SOURCE: Cosmos Magazine
DATE: July 2, 2018
SNIP: Clouds are wispy evanescent things, beloved of poets and daydreamers. They may also determine whether civilisation as we know it survives the 21st century.
Depending on how clouds react to global warming, they could cool or cook the planet. But, so far, we haven’t been able to predict which way they will swing. That’s a big problem for our ability to prepare for what’s coming.
At issue is climate sensitivity, which measures how much the temperature changes if the amount of carbon dioxide (CO2) in the atmosphere doubles. In 2014 the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) estimated this number somewhere between 1.5 and 4.5°C. This huge range comes down almost entirely to the effect of clouds.
By amplifying warming or reining it in, clouds could make the difference between a 2°C increase – where sea levels rise a metre or more and deadly heatwaves are predicted – and a truly catastrophic 4.5°C – which, according to the IPCC, means widespread extinctions, global food supplies at risk and many parts of the planet too hot to live in.
[Fascinating article, I recommend reading the whole thing!]