Dzuds, droughts, and livestock mortality in Mongolia

The country's semi-nomadic culture and harsh climate make it vulnerable to episodes of anomalously cold winters and droughts. These events are particularly detrimental to livestock, causing high mortality rates and are known locally as 'dzud' or 'zud'. The term is unique to pastoral communities in Central Asia and can be caused by a combination of summer drought, heavy snowfall, and high winds in concurrence with extremely low winter temperatures. Mongolia's livestock numbers rose significantly following the collapse of the Soviet Union in the 1990s, indirectly increasing the vulnerability of herders and livestock to climate extremes. Four mass mortality events have occurred since 1999, resulting in significant economic hardship and poverty for many Mongolians. The exceptionally harsh winter of 2009-2010 led to a 20% decline in livestock numbers, with some areas experiencing a complete loss of animals. The Mongolian index-based livestock insurance program was established in 2005 to provide financial solutions to herders facing climate-related livestock deaths. The program uses past population statistics to inform about livestock loss risk and determine exceedance thresholds for payouts. However, the program's preparedness faces challenges, including the lack of scientific understanding of the history of past events and the forcing mechanisms behind them, such as climate variability and change. A study examining mortality in 21 Mongolian aimags between 1955 and 2013 found that livestock mortality is most strongly linked to winter temperatures, with incidences of mass mortality being most likely to occur due to anomalously cold winters. Prior summer drought and precipitation deficit were also found to be important triggers for mortality, intensifying the effect of upcoming winter temperatures on livestock. A density-independent mortality model based on winter temperature, summer drought, summer precipitation, and summer potential evapotranspiration explained 48.4% of the total variability in the mortality dataset. The probability of exceedance of 6% mortality in any given year is 26% over the 59-year period between 1955 and 2013. Understanding the linkages between climate, droughts, dzuds, and livestock mortality is vital for Mongolians to adapt to and mitigate the impacts of extreme climate on their livestock and livelihoods. The study's findings highlight the need for a more comprehensive approach to index-based insurance programs, incorporating scientific understanding of the history of past events and the forcing mechanisms behind them.