Will America be a desert by 2100? Or Africa, India or China, for that matter?
Chances are, according to MIT projections, that global median surface temperature will rise by 9.4oF (5.2oC) by 2100, unless there will be rapid and dramatic action on global warming.
The wheel on the right depicts the study's estimate of the range of probability of potential global temperature rise by 2100 if no policy is enacted on curbing greenhouse gas emissions.
The wheel on the left assumes that aggressive policy is enacted, and projects a lower rise.
The projections show rises ranging up to 13.3oF (7.4oC), based on probabilities revealed by 400 simulations.
Even the worst-case scenario in the study may actually understate the problem, because the model does not fully incorporate positive feedbacks that can occur, such as large-scale melting of permafrost in arctic regions and subsequent release of large quantities of methane.
To illustrate the magnitude of such feedbacks, I have added three images that I earlier discussed in comments under Global Warming - Red Alert!
A recent study estimates that some 1672 petagrams (billion metric tons) of carbon is trapped in arctic permafrost, pictured in the above image. This is roughly equivalent to a third of all the carbon in the world's soils and twice as much as is in the atmosphere.
Secondly, a UK Met Office study find that a 4oC rise within 100 years would kill 85% of the Amazon rain forest. Loss of the rain forests will come not only with dramatic loss in biodiversity, it will also transform what now still is a huge carbon sink (see image below) into a net contributor of carbon emissions, further fueling global warming.
Finally, I've added an edited version below of an image, courtesy of New Scientist, showing what the world would look like before the end of this century, if global temperatures rose 4oC.
Without action, anthropogenic CO2 emissions will persist in the atmosphere for many millennia, as suggested by a recent study.
So, will America be a desert by 2100, perhaps filled with solar panels to power the equipment of the few people still alive on Earth? Or, can we get our act together and implement a comprehensive response to global warming, such as described in this Global Warming Action Plan.
What's your view? Feedback on all this is appreciated, feel encouraged to make comments below.