The global average temperature for December 2023 through February 2024 was by far the highest of record. The Arctic was not quite that mild, as about 30 percent of the Earth poleward of 60°N had a colder than normal winter, so overall the winter was “merely” the fifth warmest. Nonetheless, the rate of warming is so rapid that the Arctic average temperature winter this season was higher than any winter prior to 2010.
Temperatures
Figure 1 shows the winter 2023-24 average temperature departure from normal in and around the Arctic based on ERA5 reanalysis. A large portion of the central and eastern Canadian Arctic was exceptionally warm. The December through February average temperature in Nunavut, Canada was the second highest in the past 75 years: only winter 2009-10 was milder. Most of the Arctic Ocean as well as parts of Alaska’s North Slope and western Siberia had a top three warmest winter. The Nordic Arctic had another colder than normal season, as did Iceland, parts of the Greenland Ice Sheet and central Siberia. A comparatively small area in eastern Siberia, north of the Sea of Okhotsk, had a top-three coldest winter season (since 1949-50).
The lowest non-Greenland Ice Sheet temperature this winter was apparently -58.8°C (-74°F) at Yurty, Sakha Republic on New Years Day 2024. Yurty is near the Indigirka River, 125km northwest of Oymyakon (800km northeast of Yakutsk). In the North American Arctic, an automated station on the Kanuti Flats, southeast of Allakaket Alaska, reported an apparently reliable temperature of -53.3°C (-64°F) on January 28; at communities, the lowest report temperatures were from Chicken, Alaska at -52.2°C (-62°F) and Old Crow, Yukon at -51.7°C (-61°F). For more details on the Alaska cold snap see my post here.
Figure 2 plots the time series for winter average temperature in the Arctic since 1949-50. For the Arctic as a whole this winter was the mildest since 2017-18 and the fifth mildest winter on record. The trend is obvious: in the 21st century, every winter except for 2012-13 has been milder than any winter was 1950-2000. The Arctic lands were not as mild relative to normal as the Arctic overall, with this winter the 11th warmest since 1950.
Precipitation
Winter 2023-24 precipitation (liquid in melted snow plus any rain) was highly variable around the Arctic as seen in Fig. 3. A large area in the Canadian Arctic had one of the wettest winters in the past 75 years. Portions of southwest Alaska and the Russian far northeast also had a “top three” wettest winter. Inland areas in the Russian far northeast had very low precipitation, but only a small area in Greenland snuck into the '“driest three since 1949-50” category.
Arctic-wide winter precipitation has increased significantly in the past 75 year, but this winter was not notably wet, with the December through February total right at the 1991-2020 baseline normal.
El Niño and the Arctic
Winter temperatures in the Arctic overall are not strongly correlated with the El Niño-La Niña cycle (for historical reasons known as “ENSO”: El Niño-Southern Oscillation), with the marked exceptions of northwest North America and the Kamchatka Peninsula/Sea of Okhotsk region in northeastern Asia. Figure 4 shows the correlation of winter average temperatures over the 50 seasons 1973-74 to 2022-23 with NOAA’s Oceanic Niño Index (ONI), a widely used measure of El Niño-La Niña strength. Areas in the warm colors tend to be warmer in El Niño winters and cooler in La Niña winters. Areas in cool colors tend to be cooler in El Niño and warmer in La Niña winters. Winter average temperatures in areas in white or very faint shades don’t show a favored response to ENSO.
The ONI for 2023-24 December through February was the fourth highest for December through February season in the past 50 years, falling solidly into the “strong El Niño” category. Comparing Fig. 1 to Fig 4. shows that the favored El Niño response worked out over Southeast Alaska and British Columbia as well as the Kamchatka Peninsula/Sea of Okhotsk region. However, for much of mainland Alaska and the Yukon Territory, where higher than than normal temperatures are favored in winters during El Niño, the expected response did not pan out. For the Yukon Territory, this was the coolest winter season relative to normal during an El Niño in the past 50 years, and at Fairbanks, Alaska, this was the first winter to average even slightly cooler than normal during El Niño since 1968-69. I’ll explore this in more depth in an upcoming newsletter.
Side note: this post was later than I’d have preferred due to server troubles with the ECMWF’s Climate Data Store, from where I retrieve ERA5 data.
The heat around the pole doesn't bode well, nor the temperatures in Canada. Boreal forest and arctic ice loss that sequester so much carbon are becoming a disturbing issue. I'm not optimistic about fire season on Canada again this year. Thanks for the update.