2:15 PM - 2:30 PM
[MIS05-15] Global Biogenic Methane Emissions From Land And Freshwater Ecosystems:
Implications To The Global Socioeconomic And Climate Systems
Keywords:Biosphere and atmosphere interactions , methane emissions , methane biogeochemistry , land and aquatic ecosystems
Land and freshwater ecosystems play a significant role in affecting the global methane budget. With future warming, the increase of methane emissions could create large positive feedbacks to the global climate system. We use observation data of methane fluxes from diverse land and freshwater ecosystems to calibrate and evaluate extant land and freshwater biogeochemistry models of the Terrestrial Ecosystem Model (TEM) and the Arctic Lake Biogeochemistry Model (ALBM) to quantify the global methane emissions for the past few decades and the 21st century in a temporally and spatially explicit manner. TEM simulates that global wetlands emissions are 212 ± 62 and 212 ± 32 Tg CH4 yr−1 due to uncertain parameters and wetland type distribution, respectively, during 2000–2012. After combining the global upland methane consumption of −34 to −46 Tg CH4 yr−1, we estimate that the global net land methane emissions are 149–176 Tg CH4 yr−1 due to uncertain wetland distribution and meteorological input. During 1950–2016, both wetland emissions and upland consumption increased during El Niño events and decreased during La Niña events. Current global methane emissions are 24.0 ± 8.4 Tg CH4 yr−1 from lakes larger than 0.1 km2. Future projections under the RCP8.5 scenario suggest a 58–86% growth in emissions from lakes. Our studies identify the key biogeochemical and physical processes of controlling methane production, consumption, and transport in various hotspot emission regions. Our studies reveal the challenges to better constrain the quantification uncertainty of global biogenic methane emissions across the landscape.