Abstract: Throughout Central America, smallholder farmers build their livelihoods on rain-fed agriculture which is highly sensitive to seasonal variations in temperature and precipitation. Recent hydroclimatic shifts precipitated by global changes in this complex yet narrow climatic region are not well understood. This study examines how to best quantify and communicate these changes in light of sparse observations, constrained potential to assess the skill of global climate products, and a limited understanding of the complex conditions that determine which metrics are most relevant for stakeholders. Our work has approached these questions from multiple angles. We adapted prior definitions of the Central American Dry Corridor and newly delineated those regions for Central America and Mexico in order to focus on water-limited regions that are important for rain-fed agriculture and particularly vulnerable to further drying.  We examine the performance for several reanalysis and satellite-based global climate data products as compared to the observation-based GPCC precipitation dataset. These datasets were then used to evaluate the magnitude and spatial extent of hydroclimatic shifts and changes in aridity and drought over the last four decades and through the end of the century on multiple spatial and temporal scales. A key focus of the analysis is on the timing of the rainy season and the occurrence and magnitude of the mid-summer drought. We followed community-based participatory approaches to learn which metrics matter to stakeholders and strengthen locally-led climate mitigation and adaptation efforts. A climate app ('NicaAgua') has been developed by our transdisciplinary team for local capacity building.

Bio: Iris T. Stewart is a Professor in the Department of Environmental Studies and Sciences at Santa Clara University. Her research studies the impact of climate variability and change on water resources using models, and spatial & statistical analysis. She also uses a community-based approach to connect science findings to issues of justice in the distribution of environmental benefits and burdens. Professor Stewart-Frey is interested in interdisciplinary research and has collaborated with scholars from the fields of engineering, geography, ecology, and economics. Her research seeks to explain (i) recent and future impacts of climate warming on water resources, stream flows and temperatures, (ii) the impact of climate change across Central America and determinants for food and water security in the region, (iii) the role of climate, agriculture, laws, and infrastructure on water justice in Northern California, and (iv) the unequal distribution of environmental benefits and burdens in Silicon Valley with a focus on green spaces and roadway emissions. Dr. Stewart received her Ph.D. in Hydrogeology from Stanford University in 2001. Before joining the Santa Clara faculty, she was a NOAA postdoctoral fellow at Scripps Institution of Oceanography. Dr. Stewart is the co-coordinator of the Environmental Justice and the Common Good Initiative and teaches courses in water resources, water security, spatial analysis, community-based research, and earth systems.