Globally Rising Soil Heterotrophic Respiration over Recent Decades
A mutidecadal synthesis shows that soil microbes are respiring soil carbon at faster rates worldwide.
The results of this new study published in Nature show that soil microbes respire faster than photosynthesis rises in response to climate change, presumably leading to soil-carbon losses in many regions.
There is perhaps no more pressing question in all of terrestrial biogeochemistry than the degree to which soils will respond to ongoing climate change—specifically, the degree to which they may lose some of their enormous carbon pools to the atmosphere, exerting a feedback effect on the climate. Whether such losses are occurring, or will in the future, has significant consequences for current understanding of how Earth’s ecosystems are changing.
Global soils store twice as much carbon as Earth’s atmosphere. This carbon may be destabilized by ongoing climate change, though to what degree remains uncertain. If soil-carbon losses do occur, the dominant pathway will be via heterotrophic soil respiration (RH), the soil-to-atmosphere flow of carbon dioxide produced by microbes.
This study collects thousands of observations over 25 years to show that RH is rising at a faster rate than either total soil respiration (the total soil-to-atmosphere carbon flux) or plant photosynthesis (as measured by satellites or by instruments on the ground, or as simulated in models). Collectively, these results provide strong evidence that global RH is responding to climate change, and they suggest that losses of soil carbon to the atmosphere may be occurring at large scales.
These results open new avenues of research—integrating remote sensing and observational data, for example, or developing new manipulative experiments of ecosystems. These results also offer new opportunities for testing Earth system models.
Pacific Northwest National Laboratory
This research was supported by the Terrestrial Ecosystem Science program of the Office Biological and Environmental Research, within the U.S. Department of Energy Office of Science. C.M.G. received additional support from the National Science Foundation Division of Environmental Biology.
Bond-Lamberty, B., et al. “Globally rising soil heterotrophic respiration over recent decades.” Nature 560, 80–83 (2018). [DOI:10.1038/s41586-018-0358-x]