Is this not very convenient that just when COP28 is taking place a new research paper is published on November 30 and gets a lot of attention!
A lot of hot air and wild speculation!
First the facts: CO2 is a life essential atmospheric trace gas. It is currently measured at 412 parts per million (ppm) or 0.04% in the atmosphere.
They claim this new property of atmospheric CO2 was never discovered before despite several decades of intensive research!
It appears this new claim is based on climate models. Well, it well known that these climate models are junk! We still know very little about the very complex climate!
Further, a doubling of the CO2 concentration is assumed to have a 25% effect. Well it took from 1960 - 2020 (or 60 years) to increase this concentration by about 38% (see chart below).
From today's AAAS ScienceAdvisor:
"There’s nothing more fundamental to understanding global warming than the greenhouse effect of carbon dioxide (CO2). Transparent to incoming sunlight, CO2 absorbs infrared heat coming off the Earth’s surface; add more of it to the atmosphere, and the planet’s surface warms. And until recently, the strength of this effect was thought to scale linearly with the CO2 in the air.
However, new work in the most recent issue of Science shows that the strength of CO2 depends on the climate it is in. It’s long been known that increasing CO2 cools the less-dense stratosphere, the placid realm above the weather. By studying climate models, researchers have now shown that as this cooling increases, the overall strength of CO2 heat-capturing ability at the surface effectively increases, as the increased heat emissions from the stratosphere crowd out those from CO2 lower down.
The finding doesn’t really change predictions for future warming, as the most up-to-date climate models have already factored this effect in, even if they didn’t understand it yet. But researchers often use simpler models to simulate ancient climates—when swings in CO2 have been even larger than the present day—and by missing the scaling nature of CO2, those analyses could miss major drivers. And on the upside, though this effect means that the carbon dioxide added to the air now leads to more warming than it would have a century ago, it also means that geoengineering schemes to release sunlight-reflecting particles could be more effective than thought by heating the stratosphere and reducing CO2’s strength."
From the editor's summary and abstract:
"Editor’s summary
The effect of increasing the concentration of atmospheric carbon dioxide (CO2) on global average surface air temperature might be expected to be constant. However, H. He et al. found that this is not the case. Doubling the atmospheric CO2 concentration increases the impact of any given increase in CO2 by about 25%, owing to changes induced in the climatological base state. The more anthropogenic CO2 emissions raise the atmospheric CO2 concentration, the more serious the consequences will be. ...
Abstract
When evaluating the effect of carbon dioxide (CO2) changes on Earth’s climate, it is widely assumed that instantaneous radiative forcing from a doubling of a given CO2 concentration (IRF2×CO2) is constant and that variances in climate sensitivity arise from differences in radiative feedbacks or dependence of these feedbacks on the climatological base state. Here, we show that the IRF2×CO2 is not constant, but rather depends on the climatological base state, increasing by about 25% for every doubling of CO2, and has increased by about 10% since the preindustrial era primarily due to the cooling within the upper stratosphere, implying a proportionate increase in climate sensitivity. This base-state dependence also explains about half of the intermodel spread in IRF2×CO2, a problem that has persisted among climate models for nearly three decades."
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