As reported by the New York Times, the IPCC report makes clear that “a hotter future . . . is now essentially locked in.” This hotter future, even if limited to 1.5ºC—the target threshold under the Paris Agreement—will have irreversible global impacts such as “[n]early 1 billion people worldwide could swelter in more frequent life-threatening heat waves. Hundreds of millions more would struggle for water because of severe droughts. Some animal and plant species alive today will be gone. Coral reefs, which sustain fisheries for large swaths of the globe, will suffer more frequent mass die-offs.”
Here are a few of the key takeaways in the IPCC report:
It is unequivocal that human influence has warmed the atmosphere, ocean and land.
- Each of the last four decades has been successively warmer than any decade that preceded it since 1850.
- Human influence has warmed the climate at a rate that is unprecedented in at least the last 2000 years.
- Observed warming is driven by greenhouse gas emissions from human activities such as the extraction and combustion of fossil fuels including coal, natural gas and oil.
The scale of recent changes across the climate system as a whole and the present state of many aspects of the climate system are unprecedented over many centuries to many thousands of years.
- In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years, and concentrations of methane and nitrous oxide were higher than at any time in at least 800,000 years.
- Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years.
Human-induced climate change is already affecting many weather and climate extremes in every region across the globe.
- Projected changes in extremes are larger in frequency and intensity with every additional increment of global warming.
- Many changes due to past and future greenhouse gas emissions are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level.
- Global surface temperature will continue to increase until at least the mid-century under all emissions scenarios considered. Global warming of 1.5ºC and 2ºC—the target thresholds we must meet to avoid the worst outcomes of a changing climate—will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades.