"Humanity is waging war on nature," Guterres said. "This is suicidal."
The global temperature in 2020 is on track to end about 1.2 degrees Celsius warmer than the end of 1800s, dangerously close to the 2-degree Celsius cap scientists have warned against hitting before conditions in much of the world become unlivable, according to a report by the World Meteorological Organization.
On Dec. 12, the U.N. is hosting a virtual climate summit in France on the fifth anniversary of the Paris agreement. Pledges have been made by more than 100 countries to avoid adding more heat-trapping gases to the atmosphere than trees and technology can remove, a promise about which Guterres expressed optimism.
Both Chinese President Xi Jinping and U.S. President-elect Joe Biden have pledged to strive for net-zero emissions.
On Monday, Biden and Guterres spoke about the need for a strengthened partnership between the U.S. and U.N. on urgent issues, including confronting the threat of climate change and advancing sustainable development.
Guterres said Wednesday that the world can not curb emissions "without U.S. leadership."
The Associated Press contributed to this report.