It’s Not CO2 Causing Warming, It’s Reduced Cloud Cover
Global cloud cover has dropped over the past decade and, according to a recent study from researchers in Germany, the warming surge in the last few years is closely associated with that decline, which allows more solar radiation to be absorbed by the surface
The big question, and one to which no one currently claims to know the answer, is what is driving what.
If ‘greenhouse gas’ warming caused the cloud cover to drop resulting in yet more warming, it means the climate has a strong positive feedback and future warming will be greater than expected runaway man-made disaster etc.
But if something else like ocean circulation cycles caused the cloud cover to drop, that drove the recent warming, and CO2 isn’t to blame.
The clouds will eventually come back and future warming will be less than expected, or they won’t but it’s nothing to do with us. For obvious reasons it’s a topic we plan to watch closely. Will the alarmists do the same, or refuse to look up?
The new paper (non paywalled-version here) presents data from satellite and other monitoring systems that measure the amount of solar radiation being absorbed at the surface, the amount of low cloud cover around the world, and other climate measures.
In the following chart the top panel shows Absorbed Solar Radiation the middle line shows total cloud cover and the bottom line shows low cloud cover, while the grey bars mark El Nino episodes:
As cloud cover drops, more solar energy is absorbed at the surface. And the increase in absorbed solar energy since 2015 has been about 1.7 Watts per square meter, which is small in absolute terms (total incoming solar radiation at the top of the atmosphere being roughly 340 W/m2 about 70 percent of which, or 238, gets absorbed at the surface).
This is large in comparison to the contribution alleged to come from ‘greenhouse gases’. As Roger Pielke Jr notes (quoting James Hansen), it is equivalent to the forcing from about 140 ppm CO2, which is more than the entire increase over the past 100 years.
Thus, stunningly, the thinning low cloud cover over the past 10 years has had as big an effect on the climate as 100 years of CO2 emissions. Surely it matters.
The new study doesn’t jump to any conclusions about causation. It explains why ocean cycles may be to blame, but also why there might be an unknown feedback connecting previous warming to cloud cover.
There isn’t enough data at this point to say one way or the other. (Editor’s note: PSI would argue there is but one ‘greenhouse gas’; water vapour, and CO2 has zero effect on temperature)
The rival theories predict different future warming paths so in another few years we should start to figure out which theory is correct.
Watch this space.
See more here climatediscussionnexus.com
Please Donate Below To Support Our Ongoing Work To Defend The Scientific Method
PRINCIPIA SCIENTIFIC INTERNATIONAL, legally registered in the UK as a company 
incorporated for charitable purposes. Head Office: 27 Old Gloucester Street, London WC1N 3AX.
Trackback from your site.
VOWG
| #
I want to have less cloud cover where I live. This spring it has been wet and cloudy constantly. The warming lie has to stop.
Reply