This is just appalling.
A new study by MIT's Center for Global Change Science attempts to account for policy action to reduce carbon outputs on climate change. In this report, the model analyzed scenarios in which policies were adopted to reduce carbon output strongly, moderately, or not at all.
The most comprehensive modeling yet carried out on the likelihood of how much hotter the Earth's climate will get in this century shows that without rapid and massive action, the problem will be about twice as severe as previously estimated six years ago - and could be even worse than that.
Climate change odds much worse than thought
The study will be published in this month's issue of the American Meteorological Society's Journal of Climate. CGCS Director Dr. Ronald Prinn, co-author of the report, dryly notes that regarding global warming, it is important "to base our opinions and policies on the peer-reviewed science."
The study analyzed a range of possible outcomes based on fluctuations in many different variables - including active steps to reverse anthropogenic climate change, and estimated the probability of each outcome. The results are disheartening. The median probability of surface warming - meaning half of the outcomes are lower, half higher - is 5.2 degrees Celsius by 2100.
Only six years ago, the MIT model's median projected increase was only 2.4 degrees. The study predicts a 90% probability of a global increase in the range of 3.5 to 7.4 degrees.
A three degree rise in global temperature has already been identified as a tipping point for devastating climate-related changes: droughts in some areas, flooding in others; disruptions in the crop cycle, leading to famine; outbreaks of disease; rising sea levels; more violent storms; the disappearance of glaciers and rain forests.
The study's authors used a novel approach to illustrate the chances we are taking by not acting forcefully to reverse climate change:
To illustrate the range of probabilities revealed by the 400 simulations, Prinn and the team produced a "roulette wheel" that reflects the latest relative odds of various levels of temperature rise. The wheel provides a very graphic representation of just how serious the potential climate impacts are.
"There's no way the world can or should take these risks," [CGCS Director Ronald] Prinn says. And the odds indicated by this modeling may actually understate the problem, because the model does not fully incorporate other positive feedbacks that can occur, for example, if increased temperatures caused a large-scale melting of permafrost in arctic regions and subsequent release of large quantities of methane, a very potent greenhouse gas. Including that feedback "is just going to make it worse," Prinn says.
Scared yet? I sure am. Dr. Prinn's pronouncement makes A Siegel's excellent diary today on the American Clean Energy and Security Act of 2009, 16 Times Louder even more timely.