Global Boiling Roulette: The Margin For Error Is Gone

In 2002, the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change designed the “Greenhouse Gamble” roulette wheels to depict the “probability of potential global warming over the next hundred years,” based on the latest scientific research. They compared the gamble of warming with and without an international agreement to reduce emissions through programs like the cap and trade system proposed by President Obama. Today, they released updated roulette wheels, reflecting how much worse the gamble has gotten:

The ‘No Policy’ Gamble (2002 v. 2009)
2002 2009
No Policy - 2002 No Policy - 2009
These wheels assume a scenario in which “no policy” action is taken to try to curb the global emissions of greenhouse gases. In the previous wheel the likelihood of exceeding 5°C was about 4%, but in the new wheels that likelihood is 57%.
MIT Joint Program on the Science and Policy of Global Change, 2009.

The ‘Policy Action’ Gamble (2002 v. 2009)
2002 2009
Policy - 2002 Policy - 2009
If greenhouse gas emissions are controlled to relatively low levels then the Earth systems feedbacks are much lower, but there is no longer any possibility of less than 1°C warming.
MIT Joint Program on the Science and Policy of Global Change, 2009.

The “policy” scenario reflects the establishment of mandatory policies to reduce emissions, such as building standards and cap and trade systems, that limit total carbon dioxide concentrations to 550 parts per million. However, as climate scientist Stefan Rahmstorf recently explained, even limiting warming to two degrees Centigrade cannot be considered safe, which is why there is a growing demand for policies that limit CO2 concentrations to 350 ppm.

The new roulette wheels were initially released in February 2009, with a reset color scale that made a direct comparison between the old and new scenarios difficult. The Wonk Room thanks the Global Change Program for taking our suggestion to update the wheels.

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