A new paper, lead authored by Australian Randall Donohue of CSIRO, could provide a new clue as to why global temperatures have stood still for almost a decade and a half.
The paper finds that there was a more or less straight line relationship between the 14% increase in CO2 in the atmosphere between 1982 and 2010 and the increase in foliage of 11% due to the CO2 fertilisation effect.
This ought to surprise no-one, but it does give an insight into negative feedbacks to CO2 induced warming.
Most of the really hot weather that we experience is driven by desert and grasslands. On the east coast of Australia that means that the summer winds that come west over the inland plains can produce temperatures in the 40s, while the easterlies and south-easterlies from the ocean don’t produce anything much over 30.
Now, if the area of desert is shrinking, then the heating effect has to be modified, and the paper does note that woody weeds (aka trees) are tending to invade and supplant the grasslands.
That means more shade, and more uptake of energy to build and maintain trees, leading to less energy being released back into the atmosphere for warming.
And there could be another negative effect on temperature. A paper by Sheil and Murdayarso hypothesises that forests create rain by effecting atmospheric circulation. While I’m not endorsing this claim, if it is true, then greater forestation equals higher rainfall, which also equals lower temperature, and faster vegetation growth.
This is all pretty significant stuff, and it makes you wonder why, when I search Google News using Randall Donohue’s name, not one result was from an Australian media organisation.