CO₂, one of the major greenhouse gases, doesn’t distribute evenly around the globe. Spatial variation of CO₂ regulates the climate system and carbon cycle through physiological effects and radiative forcing. Understanding its impact is therefore important for climate prediction and understanding changes in the terrestrial carbon cycle. However, there is still great uncertainty about how this non-uniform spatial distribution of atmospheric CO₂ concentration affects the carbon cycle of the Northern Hemisphere. Recently, Dr. Peng Jing from Professor Dan Li’s research team at the CAS Key Lab of Regional Climate-Environment for East Asia (TEA) at the Institute of Atmospheric Physics of the Chinese Academy of Sciences (CAS), conducted a systematic study on how the spatial distribution of atmospheric CO₂ concentration influences carbon sinks of terrestrial ecosystems.

Variation of concentration in heterogeneous CO₂ (a, c) and its impacts on NEP (b, d) under historic conditions of 1976-2005 and future conditions of 2031-2060 [IMAGE: IAP]

In this work, the Earth System Model (ESM) was used to estimate the carbon uptake in mid-high latitudes from 2031 to 2060 under the SSP5-8.5 future emissions scenario. Results showed that, in the high latitudes, non-uniform CO₂ led to a reduction in Net Ecosystem Production (NEP) by -0.1 Pg C yr-1. This mainly resulted from a 1.5-fold greater increase in soil respiration than in Net primary production (NPP). In the mid-latitudes, meanwhile, the decrease in carbon uptake was generally due to a two-fold greater decrease in NPP than soil respiration.

In addition, the decrease in precipitation was closely correlated with local carbon uptake, which could explain this decrease in NPP. “We also found that, in East Asia, changes in atmospheric circulation induced by the non-uniform CO₂ might have reduced the amount of large-scale precipitation by -9 mm yr-1,” said Peng, “This reduction was the primary contributor (98 percent) to the decrease in overall precipitation, possibly strengthening the limitation of water on plant growth, which would cause a decline in NEP.”

Peng suggested that such spatial variation in CO₂ concentrations should be assessed in ESM for possible impacts on local carbon uptake.

This study was recently published in the Journal of Geophysical Research: Atmospheres.

For more information, please contact:

Ms. Lin Zheng (for Media)

E-mail: jennylin@mail.iap.ac.cn

Institute of Atmospheric Physics,

Chinese Academy of Sciences

Source: Institute of Atmospheric Physics,

Chinese Academy of Sciences