More bad news on climate change from MIT

James Lovelock’s prediction that the environment is past the tipping point, and that the human population will have collapsed by 80% by 2100 look increasingly likely to be accurate, given the data in a new report from MIT’s Centre for Global Change Science based on their Integrated Global System Model.

Their model, which is unique in that it incorporates data on human-activity—such as economic growth and energy use—as well as analyzing atmospheric, oceanic, and biological systems, suggests that global warming is likely to be twice as severe as previously thought. Their analysis is based upon running multiple scenario variations, giving probabilities of possible outcomes. After 400 runs, their model suggests that there is a 90 percent probability that temperatures will have risen 3.5 to 7.4 degrees Celsius by the end of the century. Their models suggest a very low probability of less than two degrees warming, which is generally agreed to be the point at which runaway warming starts due to positive feedback from various sources (such as reduction in albido and methane release.) These kinds of temperature changes are widely agreed to mean the catastrophic collapse of planetary ecosystems, and the total breakdown of current social and economic structures: see for example the Stockholm Networks Report.

“There is significantly more risk than we previously estimated,” according to Ronald Prinn, the co-director of the program. “This increases the urgency for significant policy action. There’s no way the world can or should take these risks.”

The latest article is available here (http://dx.doi.org/10.1175/2009JCLI2863.1), although this journal does not have Athens login. An older version can be downloaded here: http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt169.pdf

The report abstract is below:

The MIT Integrated Global System Model is used to make probabilistic projections of climate change from 1861 to 2100. Since the model’s first projections were published in 2003 substantial improvements have been made to the model and improved estimates of the probability distributions of uncertain input parameters have become available. The new projections are considerably warmer than the 2003 projections, e.g., the median surface warming in 2091 to 2100 is 5.2°C compared to 2.4°C in the earlier study. Many changes contribute to the stronger warming; among the more important ones are taking into account the cooling in the second half of the 20th century due to volcanic eruptions for input parameter estimation and a more sophisticated method for projecting GDP growth which eliminated many low emission scenarios. However, if recently published data, suggesting stronger 20th century ocean warming, are used to determine the input climate parameters, the median projected warning at the end of the 21st century is only 4.1°C. Nevertheless all our simulations have a much smaller probability of warming less than 2.4°C, than implied by the lower bound of the IPCC AR4 projected likely range for the A1FI scenario, which has forcing very similar to our median projection. The probability distribution for the surface warming produced by our analysis is more symmetric than the distribution assumed by the IPCC due to a different feedback between the climate and the carbon cycle, resulting from the inclusion in our model of the carbon-nitrogen interaction in the terrestrial ecosystem.