Arctic News: Did a Terminal Temperature Acceleration Event start in December 2024?
The shading indicates El Niño (June 2023 up to May 2024, pink), surrounded by ENSO-neutral conditions and a short, weak La Niña (all blue). Two trends are added based on these data (red dots). The linear trend (black) shows a steady, rapid rise. The non-linear trend (red) better follows variations such as El Niño and sunspots, and it indicates that a Terminal Temperature Acceleration Event may have started in December 2024 (in the area with the grey shading). [ click on images to enlarge ]The above comparison image illustrates that the use of a 1901-1930 base instead of the default Copernicus 1991-2020 base comes with an adjustment of the temperature anomaly of 0.91°C. Note that neither of these bases are pre-industrial. As discussed at the pre-industrial page, using pre-industrial as a base requires a further adjustment of as much as an additional 0.99°C, which would correspond with a total temperature anomaly for the year 2023 of as much as 2.47°C. The image below, created with NASA data through November 2024 while using a 1903-1924 custom base, illustrates that the monthly temperature anomaly has been more than 1.5°C above this base for 17 consecutive months (from July 2023 through November 2024). The red line shows a trend (2-year Lowess Smoothing) associated with recent data and the trend indicates that the anomaly is rising. Note that the 1903-1924 base is not pre-industrial. When using a genuinely pre-industrial base, anomalies such as the above-mentioned 1.89°C for February 2024 will exceed 2°C, as discussed at the pre-industrial page. The current La Niña is predicted to be weak and short-lived, as illustrated by the image below, from NOAA, with probabilities for an El Niño getting progressively higher in the course of 2025. Since a La Niña typically suppresses temperatures, the question arises as to what is causing the temperatures to keep rising rapidly. As the image below shows, temperature anomalies in November 2024 were particularly high in the Arctic. The 1951-1980 base for the above map is NASA's default base, but none of the bases used in the above images is pre-industrial. As said, anomalies from a pre-industrial base are higher. Mechanisms behind accelerated temperature rise Research led by Helge Goessling suggests that global warming itself is reducing the number of low clouds, resulting in less sunlight getting reflected back into space. “If a large part of the decline in albedo is indeed due to feedbacks between global warming and low clouds, as some climate models indicate, we should expect rather intense warming in the future,” Helge Goessling warns. A Terminal Temperature Acceleration Event could be occur soon due to a number of mechanisms, including: - a drop in albedo as a result of a reduction in lower clouds - a drop in albedo as a result of reduction in sea ice extent - El Niño developing in the course of 2025 - sunspots reaching a maximum in the current cycle (predicted to occur July 2025) - less ocean heat reaching deeper parts of the ocean as a result of slowing down of AMOC - reductions in sulfur aerosols combined with an increase in black carbon and brown carbon as civilization grinds to a halt The above mechanisms have been described in more detail recently in the post Double Blue Ocean Event 2025? Slowing down of AMOC could be causing more heat to accumulate at the ocean surface. Where the temperature of the (saline) ocean water rises above -1.8°C (28.7°F), the sea ice will melt away. Antarctic sea ice is melting from below and is getting very thin, as illustrated by the image on the right. The compilation of four images by the University of Bremen below illustrates the decline in Antarctic sea ice thickness from August 27, 2024, to November 28, 2024. North Atlantic (0-60°N 0-80°W) sea surface temperature anomalies vs 1882-2010 rose strongly in line El Niño in 2023. In 2024, temperature anomalies remained consistently high despite La Niña conditions. The North Atlantic sea surface temperature was 22.01°C on December 7, 2024, a record high for the time of year and 1.08°C above 1982-2010, as further illustrated by the image below. As discussed in earlier posts, Arctic sea ice has also become very thin, diminishing its capacity to act as a buffer that consumes ocean heat entering the Arctic Ocean from the North Atlantic. In September 2024, Arctic sea ice volume reached a new record low, as illustrated by the image below, adapted from the Danish Meteorological Institute, with markers for September (red) and April (blue) corresponding with the year's minimum- and maximum volume.
Two trends are added based on these data (red dots). The linear trend (black) shows a steady, rapid rise. The non-linear trend (red) better follows variations such as El Niño and sunspots, and it indicates that a Terminal Temperature Acceleration Event may have started in December 2024 (in the area with the grey shading). [ click on images to enlarge ]The above comparison image illustrates that the use of a 1901-1930 base instead of the default Copernicus 1991-2020 base comes with an adjustment of the temperature anomaly of 0.91°C. Note that neither of these bases are pre-industrial. As discussed at the pre-industrial page, using pre-industrial as a base requires a further adjustment of as much as an additional 0.99°C, which would correspond with a total temperature anomaly for the year 2023 of as much as 2.47°C. The image below, created with NASA data through November 2024 while using a 1903-1924 custom base, illustrates that the monthly temperature anomaly has been more than 1.5°C above this base for 17 consecutive months (from July 2023 through November 2024). The red line shows a trend (2-year Lowess Smoothing) associated with recent data and the trend indicates that the anomaly is rising.
