Arctic temperature soared to an unprecedented 100 degrees in 2020, scientists confirm

"This new Arctic record is one of a series of observations reported to the WMO Archive of Weather and Climate Extremes that sound the alarm bells about our changing climate," said WMO Secretary General Petteri Taalas in a statement.

Last year, 2020, was a record-breaking year across the globe, ranking in the top three warmest years on record. The Arctic, which has been warming more than twice as fast as the global average, experienced an abnormally hot January-to-June time period that year. During those six months, monthly temperatures in Siberia were as high as 18.5 degrees Fahrenheit (10 degrees Celsius) above average.

The warm temperatures helped fuel a large number of wildfires in the region, which started earlier than normal in 2020. Around half of the fires burned through areas with thawed peat soil - decomposed organic matter abundant in carbon. Fires on peatlands can release large amounts of carbon into the atmosphere. In June and July, fires in Arctic Russia released more carbon dioxide into the atmosphere than any entire previous fire season since records began in 2003.

Shortly after the temperature spike, researchers determined Siberia's anomalously warm months, as well as Verkhoyansk's record-breaking temperature in June, were virtually impossible without human-induced climate change. Climate change made the prolonged heat from January to June at least 600 times more likely; such extended heat in the region would occur less than once in 80,000 years without the observed increase in temperatures.

To verify the June record, an international committee of experts conducted a thorough analysis of data, including from European weather forecast models. The group also evaluated information from the Russian meteorological agency on the type of equipment used, quality-checks, calibration of the instrument, monitoring techniques and data from surrounding stations.

"Verifying records of this type is important in having a reliable base of evidence as to how our climate's most extreme extremes are changing," said Blair Trewin from Australia's Bureau of Meteorology and a member of the evaluation committee, in a statement.

The record also prompted the WMO to create a climate category for such extreme events in the region - "highest recorded temperature at or north of 66.5⁰, the Arctic Circle," encompassing both polar regions. The committee also included the official coldest temperature at or north of the Arctic Circle and Northern Hemisphere: minus-93.3 degrees (minus-69.6 Celsius) on Dec. 22, 1991, in Greenland. Verkhoyansk also holds the record for one of the coldest temperatures in the Northern Hemisphere at minus-90 degrees (minus-67.8 Celsius) in February 1892.

The WMO stated that greater extremes will likely in occur again in the Arctic region. While 2021 did not experience all-time highs, warm and dry conditions prompted one of the worst fire seasons in Siberia. Wildfires in Siberia were greater than all other blazes in the world at the time, including those in Greece, Turkey and the western United States. Smoke transited the North Pole. The Copernicus Climate Change Service of the European Union reported carbon emissions from fires in northeastern Siberia during the summer were record-setting "at more than double previous years."

The record-high Arctic temperature came in the same year that Antarctica posted its highest temperature ever observed of 65 degrees on Feb. 6, which the WMO confirmed this summer.

The confirmation of these records serves as a "snapshot" of our warming climate, the WMO said. The agency is also verifying extreme temperature readings of 129.9 degrees (54.4 degrees Celsius) in both 2020 and 2021 in Death Valley, Calif. and a new European record of 119.8 degrees (48.8 degrees Celsius) in Sicily this past summer.

"The WMO Archive of Weather and Climate Extremes has never had so many ongoing simultaneous investigations," Taalas said in a statement.