The World Was Cooler In 2021 Than 2020. That’s Not Good News. – Slashdot


2021 was actually cooler than 2020, points out Wired science journalist Matt Simon. So is that good news?

No.
One reason for cooler temperatures in 2021 was likely La Niña, a band of cold water in the Pacific. It’s the product of strong trade winds that scour the ocean, pushing the top layer of water toward Asia, causing deeper, colder waters to rush to the surface to fill the void. This in turn influences the atmosphere, for instance changing the jet stream above the United States and leading to more hurricanes in the Atlantic. The sea itself cools things off by absorbing heat from the atmosphere.

The Covid-19 pandemic may have had an additional influence, but not in the way you might think. As the world locked down in 2020, fewer emissions went into the sky, including aerosols that typically reflect some of the sun’s energy back into space. “If you take them away, you make the air cleaner, then that’s a slight warming impact on the climate,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, during a Thursday press conference announcing the findings. But as economic activity ramped back up in 2021, so did aerosol pollution, contributing again to that cooling effect. The 2021 temperature drop “may be possibly due to a resumption of activity that produces aerosols in the atmosphere,” Schmidt said…

Today’s findings are all the more alarming precisely because 2021 managed to overcome these cooling effects and still tally the sixth-highest temperature. And while global temperatures were cooler in 2021 than the year before, last year 1.8 billion people lived in places that experienced their hottest temperatures ever recorded, according to a report released today by Berkeley Earth. This includes Asian countries like China and North and South Korea, African nations like Nigeria and Liberia, and in the Middle East places like Saudi Arabia and Qatar. “We talk a lot about global average temperatures, but no one lives in the global average,” says Zeke Hausfather, a research scientist at Berkeley Earth. “In fact most of the globe, two-thirds of it, is ocean, and no one lives in the ocean — or very few people at least. And land areas, on average, are warming much faster than the rest of the world….”

Last summer in western Canada and the US Pacific Northwest, absurd temperatures of over 120 degrees Fahrenheit killed hundreds of people. According to Hausfather, the heat wave in Portland, Oregon, would have been effectively impossible without climate change, something like a once-every-150,000-year event.
It’s a fascinating article, that looks at trouble spots like Antarctica’s sea level-threatening “Doomsday Glacier” and a warming Gulf of Mexico, mapping the intensity of 2021’s temperature anomalies along with trend graphs for both global temperatures and land-vs-ocean averages. It touches on how climate change is impacting weather — everything from rain and floods to wildfires and locusts — as Bridget Seegers, an oceanographer at NASA, points out that “Extremes are getting worse. People are losing their homes and their lives and air quality, because the wildfires are bad.”

But Seegers somehow arrives at a positive thought. “There’s just a lot going on, and I want people to also feel empowered that we understand the problem. It’s just this other issue of deciding to take collective action….

“There’s a lot of reasons for optimism. We’re in charge. This would be a lot worse if we’re like, ‘Oh, it’s warming because we’re heading toward the sun, and we can’t stop it.'”

(Thanks to Slashdot reader Sanja Pantic for sharing the article!)



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