resource scarcity. Japan already have a rapidly declining population.



We can feed everyone too, according to experts, so long as we continue with the measures we are doing already such as starting a new green revolution in Africa that got missed out in the 50s through to 70s. It's not going to happen automatically, but we can do it, with food security, and we can do it while ramping up power levels too and bringing everyone up to the quality of life we enjoy in the more developed countries. This is not pie in the sky, it is the view of leading scientists and hard nosed politicians, as we'll see as I get into the details.



according to the UN population division. There are challenges but it is well within our capability. With higher standards of living, and better medical care, most families are content to have two children. Once you take account of the childless and single, that leads to populations that drop below replacement through social changes, in a situation of resource abundance rather than resource scarcity. Japan already have a rapidly declining population. We can feed everyone too, according to experts, so long as we continue with the measures we are doing already such as starting a new green revolution in Africa that got missed out in the 50s through to 70s. It's not going to happen automatically, but we can do it, with food security, and we can do it while ramping up power levels too and bringing everyone up to the quality of life we enjoy in the more developed countries. This is not pie in the sky, it is the view of leading scientists and hard nosed politicians, as we'll see as I get into the details. We can ramp up power as well, while keeping everything headed towards a carbon neutral eventual future. That is not “pie in the sky”. It is feasible, it's what the Paris Agreement is all about, and hard nosed politicians have signed up for it in every country worldwide except the US, which also was signed up for it before the current president withdrew. Actually technically the US is still in it to the end of his current term. So, yes, we can have a decent standard of living for everyone too.

What could happen even longer term?

The carrying capacity of Earth is rather “soft” - using the technology proposed for space habitats, we could have the equivalent of the population of four new planets from floating sea cities covering just 0.5% of the Pacific , growing all their food and getting all their water just using sea water and the air and not exploiting anything else. We could do that for far less technology per person than a space colony.



, growing all their food and getting all their water just using sea water and the air and not exploiting anything else. We could do that for far less technology per person than a space colony. We also have the possibility of vast amounts of power in the future, either from nuclear fusion (if we manage to develop it by then, and it is easy to use) or space based solar power (which Japan is exploring) - or maybe some other power source (including possibly ideas we haven't thought of yet). It could increase by orders of magnitude.

They never claimed any direct relevance to Earth and expect future studies to be more detailed, exploring the range of futures for extra terrestrial civilizations. As they do so, perhaps they may find trajectories resembling the one we ourselves are on, but at present it is just too simple a model to apply to Earth.

For more on this see my

What about cascades of tipping points leading to a 'Hothouse Earth'?

The article is mainly about things that could happen centuries to thousands of years into the future. It doesn't really conflict with the IPCC who have already concluded that these tipping points may have significant but probably minor effects before 2100 - because it is a meta study and it is just looking at ideas for future research. There are no dates in it, and there is no new fundamental research.

The press release didn’t give timescales, and many of the news stories just riffed off the press release, and the authors don’t read the paper itself. When you read the paper, they still don’t give timescales, but it becomes clear that for most of this, they are talking about things that could happen over centuries to millennia.

They are not conflicting with the IPCC, which does climate projections mainly through to 2100. It is more that they are looking at a much longer future timescale.

Also, they don’t have any proof, and no new data or research, it’s more like a “meta study”, a result of looking at many other papers and then drawing up a hypothesis for other scientists to study. As they say in their conclusion:

Our initial analysis here needs to be underpinned by more in-depth, quantitative Earth System analysis and modeling studies to address three critical questions. (i) Is humanity at risk for pushing the system across a planetary threshold and irreversibly down a Hothouse Earth pathway? (ii) What other pathways might be possible in the complex stability landscape of the Earth System, and what risks might they entail? (iii) What planetary stewardship strategies are required to maintain the Earth System in a manageable Stabilized Earth state?

Indeed there is not a single future date in the article. It is all qualitative. The diagrams in it are just sketches with an arrow indicating time - but no markers along the time axis of centuries or millennia. It isn’t really adding anything new over the previous studies. It is more of a meta study.

This is one of their diagrams:

They are saying there are things we can do in the next couple of decades that can get the Earth into a good state, one in which it will neither get too hot nor too cold for hundreds of thousands of years.

They call this “Earth System Stewardship”. We are currently in that "Stabilized Earth" region of the chart.

If we stay well within 2 C, which is the ideal target of the Paris agreement, to stay within 1.5 C, then we are good for hundreds of thousands of years into the future, to have a stable temperature without the huge fluctuations of the ice ages.

However they say we are at a kind of decision point where the things we do for the next several decades could tip us into the “Hothouse Earth” cycle. That then could lead to Earth getting a lot hotter centuries to more like thousands of years into the future. Other scientists are skeptical of this report. It is not proved and there are no actual future dates in the article. It is all qualitative about things that might happen, mostly centuries to millennia into the future.

It has good news however. If we do manage to avoid the higher “business as usual”, which we are already doing, we have also avoided the next ice age too, and we are headed for the optimal “stabilized Earth”.

So, this is good news for future generations. So long as we manage to avoid excessive temperature rises, we can avoid the hothouse Earth and even thousands of years into the future our climate will be stable.

See my

Also see later in this page, Next ice age - postponed.

Aren’t we all going to run out of oxygen to breathe in a warmer world?

No not true at all.

There is plenty of oxygen in the atmosphere for many thousands of years and so there is nothing to worry about of that nature.

It’s not only us that will be fine. There is enough oxygen there for all the animals in the world to breathe for the foreseeable future even if, impossibly, photosynthesis ceased completely world wide. This is also taking account of all the natural processes that remove it. We are fine for oxygen for thousands of years no matter what happens.

Are we headed for a world without insects?

Are we headed for a world without insects?

This featured as main story on the TV with a claim that we risked all insects vanishing in 40 years.

But this is not true at all. It is a case of low quality research with a dramatic and scary conclusion being promoted through the roof by the press, and high quality research with the opposite conclusion quietly ignored or not even noticed.

This research was immediately criticized by ecologists. It was a not a systematic survey for one. The researchers just did a search for articles with “declin*” in the title, so of course they mainly found articles about declining populations.

They also found very few studies outside of Europe and the US. For the whole of China and for Australia the only articles they found were about honey bees, a domesticated insect. This is like including reports of declining numbers of sheep in an article on declining numbers of mammals. Most of their world map was a complete blank.

Those purple bars in Australia and China are for the domestic honeybee

There were some points in it of interest to academic readers who knew how to evaluate its limitations, but it should never have got so much publicity.

A week or so later the UN biodiversity in agriculture report came out. Their section on insects was systematic and thorough, based on sent in reports by experts in many countries reporting to the UN found a mixed picture. Some stable, some with mixed trends. Some countries reported increases of pollinators, such as Nepal, and also parts of Europe due to a policy encouraging flower rich field margins.

They reported that the German study, which found decreased insect numbers in nature reserves had lead to a new organization to do something about it. It is probably due to insecticides and agricultural practices reducing field margins, so there is much one can do.

The only habitats they identified with a significant decreasing trend in insects worldwide were for pastures grazed by livestock.

We can pollinate the few crops that need pollination using domesticated insects such as honey bees and the tropical “stingless bees”. But wild insects add to the diversity and increase crop yields. They reported on many projects to help improve pollinator diversity.

More on this later (see below).

Do we risk a runaway to a Venus hothouse?

Don’t we risk making the world as uninhabitable as Venus, by triggering a runaway greenhouse effect by burning all the fossil fuels?

This is not true. It was a theory due to James Hansen, who though he is a climate scientist, has a reputation of exaggerated statements about climate change. He published this idea, without any calculations to back it up, in a popular book with no peer review. He did not cite any published work on the subject in is book. Stephen Hawking also believed this and promoted it in an interview with the BBC.

It was soon disproved, as soon as the theorists set to work to run the calculations carefully. To do that we would have to burn ten times the total reserves of oil, gas and coal in the world.

More on this later (see below).

What about the methane bomb / clathrate gun?

Others will tell you that the methane below the ocean floor in the Arctic will cause a rapid temperature increase of several degrees. There were scientists skeptical of this from the beginning and it is now effectively disproved.

The methane has been leaking for millions of years, since before there was ice in the Arctic. The warming temperatures only affect the top 1.6 meters which are indeed very slowly destabilizing, in summer months only, and they are not able to contribute significantly to global warming.

More on this later (see below).

Melting of polar ice

Others say that when we have an ice free summer in the Arctic, this will lead to rapid melting of all the ice at the poles. No that is not true. The sun is always low near the horizon in the Arctic region and it is dark for half the year, sun never rises at all.

The extra albedo from ice melting there has a feedback effect locally, leading to more ice melt in summer than otherwise, but not globally. Also this is sea ice, floating on the sea, and it melting makes no difference to sea levels worldwide. This is taken account of in the models used by climate change and is a minor effect. There was a mistaken report said that depending on the scenario the Arctic has 5 to 9 C locked in if we meet the Paris agreement 1.5 C. It should have said 0.5 to 9 C. Was a typo. Factcheck: Is 3-5C of Arctic warming now ‘locked in’?

In Permian times the poles were ice free. Yes. But the Earth looked very different with no land locked Arctic ocean and no Antarctica at the south pole either. Earth at the time of the Permian / Triassic extinction

Ice ages like we have now normally happen when there are land masses or enclosed oceans at the poles. So you wouldn't expect it to have ice at the pole anyway even if it was as cold as us, it probably would have ice free polar regions, not just have an ice cap floating in open ocean with no land anywhere near - and it was also a lot warmer for other reasons, not fully understood yet. So it's just not valid to infer that because the poles were ice free in the Permian they will be for us. Antarctica doesn't melt totally for many tens of thousands of years under any scenario. Greenland could become ice free under "Business as usual" after a thousand years but for any other scenario

Siberian and Canadian permafrost

Nor can the Siberian permafrost melting do this. If the temperature goes up a bit, they start destabilizing and add to the CO 2 long term. But they can't warm up the climate enough to significantly increase their own effects. I

It's a result of something else, us warming the climate, then a bit extra added. Not a runaway. And it can go both ways on the 3 °C pathway we are on now. It could be a carbon sink through peat and vegetation growing. We can also encourage vegetation to help make it more carbon negative by irrigation. On our present pathway, the range of CO 2 emissions is enough for something between a temperature rise by a small fraction of a degree by 2200 and a temperature drop by the same amount, most of it after 2100 (both less than a tenth of a degree total).

More on this later (see below).

No known runaway effects

The sensationalist press make a lot of this, that there are some effects that are not included in the models such as the Arctic permafrost. What they ignore is the reasoning that gives justification for leaving them out.

In a systematic review by the Royal Society they concluded that there are no known runaway effects. Nothing that acts like a gun or bomb. Yes, if we warm the climate and that can lead to some additional warming over long timescales. But nothing that exhibits “threshold behaviour”.

I go into all of these in more detail with cites in the section DELAYED EFFECTS (below)

The IPCC say that whenever we stop CO 2 emissions, if we ramp down all the way to carbon neutral, then whatever temperatures we reached by the, those are the temperatures we are at from then on apart from a fraction of a degree (perhaps 0.15 C)

This said, in the summary for policy makers, that anthropogenic emissions so far have contributed 0.8 to 1.2° C since pre-industrial and that the emissions so far have will have effects that last for centuries to millennia, such as sea level rise and associated impacts, but these are unlikely to cause even a long term global warming of 1.5°C (medium confidence) and that with high confidence this is not possible over the next few decades. This is the figure they use to illustrate it: Even the purple path with no reduction in non CO2 radiation forcing (such as methane emissions and soot) doesn't have any increases or tipping points.

A.2. Warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia and will continue to cause further long-term changes in the climate system, such as sea level rise, with associated impacts (high confidence), but these emissions alone are unlikely to cause global warming of 1.5°C (medium confidence). (Figure SPM.1) {1.2, 3.3, Figure 1.5} A.2.1. Anthropogenic emissions (including greenhouse gases, aerosols and their precursors) up to the present are unlikely to cause further warming of more than 0.5°C over the next two to three decades (high confidence) or on a century time scale (medium confidence). {1.2.4, Figure 1.5}

There may be some temperature rise “baked in” as a result of the masking effect of SO2 aerosols from coal burning and the like, which cool the planet down slightly, but if so, it’s only a fraction of a degree, around 0.15 °C and if we stop the CO 2 , and remove the black soot (which has a warming effect) at the same time as we reduce the SO2, we can prevent even that.

From: power point presentation by Professor Myles Allen. Based on Global Warming of 1.5 ºC - chapter 1, figure 1.5 If we stop all aerosol emissions, yellow line, there is a short term bump in temperature by 0.15 degrees, and returning to the previous temperatures in 20 years and ending with a reduction to 0.2 °C below the present by 2100

Temperatures go down slowly as soon as we reach carbon neutral, depending how you define carbon neutral.

If you define carbon neutral as continuing to produce enough CO 2 to exactly match the natural negative emissions from all CO 2 sinks including the sea, then temperatures stay more or less level, rising slightly, the blue line. If it means a net zero anthropogenic emissions they go down because the excess CO 2 in the atmosphere is gradually removed over time by natural processes, with the yellow and purple lines.

Current policies - a little over 3 °C

According to Climate Action Tracker our current policies keep us within 3.3 °C, while the unconditional pledges and targets keep us within 3. 0 °C with a 66% or greater chance of remaining within 3.2 °C. This is their summary graphic

.

“In the absence of policies global warming is expected, to reach 4.1 °C – 4.8 °C above pre-industrial by the end of the century. ... Current policies presently in place around the world are projected to … result in about 3.3°C warming above pre-industrial levels. The unconditional pledges and targets that governments have made, including NDCs 2 as of December 2018, would limit warming to about 3.0°C above pre-industrial levels, or in probabilistic terms, likely (66% or greater chance) limit warming below 3.2°C.” Temperatures | Climate Action Tracker

They keep track of most of the pledges including all the largest emitters, and how well they are achieving, frequently updated, probably the best source on this. They conclude:

"If all governments achieved their Paris Agreement commitments the world will likely warm 3.0°C—twice the 1.5°C limit they agreed in Paris."

Their methodology is described here

As soon as we stop emissions - that's it as far as temperature increases go. But the temperature reached, whatever it is, persists for centuries. From: the IPCC here

Yes, there are some lingering minor effects such as the Siberian permafrost or removal of masking effect of anthropogenic emissions. The climate doomsdayers make a lot of those minor effects and claim they are major but there is no basis for that as we’ll see.

The IPCC report is not rewritten by governments

This is something that is often said to discredit the IPCC. But it is not true at all.

It arises from a confusion over the review process for the summary for policy makers. This is indeed scrutinized line by line by the governments worldwide as a final stage, but only to ensure that the report has been summarized accurately for the general public. They do not rewrite the report itself. This is done at the end after the report has been finished by the scientists,

There are three stages, first the experts review the entire report, then experts together with the governments, and the final stage focuses only on the Overview chapter.

The governments are involved to make sure that the overview chapter is

"is accurate, well balanced and presents the findings of the underlying report clearly."

It is most helpful for non scientists anyway and won’t make much difference to those interested in the background science who will probably focus on the main report. It does also give you an index into the rest of the report helping you to find relevant material - they give the chapter headings and sections in the overview so you can then go to the sections written by the scientists in the original report to check what it is they are summarizing.

For the scientifically literate reader anyway, it is often more helpful to start with the technical summary rather than the summary for policy makers. This is written by scientists for scientists.

The IPCC do not do any research themselves. Rather they are a review body that looks over the climate change literature of the last several years , and scrutinize it carefully, assessing things not just by the number of studies but their scientific merit and the amount of certainty in their conclusions. They are widely respected by the climate scientists.

Yes we can stay within 1.5 °C

In the 2018 report the IPCC said in their review that we can stay within 1.5 °C if we act right away. They were clear about this in both the report itself and the speeches made by the co-chairs in the extended press conference. We need to increase the pledges for the Paris agreement considerably by 2030, but we can do it. There is a mechanism in place to increase pledges every year, so this is certainly possible, if there is the political will.

The graph that came with the report shows this 1.5 °C pathway. It reaches 1.5 °C at 2040 and then levels off. Graph here.

Note that it doesn’t mean we have to stay within 1.5°C every year. Here is a more detailed version from the summary for policy makers, showing some of the possible pathways:

The observed monthly global mean surface temperature has already gone over 1.5°C. This is not the same as reaching 1.5°C in the sense of the IPCC report.

The background here is that they had many different ideas about how to calibrate their reports and predictions of possible effects of future warming.

In the end they decided on the global average surface temperature. But not on a monthly basis or even yearly, as it varies too much.

Nor the surface temperature change over a particular region - it is much more in the Arctic, and in Antarctica the world is actually cooling in a few places.

Nor the global average surface temperature over land. The average surface temperature over land varies a lot more than it does over the sea.

In the end they settled on the multiyear global average surface temperature. All their predictions are now calibrated to a running average of the global surface temperature over thirty years.

From: final version of summary for policy makers for the 2018 report

They chose thirty years because of multi-decadal oscillations in the Atlantic and the Pacific. These move heat from the atmosphere into the ocean where it can stay for up to several decades before it returns to the surface, warms the atmosphere and increases the global average surface temperature. On a shorter timescale we also have the La Nina / El Nino changes. The warmest years normally happen during El Nino years..

This was all hugely misrepresented in the press, even in the mainstream press.

CO 2 pricing misunderstanding in the New York Times

I’ve already touched on the New York Times report which said that we need carbon pricing at $27,000 per ton by 2100, confusing mitigation costs with incentive pricing.

This is what they said:

For instance, the report says that heavy taxes or prices on carbon dioxide emissions — perhaps as high as $27,000 per ton by 2100 — would be required. Major Climate Report Describes a Strong Risk of Crisis as Early as 2040:

This has been taken up by many other media outlets and blogs in support of climate catastrophism and the idea that it is hopeless, or that the measures are politically impossible to implement.

However this is completely mistaken. The section they got that number from says in its intro

The price of carbon assessed here is fundamentally different from the concepts of optimal carbon price in a cost–benefit analysis, or the social cost of carbon 2.5.2.1 Price of carbon emissions from Global Warming of 1.5 ºC, chapter 2, page 152

In the rest of the intro, they explain that what they are referring to here is the cost of mitigating the effects of that extra ton of CO 2 .

To unpack this a bit more, then, for instance, if our CO 2 emissions lead to a sea level rise, that $27,000 would include a contribution to the cost of all the sea barriers to contain the rising sea through to 2100. It is a completely different idea from the pricing you need to use as an incentive to stop emitting the CO 2 , which is only one of many measures you might use in a combined program. Some countries use carbon pricing, others don’t.

Later in that very same section from the IPCC that the NY times misquoted, they talk about an incentive price, and they make various suggestions, mostly in the range of $5 to $50 or so depending on whether it is used on its own or as part of a larger program of measures. Taking the US electrical sector as an example they say

Furthermore, a mix of stringent energy efficiency policies (e.g., minimum performance standards, building codes) combined with a carbon tax (rising from $10 per ton in 2020 to $27 per ton in 2040) is more cost-effective than a carbon tax alone (from $20 to $53 per ton) to generate a 1.5°C pathway for the U.S. electric sector. Likewise, a policy mix encompassing a moderate carbon price ($7 per ton in 2015) combined with a ban on new coal-based power plants and dedicated policies addressing renewable electricity generation capacity and electric vehicles reduces efficiency losses compared with an optimal carbon pricing in 2030. 2.5.2.1 Price of carbon emissions from Global Warming of 1.5 ºC, chapter 2, page 153 (to make it more readable, I removed cites and rewrote USD2010 to $ and tCO 2 t−¹ to “per ton”)

The NY Times journalist just cherry picked one paragraph with that high number in it, without understanding its context at all. Yet this has been taken up by so many other blogs and articles.

Search Google and this is the top result, a search snippet highlighted by Google’s algorithm:

The Hill reports it the same way as the NYTimes:

The IPCC claims in its latest report that action must be taken to avert global warming of 1.5 degrees Celsius by the end of the century — a benchmark it says comes with costly climate consequences. Its recommendation: a carbon tax of as much as $200 per ton of carbon dioxide emissions by 2030 to an astonishing $27,000 per ton by 2100. For America families, this could mean the price of gasoline soaring to $240 per gallon. Remember when we thought $4 per gallon was high? Gas at $240 per gallon? IPCC report lays out high cost of carbon taxes

And a Google search turns up many more articles and blog posts saying the same thing

This is all completely mistaken, as you can see from the quotes from the IPCC report itself that I just gave.

Four ways to get to 1.5 °C

What they actually said is that if we cut CO 2 emissions rapidly in the next 12 years then we can achieve a 1.5 °C rise easily. If we don't do that, it is hard to avoid 2 °C by 2050 to 2060 though we can still get back to 1.5 °C by burning lots of biofuel and capturing the CO 2 from burning it for the rest of the century and other forms of carbon capture and storage. They looked at four different ways of staying within 1.5 °C.

The best is to cut emissions quickly especially since coral reefs are nearly extinct after just two years at 2 °C and delayed reductions mean a few years at 2 °C.

These are the four main pathways the cover in the report, in their investigation of ways to remain within 1.5 °C. (That’s the goal of the Paris agreement and they were tasked with both finding out what was needed to remain within this, and what the difference is between effects at 1.5 °C and 2 °C)

The first one is the one that we are aiming for at present, with no overshoot. Notice that they expect CO2 emissions to increase slightly through to 2020 with existing pledges and then with the 2020 round of pledges we need to increase our pledges storngly. It could alternatively happen in stages with some reduction in 2020 and more in 2025, and the more we delay this, the stronger the pledges have to be later on to reach carbon zero by 2050.

AFOLU: agriculture, forestry and other land us

BECCS: Bio energy carbon capture and storage (burning biofuels in power stations and then capturing the exhausts from the flues and storing it - or alternatively making it into something useful like cement

Despite what the press often say, BECCS is already proven at a commercial scale, the two components, burning biofuels and capturing CO2 from flues are both in use at commercial scale and it’s a case of combining them together. It’s not removing carbon dioxide directly from the air with technologies that barely exist.

We can do BECCS to burn biowastes which are currently generated far from where the crops grow and then just decompose and produce methane - we can burn it in power stations, and capture the CO2. A small amount of BECCS would probably be part of the solution even on the P1 path, but it’s not needed, on that path we can do it all via land use changes, soil improvement, reversing desertification and planting lots of trees through reforestation.

The P1 pathway assumes rapid reduction by 45% by 2030 and then a reduction to to 0% emissions by 2050.

C.1. In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range). Summary for Policy Makers

It never requires a negative emissions in total, but some of the CO 2 is offset by negative emissions through afforestation shown in brown in the diagram. Which is already going on, China particularly is doing a lot of afforestation.

(The yellow in these diagrams is active removal by continually recycling the trees in forests by burning biofuels and capturing the CO 2 )

I shared this graph before, but let’s look at it again, which shows conceptually the idea of the two approaches. The P1 path is like the one on the right, and the other ones have increasing amounts of temporary excess like the one on the left:

The other main alternative they discussed involves reaching 2 °C at around 2050-2060 but then for the rest of the century we use carbon capture and storage.

However they were widely misrepresented in the press with a claim that they required as yet unproven expensive methods for taking carbon directly from the atmosphere. This is not what they said.

Instead they said we could do it by growing vast forests for fuel and then burning that fuel in plants that capture the CO 2 emissions from the fuel burning. This works because the trees as they grow take CO 2 from the atmosphere and as they are burnt the CO 2 is then captured and the next generation of trees repeats the process.

It would be a huge challenge to do that, but it is known technology. The main thing would be scaling up the carbon capture and storage for the emissions from the wood burning power stations. But that’s far easier than taking it out of the atmosphere with several plants already doing this.

The main disadvantages of this second approach, apart from the expense and complexity, is that it means that the corals are nearly extinct at 2 °C and it just takes a couple of years at that temperature to kill most of them to the extent that recovery is difficult.

The other two ways they discuss in the report are a mix of some early reductions and some reafforestation and biofuels with later carbon capture and storage, with more capture needed if the early reductions are less.

They didn't find any other ecosystems that are as sensitive as the corals. Not even the mangrove swamps which was one of the other ones they looked at for climate sensitivity.

The 2018 report was actually a little more optimistic than expected, if anything. They raised the CO 2 emissions level needed to stay within 1.5 °C due to re-examining of past data. See

Thick layers of ice take a very long time to melt - centuries to millennia

When our emissions reach a net zero (no more added than is removed) then the temperature increases stop and then start to go down as the CO 2 levels reduce. However the world does continue to change and there is a lot of lag there, mainly because of the ice, and the ocean.

The permafrost would continue to melt as would the ice in Western Antarctica and Greenland. That’s a slow process because ice has huge thermal inertia.

Icebergs can spend months, and longer, in warm water before they melt. There are lakes in New Zealand that often gets icebergs from glaciers and once there they continue for ages. Bizarrely you get ice bergs in warm water in summer.

Click to watch in YouTube

Those are icebergs in the full sunlight of a New Zealand summer day. So think how slowly ice must melt in the far colder conditions at the poles.

The poles will still experience the six month polar winter every year and only glancing sunlight even in the Arctic or Antarctic summer. So, yes, the ice in Greenland and Antarctica will melt eventually, until it reaches whatever level of cover is in equilibrium with the climate. But this is an immensely long process.

The Greenland and Antarctic ice will persist for a long time in a warmer world for much longer than the year or two of those New Zealand icebergs. Indeed both will be covered in kilometers thick layers of ice for tens of thousands of years in any of the future scenarios. It just takes that long to melt so much ice in a slightly warmer world.

The sea level continues to rise partly from this ice melting, and partly also from the sea warming up. The sea has a huge thermal capacity and will gradually take up heat from the atmosphere but that’s another thousands of years process. The warmer sea expands. For the smaller sea level rises about half the sea level rise is from the sea expanding rather than ice melting.

All that would continue, if we stopped emissions right away, but at a lesser rate than if we were going to a warmer world. About 15- 40% of the emitted carbon remains in the atmosphere for 1000 years.

However none of this changes the situation that the world slowly starts to cool as soon as emissions stop in the 1.5 °C scenario, on most scenarios that end up with zero emissions. Even as the ice melts, the world is cooling down, as CO 2 gradually comes out of the atmosphere dissolved in the sea, taken up in peat bogs, swamps and salt marshes, in the soil as it builds up, and so on.

Removing CO 2 through re-afforestation

We can also remove CO 2 from the atmosphere more rapidly, by burning wood and then using carbon capture on the CO 2 produced - every time you do that it takes some CO 2 from the atmosphere.

We can also remove CO 2 by re-afforestation, and reversing desertification. Improving the soil also takes CO 2 out of the atmosphere, as does making forests more species rich.

If eventually for instance we regreen the Sahara desert back to the way it was 5000 BC when it was pastureland rather than desert - that would take large amounts of CO 2 from the atmosphere.

The Sahara dust fertilizes the Amazon. Massive amounts of Saharan dust fertilize the Amazon rainforest But 11000 to 5000 BC then the Sahara was green.

Green Sahara: African Humid Periods Paced by Earth's Orbital Changes

So the Amazon jungle can manage fine without the Sahara dust or less of it.

We are already doing afforestation as part of the measures to deal with climate change.

China planted nearly 79 million hectares by 2015. Under the Bonn Challenge, 56 countries, from central and south America mainly, are pledged to restore 350 million hectares of forest by 2030. All four of the IPCC's scenarios for remaining within 1.5 °C involved some measure of afforestation.

In a recent study reported in Scientific American, researchers who planted a mix of trees rather than a single species found that they removed 32 tons per hectare instead of the more usual 12 tons.

Reverting non forest land to forests globally could offset around 253 billion tons of CO 2 between 2018 and 2100, which is equivalent to seven years of global CO 2 emissions at current levels.

Carbon brief have a map of where reafforestation is happening around the world and with a summary of the research, and the opportunities and challenges here.

Mapped: Where ‘afforestation’ is taking place around the world

Effect of CO 2 on plant growth

Trees and plants grow faster in a world with more CO 2 due to the CO 2 fertilization effect

Trees increase in productivity by around 23 percent over pre-industrial and crops boosted by 11.5 percent for most, like wheat and rice but some like corn which use a more efficient form of photosynthesis can’t benefit so much from the extra CO 2 because they are so efficient at fixating CO 2 already and are only boosted by 8.4 percent.

A downside is that food crops can lose a significant amount of zinc and iron in a warming world and grains also lose protein.

Ask the Experts: Does Rising CO 2 Benefit Plants?

There’s a likely increase of productivity of trees by 23 to 28% until 2050. But the responses are more pronounced in young trees.

Also a study of European trees in 2018 found that though the volume increased by 29 to 100% (up to a doubling of the volume added) the density decreased by 8 to 12 percent.

So they produce much more wood, but it tends to be lighter, offsetting some of the gains.

Trees and climate change: Faster growth, lighter wood

Grasses also increase in productivity with more CO 2 , but it depends on the species. One study for instance found that the optimal levels of CO 2 for grass depend on the species

“We found that the optimal CO 2 concentrations occurred at 945, 915, and 1151 ppm for the aboveground biomass of tall fescue, perennial ryegrass, and Kentucky bluegrass, respectively.

The optimal CO 2 concentrations for the growth of three perennial grass species

Overview of some of the research through to 2012 here:

The effect can also be seen from orbit with satellite measurements. Leaf area is increasing.

This greening is a combination of new leaves on existing plants as well as an increase in the amount of land covered by plants and shrubs. Only a few areas, less than 4%, show a browning effect. Many areas have an increase of more than 50%.

Rising CO 2 has 'greened' world's plants and trees | Carbon Brief

The researchers estimated that 70% of the extra growth is due to rising CO 2 in the atmosphere.

Another 8% is due to climate shifts in temperature and rainfall patterns, especially for high latitudes like the Tibetan Plateau and the Sahel region in Africa.

The Arctic is getting greener of course because of the melting permafrost. And the Amazon jungle areas are too however, interestingly.

Then the rest is due to effects such as more nitrogen in the soil from fertilizer, changes in forest cover, grazing and intensive farming.

This is a video summary:

Click to watch in YouTube

Soil improvement

It is possible that soil improvement also could make a big difference. As the soil is improved, CO 2 is taken up from the atmosphere.

The amount that can be removed in this way is hard to estimate, but it could remove 200 Gt by 2100 which could increase to 500 Gt by techniques such composting (rather than burning) soil revenues, limited tilling, and mixing biochar. Currently human activities are running at just under 37 Gt in 2017. So, soil improvement could take up between 5 and 13 years of emissions at 2017 levels. I got those figures of CO 2 emissions from here:

This is a summary in a recent review from 2018 of CO 2 removal methods:

"In addition to mixing biochar into soils, recent studies have focused on replenishing or enhancing organic carbon in cultivated soils through various agricultural practices, such as limiting tilling, and composting (rather than burning) crop residues. … Earlier studies suggested a very limited possible role for soil enrichment; however, more recent analyses suggest a physical removal potential of ~200 Gt(CO 2 ) by 2100, … and this could possibly be increased up to 500 Gt(CO 2 ) by practices such as soil carbon enrichment at greater depths. …“

Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals

No we are not going to lose all the world's soil in 40 years

This is a much shared old Scientific American article from 2013, at the early stages of the Food and Agricultural Organization’s global soil partnership. The article itself is here, as we’ll see it is hyperbole and click bait - even the Scientific American does do occasional click bait titles. It never was literally true. However it was the beginning of the FAO soil health initiative which has continued and is making a big difference to soil health worldwide.

Subtitle: “Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said”

It was followed up by a big report in 2015 that confirmed that preserving the health of world soils is very important and mapping out the problems and solutions. This has been followed by global action and co-ordination focused on world soil health.

This has been going on for a long time. Back in 1996, GLASOD gave this summary:

The global assessment of human-induced soil degradation (GLASOD) has shown that damage has occurred on 15 percent of the world’s total land area (13 percent light and moderate, 2 percent severe and very severe), mainly resulting from erosion, nutrient decline, salinization and physical compaction.

However, during this period, agricultural productivity has increased and food security increased. So while some of the soil is degrading, in other places we are doing things right and finding ways to increase productivity hugely through a four-fold increase in the global population.

Though soil degradation is a serious matter, there’s a lot being done to reverse desertification and improve soils.

Here is an example of what you can achieve at a local level, a rather dramatic greening the desert in the Jordan, using only the methods of permaculture. They didn’t extract water from any subsurface aquifers, just used the natural rainfall that fell on their plot in winter, and techniques of permaculture to improve the soil health:

Click to watch in YouTube

Here is his Ted talk:

Click to watch in YouTube

There are many initiatives underway to reverse desertification, such as the Sahara “Great Green Wall” project. It started as an idea of a literal “wall of trees” but this was not successful, and it has evolved into a vision of a mosaic of many practices, such as incorporating trees into the agriculture they are doing already and other methods of reversing desertification depending on the local situation. For instance in many places then shrubs and grass may grow better than the trees.

You can also grow food without soil. That's what aquaponics and aeroponics does. A world without soil is not a world without agriculture.

We could have a civilization on the Moon according to the dreams of space colonists, growing crops with no soil at all, or making soil directly from lunar basalt.

This is a frame from a charming Russian movie about the Moon made in 1965, before humans landed there.

Looking out on the lunar surface from inside a Moon city, in a frame from the 1965 Russian film Luna

And here is a section of the movie itself with the peaches a few seconds in:

Click to watch in YouTube

You can also watch The full movie, in restored colour, with machine translation subtitles for part of it.

There has been a lot of research on this since then, and it does seem feasible to have agriculture on the Moon.

For more about this see my

in my Why Humans on Mars Right Now are Bad for Science. Includes: Astronaut gardener on the Moon

But we can also keep our soils in good condition.

For more on this see my

What is the worst can happen?

We continue to have winter and summer in all the scenarios - this does nothing to the tilt of Earth which leads to the changes of temperature between summer and winter. Where I live on the Isle of Mull, we have less than seven hours of daylight in the middle of winter, while in the middle of summer it gets so light at night that the entire night counts as twilight, never reaching complete darkness. That won’t change.

We will still have six month long winters of total darkness at the poles.

The Himalayas are also always going to be cold in all the scenarios even with no climate policies at all. Tibet, Mongolia, the high Andes, the Alps, these are all going to remain cold in all scenarios, if warmer than before.

The ice in Greenland and Antarctica is still there for thousands of years in a warming world as it takes that long to melt it all. The Arctic sea ice can melt in summer at the highest temperatures but in winter when the sun never rises at all it will still be very cold in the Arctic.

It’s a world of less ice and fewer glaciers but not no ice. So clearly not an uninhabitable world on any scenario.

James Hansen's Venus hothouse syndrome - can't happen

James Hansen is a climate scientist, but he is well known for his hugely exaggerated statements not based on any peer reviewed research. This is an example. It was just speculation which he could publish in a book without going through peer review.

After his book was published, researchers quickly disproved it. But his book is still on sale and still quoted even though everyone in the topic of climate change knows it is wrong.

Short sum