You don’t exactly need a scientist to know the climate is in trouble. But the latest Intergovernmental Panel on Climate Change report dropped on Monday, and it’s an exclamation point to the real-world impacts of the climate crisis already playing out.
In a summer of unprecedented heat waves, wildfires, floods, and all the attendant death and suffering that’s come with them, the world’s leading climate scientists have issued their starkest warning yet. Humanity’s influence on the climate is “unequivocal,” the report warns, before going on to list a litany of climate impacts that will exponentially worsen if we fail to act.
“The fact that the IPCC has agreed, with the agreement of all member countries, 195 member countries, that it is ‘unequivocal’ that human activity is causing climate change, is the strongest statement the IPCC has ever made,” Ko Barrett, the vice chair of the IPCC, said on a press call.
The 234 scientists behind the report also make clear that it’s now or never for the world’s best chance to avert even more horrifying impacts of climate change—while showing that every ton of carbon pollution and every tenth of a degree matter.
The report’s timing comes not just in the midst of the unfolding climate emergency, but also just mere months away from a major climate conference in Glasgow that will put pressure on countries to improve their pledges to the Paris Agreement. Right now, the current batch of commitments would leave the world on track to blow past the agreement’s goal of limiting heating to 2 degrees Celsius (3.6 degrees Fahrenheit), let alone the stretch goal of capping emissions to meet the 1.5-degree-Celsius (2.7-degree-Fahrenheit) target. Big Oil—the culprit driving so much of the climate crisis—has done everything it can to influence those talks. The latest IPCC report adds to the urgency for countries to improve their pledges, and ignore the agents of delay.
“It is still possible to forestall many of the most dire impacts, but it really requires unprecedented transformational change—the rapid and immediate reduction of greenhouse gases,” Barrett said.
You know that, of course, if you read this site. But the report—the sixth released since 1990—still lays them out in stark terms. Burning fossil fuels has boosted the global average temperature by 2 degrees Fahrenheit (1.1 degrees Celsius). The impacts of that heating aren’t distributed evenly, though. The Arctic is warming more than twice as quickly as the global average. The already vulnerable, from coastlines where seas are rising to drought-stricken regions around the globe, are suffering more as well.
But though some are more vulnerable than others, the effects of the climate crisis are hitting every corner of the Earth. No region is safe, and the impacts will worsen unless society acts.
The report warns that some changes may be locked in. The damage already done to ice sheets may be irreversible for hundreds of years if not millennia, and sea levels will “remain elevated for thousands of years.” That doesn’t mean we should throw in the towel. In fact, the report shows we can’t. Decarbonization is our only path to survival.
Three years ago, the IPCC released a stark report warning that allowing Earth to warm by 1.5 degrees Celsius would have devastating consequences. The new report shows that future is near certain. In fact, it will be here sooner than we expected—likely within the next decade or two. While the IPCC’s estimations from 2018 said we’d likely reach this point in 2040, the new report uses updated modeling that shows we may be on track to breach that threshold by 2030. Even in the best-case scenario in which the world undertakes quick and far-reaching climate action, we very well may still cross 1.5 degrees Celsius (at least for a bit).
By midcentury, the world’s choices on how fast to limit carbon pollution will start to lead to divergent climates. Curtail emissions rapidly and now, and global warming will halt around 1.5 degrees Celsius. If world leaders make unprecedented changes to every economic sector and society at large to stop emissions, we will still likely cross 1.5 degrees. But we can bend the curve back in the right direction and, by the end of the century, keep the climate from going off the rails.
Continue emitting, though, and the world will heat up further. Doing so will come with major consequences. Not all life will be able to adapt to the new, hotter, more dangerous conditions.
To study the climate crisis, scientists have created a number of scenarios known as Socioeconomic Shared Pathways or SSPs. They offer the broad contours of what the world could look like, both societally and climate-wise.
“The new report pulls no punches in outlining the ongoing consequences of our rising greenhouse gases emissions, and how these choices over the next few decades will lead to starkly different climate futures,” Kim Cobb, report co-author and a coral researcher at Georgia Tech, told reporters on Sunday.
What the new IPCC reveals are pathways that are all wildly different from the present. But how they’re different is, well, different. The most pessimistic scenarios, dubbed SSP5-8.5 and SSP3-7.0, show greenhouse gas emissions climbing to new highs through much of the 21st century. The world would blow past the Paris Agreement temperature goals by midcentury. Global warming would continue to crank up and the planet would be up to 7.9 degrees Fahrenheit (4.4 degrees Celsius) by century’s end.
That would usher in a planet unrecognizable to those of us alive today: The biosphere would break down, swaths of the planet would become uninhabitable, and heat waves that happen once every 50 years in today’s climate would become the norm. Not only that, those heat waves would be 9.5 degrees (5.3 degrees Celsius) hotter.
A more middle-of-road scenario that aligns with the world’s current climate pledges would only be slightly better. Andrew Dessler, a climate scientist at Texas A&M, said in an email that that even in that scenario, the impacts would be “so severe that we’ll refer to Hurricane Harvey, the PNW heatwave, and the California fires as ‘the good ol’ days.’”
Equally unrecognizable are the more positive scenarios. Dubbed SSP1-1.9 and SSP1-2.6, these scenarios would see the world meet the Paris Agreement targets and in the case of SSP1-1.9, meet the 1.5-degree target in all likelihood. What would be foreign, though, would be society rather than the climate system. Yes, a 1.5-degree-Celsius world would be hotter and more dangerous. Fifty-year heat waves, for example, would be roughly eight-and-a-half times more likely and 3.6 degrees Fahrenheit (2 degrees Celsius) hotter. Not great, but certainly more manageable than the alternative.
To meet that goal will require a reshuffling of society on a scale unseen in human history. It would be akin to cramming all the medical advances made between penicillin and today’s mRNA vaccines into a few beautiful decades.
But just as those advances have treated us well, so would addressing carbon pollution. The report notes it would lower air pollution associated with burning fossil fuels in addition to lowering the impacts of climate change on the most vulnerable. In choosing this radically different future, we’d be choosing to reorganize society around saving lives. We’d be choosing to focus on shared prosperity. We’d be choosing to protect nature.
Climate scientists have long warned that global warming could trigger certain “tipping points”—scenarios where global warming sets off a cascade of self-perpetuating feedback loops. The new report is the first IPCC report to take a deep dive into them. It finds that while most are unlikely, we can’t rule them out.
Just last week, a harrowing study found that another tipping point, the collapse of the Atlantic Meridional Overturning Circulation, is currently at a “point close to a critical transition.” If that global current is destabilized, temperatures in the Global North could fall precipitously and sea levels could rise rapidly. Other recent reports have said the Amazon rainforest recently reached a tipping point and is now producing more carbon than it is sequestering due to fires.
The IPCC finds these and other events such as the collapse of the Greenland ice sheet are possible though unlikely. That the notoriously conservative IPCC is acknowledging these prospects is a sign of increasing concern among climate scientists and chilling to even think about.
The topline observations in this report have been clear for decades. Early IPCC models predicted the warming track we’re on. And each IPCC report has generally made it clear that the longer we stave off decarbonization, the greater the risk of catastrophic climate breakdown—and the more challenging the actual decarbonization process itself will be.
These reports are also conservative by nature. It’s been seven years since the last IPCC came out. The new version summarizes all the science that happened in between, compiling 14,000 citations for the final product. That conservatism can be helpful; it’s nice to have a gold standard for climate science. But it can also be infuriating; people are dying from climate change right now, and waiting seven years to put a report out feels like a luxury.
That said, the timing of this IPCC report is absolutely vital. In the U.S., Democrats are weighing a set of major infrastructure bills that could be the best—and maybe only—chance this decade to get the world’s largest historical emitter on track to clean up its act. The November meeting in Glasgow is also put up or shut up time for all countries.
“We know how to solve this problem,” Dessler said. “We need to switch our energy system away from fossil fuels to climate-safe energy. There’s no mystery here.”
There’s no one-click option to cutting emissions. It takes real work. Scientists have dropped the gauntlet. Now, it’s time for civil society to put pressure on leaders to meet the moment.