Are we running out of time to stop climate change? Nearly a year has passed since the Intergovernmental Panel on Climate Change (IPCC) warned that limiting global warming to the 1.5-degree Celsius (2.6 degrees Fahrenheit) mark by the end of the century — a goal set to stave off the worst impacts of climate change — "would require rapid, far-reaching and unprecedented changes in all aspects of society."

Some politicians and writers have thrown their hands up in the air and argued that it's too late, and that human civilization is simply not up to the task. Others, meanwhile, took the report as a call to arms, reframing one of its points as a political organizing message: We have only 12 years to stop climate change, and the clock is ticking. (A year later, we're down to 11.)

But the full picture is both more and less dire than a slogan can capture. We can't stop climate change — because it's already here, and it's already too late to reverse many of its catastrophic effects. What's true is that things are on track to get much worse over the course of this century, and that if we're going to stop those things from happening, society is going to have to start hitting some important deadlines fast. There's a big one coming 12 years after the IPCC report. Blowing through it won't immediately plunge society into a "Mad Max"-style dystopia, as some have suggested — perhaps tongue in cheek — but it will make sure everything keeps getting steadily worse, and it will make turning things around down the road that much harder.

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Some scientists are nervous that overemphasizing the 2030 deadline might mislead the public about the nuances of climate change. But others pointed out to Live Science that activists have a task that's different from that of researchers — one that requires straightforward goals and clear, simple ideas.

The IPCC report, which the U.N. climate science body released Oct. 8, 2018, revealed that the best path to limiting warming to an increase of 1.5 C by 2100 involves cutting net human carbon dioxide (CO2) emissions 45% by 2030 (12 years after the report was published) and then cutting emissions further to net zero by 2050. It was far from the first dire warning that the agency had issued. But this one seemed to take root in the public discourse around climate change, possibly because of how news stories summarized the report. An Oct. 8, 2018, headline in The Guardian read, "We have 12 years to limit climate change catastrophe, warns UN." Vox headlined its article "Report: we have just 12 years to limit devastating global warming." Smithsonian.com wrote, "The World Was Just Issued 12-Year Ultimatum On Climate Change."

In an interview with writer Ta-Nehisi Coates three months later, on Jan. 21, Rep. Alexandria Ocasio-Cortez, D.-N.Y., spelled out how the report's conclusions had entered the zeitgeist:

"Millennials and Gen Z and all these folks that 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?'"

Here's the thing: Scientists never said the world was going to end in 12 years if we don't stop climate change. Even researchers known for ringing the alarm bells on climate change are far more likely to speak in terms of decimal places and nonlinear effects than to talk about the end of civilization as we know.

Prominent activists rarely bring up doomsday, either. Messages from the Global Climate Strike organizers and the U.S.-based Sunrise Movement focus on long-term climate shifts, not an impending, sudden disaster. Still, the 12-year deadline looms large in the culture.

"It has achieved an absoluteness in its role in societal dialogue that's not in line with scientific fact," said Katharine Mach, a climate scientist at the University of Miami and one of several lead authors of the IPCC report.

"The world will not end if we pass 1.5 degrees Celsius of warming above preindustrial levels," Mach said.

Related: 8 Ways Global Warming Is Already Changing the World

And failing to hit a 45% reduction target won't lead to 1.5 C of warming by 2030, as Lini Wollenberg, a University of Vermont climate researcher and leader of the CGIAR Research Program on Climate Change, Agriculture and Food Security, told Live Science. It does, however, increase the chances of hitting 1.5 degrees C by 2100 and experiencing many more climate catastrophes on our way through the 21st century, Wollenberg said.

The issue is that any program set up to mitigate warming will have two basic components: short-term cuts to emissions and longer-term efforts to pull carbon out of the atmosphere. (This doesn't necessarily mean giant, futuristic CO2-sucking machines, but may mean things like growing forests.)

"Some people — I'm hazarding industry and those focused on maintaining a growth-focused economy — would argue that we don't want to sacrifice things in the short term, and that society will figure out the technology to deal with it later," Wollenberg said.

But every year of delay on cutting greenhouse gas emissions means that carbon-capture efforts down the road will have to be even more fantastical and dramatic (including heavy reliance on carbon-capture technologies that may never work). And each year in which we do nothing, the world will cross more climate tipping points that will be difficult to undo, Wollenberg said.

The year 2030 has been bouncing around climate-policy documents for a while, Wollenberg said. (It also turned up in the Paris Agreement, for example, as did the goal of net zero by 2050.) Researchers saw that target as part of a reasonable time frame for drawing down emissions without it resulting in unbearable economic costs or having humanity rely too heavily on future carbon-capture efforts, she said.

"It could have been 2020, 2012 or 2016," Wollenberg said, adding that 2030 "used to seem a lot further away."

The 1.5 C target was picked for similar reasons — an effort to balance what's possible against what's necessary. But, similar to the 12-year time frame, 1.5 degrees is a target set by scientists, not an immutable scientific fact.

"We know that the risks go up [as temperature rises]. We're already experiencing widespread impacts of the changing climate," Mach said, pointing to the ongoing consequences of 2019's 1 C (1.8 F) of warming above preindustrial levels. "It will be greater at 1.5 degrees of warming, and may go up from there in some very substantial ways … with severe, irreversible impacts."

Holding warming to 1.5 degrees won't reverse climate change. In fact, the catastrophic impacts in that idealized scenario will be much worse than they are now.

Colin Carlson, an ecologist at Georgetown University who studies how climate change influences infectious diseases, said that one problem with imagining that we have 12 years until a huge disaster hits is that such thinking obscures the ongoing horrors of climate change in 2019.

"Climate change has already killed hundreds or thousands — or more — of people," Carlson said, "through malaria, through dengue, through a hundred other avenues that we're only now starting to be able to quantify."

Mosquito-borne diseases flourish in a warming world, his research has shown. And the world has already warmed enough that many people have gotten sick and died from those diseases — people who otherwise would have been spared.

Related: 5 Deadly Diseases Emerging from Global Warming

"So this is not as simple as 'Can we stop this coming?' It's already here," he said.

Similarly, Wollenberg’s work has shown that severe climate impacts are devastating food production worldwide in 2019. Vast regions of North and South America, Asia and Africa are becoming too hot for growing grains. The soil in low-lying, coastal regions of Bangladesh and China is getting saltier as rising seas contaminate groundwater, threatening rice production. (A few places are becoming more hospitable to certain crops. A warming Vermont, for example, is growing more hospitable to peaches, even as a shortened ski season threatens its economy.) The overall impact is to drive up food prices and create global unrest. Long term, these trends will make it impossible for some countries to produce enough food to feed their populations, she said.

To manage all that complexity, researchers tend to break down responses into two broad categories: mitigation and adaptation. Mitigation is, in short, the work of preventing climate change from worsening. Reducing emissions and growing forests fall into this category.

Adaptation is learning to deal with the warming that's already here and the additional warming that's coming: building sea walls and flood-abating salt marshes around coastal cities; studying changes in precipitation so farmers know when to plant their crops; and engineering crops to better withstand harsh environments.

But ultimately, all the researchers Live Science contacted said these problems become less catastrophic with less warming. Holding the world to a 1.5-C warming increase by the end of the century creates much more manageable short- and long-term problems than holding it to 2 C of warming, which is much less harmful to Earth than 3 C, which is much more survivable than 4 C, which is still less catastrophic than 6 C … and so on. None of those possible futures necessarily leads to a charred, lifeless global desert in our lifetimes. But each increase is almost unimaginably more dire for life on this planet than the one preceding it.

"It's always worth it to prevent more warming," Mach said.

With regard to the spread of mosquito-borne diseases, Carlson said, "We can stop it. Mitigating climate change is truly the silver bullet. Sometimes it is as simple as, 'If we stop climate change, we can stop a lot of the bad health impacts that are coming.'" (Though the devil is in the details, he added. The level of disease reduction will depend on how fast the carbon-mitigation project moves, and its effects won't be felt immediately or equally everywhere.)

The science points relentlessly to one reality: The best way to deal with climate change is to start cutting emissions now. It's easier to stop warming by keeping CO2 in the ground now than it is to pull carbon out of the air later. And mitigation makes adaptation much more effective.

Bringing up the 12-year time frame, then, is a way of drilling down on the first step the world has to take to move down the most effective mitigation path still available — even if it doesn't capture the full scope of the issue.

So, is it irresponsible for public figures to employ the 12-years rhetoric?

"I think the role of public figures is to set visions and create the urgency that we need," Wollenberg replied. "The scientific community is sometimes uncomfortable with that, but if you started talking to the general public about, 'Well, you could trade off your long-term emissions and delay the decline by 5%, or we could do a 4% reduction every year, but that would contrast with a 7% reduction where we could wait until 2035,' it would not be an effective message."

“I would blame the public figures who aren't taking steps more than I would blame the people who are trying to promote a vision," she said.

We're at a point in time when people are feeling the effects of climate change on their lives, said Jewel Tomasula, a doctoral student ecologist at Georgetown University, who studies the health of salt marshes in New Jersey. As Live Science has previously reported, the world in 2019 is hotter, monster storms are more frequent, diseases are on the move, and fires and floods are happening more often. Talking about 2030, Tomasula said, is about creating a window for activism to take effect — a decade of meaningful global movement on the problem.

"Science is great for understanding the problem," she said. "Climate change is a physical problem, and we can work on it with our data and really understand it. But that's not what's really going to fix it. … The way that problems like this have been addressed in the past is by having that political will and mobilization."

The notion of a 12-year deadline can be misleading and obscures some of the hedging and nuance scientists like to emphasize. But it also seems to offer climate mobilizers a focal point for their efforts, and people really are getting out into the streets.

Originally published on Live Science.