Large atmospheric waves present risk to global food production

10 December 2019

Oxford University’s Kai Kornhuber and colleagues have discovered jet stream patterns that could affect up to a quarter of global food production.

In a new study published today in Nature Climate Change, Kai Kornhuber from the University of Oxford and Colombia University’s Earth Institute and international colleagues show how specific wave patterns in the jet stream strongly increase the chance of co-occurring heatwaves in major food producing regions of Northern America, Western Europe and Asia. Their research finds that these simultaneous heatwaves significantly reduce crop production across those regions, creating the risk of multiple harvest failures and other far-reaching societal consequences.

Unexplored vulnerability

Lead author Kornhuber comments: ‘Co-occurring heatwaves will become more severe in the coming decades if greenhouse gases are not mitigated. In an interconnected world, this can lead to food price spikes and have impacts on food availability even in remote regions not directly affected by heatwaves.

‘We found a 20-fold increase in the risk of simultaneous heatwaves in major crop producing regions when these global scale wind patterns are in place,’ explains lead author Kornhuber. ‘Until now this was an underexplored vulnerability in the food system. We have found that during these events there actually is a global structure in the otherwise quite chaotic circulation. The bell can ring in multiple regions at once and the impacts of those specific interconnections were not quantified previously.’

Risks for global food production

Western North America, Western Europe and the Caspian Sea region are particularly susceptible to these atmospheric patterns that get heat and drought locked into one place simultaneously where they then affect crops production yields.

‘Normally low harvests in one region are expected to be balanced out by good harvests elsewhere but these waves can cause reduced harvests in several important breadbaskets simultaneously, creating risks for global food production,’ adds co-author Dim Coumou from the Institute for Environmental Studies at VU Amsterdam.

A warming climate

Elisabeth Vogel, co-author from Melbourne University adds: ‘During years in which two or more summer weeks featured the amplified wave pattern, cereal crop production was reduced by more than 10% in individual regions, and by 4% when averaged across all crop regions affected by the pattern.’

Radley Horton from the Lamont-Doherty Earth Observatory at Colombia University points out: ‘If climate models are unable to reproduce these wave patterns, risk managers such as reinsurers and food security experts may face a blind spot when assessing how simultaneous heat waves and their impacts could change in a warming climate.’

Kornhuber concludes that a thorough understanding of what drives this jet stream behaviour could ultimately improve seasonal predictions of agricultural production at the global scale and inform risk assessments of harvest failures across multiple breadbasket regions.

Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions by Kai Kornhuber et al, Nature Climate Change

Image © NASA Earth Observatory/NASA GSFC Global Modeling and Assimilation Office