On Sunday night,the UN’s Intergovernmental Panel on Climate Change dropped an urgent report on the state of global warming. Simply put: The laws of the physical universe say that we can keep global warming to 1.5 degrees Celsius above pre-industrial levels, the optimistic goal set out in the Paris Agreement, but we’re quickly running out of time. As in, we may reach that 1.5 in as little as a dozen years at the rate we’re spewing emissions. And the consequences will be disastrous.

To correct course and avoid 1.5 C, or 2.7 degrees Fahrenheit, we’ll need to cut emissions by half before 2030, and go carbon-neutral by 2050, the report says. That gives us three decades to transform our energy production into something unrecognizable, with renewable energy galore combined with carbon capture techniques like the bolstering of forests, and maybe even sucking the stuff out of the atmosphere and trapping it underground. We’ll have to change our behavior as individuals, too. Meaning, we’re looking at unprecedented change, what is essentially the restructuring of civilization.

“The report has sent a very clear message that if we don’t act now and have substantial reductions in carbon dioxide emissions over the next decade, we are really making it very challenging to impossible to keep warming below 1.5 degrees,” said the IPCC’s Jim Skea at a press conference announcing the report, a massive survey by almost 100 authors (and 1,000 reviewers) citing 6,000 studies.

The 2015 Paris Agreement included the 1.5 goal at the urging of island nations, which rising seas are threatening to drown. The less ambitious—though still very daunting—goal is 2 degrees.

Which, according to this new report, would be far more ruinous. At 2 degrees, 10 million more people will be at risk of rising seas than at 1.5 degrees. That extra half a degree also means significantly larger populations will be exposed to water shortages. You’re looking at an ever greater loss of biodiversity, worsening storms, ever more people thrust into poverty, and relentlessly shrinking yields for essential crops like rice and maize and wheat.

Basically, a difference of just half a degree may not seem like much when you’re choosing what to wear for the day, but it’s going to make climate change far, far worse, a point this report drives home in exhaustive detail. “It shows that half a degree of global warming does matter and that limiting it to 1.5°C instead of 2°C would avoid several impacts, including increases in heatwaves and hot extremes in most inhabited regions, heavy precipitation in several regions, and droughts in some regions,” says Sonia Seneviratne, a climate change scientist at ETH Zurich. Plus, limiting warming would avoid certain irreversible changes related to sea level rise and the destruction of coral reefs.

“Even more importantly,” Seneviratne adds, “it shows that limiting global warming to 1.5°C is still physically possible and could be in principle achieved, although it requires rapid, far-reaching and unprecedented changes in all aspects of society.”

Still, the outlook is grim. The technological and social change the world needs dwarfs anything that’s come before in history. “It’s not a happy report,” says Thanu Yakupitiyage, spokesperson for the climate advocacy group 350.org. “They’re reporting on the real needs of the now. We are in the middle of the climate crisis.”

“At the end of the day, what we’re talking about is millions of lives at stake,” Yakupitiyage adds. “We’re already seeing the ways in which people are impacted by heat waves, by rising sea levels, by wildfires, by hurricanes.”

The Paris Agreement is a remarkable act of international cooperation to address climate change and these consequences of it, but the pledges made by individual nations are not enough to limit warming to 1.5 degrees, this report argues. It also makes clear that it’s not enough to promise that we’ll put more electric cars on the road, or mothball our coal energy plants, or that we’ll invest in more solar farms. Hitting that target will demand a massive rethinking of global energy consumption within a decade.

A bit of borderline rosy news here: While the world at large may be struggling to meet the ambition of the Paris Agreement, cities have been leading the way in cutting emissions, competing with each other to deploy technologies like electric cars on massive scales, but also sharing knowledge of what works and what doesn’t when it comes to fighting climate change. Consider that in 2016 alone, Los Angeles cut its emissions by 11 percent, the equivalent of yanking 700,000 cars off the road. All the while, its economy actually grew.

The IPCC report could be coming at a particularly convenient time. In December, leaders will gather in Poland for COP24, known more formally as the 24th Conference of the Parties to the United Nations Framework Convention on Climate Change. And let’s just say they won’tnot be talking about this new report.

Janos Pasztor, executive director of the Carnegie Climate Geoengineering Governance Initiative and former UN assistant secretary-general for climate change, predicts that meeting “will be a significant next step to see what governments actually say in the context of the climate negotiations about this report.”

The starkness of the report may also spark talk of more elaborate strategies for fighting climate change than cutting emissions. Scientists are also toying with the notion of geoengineering. This could entail carbon capture techniques or solar geoengineering to bounce the sun’s radiation back into space by spraying aerosols in the atmosphere or by brightening clouds.

“There will be some pressure from some corners to increasingly look at options like solar geoengineering,” says Pasztor. “That’s a fact of life. That doesn’t mean necessarily that we will have touse solar geoengineering, but if you want to prudently manage global climate risk, then it’s fair to say that one needs to look at all the options.”

Geoengineering, though, comes with a slew of potential problems. You might spray foam on the ocean surface to reflect light back into space, but that could also change the weather. And the issue with such solar radiation management, or SRM, is that even in the best case, it doesn’t address the underlying problem. “Once emitted, CO2 stays in the atmosphere for millennia,” says Seneviratne. “Any approach related to SRM only mitigates some of the symptoms of climate change, but not its root cause, which is the elevated CO2 concentrations.” That means issues like ocean acidification, which is inflicting wide-ranging harm on marine life, would remain unaddressed.

Again, we aren’t going to geoengineer our way out of this mess—cutting emissions is our number one priority. But as this new report makes abundantly clear, the disease we’ve unleashed on this planet is only getting worse, and we aren’t doing nearly enough to find the cure.