“It’s easy to focus on year-to-year variability,” said Bridget Siggers, a NASA oceanographer. “But it’s important to look at the trend: the last eight years have been the hottest on record.”
To calculate global temperatures, the two agencies pull data from weather stations around the world, as well as measurements taken from ships and boats at sea. Other groups, such as Berkeley Earth, a non-profit research organization, do the same thing in their own slightly different ways. But the analyzes are almost identical in their search. As you can see in the graph below, which compares the results of Berkeley Earth, NOAA, NASA and the other two groups in Europe, the global average temperature in 2021 may be lower than in 2020, but it is still rising.
One reason for the cooler temperatures in 2021 is probably La Nina, a band of cold water in the Pacific Ocean. It is the product of strong trade winds that rotate the oceans, pushing the upper layers of water toward Asia, causing deep, cold water to rush to the surface to fill the void. For example, it affects the atmosphere Jet stream changes Above and leading the United States More hurricanes In the Atlantic, the oceans themselves absorb heat from the atmosphere and cool things.
The Covid-19 epidemic may have an additional effect, but not in the way you might think. With the world locked down in 2020, low emissions skyrocketed, including Aerosol Which usually reflects some of the energy of the sun into space. “If you take them away, you clean the air, it’s a slight warming effect on the climate,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, while announcing the results at a news conference Thursday. But as economic activity returns in 2021, aerosol pollution is again contributing to that cooling effect. The 2021 temperature drop could be “probably due to a resumption of activity that creates aerosols in the atmosphere,” Schmidt said.
(Epidemic based Carbon dioxide reduction The production did not have a cooling effect. Human civilization produces so much planet-warming gas every year and it stays in the atmosphere for so long that the epidemic is not even registered as a blip.)