New Progress in the Study of Summertime Decadal CO₂ Increase in the Western Arctic Ocean

On 15 June 2020, a new progress “Sea-ice loss amplifies summertime decadal CO2 increase in the western Arctic Ocean” was published on Nature Climate Change (IF=20.9) by collaboration between Prof. Wei-Jun Cai’s team from University of Delaware, the United States and Dr. Di Qi, Prof. Liqi Chen and Prof. Zhongyong Gao et al. This study synthesized all the CHINARE cruises in the Arctic Ocean as well as global datasets, and investigated the decadal variation of sea surface pCO2 in summer in the western Arctic from 1994 to 2017. The work marks another important milestone in the collaboration between Chinese and American scientists following previous work published in Science (2010) and Nature Climate Change (2017).

Rapid climate warming and sea-ice loss have induced major changes in the sea surface partial pressure of CO2 (pCO2). However, the long-term trends in the western Arctic Ocean are unknown. We found that in 1994–2017, summer pCO2 in the Canada Basin increased at twice the rate of atmospheric increase. Warming and ice loss in the basin have strengthened the pCO2 seasonal amplitude, resulting in the rapid decadal increase. Consequently, the summer air–sea CO2 gradient has reduced rapidly, and may become near zero within two decades. In contrast, there was no significant pCO2 increase on the Chukchi Shelf, where strong and increasing biological uptake has held pCO2 low, and thus the CO2 sink has increased and may increase further due to the atmospheric CO2 increase. Our findings elucidate the contrasting physical and biological drivers controlling sea surface pCO2 variations and trends in response to climate change in the Arctic Ocean.

The aforementioned work has been supported by National Natural Science Foundation of China, the Chinese Projects for Investigations and Assessments of the Arctic and Antarctic, the Natural Key Research and Development Program of China, the Scientific Research Foundation of Third Institute of Oceanography, MNR. (paper available at:

Figure 1. The spatial distribution of sea surface pCO2 measurements.

Figure 2. The decadal variations of pCO2 in the western Arctic Ocean.

Figure 3. The loss of sea ice in the Canadian Basin amplifies sea surface pCO2 gradient.

Extended reading

In the recent 20 years, under the supports from Ministry of Natural Resources and the then State Oceanic Administration of P.R.C and National Oceanic and Atmospheric Administration (NOAA) of the United States, Chinese and American scientists were able to focus on the studies of ocean acidification and carbon cycle, taking advantage of the “XueLong” Research Vessel and CHINARE Arctic cruises. By applying the advanced sea-air pCO2 underway system and Ice-Sea-Air observational system, we have achieved a series of cutting-edge findings:

In 2010, the joint publication of “Decrease in the CO2 uptake capacity in an ice-free Arctic Ocean basin” on Science was regarded as “This is the first time in the ocean sciences the Chinese have come out that strong," says Tremblay, "It can definitely be taken as a scientific awakening." by Nature News.

In 2017, the joint publication of “Increase in acidifying water in the western Arctic Ocean” as the cover paper on the Nature Climate Change investigated the mechanism of the expanding of Arctic acidified waters, and thus provided a model of successful scientific collaboration between China and US.

In addition, the Chinese and American scientists have devoted to understanding the rapid acidification in the Arctic Ocean in the context of global change, and they have shed lights on the importance of carbon emission reduction on maintaining the climate and the marine ecosystems. It has now become a consensus that strengthening the scientific collaborations in ocean acidification and carbon cycle between China and US is necessary, which has also been included in the 7th and 8th rounds of China-US Strategic and Economic Dialogue and the Outcome list of the Summit.


  1. Zhangxian Ouyang, Di Qi, Liqi Chen, Taro Takahashi, Wenli Zhong, Michael DeGrandpre, Baoshan Chen, Zhongyong Gao, Shigeto Nishino, Akihiko Murata, Heng Sun, Lisa Robbins, Meibing Jin, Wei-Jun Cai*. Sea-ice loss amplifies summer-time decadal CO2 increase in the western Arctic Ocean, Nature Climate Change. 2020,10:678-684.
  2. Di Qi, Liqi Chen*, Baoshan Chen, Zhongyong Gao, Wenli Zhong, Richard A. Feely, Leif G. Anderson, Heng Sun, Jianfang Chen, Min Chen, Liyang Zhan, Yuanhui Zhang, Wei-Jun Cai*. Increase in acidifying water in the western Arctic Ocean, Nature Climate Change (cover paper), 2017, 7(3): 195-201.
  3. Weijun Cai, Liqi Chen, Baoshan Chen, Zhongyong GAO et al, Decrease in the CO2 Uptake Capacity in an Ice-Free Arctic Ocean Basin, Science, 329:556-559 (2010); DIO: 10.1126/science. 1189338.


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