No mention of atmospheric trace gases here, only clouds. The researchers suggest global warming itself is reducing the number of low clouds, thus lowering the albedo of the Earth. Then we’re off into alarmist runaway feedback loops again, but behind that it could be one step closer to accepting the high significance of cloud variations in regulating the temperature of the planet, as opposed to minor trace gases.
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2023 set a number of alarming new records, claims Phys.org.
The global mean temperature also rose to nearly 1.5 degrees Celsius above the preindustrial level, another record.
Seeking to identify the causes of this sudden rise has proven a challenge for researchers. After all [Talkshop comment – unscientific words], factoring in the effects of anthropogenic influences like the accumulation of greenhouse gases in the atmosphere, of the weather phenomenon El Niño, and of natural events like volcanic eruptions, can account for a major portion of the warming.
But doing so still leaves a gap of roughly 0.2 degrees Celsius, which has never been satisfactorily explained.
A team led by the Alfred Wegener Institute puts forward a possible explanation for the rise in global mean temperature: our planet has become less reflective because certain types of clouds have declined. The work is published in the journal Science.
“In addition to the influence of El Niño and the expected long-term warming from anthropogenic greenhouse gases, several other factors have already been discussed that could have contributed to the surprisingly high global mean temperatures since 2023,” says Dr. Helge Goessling, including increased solar activity, large amounts of water vapor from a volcanic eruption, or fewer aerosol particles in the atmosphere.
But if all these factors are combined, there is still 0.2 degrees Celsius of warming with no readily apparent cause.
Dr. Goessling from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI), is the main author of the study.
“The 0.2-degree-Celsius ‘explanation gap’ for 2023 is currently one of the most intensely discussed questions in climate research,” says Goessling.
In an effort to close that gap, climate modelers from the AWI and the European Center for Medium-Range Weather Forecasts (ECMWF) took a closer look at satellite data from NASA, as well as the ECMWF’s own reanalysis data, in which a range of observational data is combined with a complex weather model.
In some cases, the data goes back to 1940, permitting a detailed analysis of how the global energy budget and cloud cover at different altitudes have evolved.
“What caught our eye was that, in both the NASA and ECMWF datasets, 2023 stood out as the year with the lowest planetary albedo,” says co-author Dr. Thomas Rackow from the ECMWF.
Planetary albedo describes the percentage of incoming solar radiation that is reflected back into space after all interactions with the atmosphere and the surface of the Earth.
. . .
What they found: without the reduced albedo since December 2020, the mean temperature in 2023 would have been approximately 0.23 degrees Celsius lower.
One trend appears to have significantly affected the reduced planetary albedo: the decline in low-altitude clouds in the northern mid-latitudes and the tropics. In this regard, the Atlantic particularly stands out, i.e., exactly the same region where the most unusual temperature records were observed in 2023.
“It’s conspicuous that the eastern North Atlantic, which is one of the main drivers of the latest jump in global mean temperature, was characterized by a substantial decline in low-altitude clouds not just in 2023, but also—like almost all of the Atlantic—in the past 10 years.”
The data shows that the cloud cover at low altitudes has declined, while declining only slightly, if at all, at moderate and high altitudes.
Full article here.
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Image: Cumulus clouds over the Atlantic Ocean [credit: Tiago Fioreze @ Wikipedia]
via Tallbloke’s Talkshop
December 6, 2024 at 03:57AM
Iowa Climate Science Education 