CAREER: Characterizing the Uncertainty in Projections of Climate Change in the Semi-Arid Tropics Based on the Moist Static Energy Framework

Anthropogenic climate change is expected to affect vulnerable 'less-developed' societies with greater severity, yet it is in the tropics where these societies are located that projections of change, especially of regional precipitation change, suffer from the greatest uncertainty. The goals of this project are: (1) to advance understanding of the physical processes that cause uncertainty in model projections in semi-arid regions of the tropics such as the African Sahel, and (2) to exchange knowledge with community organizations and public schools in the Columbia University neighborhood, a historically African-American neighborhood with a sizable West African/Sahelian immigrant population.

The research component adopts the moist static energy framework to guide scientific advancement through three project phases: (a) diagnosis of the divergence in model projections of regional rainfall change, (b) characterization of the interaction of the observed diurnal cycle of precipitation with cloud-radiative processes at a Sahelian site, and (c) investigation of the sensitivity of model projections to parameterizations of convection, clouds and radiation. The first two phases rely solely on statistical data analysis, of model output and observations respectively. The third requires running and analyzing model simulations.

The educational component revolves around two phases: (a) consolidation of an interdisciplinary graduate-level course on 'Climate change in Africa' through outreach aimed at discussing perceptions of change and implications of scientific uncertainty for policy and practice in community forums, (b) curricular development on the science of climate change from an environmental justice perspective to teach climate change to under-represented students in the Earth sciences, and involve them in research.

The investigator plans to reconcile and transcend contrasting views of regional variability and change, which have in the past emphasized local land-atmosphere interaction or remote oceanic influences. In the moist static energy framework, these influences can be directly related to the local energy budget, hence to perturbations imposed by anthropogenic emissions of greenhouse gases and other pollutants. This process-based characterization of the causes of uncertainty connects to basic physical principles whose workings can be observed daily, and aids in the discussion of scientific results with the broader community, including high-school students. In sum, with the support of graduate, undergraduate and high school students, this project will advance climate change research, improve effective communication of its results to the broader community, and begin to educate a generation of environmentally conscious citizens.

Broader impacts of the proposed research are primarily educational and in the potential to reduce the uncertainty in projections of climate change in semi-arid regions of the tropics, which has implications for policy and for practice.