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In 2015, the world found its environmental rallying cry. A single line in the Paris Agreement – a pledge to “pursue efforts” to limit global temperature increase to 1.5 degrees above pre-industrial levels – became the bar against which efforts to stop climate change have been judged since.

When Greta Thunberg chastised world leaders at Davos in January 2020, she warned that we are rapidly burning through the carbon budget we have left to avert warming of more than 1.5 degrees. In headlines, the number of years we have left to avoid this limit counts down – first 12, now 11, or fewer. Unlike any of the goals that have come before or after it, 1.5 degrees looms in the popular imagination like a finish line we’re desperate to avoid.


But here is the awkward truth: we have already failed. To stay below 1.5 degrees of warming, global greenhouse gas emissions need to fall by 7.6 per cent every year until 2030. Instead, they are projected to keep on rising. The level of decarbonisation needed to stay under 1.5 degrees has gone from monumental to staggeringly unlikely. If countries stick to their current climate policies, by 2100 we’ll likely exceed three degrees of warming.

We don’t know exactly when it’ll happen, but at some point in the next two decades or so the world will blast past 1.5 degrees of warming. For many climate scientists – although some have been unwilling to say so publicly – this has been obvious from the moment the Paris Agreement was signed. But as the prospect of leaving our most ambitious climate target in tatters slowly morphs into reality, a more pressing question is looming. What if we were chasing the wrong goal all along?

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Greta Thunberg outside the World Economic Forum in Davos, January 2020 Bloomberg / Contributor / Getty

For 40 years, the now-ubiquitous 1.5 degrees target barely featured the climate change conversation. In the mid-1970s Yale economist William Nordhaus published a pair of papers arguing that the world should aim to stay within temperatures humans have lived with for the last 100,000 years. The range he settled on was two degrees. Any more than that, he wrote, and the climate would be pushed beyond what humans are familiar with.


In 1990, Nordhaus’ back-of-the-envelope calculation was backed-up by a study from the Stockholm Environment Institute (SEI) which analysed the impact of rising greenhouse gas emissions. The authors set two limits – a lower one at one degree and another at two degrees above pre-industrial temperatures, but noted that the lower limit might already been impossible to meet. Two degrees must be the absolute limit, they decided, cementing its place at the heart of climate policy for the next three decades.

Not long after, two degrees started to catch on more widely. The target was first endorsed by the European Council of environment ministers in 1996, then in the 2010 Cancun Agreements, which committed governments to keeping global average temperature below two degrees. “Ten years ago the goal was two degrees and there was no discussion around 1.5 degrees,” says Pierre Friedlingstein, chair of mathematical modelling of climate systems at the University of Exeter.

While the two degrees target was making its tortuous way into international agreements, global carbon emissions were racing upwards. In 1990, the year the SEI first suggested the two degrees limit, total global emissions stood at 16 billion tonnes of CO2 annually. By the Cancun Agreements in 2010 they had more than doubled to 33bn tonnes and temperatures were already 0.8 degrees above pre-industrial times.

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“Most people that know anything about trends, inertia and feasibility would say that two degrees would be enormously difficult to meet,” says David Reiner, assistant director of the energy policy research group at the University of Cambridge. But even as two degrees was slipping out of reach, the political consensus had started teetering towards an even more ambitious target: 1.5 degrees.


While the rest of the world had coalesced around two degrees the Alliance of Small Island States (AOSIS) – an intergovernmental group that represents low-lying coastal and island states – had its eyes on a lower target. At the Copenhagen Conference in 2009, a representative from Tuvalu – a tiny island nation that stands just 4.6 metres above sea level at its highest point – called for a temperature limit of 1.5. At the conference the Tuvalu delegate, Ian Fry, tearfully concluded his speech with the words “the fate of my country rests in your hands.”

By 2015, the weight of opinion had swung firmly behind 1.5 degrees. In June, a report based on the the views of 70 experts concluded that – although they were unclear on the difference of impact between two and 1.5 degrees of warming – the temperature limit should be placed “as low as possible.” The Paris Agreement, later signed by all 197 parties at the United Nations Framework Convention on Climate Change, set an upper limit of “well below” two degrees and the now-ubiquitous reference to the lower emissions target, committing countries to “pursuing efforts to limit the temperature increase to 1.5 degrees above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change.” Since then, the limit has rarely been far from climate change headlines.

Teenage climate crisis activists protesting in London on February 14, 2020 Ollie Millington / Getty Images

From the moment the Paris Agreement was adopted on December 12 2015, the odds were stacked against 1.5 degrees. “I think the speed and suspension of disbelief you need to get to 1.5 degrees is almost problematic,” says Reiner. In 2018, humans added 55.3bn tonnes of greenhouse gases to the atmosphere. To keep within 1.5 degrees of warming, this figure would need to fall 55 per cent by 2030. But over the last decade greenhouse gases have risen at an average rate of 1.5 per cent per year and, according to the United Nations Environment Programme, there are still no signs that they will peak in the next few years.

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Although the overall emission trends are still heading in the wrong direction, there are plenty of pockets of optimism out there. The cost of renewable energy has dropped faster than many expected and global energy intensity – the amount of energy needed to create one unit of GDP – has been dropping since the 1990s meaning we’re getting better at creating more value while consuming less fossil fuel. In China – the world’s biggest emitter of greenhouse gases – energy intensity has dropped by 40 per cent between 2000 and 2018.

In Europe, greenhouse emissions have dropped by 21.7 percent compared to their peak in the 1990s and eight countries have committed to net zero emissions targets of 2050 or earlier. Even closer to home the UK has shifted dramatically towards low carbon sources of electricity, pushing fossil fuels to the lowest ever share of the UK’s energy mix. In 2010, 75 per cent of the UK’s electricity was generated from fossil fuels, but by 2019 that has fallen to just 43 per cent.

Part of the reason for these dramatic changes is because of the urgency implied by the 1.5 degrees target, and the subsequent Intergovernmental Panel on Climate Change (IPCC) report in 2018 that detailed for the first time the effects of 1.5 degrees of heating. “It really told us we have to act today, and we have to act immediately,” says Piers Forster, director of the Priestley International Centre for Climate at the University of Leeds and a member of the UK Committee on Climate Change (CCC). “It told us we can't just reduce emissions of CO2, we have to take them right down to absolute zero.”

But against the backdrop of growing global emissions, these pockets of hope can start to look like outliers rather than symbols of a changing tide. “1.5 degrees is a global discussion that we have very little control over,” says Reiner. “By its nature [the 1.5 degrees target] makes it a discussion about what is China doing, what is India doing, what is Vietnam doing [...] and that starts to feel very disempowering.”

Further abroad, the picture is much more mixed. Despite vast investment in renewable energy, China is still constructing a 121 gigawatts of coal power power plants – more than half of that being built in the rest of the world combined. In the wake of the Fukushima nuclear disaster, Japan has dramatically cut back its nuclear power generation and now plans to build 22 coal-burning power plants over the next five years. In the world’s second-largest polluter, the United States, which is expected to withdraw from the Paris Agreement in November 2020, emissions in 2018 rose by 3.4 per cent year-on-year – the biggest rise in eight years. “There is no clear indication that global CO2 emissions are declining,” says Friedlingstein.

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If the 1.5 degrees target was extremely ambitious the moment it was agreed upon, then five years on it’s starting to look hopeless. Sure, it’s still technically possible to stay within the limit but hitting that target would mean getting everything right – every policy, every technological hurdle, every economic incentive – and still hoping that there’s enough wiggle-room in climate models to let us squeeze under 1.5 degrees of warming.

If half a century of inaction around climate change has taught us anything, it’s that these hoped-for changes will not come soon enough to keep us under 1.5 degrees. Despite these long odds the climate commentariat – scientists, activists and politicians – have maintained publicly optimistic, and for good reason. If you admit the 1.5 degrees target is bust, do we just keep moving the finish line backwards? How do we acknowledge our inability to meet our ambitions without denting enthusiasm for making real cuts to emissions?

But there is an opportunity in this failure. Admitting that we failed to prevent 1.5 degrees of warming might force us to get to grips with the reality of our climate situation: that it’s a long haul slog of reduction and adaptation with no clear finishing points. Leaving behind 1.5 degrees might not be the ending that it feels like – it could be the start of a whole new era of climate action.

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While the 1.5 degrees target might suggest we’re approaching a climate cliff edge, the reality of climate change is very different. “If we fail to reach a target it doesn’t mean there is nothing to do,” says Friedlingstein. “Every tenth of a degree of avoiding climate change is better.”

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In 2018, the IPCC released a report detailing the difference between 1.5 degrees of warming and two degrees. Just that half-degree difference will have a huge impact on the world: twice the species loss of vertebrates and plants; 2.6 times more people exposed to severe heat; six more centimetres of sea level rise.

For Forster, these are the numbers we should really be focusing on. “I'm certainly becoming quite concerned that a lot of people are becoming quite fixated by this 1.5 degrees [...] [climate scientists] don't care about the 1.5 degrees as a thing. We care about the impact,” he says. “We are experiencing the impacts of climate change today. And those impacts will get increasingly worse with every bit of increasing surface temperature we subsequently have on top of where we are currently.”

This is the problem with the narrative that only have 12, or 11, or ten, years to save the planet. If we focus too much on ceilings in the form of temperature limits, we risk reducing climate change to a series of finite steps. It can look like there is nothing at all between us and the ceiling, until we smash right through it. And when we get to the other side of 1.5 degrees we might peer at the wreckage below, realise that the world is still intact, and wonder what all the fuss is about.

But climate change is not a series of ceilings. It’s a staircase that we’ve been walking up for the last century-and-a-half. Every time we fail to reduce emissions we take another step upwards – towards a world with more climate refugees, less biodiversity and more extreme weather. But each step comes with a choice. Do we carry on moving upwards, or do we stop and begin the hard work of unpicking the impact humans have had on the world, and defending ourselves against the changes we know are about to happen?

It is not the case that if we fail to hit 1.5 degrees of warming that we’ve lost the climate battle. “There fundamentally is not a cliff edge – the world does not end in 2050, nor does it end in 2100,” say Niall Mac Dowell, leader of the Clean Fossil and Bioenergy Research Group at Imperial College London. And if we focus too much on the 1.5 degrees deadline – and the kind of radical decarbonisation that would require – we might end up extinguishing the political will we need to bring about clean policies.

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“My real worry is that if we try to do something too hard too fast, and that does not get popular support, we won't do it,” says Mac Dowell. “We need to recognise that the transition can, if done right, result in the creation of new jobs and industries, and we can therefore ensure continued provision of energy services and industrial products, but in an affordable and sustainable manner.”

That will mean convincing other countries to follow the kind of net zero pledges the UK set for itself in June 2019. “This whole net zero target is quite synonymous with trying to prevent further rises in temperature,” Forster says. “There are still a whole lot of countries that really aren’t thinking about these net zero targets.”

Forster doesn’t think that our obsession with 1.5 degrees will ever go away completely but focusing much more on our progress towards net zero carbon emissions is a much more useful guideline for how we’re tackling the climate crisis. Lowering the amount of greenhouse gases we put into the atmosphere, after all, is the only way we can realistically limit temperature increases. “Perhaps we won't make 1.5 but if we try really hard to get net zero we might make 1.8, or 1.9 or two degrees,” he says.

And while it’s hard for any one person or country to see the impact that they have on temperature increases, the net zero target is much more tangible. The UK could decarbonise overnight and not change a thing about global temperature levels, but every airport expansion, every new electric car charging point, every new home built to lower emissions standards, has a direct impact on net zero. Whatever happens to the 1.5 degrees target, only one thing is certain: in ten years the world will still be here, and the climate crisis will be more urgent than ever.

Matt Reynolds is WIRED's science editor. He tweets from @mattsreynolds1

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