MIT Joint Program on the Science and Policy of Global Change co-director and TEPCO professor of atmospheric science Ron Prinn was recently interviewed on his latest publication released today in the Proceedings of the National Academy of Sciences. The report, “Development and Application of Earth System Models,” focuses on the importance of Earth System Models in studying climate change. It is based on a lecture Prinn gave at the National Academy of Sciences Sackler Colloquium last year (watch the speech here).
Below is a transcript of the interview:
Q: Why do we need Earth System Models?
A: In laboratory science, we have the luxury of running “control” experiments in which selected conditions that would otherwise influence the “main” experiment are omitted. In the case of our environment, the influencing conditions come from humans. Because we do not have another earth without human influence to serve as a “control,” we often cannot directly measure the impacts of human development on the environment. So we form computer models of the combined natural and human systems, compare the models with observations, and then apply the models as “numerical control” experiments. Our specific earth system model – MIT’s Integrated Global System Model (IGSM) – is so unique because it combines the human system with the natural system to see how the two systems impact each other for the purpose of improving our understanding of both systems and informing policy decisions. The IGSM is in fact a “framework” of linked sub-models of varying complexity with the choice of the sub-models being governed by the issues being addressed; uncertainty studies dictate use of the most computationally efficient models, whereas studies of specific scenarios allow use of the more complex but computationally demanding sub-models.
Q: What is the value of integrated Earth System Models like the IGSM, as opposed to other approaches, for those making decisions about climate mitigation and adaptation?
A: Applied, for example, to the climate issue, the IGSM framework allows us to determine, in a self-consistent way, the probabilities of various amounts of climate change, the relationship between greenhouse gas reduction targets and temperature changes, and the uncertainty in the costs of various proposed policies. The IGSM framework also enables integrated assessments of the economic and environmental implications of proposed new low emission energy technologies. In making these analyses, we are able to help decision-makers compare the value of various mitigation policies, energy technologies, and adaptation strategies in lowering the risks to society. We can also assess the costs for stabilization of greenhouse gases at various levels, and how these costs can be justified by the expected benefits from the avoided damages.
Q: What can the MIT IGSM tell us about our climate and energy future?
A: In this paper, I outline just some of the ways we’ve used the full IGSM framework, or the relevant parts of it, in the past. These uses include the examination of the effect of different greenhouse gas stabilization targets on forecasts of the odds of various amounts of temperature, precipitation, sea-level, and sea-ice change, and of the costs of these stabilization policies. Also, the relationship between stabilization targets and the future loss of the ability of the oceans to slow warming by absorbing heat and carbon dioxide has been examined. The Kyoto Protocol uses a CO2-only strategy to reduce emissions, and our work with the IGSM shows that a multi-gas control strategy greatly reduces the costs of fulfilling the Kyoto Protocol with little difference between the two strategies in mitigating climate and ecosystem impacts. Assessments of the substantial impact of air pollution on human health costs and carbon uptake by land vegetation have been investigated. Another example stems from our work in examining the consequences of renewable energy at large scales – like wind power and bio-fuels. Our studies of wind power show that offshore wind turbines can cause a surface cooling over the installed regions due to an increase in turbulent mixing caused by the turbines. Additionally, while wind power is an important renewable resource for our future, it suffers from significant intermittency caused by large seasonal wind variations over most major offshore sites. We’re expanding on this research to measure wind power intermittency over land in the U.S. Stay tuned for that study. Learn more about our offshore study here.
To read "Development and Application of Earth System Models," please click here.
Learn more about Dr. Ron Prinn here.