2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Methane emissions from swamps could increase by 80 percent by the end of the 21st century if humans do not reduce anthropogenic greenhouse gas emissions. At the moment, the contribution of methane to climate change is not so great, but its concentration in the atmosphere can sharply increase against the background of an increase in the average annual temperature and the amount of precipitation. Scientists have analyzed the response of wetland ecosystems to climate change in five natural zones using different scenarios of anthropogenic greenhouse gas emissions. The results of their research are published in the journal Science Advances.
Methane is the second most important greenhouse gas after carbon dioxide: the level of its emissions is much lower, but the potential for influencing global warming is 28-34 times higher. Wetlands are the main source of methane, contributing 30 to 40 percent of total methane emissions. The emission of methane by bog ecosystems depends on the air temperature, the depth of groundwater, as well as on the characteristics of the accumulated organic matter. Climate change affects all three factors of methanogenesis and raises questions about the feedback loop between natural methane production and climate change.
Also, wetland ecosystems take an active part in the absorption and conservation of carbon dioxide, for a long time taking it out of the biological cycle. Their violation in the course of economic activity and growth as a result of melting permafrost threatens to shift the balance in the exchange of methane and carbon dioxide between the swamps and the atmosphere. The role of wetland ecosystems in the global climate system is often underestimated, but they are in dire need of protection and careful study.
Ernest N. Koffi and colleagues at the European Commission's Joint Research Center conducted a comprehensive assessment of the planet's wetland ecosystems' response to climate change. They divided the globe into five climatic zones, which are characterized by different conditions for the formation of swamps: arctic, boreal, temperate, tropical and arid (desert). They also included in the reverse modeling not only air temperature changes, but also the amount of precipitation according to the Clapeyron-Clausius equation (with an increase in air temperature by one degree Celsius, there is an increase in precipitation by seven percent).
The response of methane emission (En) to temperature change (ordinate scale) and precipitation (abscissa scale) in five climatic zones: A - arctic, B - boreal, C - moderate, D - tropical, E - desert, F - on average. planet.
Swamps in colder climates (arctic and boreal) are susceptible to increases in air temperature, while swamps in warmer climates (temperate, tropical and arid) are susceptible to increased precipitation.
Scientists have found that methane emissions will increase in response to an increase in air temperature and precipitation. Then they applied a scenario approach to assess the impact of anthropogenic greenhouse gas emissions on the development of the situation. The RCP 2.6 scenario assumes a significant reduction in emissions due to the coordinated efforts of the world community, and the RCP 8.5 scenario - maintaining these emissions at the current level. To construct the curves, the authors of the study made two assumptions: the first was that wetlands can fully adapt to climate change, and the second considered the absolute impossibility of their adaptation. They decided to compare the resulting curves with the results of a study that included potential increases in wetland areas around the world.
Forecasted methane emissions by swamps in scenarios RCP 2.6 (significant reduction in anthropogenic greenhouse gas emissions) and RCP 8.5 (no reduction in anthropogenic emissions). The authors compare their projections of methane emissions in cases where ecosystems adapt to climate change (green line) and if adaptation does not occur (red line) with the emission trajectory previously predicted by Zhang et al. (Gray line)
The authors of the study concluded that the expected prolonged increase in air temperature and precipitation will lead to an increase in methane emissions from wetland ecosystems by 40-60 percent while maintaining their current areas, and if their areas increase, emissions will increase by 50-80 percent by 2100. If the world community manages to reduce anthropogenic greenhouse gas emissions and implement the RCP 2.6 scenario, then emissions will not go beyond safe limits and will not lead to a shift in positive feedbacks in the global climate system. This once again underlines how important it is to prevent global warming by two degrees Celsius or more.
Scenarios of possible volumes of anthropogenic greenhouse gas emissions RCP 2.6 and RCP 8.5 have already been discussed by scientists in the context of threats to biodiversity, and climatologists for the first time have estimated the greenhouse effect of methane using field measurements.
