Increased temperature variation poses a greater risk to species than climate warming

TLDR

Future climate change is expected to increase the frequency, severity, and duration of temperature extremes, yet most ecological studies focus on mean temperature shifts despite evidence that variation may have greater species impacts. The study links 2050–2059 fine‑grained climate projections to thermal performance data from 38 ectothermic invertebrates, comparing results to a simple model. Projections that include temperature variation differ markedly from mean‑only models; while many species improve with higher means, combined mean‑and‑variance shifts produce diverse responses, with temperate species most at risk of performance declines, underscoring the need for fine‑grained temporal data.

Abstract

Increases in the frequency, severity and duration of temperature extremes are anticipated in the near future. Although recent work suggests that changes in temperature variation will have disproportionately greater effects on species than changes to the mean, much of climate change research in ecology has focused on the impacts of mean temperature change. Here, we couple fine-grained climate projections (2050-2059) to thermal performance data from 38 ectothermic invertebrate species and contrast projections with those of a simple model. We show that projections based on mean temperature change alone differ substantially from those incorporating changes to the variation, and to the mean and variation in concert. Although most species show increases in performance at greater mean temperatures, the effect of mean and variance change together yields a range of responses, with temperate species at greatest risk of performance declines. Our work highlights the importance of using fine-grained temporal data to incorporate the full extent of temperature variation when assessing and projecting performance.