Climate Letter #1123

A new study does the math (and the chemistry) of how deforestation affects global warming.  This was a monumental type of study, and quite some bit of the information produced is either highly unfamiliar or downright surprising—and possibly controversial.  The ultimate conclusion is that if you remove all of Earth’s forests the net effect would be an addition of 0.8C to mean global temperature, an amount that is not included in other models.  Most of that gain would be due to the elimination of certain volatile compounds given off by tropical rainforests, which currently have a considerable cooling effect.  Their preservation can thus be seen as crucially important, as much so as eliminating fossil fuel burning.  Northern forests are different.  Surprisingly, once everything is considered, their elimination would help to cool the planet!  Everything is explained in the study, in a head-spinning sort of way, and I have included a link to it, which has open access.  Apart from a few puzzling complications much of it is readable and quite informative.
Tropical deforestation also affects the rainfall rate for nearby cities.  One of the largest cities in the world that is directly in line for this effect is Sao Paulo, Brazil.  Three years ago it had a close call, similar to that of Cape Town today except not for the same reason.  Now the warming flags are coming out again.
–Another story, published last November in the Guardian, adds more depth to this city’s plight:
How the UK has reduced its CO2 emissions by cutting back coal.  This post from Carbon Brief has a great chart of UK coal consumption back to 1858, peaking at 221 million tons in 1956.  Now it almost gone, bringing CO2 emissions all the way back to where they were in 1890 because the substitutes are so much cleaner.  Now we need to see a similar change in the path followed by China, only quicker.
A look at some of the worst consequences of what we have already done and keep doing.  The author of this piece is not properly identified but the website is managed by solid scientists who probably approve of the content and the message.  James Hansen’s views on superstorms and sea level rise are not easy to explain and do not get much exposure.  With all that is happening in the Arctic and along the US northeast coast this is a good time to bring them up.  Methane, by the way, has risen by more than 1000 ppb in the last 150 years, as you can see, which is equal to a bit over one part per million on the regular CO2 scale.  But a methane molecule is around 86 times more powerful than a CO2 molecule on a day-by-day basis when it comes to trapping heat.  Is its increase conceivably doing more damage right now than generally accounted for?
–The link between the “crazy” Arctic warmup this winter and the harsh storm systems further south is getting much  attention from scientists:
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