Risk of crop failure due to compound dry and hot extremes estimated with nested copulas

Abstract

Abstract. The interaction between co-occurring drought and hot conditions is often particularly damaging to crop's health and may cause crop failure. Climate change exacerbates such risks due to an increase in the intensity and frequency of dry and hot events in many land regions. Hence, here we model the trivariate dependence between spring maximum temperature and spring precipitation and wheat and barley yields over two province regions in Spain with nested copulas. Based on the full trivariate joint distribution, we (i) estimate the impact of compound hot and dry conditions on wheat and barley loss and (ii) estimate the additional impact due to compound hazards compared to individual hazards. We find that crop loss increases when drought or heat stress is aggravated to form compound dry and hot conditions and that an increase in the severity of compound conditions leads to larger damage. For instance, compared to moderate drought only, moderate compound dry and hot conditions increase the likelihood of crop loss by 8 % to 11 %, while when starting with moderate heat, the increase is between 19 % to 29 % (depending on the cereal and region). These findings suggest that the likelihood of crop loss is driven primarily by drought stress rather than by heat stress, suggesting that drought plays the dominant role in the compound event; that is, drought stress is not required to be as extreme as heat stress to cause similar damage. Furthermore, when compound dry and hot conditions aggravate stress from moderate to severe or extreme levels, crop loss probabilities increase 5 % to 6 % and 6 % to 8 %, respectively (depending on the cereal and region). Our results highlight the additional value of a trivariate approach for estimating the compounding effects of dry and hot extremes on crop failure risk. Therefore, this approach can effectively contribute to design management options and guide the decision-making process in agricultural practices.

A framework for complex climate change risk assessment

“…97 For example, crop loss has been attributed more to drought stress rather than heat stress in this heatwave's compound drought and extreme heat. 102,103 This highlights how interactions of drivers can have different interaction effects. Further, agricultural losses in Northern and Central Europe were partially compensated by a ''water seesaw'' event among hazards where drought in Northern and Central Europe was correlated with higher rainfall in Southern Europe, such that favorable yield conditions in Southern Europe prevented greater market volatility and price spikes for consumers.…”

Identifying meteorological drivers of extreme impacts: an application to simulated crop yields

“…Northern Hemisphere winter wheat yields were simulated using the Agricultural Production Systems sIMulator (APSIM)-Wheat model (Zheng et al, 2014), which is a process-based model incorporating wheat physiology, water and nitrogen processes under a wide range of growing conditions. It was previously used for field (Li et al, 2014), regional (Asseng et al, 2013) and global-scale (Rosenzweig et al, 2014) wheat studies. A grid-point-specific sowing date was used based on Sacks et al (2010).…”

Reply on RC2

“…Previous research shows that the specific contributions of temperature and precipitation anomalies to drought are difficult to isolate (Zscheischler and Seneviratne, 2017;Vogel et al, 2019). Furthermore, the negative yield effects of high temperatures are associated with water stress and can be mitigated by irrigation (Frieler et al, 2017;Vogel et al, 2019;Ribeiro et al, 2020). However, for Germany studies show that heat was more harmful than drought during sensitive growing stages in Germany in the past (Lüttger and Feike, 2018;Trnka et al, 2014).…”