Some climate change activists oppose doom-and-gloom rhetoric. They know that, if we don’t reduce greenhouse gas emissions quickly, the planet will soon become more habitable to flesh-eating bacteria than for human beings. But focusing too much on that risk promotes widespread hopelessness, they argue. And without hope, there will never be action.

This logic is understandable in principle, but feels increasingly deluded in practice. The Trump administration has all but dismantled U.S. climate policy. Emissions are still rising globally, with no sign that the world’s fastest-growing emitters, notably China, America, and India, are slowing down. As the executive director of the International Atomic Agency tweeted on Monday:

We expect energy-related CO2 emissions will increase once again in 2018 after growing in 2017 pic.twitter.com/rb0Em2folC — Fatih Birol (@IEABirol) October 8, 2018

Also on Monday, the world’s most influential climate research body released a report stating we only have 12 years to stop global warming of more than 1.5 degrees Celsius above pre-industrial levels—the point at which irreversible sea level rise, widespread food shortages, and massive coral reef die-offs will start to occur.

Written by 91 researchers on behalf of the U.N Intergovernmental Panel on Climate Change, Monday’s report makes the case that allowing 1.5 degrees of warming is at least far better than allowing an increase of 2 degrees, which is the current goal of the Paris agreement. Only 70 to 90 percent of the world’s coral reefs would be wiped out under a 1.5 degree scenario, for example, but at 2 degrees almost all coral species would be gone. At 1.5 degrees, fisheries would only lose 1.5 million tons of fish per year, compared to more than 3 million tons at 2 degrees. Far fewer people would be exposed to malaria, dengue fever, and other diseases under a 1.5 degree scenario, and some low-lying island nations might not be wiped out.

Achieving this goal, however, requires rapid and massive global changes. Greenhouse gas pollution must be reduced 45 percent from 2010 levels by 2030—and then by 100 percent by 2050.