Four degrees C by 2050
October 15th, 2009 by Jim JustTwo degrees C is already gone as a target. Four degrees C is definitely possible. . . This is the biggest challenge in our history.
That’s what Chris West of the University of Oxford’s UK Climate Impacts Programme told participants at a climate conference last week.
A four-degree C overall increase means a world where temperatures will be two degrees warmer in some places, 12 degrees and more in others, making them uninhabitable.
It is a world with a one- to two-metre sea level rise by 2100, leaving hundreds of millions homeless. This will head to 12 metres in the coming centuries as the Greenland and Western Antarctic ice sheets melt, according to papers presented at the conference in Oxford.
Four degrees of warming would be hotter than any time in the last 30 million years.
John Schellnhuber, director of the Potsdam Institute for Climate Impact Research and one of the world’s preeminent climate scientists, told the conference about a recent briefing with officials from the Barack Obama administration. He told them that the U.S. must reduce its emissions from its current 20 tonnes of carbon per person average to zero tonnes per person by 2020 to have even a chance of stabilizing the climate around two degrees C. To put it more bluntly, the U.S. must quit carbon entirely within 10 years if the world is to have any chance of avoiding catastrophic climate change.
The response from Obama’s representatives? Schellnhuber’s findings were “not grounded in political reality” and that “the Senate will never agree to this”.
As Schellnhuber told the conference, the laws of physics trump politics:
Political reality must be grounded in physical reality or it’s completely useless.
Even a two-degree rise means that most of the world’s coral reefs will be lost, large portions of the ocean will become dead zones, mountain glaciers will largely vanish along with many other ecosystems – and risking crossing a “tipping point” where feedback loops cause global warming to rapidly accelerate. Already, scientists are predicting the Arctic Ocean will be ice-free in summer within 20 years -with much of that decrease coming within the next 10 years. As the Arctic Ocean plays a vital role in the world’s climate, the changes will lead to a dramatically warmer world. The Arctic will turn blue rather than white during the summer as the ice melts. Heat from sunlight will be absorbed by the darker-colored ocean water rather than being reflected by white ice, further accelerating the effect of global warming.
Schellnhuber was at another climate conference at New Mexico’s Santa Fe Institute recently. There he talked about his just-released study Solving the climate dilemma: The budget approach which lays out the science behind the imperative that the United States must halt all emissions by 2020, China by 2035, and the world as a whole by 2050.
Schellnhuber cautions that even that “brutal” timeline would not guarantee staying within the 2 C target. It would merely give humanity a two out of three chance of doing so.
As he points out:
Worse odds than Russian roulette.