1/
Gavin Schmidt trying to explain "why 2023 turned out to be the warmest year in possibly the past 100,000 years"
"For the past nine months, mean land and sea surface #temperatures have overshot previous records each month by up to 0.2 °C — a huge margin at the planetary scale. A general warming trend is expected because of rising #GreenhouseGasEmissions, but this sudden heat spike greatly exceeds predictions made by statistical climate models that rely on past observations" [1]
2/
"#climate conditions one year ago would have suggested that a spell of record-setting warmth was unlikely.
Early last year, the tropical Pacific Ocean was coming out of a three-year period of #LaNiña [...] #ElNiño — the inverse of La Niña — causes the eastern tropical Pacific Ocean to warm up" setting in only in the second half of 2023.
"The observed #temperature #anomaly has not only been much larger than expected, but also started showing up several months before the onset of El Niño" [1]
3/
"However, starting last March [2023], sea surface temperatures in the North Atlantic #Ocean began to shoot up. By June, the extent of #SeaIce around #Antarctica was by far the lowest on record. Compared with the average ice cover between 1981 and 2010, a patch of sea ice roughly the size of Alaska was missing. The observed temperature anomaly has not only been much larger than expected, but also started showing up several months before the onset of #ElNiño" [1]
4/
The "2023 #temperature #anomaly has come out of the blue, revealing an unprecedented #KnowledgeGap perhaps for the first time since about 40 years ago [...] If the anomaly does not stabilize by August — a reasonable expectation based on previous #ElNiño events — then the world will be in uncharted territory" [1]
[1] Schmidt, G., 2024. Climate models can’t explain 2023’s huge heat anomaly — we could be in uncharted territory. Nature 627 (8004), 467. https://doi.org/10.1038/d41586-024-00816-z
5/
Updated visualisation of the daily #SeaSurfaceTemperature (SST):
https://climatereanalyzer.org/clim/sst_daily/
(2023-2024 trends highlighted on the diagram exported from the URL above, see "License and Citation" section: "Climate Reanalyzer content is licensed under a #CreativeCommons Attribution 4.0 International License" https://creativecommons.org/licenses/by/4.0/ )
Data from #NOAA Optimum Interpolation SST (#OISST: https://www.ncei.noaa.gov/products/optimum-interpolation-sst ) - from latitude 60°S to 60°N, global scale.
See also @ZLabe
https://fediscience.org/@ZLabe/112123321294788366
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Just for reference on the #OrderOfMagnitude at play (details may be subect to adjustment), a famous (https://scholar.google.com/scholar?cluster=3044384235203044484 ) outline from 1982 on #atmosphere vs. #ocean dynamics, by Adrian E. Gill:
"#Water is very much denser than #air" [...] "The density contrast between air and water means that the mass of the ocean is very much greater than (270 times) that of the atmosphere" [2]
"The large difference in mass between air and water also implies a large difference in #heat capacity" [2]
7/
"[...] a mere 2.5-m depth of #water has the same heat capacity per unit area [...] as the whole depth of the #atmosphere. In other words, the #heat required to raise the #temperature of the atmosphere by 1 K can be obtained by changing the temperature of 2.5 m of water by the same amount" [2]
[2] Gill, A.E., 1982. Transfer of properties between atmosphere and ocean. In: Atmosphere-ocean dynamics, Elsevier, pp. 19-38. https://doi.org/10.1016/S0074-6142(08)60027-3
Daniele de Rigo