Livestock heat stress risk in response to the extreme heat event (heatwave) of July 2022 in the UK

On the 18th and 19th of July 2022, the UK experienced a record-breaking extreme heat event. For the first time, temperatures exceeding 40C were recorded. Whilst this may seem exceptional or unprecedented, the progression of climate change is expected to increase both the likelihood and severity of such events. Livestock are vulnerable to heat stress, which manifests as losses to health and welfare, productivity, and sustainability. Here, we characterize the heatwave of July 2022 in the context of livestock heat-stress risk, with a focus on cattle. Meteorological data was obtained from 85 weather stations and the Comprehensive Climate Index (CCI) was calculated, hourly, for each station. The CCI was mapped across the UK for 18/07/22 and 19/07/22 and compared against heat stress risk thresholds. Across both days, >25% of sites experienced 'severe' heat stress risk. On 19/07/22 there was an 'extreme' risk across >5% of sites. The site that experienced the highest risk was near Rugby, in the West Midlands. Across all sites, night-time temperatures fell below risk thresholds and may have mitigated some of the heat stress risk. Whilst there was some evidence of productivity losses, this was not conclusive. The impacts of this event on livestock were not just direct, but indirect through negative impacts on water and forage availability. The heatwave of July 2022 must serve as a warning for the UK livestock industry and these results may act as a case study of what the sector may be increasingly likely to experience in the future.