How Clouds Hold the Key to Global Warming
November 02, 2020
One of the biggest weaknesses in computer climate models – the very models whose predictions underlie proposed political action on human CO2 emissions – is the representation of clouds and their response to global warming. The deficiencies in computer simulations of clouds are acknowledged even by climate modelers. Yet cloud behavior is key to whether future warming is a serious problem or not.
Uncertainty about clouds is why there’s such a wide range of future global temperatures predicted by computer models, once CO2 reaches twice its 1850 level: from a relatively mild 1.5 degrees Celsius (2.7 degrees Fahrenheit) to an alarming 4.5 degrees Celsius (8.1 degrees Fahrenheit). Current warming, according to NASA, is close to 1 degree Celsius (1.8 degrees Fahrenheit).
Clouds can both cool and warm the planet. Low-level clouds such as cumulus and stratus clouds are thick enough to reflect 30-60% of the sun’s radiation that strikes them back into space, so they act like a parasol and cool the earth’s surface. High-level clouds such as cirrus clouds, on the other hand, are thinner and allow most of the sun’s radiation to penetrate, but also act as a blanket preventing the escape of reradiated heat to space and thus warm the earth. Warming can result from either a reduction in low clouds, or an increase in high clouds, or both.
https://www.scienceunderattack.com/blog/2020/11/2/how-clouds-hold-the-key-to-global-warming-64
