2020 was a year of incessant climatic events, from heat waves to forest fires and hurricanes, many of which scientists linked directly to human-induced climate change (SN: 27/08/20). Each event caused a huge toll on lost lives and damage. By early October, the United States alone had endured at least 16 climate or meteorological disasters that each cost more than $ 1 billion. The prices of the Delta, Zeta and Eta hurricanes at the end of the season could further increase the final balance of 2020 for such expensive disasters, setting a new record.
With the COVID-19 pandemic dominating the news, some of these events may already be gone in memory. Here, Science News takes a look at this year’s climate extremes.
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Australia's "black summer"
Forest fires that burned southeastern Australia between July 2019 and March 2020 burned approximately 11 million hectares and killed dozens of people. Climate change has made those devastating fires at least 30 percent more likely to occur, the researchers reported (SN: 3/4/20). The main reason: a prolonged and severe heat wave that burned the country in 2019 and 2020, which in itself has been exacerbated by climate change.
The intensity of Australia’s fires has produced some startling views. A particularly intense fire caused the formation of high clouds of pyrocumulonimbus that released hundreds of thousands of tons of smoke into the stratosphere (SN: 15/06/20).
A huge plume of smoke, enveloped in whirling winds, rose to a record 31 miles in the atmosphere, deep in the Earth’s ozone protective layer. While it’s not clear what chemical scars left, such a large plume of smoke has the potential to trigger ozone-depleting chemical reactions.
Lisa Maree Williams / Getty Images
The burning West
Forest fires recorded in the western United States have also produced heartbreaking images: furious flames, orange skies, destroyed houses, neighborhoods shrouded in pungent smoke (SN: 18/9/20). By mid-November, more than 9,200 fires in California had burned about 1.7 million acres, more than double the area burned in 2018, the state’s record year for fires. Meanwhile, Colorado has fought three of the largest wildfires in state history. Combined, those fires burned more than 219,000 acres.
The role of climate change in these flames is broad. From California to Colorado, rising temperatures due to climate change caused the snow to melt before spring, leading to drier vegetation for the summer. In California, that extremely dry vegetation combined with a heat wave that set the record prepared the landscape for wildfires (SN: 17/08/20).
Climate change is increasing the frequency of extreme weather conditions. California’s average heat and drought, both in summer and fall, have become more severe, drastically increasing the number of days a year prone to extreme weather conditions (SN: 8/27/20). Future climate change simulations are projected to increase drought for at least the next few decades, meaning 2020 fire records are unlikely to be maintained for long.
From January to July, Siberia was in the hands of a powerful heat wave that caused record temperatures (SN: 23/06/20), unprecedented forest fires in the Arctic and thawing of permafrost, which in turn could lead to collapse. of a fuel storage tank that flooded nearby rivers with diesel (SN: 01/07/20).
Denis Kozhevnikov / TASS / Getty Images
Such heat in Siberia – with temperatures of up to 38 ° C (100 ° Fahrenheit) – would be impossible without climate change (SN: 15/07/20). Human influence has made the heat wave at least 600 times more likely and possibly up to 99,000 times more likely, scientists reported. In addition, carbon dioxide caused the atmosphere by this year’s Arctic forest fires also broke the region’s previous record, set in 2019 (SN: 2/08/19). That CO2 can generate more warming and fires can also accelerate the thawing of permafrost, which could add more to the atmosphere another greenhouse gas, methane.
This year also saw the second lowest extent of Arctic sea ice. Meanwhile, a Manhattan-sized piece of the Canadian Milne ice shelf, nearly half of what had been the country’s last intact ice shelf, suddenly fell into the Arctic Ocean in August, carrying with it an ice observation station.
Back in April, scientists predicted that the Atlantic hurricane season, which runs from June 1 to November 30, would be busy, with about 18 named storms, compared to an average of 12 (SN: 16/04 / 20). In August, scientists increased their predictions to 25 (SN: 8/7/20). But 2020 has also exceeded those expectations: by mid-November there were 30 named storms, eclipsing a record set in 2005 (SN: 10/10/20).
Thomas B. Shea / Getty Images
It is difficult to link climate change to the number of storms that form in a given year. Very warm ocean waters, as in the Atlantic Ocean this year, encourage the formation of tropical cyclones. It is true that such warm waters are linked to climate change, as the surface ocean brings in excess heat from the atmosphere. But other factors are also involved in hurricane formation, including wind conditions, making it difficult to establish a link.
But there are established links between warming oceans and increasing hurricane intensity, as well as rainfall (SN: 13/09/18). The warm waters of the Atlantic have given a boost to the intense storms of the 2017 hurricane season, for example (SN: 9/28/18). Warm waters can also provide enough energy to give hurricanes an extra capacity to stay even after landing (SN: 11/11/20).
And, as the world saw in 2020, very warm ocean waters can also accelerate how quickly a storm strengthens, leading to dangerous, hard-to-predict, suddenly overloaded storms. This rapid intensification is defined as sustained wind speeds that increase at least 55 miles per hour in just 24 hours. 2020 saw this in abundance, with 10 Atlantic storms intensifying rapidly in the region’s bathing waters before touching down.