Earth just wrapped up one of its hottest years on record, something it's done for eight years in a row now.
Independent analyses of the past year's climate data, released Thursday by NASA and the National Oceanic and Atmospheric Administration, found that 2021 tied with 2018 for the sixth warmest year since modern record keeping began in 1880. It's a sign of human-caused climate change, fueled in large part by burning fossil fuels for energy.
"Science leaves no room for doubt: Climate change is the existential threat of our time," NASA Administrator Bill Nelson said in a Thursday release. "Eight of the top 10 warmest years on our planet occurred in the last decade, an indisputable fact that underscores the need for bold action to safeguard the future of our country -- and all of humanity."
NASA said that Earth's average temperature in 2021 was approximately 1.1 degrees Celsius (about 1.9 degrees Fahrenheit) warmer than the average in the late 19th century, when the Industrial Revolution began. In the 2015, member countries of the United Nations set a goal of limiting global warming to Celsius above preindustrial levels. Late last year, at the UN's annual climate conference, , that goal was reaffirmed, but it'll take drastic reductions in carbon emissions to meet that goal.
China, the US and the European Union emit the most greenhouse gasses today, with the US and Russia responsible for the highest emissions per capita, according to the Center for Climate and Energy Solutions. The US accounts for the most greenhouse gas emissions during the period from the middle of the 18th century until 2017, according to Our World in Data.