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Wednesday, April 17, 2013

Jim Hansen: Can Earth Become Like Venus?

Jim Hansen explains in Exaggeration, Jumping the Gun, and the Venus Syndrome that it would take a very long time for Earth to reach a state similar to our neighboring twin planet Venus. But, things could easily get bad enough to preclude habitability long before that:

If we should "succeed" in digging up and burning all fossil fuels, some parts of the planet would become literally uninhabitable, with some time in the year having wet bulb temperature exceeding 35°C. At such temperatures, for reasons of physiology and physics, humans cannot survive, because even under ideal conditions of rest and ventilation, it is physically impossible for the environment to carry away the 100 W of metabolic heat that a human body generates when it is at rest. Thus even a person lying quietly naked in hurricane force winds would be unable to survive. Temperatures even several degrees below this extreme limit would be sufficient to make a region practically uninhabitable for living and working.

The picture that emerges for Earth sometime in the distant future, if we should dig up and burn every fossil fuel, is thus consistent with that depicted in "Storms" -- an ice-free Antarctica and a desolate planet without human inhabitants. Although temperatures in the Himalayas may have become seductive, it is doubtful that the many would allow the wealthy few to appropriate this territory to themselves or that humans would survive with the extermination of most other species on the planet. At least one sentence in "Storms" will need to be corrected in the next edition: even with burning of all fossil fuels the tropical ocean does not "boil". But it is not an exaggeration to suggest, based on best available scientific evidence, that burning all fossil fuels could result in the planet being not only ice-free but human-free.

This is why it is urgent that we immediately replace all burning of fossil fuels with alternative energy. By the time the majority realizes this and demands action may very well be too late.