Climate change may increase the risk that key food-producing regions of the world — such as Eastern Europe and North America — see simultaneous harvest failures.
This is the warning of researchers from the US and Germany, who studied the impact of global warming on weather extremes that can affect crop yields.
The occurrence of simultaneous extreme weather events in different regions of the world can have combined consequences that are greater than the sum of their parts, the team said.
Combined episodes, they added, could lead to spikes in food prices, conflict and undernutrition in countries that rely on exports.
The findings, the team conclude, highlight the importance of reducing emissions to combat climate change and modelling the impact of extreme conditions in the future.
The study was undertaken by climate physicist Dr Kai Kornhuber of New York’s Columbia University and his colleagues.
In their paper, the team explained: “Simultaneous harvest failures across major crop-producing regions are a threat to global food security.
“Concurrent weather extremes driven by a strongly meandering jet stream could trigger such events, but so far this has not been quantified.”
Jet streams are cores of strong winds that blow from west to east around five to seven miles above the Earth’s surface.
Changes to the path of the jet streams induced by global warming can cause so-called “blocking” events that keep clear, dry conditions over given areas for days and weeks on end.
This leads to phenomena like droughts and heatwaves in summer and bouts of bitter cold in the winter.
To investigate further, the researchers analysed both observational and climate model data for crucial breadbasket regions for both the period from 1960–2014 and future projections from 2045–2099.
The team found that, in summers with meandering jet streams high in the atmosphere, there is an increased likelihood of one or more food-producing regions seeing low crop yields.
This trend, they noted, was seen both in the observational data as well as their climate models.
In projections, hot spots of particularly low yields were spread over the Northern Hemisphere — and affected regions including East Asia, Eastern Europe and North America.
The findings, the researchers said, highlight the need for rapid reductions in greenhouse gas emissions before climate extremes become “increasingly unmanageable”.
The team added: “While climate models accurately simulate atmospheric patterns, associated surface weather anomalies and negative effects on crop responses are mostly underestimated in bias-adjusted simulations.
“Given the identified model biases, future assessments of regional and concurrent crop losses from meandering jet states remain highly uncertain.”
They concluded: “Our results suggest that model-blind spots for such high-impact but deeply-uncertain hazards have to be anticipated and accounted for in meaningful climate risk assessments.”
The full findings of the study were published in the journal Nature Communications.
