Global maps of soil temperature
Abstract
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2ￂﾠm above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1￢ﾀﾐkm2resolution for 0￢ﾀﾓ5 and 5￢ﾀﾓ15ￂﾠcm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1￢ﾀﾐkm2pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse￢ﾀﾐgrained air temperature estimates from ERA5￢ﾀﾐLand (an atmospheric reanalysis by the European Centre for Medium￢ﾀﾐRange Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10ￂﾰC (meanￂﾠ=ￂﾠ3.0ￂﾠￂﾱￂﾠ2.1ￂﾰC), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6ￂﾠￂﾱￂﾠ2.3ￂﾰC) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (￢ﾈﾒ0.7ￂﾠￂﾱￂﾠ2.3ￂﾰC). The observed substantial and biome￢ﾀﾐspecific offsets emphasize that the projected impacts of climate and climate change on near￢ﾀﾐsurface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil￢ﾀﾐrelated bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
Created: 2021-12-30
Updated: 2026-07-17T16:25:20Z
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