Impacts of Climate and Environmental Change, Adaptation, and Feedbacks on the Climate System

Characterizing the impacts of climate and environmental change in terms relevant to the general public and to decision makers at varying levels -- from local and regional resource managers to national policymakers and international negotiators, who must decide how aggressively to mitigate greenhouse gases -- is one of the most difficult challenges faced by the research community. hurricaneThe Joint Program seeks to provide an integrated analysis of how climate and environmental change affects natural and managed systems, the economic consequences of those effects, the role of adaptation, and the resulting feedbacks on emissions and mitigation.

How does the world add up the impacts of climate change on ecosystems, human health, agriculture, recreation opportunities, and hard to define risks, in a meaningful way to determine how much mitigation should be undertaken? Or is that even a meaningful question? To approach the task, some balancing of costs and benefits must occur, but it is probably an ongoing conversation rather than a definitive final number (Informing climate policy given incommensurable benefits estimates).

Analytically, it is useful to integrate market impacts of environmental change into the same framework we use to assess mitigation costs. The response of farmers to existing weather variation provides one line of evidence on the potential impacts of climate on agriculture. But experimental evidence and mechanistic modeling of plant response to changing environmental conditions provides another line of evidence. Putting this work together, recognizing that impacts are global and that markets and market prices will be affected -- and will change the comparative advantage of different regions -- is necessary, even as climate change is only one of the environmental stresses agriculture and crops may face.

Built systems of coastal regions are vulnerable, but with significant capital already invested in their infrastructure, the economics of investing further to enact protection may be favorable. That may be less true of natural systems, low lying coastal systems, and estuaries that extend for hundreds or thousands of miles -- protection of those areas, even if possible, would change them. How to evaluate protection costs and decisions raises important questions. The energy system will also be affected by climate change -- a warmer climate may entail overall greater expenditure on energy. And a lurking issue for climate impacts is hydrology and water resources. There are important feedbacks on the atmosphere directly and indirectly through biogeochemistry (A global land system framework for integrated climate-change assessments). How precipitation patterns might change with climate is one of the more difficult prediction questions. Integrating water resources into climate feedbacks and climate impacts is an important direction for the Program's current research.