Research priorities for global food security under extreme events.

Extreme events, such as those caused by climate change, economic or geopolitical shocks, and pest or disease epidemics, threaten global food security. The complexity of causation, as well as the myriad ways that an event, or a sequence of events, creates cascading and systemic impacts, poses significant challenges to food systems research and policy alike. To identify priority food security risks and research opportunities, we asked experts from a range of fields and geographies to describe key threats to global food security over the next two decades and to suggest key research questions and gaps on this topic. Here, we present a prioritization of threats to global food security from extreme events, as well as emerging research questions that highlight the conceptual and practical challenges that exist in designing, adopting, and governing resilient food systems. We hope that these findings help in directing research funding and resources toward food system transformations needed to help society tackle major food system risks and food insecurity under extreme events.

Extreme rainfall deficits were not the cause of recurring colonial era famines of southern Indian semi-arid regions.

Using information contained in the eighteenth to twentieth century British administrative documents, preserved in the National Archives of India (NAI), we present a 218-year (1729-1947 AD) record of socioeconomic disruptions and human impacts (famines) associated with 'rain failures' that affected the semi-arid regions (SARs) of southern India. By mapping the southern Indian famine record onto long-term spatiotemporal measures of regional rainfall variability, we demonstrate that the SARs of southern India repeatedly experienced famines when annual rainfall reduced by ~ one standard deviation (1 SD), or more, from long-term averages. In other words, 'rain failures' listed in the colonial documents as causes of extreme socioeconomic disruptions, food shortages and human distress (famines) in the southern Indian SARs were fluctuations in precipitation well within the normal range of regional rainfall variability and not extreme rainfall deficits (≥ 3 SD). Our study demonstrates that extreme climate events were not necessary conditions for extreme socioeconomic disruptions and human impacts rendered by the colonial era famines in peninsular India. Based on our findings, we suggest that climate change risk assessement should consider the potential impacts of more frequent low-level anomalies (e.g. 1 SD) in drought prone semi-arid regions.

Hydrological linkages between different water resources from two contrasting ecosystems of western peninsular India: a stable isotope perspective.

Water scarcity is a leading concern in both developing and developed nations. Coping with water scarcity requires an understanding of various hydrological processes that act upon precipitation, surface and groundwater at a local scale. We measured isotopic signatures of several water samples from two distinct ecosystems, i.e. tropical savanna in the West and the warm semi-arid region in the East lying across the Western Ghats mountain range, India, to understand the hydrological processes. The results show that the hydrogeological conditions strongly influence the isotopic characteristics of water of different resources, governed by different hydrological processes, even at close spatial scales. Based on the local evaporation lines of different water resources within a particular ecosystem, it is inferred that the water resources are well linked at one site, but have diverse connectivity at the other site. Further, the isotopic signatures of all the water resources are systematically affected by the monsoon precipitation. In addition, anomalously depleted isotopic signatures are observed during known hailstorm events. This may provide a means to trace their signature in the existing water resources.