High carbon emissions from thermokarst lakes and their determinants in the Tibet Plateau
- 1Key Laboratory of Western China's Environmental systems (Ministry of Education), College of Earth and Environmental sciences, Observation
- 2Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
- 3Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China
- 5State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
- 6Beiluhe Observation and Research Station on Frozen Soil Engineering and Environment in the Qinghai-Tibetan Plateau, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
- 7State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, china
- 8Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
Thermokarst lake development significantly affects hydrologic systems, infrastructure stability, and greenhouse gas emissions. However, the spatial and temporal changes, carbon emissions patterns, and motivators in thermokarst lakes remain largely unknown. In this study, we created a thermokarst lake dataset on the Qinghai-Tibet Plateau (QTP) using a threshold-based mapping method based on Google Earth Engine (GEE) data associated with visual inspection. In addition, we measured CH4 and CO2 diffusive fluxes in 163 thermokarst lakes in the QTP over 3 years from May to October. Our results showed that thermokarst lakes on the QTP permafrost region covered a total area of 1572 ± 184 km2, with most of the thermokarst lakes <10,000 m2 in area. Over the past 30 years, the number and surface area of thermokarst lakes along the QTH have increased by 58.8 % and 83.1 %, respectively. The median carbon emissions from the QTP thermokarst lakes were 1440 mg CO2 m−2 day−1 and 60 mg CH4 m−2 day−1, respectively. The diffusive rates of CO2 and CH4 are related to the catchment land cover type. Sediment microbial abundance and hydrochemistry explain 51.9% and 38.3% of the total variance in CH4 diffusive emissions, respectively, while CO2 emissions show no significant relationship with environmental factors. When upscaling carbon emissions from the QTP thermokarst lakes, the annual average CH4 release per lake area is equal to that of the pan-Arctic region. Our findings highlight the importance of incorporating in situ observation data with different emission pathways for different land cover types in predicting carbon emissions from thermokarst lakes in the future.
How to cite: Mu, C., Mu, M., Wu, X., Jia, L., Fan, C., Peng, X., Ping, C.-L., Wu, Q., Xiao, C., and Liu, J.: High carbon emissions from thermokarst lakes and their determinants in the Tibet Plateau, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-17, https://doi.org/10.5194/ems2024-17, 2024.
