Increases to agricultural hazards over the next 50 years

Future climate change is likely to have a serious impact on two of the UK’s agricultural staples, dairy farming and potato growing, according to a recent paper published by Met Office scientists.

The authors found that future thermal heat stress in dairy cattle is likely to be greatest across England, and particularly in the South East around the London area, where in 30 – 50 years’ time there may be up to 2 months more per year where cattle are stressed, compared to the present day. In the South West, the region that contains the most dairy cattle, there may be ten times more days per year on average when cattle are stressed.

Potatoes are vulnerable to a disease called late blight, which occurs in warm, humid weather. The conditions where blight occurs are likely to occur more often in the future across the UK, with the greatest increases in western regions. Most potatoes are grown in the east of the UK, where potato blight occurs less often, and so there are likely to be smaller increases in these key regions for potato growing (20-30% increase in potato blight occurrence). However, in east Scotland, a region which currently has a high concentration of potato farming, potato blight may occur around 70% more often.

The research provides maps of how likely heat stress and potato blight conditions are to occur across each 12 km grid box of the UK, which can provide adaptation planners with important local information about where action needs to be taken. The scientists also combine hazard information with vulnerability information (e.g., the threshold at which heat stress is going to be harmful) and exposure information (e.g., where cattle are raised) to produce risk estimates of which UK regions have greatest risk now and in the future.

Compound events

Both food for cattle, crops for humans, and potato growing are all likely to be affected by drought, which we tend to experience when we have particularly hot dry summers, such as 2018. Recently, another group of scientists from the Met Office demonstrated that the summer temperatures of 2018 may occur every one in two years by the middle of the century (McCarthy et al 2019). In this work, the scientists also look at how often we are likely to see both hot and dry months during summers through the twenty-first century, and how this is likely to increase.

The new research shows how examples of a particular type of weather hazard, called a compound event, are likely to change under twenty-first century climate change. Compound events happen when one or more weather hazards occur at the same time, for example, very hot and very dry weather, or very windy and very wet weather. We often experience more serious impacts when two weather hazards occur together rather than separately, or when they occur close in time or close in space. Both case studies involving thermal heat stress and potato blight conditions occur when temperature and humidity combine.

The number of days per year that are projected to be warm and humid enough to cause mild heat stress in dairy cattle in 2051 – 2070 compared to 1998 – 2017 (averages across administrative regions).

The estimates of future change are made using the UK Climate Projections focusing on projections of the future climate under the RCP 8.5 scenario. This is a high emissions scenario above estimates for current global emissions policies, but which enables consideration of 2–4 °C of global temperature increase over the 21st century, the range for which the Committee for Climate Change (2019) recommends UK sectors should plan adaptation*.

A more detailed non-technical summary of the research is available here. This project is part of the Met Office work package, From climate hazard to climate risk.

This work was funded under the Strategic Priority Fund for UK Climate Resilience. The UK Climate Resilience programme is supported by the UKRI Strategic Priorities Fund. The programme is co-delivered by the Met Office and NERC on behalf of UKRI partners AHRC, EPSRC and ESRC.

Watch a video of lead author Dr Freya Garry explaining the project.

Garry, F., Bernie, D., Davie, J., Pope, E. 2021. Future climate risks to UK agriculture from compound events. Climate Risk Management for inclusion in Special Issue on “UK Climate Risk Assessment and Management”.

*‘Although the UK is committed to working for global action to parallel our own adoption of a net-zero statutory target, it is prudent to plan adaptation strategies for a scenario of 4°C’. Executive Summary, Progress in preparing for climate change – 2019 Report to Parliament, Committee for Climate Change.

Media coverage: this paper has been covered by the Scotsman and Farming UK and on the weather blog of  Sun Online, as well as in print versions of The Telegraph and iNews.

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Last updated April 2021

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