The world’s climate experts are clear: The planet is almost certain to warm far beyond what they’d hoped, with just a thin path to avert a host of terrifying outcomes for humanity and the animal kingdom alike.
The U.N. Intergovernmental Panel on Climate Change released its major climate synthesis report on Monday, a yearslong effort to combine scientists’ understanding of our changing world. The document finds the planet is likely to cross a dangerous and forewarned temperature threshold in the next decade. But it also maintains hope that the worst effects of climate change may be averted.
Here are five key takeaways from the report:
1. Climate change has already wreaked havoc on the planet.
The IPCC report finds climate change is unequivocally here. The planet has already warmed an average of 1.1 degrees Celsius above pre-industrial levels, altering ecosystems worldwide. The warmer world has impacted food and water security, led to the extinction of hundreds of species, caused mass mortality events and led to the irreversible retreat of glaciers and rise in sea levels. Extreme weather events are increasing in intensity and severity, with some areas of the world facing undue levels of damage and loss.
An estimated 3.3 billion to 3.6 billion people live in areas that are highly vulnerable to climate change, with the largest impacts felt by many low-income nations in Africa, Asia and Central and South America.
2. Every bit of warming matters.
Every region in the world is projected to face increases in climate hazards in the near future, the IPCC report finds, threatening entire ecosystems and human society around the globe. Those threats include heat-related mortality events, an increase in disease, flooding risks and biodiversity loss, among many others.
Those risks, however, increase with every increment of global warming and will compound and cascade on top of each other the warmer the planet gets.
“They are higher for global warming of 1.5°C than at present, and even higher at 2°C,” the report says. “With further warming, climate change risks will become increasingly complex and more difficult to manage.”
3. The impacts of climate change are and will continue to be severe.
The food production web and fisheries around the globe will see sharp drops in productivity that expand dramatically in higher warming scenarios. The heat and humidity risk to human health in a large band along the equator will increase dramatically, with some regions seeing hundreds of days a year under severe temperatures in high-warming scenarios.
Many of those impacts, including sea level rise, are now unavoidable. But the IPCC notes that if the world fails to act “the likelihood and impacts of abrupt and/or irreversible changes in the climate system, including changes triggered when tipping points are reached, increase.”
4. The warmer the world, the more animal species at serious risk.
Without adaptation, climate change will dramatically and irreversibly damage the world. The risk of species loss is great at 1.5 degrees C of warming, but at higher levels of warming entire sectors of the planet will see huge chunks of biodiversity face potentially dangerous temperature conditions.
As climate scientist Katherine Hayhoe notes, those risks will be felt keenly by ocean species that are already suffering (like the Great Barrier Reef) and animals that live in already warm tropical zones.
5. There is a window to act, but it’s small and getting smaller.
The extent at which future generations will experience a warmer world depends on decisions made now or in the very near future, the IPCC report warns.
Limiting warming to 1.5 degrees C or 2 degrees C requires “rapid, deep and in most cases immediate greenhouse gas emission reductions.” The world has not committed to anything close to that so far, and currently implemented policies will see global warming levels far higher than scientists hope.
Doing so would require the world to quickly phase out and roll back oil and gas projects and invest trillions each year in clean energy and climate mitigation measures, three to six times more than the planet’s governments and businesses already spend.
“The 1.5°C limit is achievable,” United Nations Secretary-General António Guterres said Monday. “But it will take a quantum leap in climate action.”