Climate Change And Hydrologic Instability In Yemen

Abstract:

Yemen is one of the most food insecure nations in the world. Its agriculture is strongly dependent on soil moisture that is heavily influenced by surface temperature and annual precipitation. We examine observations of rainfall and surface temperature and find that the rainfall, which exhibits strong interannual variability, has seen a moderate downward trend over the last 35 years while surface temperature has seen a very significant rise over the same period. Yemen has high vulnerability and low resilience to these climate changes stemming from many geopolitical and socioeconomic factors. The threshold of resilience has been crossed as Yemen is embroiled in chaos and conflict. We examine the relationship between climate change and agricultural and water insecurity using observed data and the Noah land surface model. We further used atmospheric reanalyses to explore the atmospheric teleconnections that affect the anomalous regional circulation. According to these investigations the robust surface temperature increase over recent decades, expected to continue under climate change, has strongly depleted the soil moisture. This drying of the soil exacerbated the acute hydrologic insecurity in Yemen, stemming predominantly from unsustainable groundwater use, and was likely a contributing factor to the ongoing conflict. We show that during naturally occurring dry years and under climate change this region experiences anomalous dry air advection from the northeast and that these regional circulation changes appear to be linked to tropical sea-surface temperature forcing and to the Northern Hemisphere midlatitude circulation. These results are an important example of the emerging influence of climate change in hydrologically insecure regions.