Tundra ecosystems observed to be CO 2 sources due to differential amplification of the carbon cycle

• Published in: Ecology Letters
• Main Authors: Belshe, E. F., Schuur, E. A. G., Bolker, B. M.
• Other Authors: Hooper, David
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: permafrost; Tundra
• Online Access: http://dx.doi.org/10.1111/ele.12164; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fele.12164; https://onlinelibrary.wiley.com/doi/pdf/10.1111/ele.12164

Abstract Are tundra ecosystems currently a carbon source or sink? What is the future trajectory of tundra carbon fluxes in response to climate change? These questions are of global importance because of the vast quantities of organic carbon stored in permafrost soils. In this meta‐analysis, we compile 40 years of CO 2 flux observations from 54 studies spanning 32 sites across northern high latitudes. Using time‐series analysis, we investigated if seasonal or annual CO 2 fluxes have changed over time, and whether spatial differences in mean annual temperature could help explain temporal changes in CO 2 flux. Growing season net CO 2 uptake has definitely increased since the 1990s; the data also suggest (albeit less definitively) an increase in winter CO 2 emissions, especially in the last decade. In spite of the uncertainty in the winter trend, we estimate that tundra sites were annual CO 2 sources from the mid‐1980s until the 2000s, and data from the last 7 years show that tundra continue to emit CO 2 annually. CO 2 emissions exceed CO 2 uptake across the range of temperatures that occur in the tundra biome. Taken together, these data suggest that despite increases in growing season uptake, tundra ecosystems are currently CO 2 sources on an annual basis.