Back in October, the nations of the world unanimously approved a landmark report from scientists warning that we must make sharp reductions in global carbon dioxide emissions by 2030 to have any plausible chance of averting catastrophic climate change.

This report — published by the U.N. Intergovernmental Panel on Climate Change (IPCC) — led to headlines like “We have 12 years to limit climate change catastrophe, warns UN” by The Guardian, and “The world has just over a decade to get climate change under control, U.N. scientists say” from the Washington Post.

But when the popular freshman Rep. Alexandria Ocasio-Cortez (D-NY) made the exact same point as the IPCC, the world’s foremost scientific panel on climate change — that millennials in the U.S. fear “the world is going to end in 12 years if we don’t address climate change” — the right-wing and even some in the media pounced.

So, ThinkProgress contacted leading experts on exactly what the science says. They confirmed that, yes, as Ocasio-Cortez says, we must act swiftly if we’re to maintain any plausible hope that we can avoid the catastrophic impacts that come with warming of 2°C or more above pre-industrial temperatures.


“Projected impacts look especially bad beyond 2°C or so of planetary warming,” leading climate expert Michael Mann told ThinkProgress. “And there is no scenario for stabilizing warming below 2°C that doesn’t require rapid reductions in carbon emissions over the next decade.”

Andrew Jones, co-director of Climate Interactive, a U.S. think tank that generated some of the scenarios the IPCC used in its report, said he “definitely” agreed with Mann’s assessment. Rapid reductions means a 30-50 percent decrease in global emissions by 2030, rather than the 10 percent increase we are currently looking at.

It is not possible to overstate the urgency of the matter. As Debra Roberts, a co-chair of the report’s working group on climate impacts, told The Guardian back in October, “This is the largest clarion bell from the science community and I hope it mobilizes people and dents the mood of complacency.”

Within this, it’s also important to note that some Ocasio-Cortez critics took her comments out of context and tried to make it seem as if she was declaring literally, “the world is going to end in 12 years if we don’t address climate change.”

But as the video of her interview with the writer Ta-Nehisi Coates makes clear, she was talking about why millennials and younger people have a different sense of urgency about climate change — it is because they are the ones who will have to deal with the consequences. For them, the world they once knew will be dramatically and irreversibly altered.

“I think the part of it that is generational,” Ocasio-Cortez explained, “is that Millennials and people, you know, Gen Z and all these folks that will come after us, are looking up and we’re like: The world is going to end in 12 years if we don’t address climate change, and your biggest issue is how are we gonna pay for it?”

She added, “This is the war — this is our World War II.”

A few hours later, after conservatives had begun taking her line out of context and attacking her, she tweeted, “For some reason GOP seems to think this is a gaffe, but it’s actually a generational difference. Young people understand that climate change is an existential threat: 3,000 Americans died in Hurricane Maria.”


Ocasio-Cortez added, “The U.N. says we’ve got 12 years left to fix it.” She included a link to The Guardian piece that made the exact same point back in October when the IPCC report first came: “We have 12 years to limit climate change catastrophe”

So did The Guardian and the Washington Post and Ocasio-Cortez understand the IPCC correctly? What exactly does the IPCC’s “Special Report on Global Warming of 1.5ºC” say?

First and foremost, the report makes clear that on our current emissions path, we will cross a key threshold of dangerous climate change — 1.5ºC (or 2.7°F) — by 2040. Furthermore, reversing any amount of global warming, and its accompanying impacts, is all but impossible on a time scale of decades if not centuries.

Even worse, absent much stronger global action and a very sharp reversal of President Donald Trump’s anti-climate policies, the world would hit a truly alarming threshold of catastrophic climate change (2°C or 3.6°F) just two decades after that.

Human-caused warming reached 1°C [1.8°F] above pre-industrial levels in 2017. At the present rate, global temperatures will hit 1.5°C around 2040 and 2°C soon after 2060. CREDIT: IPCC. Back in December 2015 in Paris, the world’s nations unanimously committed to make a series of increasingly deeper emissions reductions aimed at keeping total warming “to well below 2°C [3.6°F] above preindustrial levels.”


The Paris Climate Accord further committed the world “to pursue efforts to limit the temperature increase to 1.5°C [2.7°F] above preindustrial levels, recognizing that this would significantly reduce the risks and impacts of climate change.”

The 2018 IPCC report makes the strongest case so far that going beyond 1.5ºC warming is much, much more dangerous than we realized just a few years ago. It shows that as the planet warms from 1.5°C to 2°C, the risks grow rapidly for some very dangerous tipping points, including the irreversible collapse of the West Antarctic ice sheet (which would raise sea levels 20 feet).

For instance, the report notes that “Limiting global warming to 1.5°C rather than 2°C is projected to prevent the thawing” of as much as 1 million square miles of permafrost. And that matters because the northern permafrost contains twice as much carbon as the atmosphere does today.

This means we face the very real possibility of a snowballing catastrophe — where global warming of 2°C or more thaws a huge area of permafrost, and the resulting carbon emissions released because of this would create, say, another 1°C of warming that in turn releases yet more heat-trapping gases from the permafrost.

The IPCC report says that keeping total warming to 1.5°C is still technologically possible, but it would require “rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems… These systems transitions are unprecedented in terms of scale.”

The following chart shows the kind of abrupt reversal of emissions trends needed in order to avert dangerous global warming.

If you think that such a U-turn is increasingly unlikely given that Trump has started the process of undoing every major U.S. climate policy and abandoning the Paris Accord, you aren’t alone.

“Given the present political debate, I don’t see much chance of these near-term cuts happening,” Texas A&M climatologist Andrew Dessler emailed ThinkProgress back in October. “Overall, I’m worried people will look at this and conclude that we’re totally screwed and give up.”

But that would be a mistake. Because, as dangerous as 1.5°C warming is, 2°C is catastrophic — and warming of 3°C (5.4°F) to 4°C (7.2°F) would be worst of all, pushing us toward what would inevitably destroy human civilization as we have come to know it. Our children and grandchildren would be facing inundation of every coastal city, Dust-Bowlification of much of the world’s best farmland, and accelerating climate feedbacks (like the thawing permafrost) that could push us into a “Hothouse Earth” — warming of 5°C (9°F) or more.

Since the primary reason the IPCC wrote this special report was to create urgency, the question remains, what are reasonable rhetorical ways of conveying the extreme urgency the world faces while still being true to the science?

Jones from Climate Interactive explained to ThinkProgress how he discusses with others why many, like The Guardian, picked up on the “12 years” framing from the 2018 IPCC report.

First, he highlights a line from the report pointing out that limiting global warming to no more than 1.5°C above preindustrial levels requires very deep cuts in greenhouse gas emissions — “a 40-50% reduction from 2010 levels” — by 2030.

Then Jones shows this simple box which does some simple math; there are just 12 years between when the report was released and 2030.

We must make sharp cuts in greenhouse gases (ghgs) in the 12 years from 2018 to 2030 to keep total warming to 1.5°C. CREDIT: Climate Interactive.

But absent an increasingly implausible U-turn in emissions starting immediately we are going to warm more than 1.5°C. That means we face a multitude of dangerous impacts: more sea level rise, more extreme droughts, more extreme deluges, more loss of permafrost carbon, and so on.

So we’re stuck with some dangerous warming. But how do we avoid the catastrophe of 2°C and beyond?

“For limiting global warming to below 2°C, CO2 emissions are projected to decline by about 25% by 2030 in most pathways” compared to 2010 emissions, the report states, “and reach net zero around 2070.”

So, under most scenarios where the world is taking strong action to curb emissions, these emissions will need to start declining almost immediately.

The thing is, even as the IPCC report was being written, global CO2 emissions, which had flattened out in the middle of this decade, were on the rise again — as seen in this International Energy Agency chart from last fall:

Global CO2 emissions are on the rise again. CREDIT: IEA.

The world’s failure to reverse emissions this decade means that instead of having 20 years — 2010 to 2030 — to cut emissions some 25 percent, we now have 12 years to cut CO2 emissions more than 30 percent.

However, there is no precise amount of emissions cuts by 2030 that avoids catastrophe. Indeed, even if we hit a 2030 target, we then have just four decades or so to drive global emissions down to near zero.

And no, 2030 “isn’t a cliff we fall off, it’s a slope we slide down,” as NASA climatologist Kate Marvel explained to Axios last week. But for her, getting language right means not understating the urgency: “We don’t have 12 years to prevent climate change — we have no time. It’s already here.”

And no, “the world isn’t going to end in exactly twelve years,” Marvel said. But she added that Ocasio-Cortez is “right that decisions we make in the next decade will determine how bad climate change gets — we can’t prevent bad things, but we have the power to avoid the worst-case scenario.”

So, the world will not literally end in 2030 if we fail to make deep cuts. But figuratively, the stable climate of the past 10,000 years that made modern civilization possible will have ended. Young people today will face a lifetime of ever worsening and irreversible impacts.

Here’s one way to frame the urgency: If the world does not make substantial and sustained progress in cutting total global warming emissions by 2030, then the window will be effectively closed for averting the catastrophic warming of 2°C or higher.

Having lost the war to avoid catastrophic impacts, we will instead be fighting a war to save civilization itself.

Ocasio-Cortez is right. “This is the war — this is our World War II.” But it is a war that will last many, many decades.

Since she was speaking at a January 21 event honoring the legacy of Martin Luther King Jr., she repeated his famous line about “the fierce urgency of now.”

It’s also worth repeating his next few lines, “In this unfolding conundrum of life and history, there ‘is’ such a thing as being too late. This is no time for apathy or complacency. This is a time for vigorous and positive action.”