Methane Emissions from Wetlands

  • 25 Mar 2023

A recently published study indicates that increasing temperature and precipitation are driving the increase in methane emissions from wetlands, which are responsible for a third of total methane emissions.

  • The report highlighted that methane emissions from wetlands have risen by 5-6% since 2000-2006, with emissions in 2020 and 2021 increasing by 14-26 Tg per year and 13-23 Tg per year, respectively.
  • Wetlands store over a third of the world's terrestrial carbon but can also act as a source, releasing 127-155 Tg (teragram) of carbon annually, mostly due to microbes inhabiting them. (Note: Teragram is a unit of mass equal to one trillion (10^12) grams or one million (10^6) metric tons.)
  • Methane emissions reached record levels in 2020 and 2021.
  • Wetlands from South America were the largest contributor to these emissions, followed by Africa, South Asia, and Southeast Asia.
  • Methane emissions cause a positive climate feedback that amplifies warming.
  • Increased rain due to global warming creates more wetlands, which then increase methane emissions, leading to further global warming and rain in a feedback loop.
  • Most climate models do not consider this process, instead focusing on the long-term increase in atmospheric methane concentrations due to human activities such as industry and agriculture.
  • Researchers used data from ground-based meteorological stations and observations with past short-range weather forecasts rerun with modern weather forecasting models to simulate methane emissions.
  • Global mean annual methane emissions in 2007-2021 due to climate change impacts on wetlands increased by 8-10 Tg per year compared to 2000-2006.
  • Wetlands in the tropics contributed the most to the spike in methane emissions in 2020 and 2021, with tropical wetlands emerging as hotspots.