Global temperatures in March 2020 were the second warmest on record, helping to start spring off just as abnormally warm as winter ended. 

In 2019, air temperatures over the Arctic were the second-warmest on record, continuing a string of 6 years that have been warmer than all other periods in the historic record dating back to 1900.

During active hurricane eras, a persistent zone of high vertical wind shear along the U.S. East Coast provides protection from rapidly intensifying hurricanes. With high emissions, that shear is projected to relax.  

Global atmospheric carbon dioxide reached 405.0 parts per million (ppm) in 2017, a new record high. In the 1960s, the global growth rate of atmospheric carbon dioxide was roughly 0.6 ppm per year. Over the past decade, however, the growth rate has been closer to 2.3 ppm per year.

Using measurements taken worldwide, scientists estimated that 2015’s global average carbon dioxide concentration was 399.4 parts per million (ppm), a new record high. At Mauna Loa Observatory in Hawai’i, where atmospheric carbon dioxide has been recorded longer than anywhere else in the world, the annual average carbon dioxide concentration was 400.8—also a new record, and a new milestone.