ZJU researchers explore interaction between soil and global warming


Credit: Asian Development Bank

Since the advent of the Industrial Revolution, human activities have accelerated the consumption of fossil fuels and deforestation, thereby contributing to a significant atmospheric change.

Intimately related to that are global warming, rising sea levels, reduction in biodiversity and frequent occurrences of extreme climates. At present, scientists are more fully aware that climate change may well exert a potential and unpredictable impact on the ecological system that mankind lives by and pose a severe hazard to the sustainable development of the human society.

In the terrestrial ecological system, the amount of whole-soil carbon is three and four times as large as that in the atmosphere. Some studies postulate that soil is likely to absorb and store more carbon in the atmosphere in the context of further climate change, thus acting as a decelerator of climate change.

By elaborating on the decomposition of soil, particularly subsoil and clarifying and estimating the feedback between the whole-soil carbon and climate, it will be of considerable scientific significance to more precisely forecast the concentration of CO2 in the atmosphere and climate change and respond actively to climate change.

In recent years, a research team led by CHENG Lei, professor of ecology at Zhejiang University, has been dedicated to researches into the impact of microbes on the soil system and the response of the carbon cycle to climate change. On the basis of the theoretical framework concerning the interaction between microorganisms and climate change (Cheng et al. Science 337:1084), the research team reveals that warming may considerably alter the stability of the vast pool of old soil organic matter in subsoil, contributing to the long-term positive feedback between the carbon cycle and climate (Cheng et al. ISME Journal 11:1825). However, relevant studies are theoretically and experimentally challenging.

In a compelling study, Hicks Pries et al. (Reports, 31 March 2017, p. 1420) show that 4°C warming enhanced soil CO2 production in the 1-meter soil profile, with all soil depths displaying similar temperature sensitivity (Q10). Cheng Lei et al. argue that although the idea of subsoil carbon dynamics in response to warming is worth testing, their conclusions are critically undermined by the experimental approach and analysis.

On the strength of previous work and relevant experimental data (Hicks Pries et al. Science 355:1420), Cheng Lei et al. have conducted an in-depth exploration of theoretical foundations and calculation approaches and put forward their propositions as follows.

First, a thermal lag effect is ascribed to low thermal diffusivity and thickness of the soil profile. This effect will be immensely significant to identify the response of the whole soil to warming.

Second, Cheng Lei et al. make improvements in calculating Q10. They use a linear regression model to estimate the apparent Q10 (9) by reformatting Eq. 1. This way, they are able to resolve the potentially confounding effects of seasonal changes because the same paired data are used. This will be helpful to a more accurate analysis of the effect of subsoil on climate change. It will be enormously meaningful to take subsoil into account in the climate change model so as to predict future climate change.

Read the full article at: http://science.sciencemag.org/content/359/6378/eaao0218