Local microclimates can both amplify and mitigate extreme temperatures associated with climate change

Ashe-Jepson, E., Turner, E. C. and Bladon, A. J. ORCID: https://orcid.org/0000-0002-2677-1247 (2025) Local microclimates can both amplify and mitigate extreme temperatures associated with climate change. Frontiers in Biogeography, 18. e164843. ISSN 1948-6596 doi: 10.21425/fob.18.164843

Abstract/Summary

Climate change is a threat to global biodiversity, with changes to mean temperatures and increasing frequency and intensity of extreme weather events. Heatwaves in particular pose a threat to species’ persistence, as temperatures may rise above physiological tolerance. However, individuals rarely experience temperatures measured at the macroclimatic scale: topographic or vegetation differences result in microclimates that provide cool refugia (local temperatures below ambient) or even result in heat traps (local temperatures above ambient) during heatwaves. However, little is known about the stability of microclimates through a period of regional warming. In this study, we recorded microclimate temperatures across different microhabitats within a calcareous grassland nature reserve in Bedfordshire, UK, in 2018, 2019 and 2022. During this time, six heatwave events occurred, including the highest air temperatures ever recorded in the UK. We found that the ability of microhabitats to offset air temperatures varied with topographic aspect, slope, amount of bare ground, shelter, vegetation height, and vegetation type, with encroaching scrub and north-facing slopes showing the strongest abilities to maintain relatively stable microclimate temperatures with increasing air temperatures, in contrast to short vegetation on south-facing slopes which became heat traps. However, no combinations of environmental structures consistently maintained cool refugia during heatwaves. Microclimate temperatures were amplified close to the ground, whereas at 50 cm height temperatures were more stable and similar to the macroclimate temperature, therefore surface-dwelling species, such as many insects, may be particularly vulnerable to extreme heat. We identified a breakdown in the ability of microhabitats to maintain cool refugia above 7 °C, implying cool refugia become increasing rare and unpredictable with increasing temperatures. Our results indicate that many microhabitats will amplify the effects of climate change rather than mitigate them.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/128125
Identification Number/DOI	10.21425/fob.18.164843
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Ecology and Evolutionary Biology
Publisher	International Biogeography Society
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