No rain is bad news for farmers, and this phenomenon is documented to be true over the last decade in northern China. Scientists from the Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences (CAS), Beijing published their latest findings on the shifting of gears and bearings on the East Asian monsoon rain belt in PNAS 2015. The lead author of the paper, Dr Shiling Yang, offers us some insights of his study and the spatiotemporal pattern of C4 vegetation.
Biosketch of Dr Yang
- What are some of the predictions of how northern China’s climate would be like as global warming continues and the trend starts to reverse?
Our study has shown that the East Asian summer monsoon rain belt migrated northwestward from the cold Last Glacial Maximum (~19 ka) to the warm Holocene (~4 ka). In addition, numerous studies have demonstrated that in geological past, warm periods always coincide with increased summer monsoon intensity and resulting humid climate in northern China, and vice versa. This suggests that a warming climate shifts the monsoon rain belt northward. That’s why we believe that northern China will eventually become wet, if global warming continues. However, we cannot predict when the drying trend will reverse, because it takes time for adjustment of the monsoon system to observe changes in temperature.
- What are your thoughts on China’s climate policy and how it would play a role with regards to the findings of your published paper?
The climate has been changing throughout Earth’s history. The past 2.6 million years has witnessed cyclic alternation of glacials and interglacials. If people do not want global warming, will they like global cooling? It would definitely be a terrible disaster if our planet was plunged into a glacial period. Now, the international community is trying to keep the climate unchanged or changing slowly by reducing CO2 emission. In this regard, we think that China has taken active measures to promote energy saving and emission reduction. We do not think that the findings of our paper will play an important role in China’s climate change policy.
- How did you and your colleagues think of using the spatial distribution of C4 biomass as an analog for the study?
For the past several years, we have investigated over 20 loess-soil sections. By measuring 14C ages and carbon isotope composition (δ13C) of soil organic matter, we reconstructed the spatiotemporal pattern of C4 vegetation on the Chinese Loess Plateau for the past 20 ka. Our results show that the isolines of C4 biomass exhibit a northeast–southwest zonal distribution pattern, closely resembling the pattern of present monsoon precipitation, and thus can serve as a robust analog for the contemporary East Asian summer monsoon rain belt. It follows that the migration of C4 isolines effectively indicates a change of monsoon rain belt position. The 10–20% isolines for C4 biomass in the southeastern part of the Plateau during the LGM moved to the northwestern part during the mid-Holocene, indicating a northwesterly monsoon rain belt advance of ~300 km for the warm Holocene compared with the cold LGM. These results demonstrate that global warming will shift the East Asian monsoon rain belt northwestward.
- 4.How would this study affect the climate change communities in China? And the implications to the agricultural industry?
Our published results illustrate the migration of East Asian monsoon rain belt driven by past global warming. It thus follows that the monsoon rain belt will move northward as global warming advances, which further suggests that the observed dry-spell is a temporary phenomenon. Therefore, northern China terrain is expected to receive increased rain and to remain moist as global warming continues. This is certainly favourable for the agricultural industry and good news for the farmers.
Shiling Yang is a professor of Quaternary Geology and Palaeoclimatology at the Institute of Geology and Geophysics, Chinese Academy of Sciences. He received his BS in geology from Northwest University and earned his MS and PhD in Quaternary Geology from the Institute of Geology and Geophysics, Chinese Academy of Sciences. His research includes sedimentology and geochemistry of aeolian sediments, stable isotope geochemistry of soil carbonates, and East Asian monsoon evolution during the late Cenozoic.