Climate control of terrestrial carbon exchange across biomes and continents

TLDR

Understanding how climate drives terrestrial carbon exchange is essential for predicting future atmospheric CO₂, yet direct observations across biomes and continents are scarce. The study aims to describe how net ecosystem exchange of carbon relates to climate factors across 125 sites on six continents. Data were collected using the eddy covariance method at 125 sites across diverse ecosystems, totaling 559 site‑years. NEE is strongly linked to mean annual temperature at mid‑ and high latitudes, to dryness at mid‑ and low latitudes, and to both factors near 45°N; the temperature effect ceases above ~16 °C, after which dryness dominates.

Abstract

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate–carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid- and high-latitudes, (2) a strong function of dryness at mid- and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45°N). The sensitivity of NEE to mean annual temperature breaks down at ~ 16 °C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence.