What is in this article?:
- A new study concludes that models may be predicting releases of atmospheric carbon dioxide that are either too high or too low, depending on the region, because they don’t adequately reflect variable temperatures that can affect the amount of carbon released from soil.
In the past, estimates of that process were usually based on average temperature increases that were expected, Harmon said. But in the real world, temperatures vary greatly, from day to night, season to season, through heat waves and cold spells. And that variability, researchers say, changes the biological equation considerably and can make averages misleading.
“If the response of soil respiration to temperature was a straight line, then temperature variability would not be important,” Harmon said. “However, the response is curved, which means that as temperature variability increases, so does the average response. This general phenomenon is known as Jensen's inequality, but it had not previously been applied to soil respiration.”
In simple terms, less variability will equate to less soil carbon release. In the new analysis, considering the effects of variability, scientists found that temperature variability may be reduced in northern latitudes, in particular, and result in carbon releases that are lower than have been projected in one of the areas of the world where this phenomenon is of greatest concern.
The research was not able to precisely quantify this phenomenon and more work needs to be done in that area, the researchers said.
The study reports that:
- The amount of carbon stored in soils worldwide exceeds the amount of carbon in the atmosphere by a factor of two to three.
- There is concern that a large portion of this carbon will be released to the atmosphere as global average temperatures increase.
- Too little attention has been paid to the effect of temperature variability in this process.
- In high latitudes of the Northern Hemisphere, temperature variability is expected to decrease, and release of soil carbon will probably be lower than that predicted by changes in average temperature.
- At lower latitudes, where both average temperature and variability are expected to increase, the release of soil carbon will probably be higher than that predicted by changes in average temperature.
“The findings of this study can greatly modify past predictions about the effects of future average temperatures on ecosystem respiration,” the scientists wrote in their conclusion. “Changes in both temperature and precipitation variance would likely produce complex behaviors not incorporated in current model predictions.”
The research was done by scientists from OSU, the U.S. Geological Survey, and the National Ecological Observatory Network. The study used data from the Long Term Ecological Network Program of the National Science Foundation.