Warming-induced Carbon Emission May Be Less than Previously Assumed

Chinese Academy of Sciences

Temperature sensitivity is often expressed by the relative change of respiration at a temperature change of 10°C, which is called the Q10 value. The Q10 of terrestrial ecosystem respiration (Re) is important for quantifying climate-carbon cycle feedback.

Dr. NIU Ben and Prof. ZHANG Xianzhou from the Institute of Geographic Sciences and Natural Resources Research (IGSNRR) of the Chinese Academy of Sciences (CAS) and their collaborators found warming-induced decline in Q10 is stronger in colder regions than other locations, which may lead to less warming-induced carbon emission than previously assumed.

This study was published in Science Advances on April 9.

The researchers adopted a dataset of Q10 values from multi-year observations at 74 FLUXNET sites and 54 field warming experiments spanning diverse climates and biomes.

This work provides new insights on how the temperature sensitivity of Q10 has changed in recent years and across space, as well as for the future warmer world. It predicts that global warming will shrink the variability of Q10 values to an average of 1.44 in the worldwide under a high emission trajectory (RCP 8.5) by the end of the century.

“These results provide evidence for the potential convergence of global Q10 under ongoing climate warming, a warming response that is currently not reproduced by most Earth system models,” said Dr. NIU.

Therefore, warming-induced carbon emission through Re at high-latitude regions may be less than assumptions in Earth system models because these projections underestimate the strong downward-adjustment of Q10 under climate warming, especially at higher latitudes and in colder climates. Thus, this study calls for a careful re-assessment of the predicted large carbon loss, especially at higher latitudes and in colder regions.

However, future warming may enhance water stress in arid regions, which is likely to affect the climate-carbon feedback with more complex situations and make it more difficult to extrapolate to future climates. Future continuous water scaling researches, especially in the arid and semi-arid regions, are still needed for an adequate mechanism explanation in carbon-climate feedback.

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