PerspectiveClimate Change

The Carbon Dioxide Exchange

Science  13 Aug 2010:
Vol. 329, Issue 5993, pp. 774-775
DOI: 10.1126/science.1194353

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Summary

One key to accurately predicting future levels of atmospheric carbon dioxide (CO2) is understanding how land and atmosphere exchange CO2. Each year, photosynthesizing land plants remove (fix) one in eight molecules of atmospheric CO2, and respiring land plants and soil organisms return a similar number. This exchange determines whether terrestrial ecosystems are a net carbon sink or source. Two papers in this issue contribute to understanding the land-atmosphere exchange by elegantly analyzing rich data sets on CO2 fluxes from a global network of monitoring sites. On page 834, Beer et al. (1) estimate total annual terrestrial gross primary production (GPP) in an approach more solidly based on data than previous simple approximations. On page 838, Mahecha et al. (2) assess how ecosystem respiration (R) is related to temperature over short (week-to-month) and long (annual) time scales, and find a potentially important but difficult-to-interpret relationship.