2020 was effectively tied with 2016 for the hottest year on record, as global warming linked to greenhouse gas emissions showed no signs of letting up. Siberia and the Arctic were among the hottest regions. The heat fueled wildfires that pumped even more carbon dioxide into the atmosphere. Temperatures in the Siberian town of Verkhoyansk reached a record 100 degrees Fahrenheit in June, more than 30 degrees above average. The heat was also felt in Europe, which had its warmest year ever and experienced blistering heat waves as late as September. Surface cooling of the tropical Pacific Ocean, which started during the second half of the year, did little to offset the heat elsewhere. In central South America, warming and drought resulted in wildfires burning a quarter of the vast Pantanal wetland. In the United States, the warming was most significant in the Northeast and Southwest. Drought spread to […]