Regional Integration of CH4 Emission Studies (RICHES)

This project investigates how pollution, in the form of acid rain (globally a growing problem), can influence the emission of the powerful greenhouse gas methane (CH4) from wetlands, the largest individual source of this gas. We will tackle this important question by performing a regional integration of the many CH4 emission studies that have been published in the past 2 decades together with data on pollution in these areas. Recent experiments where acid rain sulphur pollution has been simulated in wetlands have shown that these interactions can have an important effect on the emission of CH4 at the global scale and may be offsetting the growth of methane from the wetland CH4 source that should otherwise be occurring through global warming. These assessments are based on the findings of a limited number of experimental studies. The draw back from such studies is that they may replicate conditions only at the beginning of a period of increased pollution rather than the long-term ecosystem response. There are also effects of other pollutants such as reactive nitrogen (nitrate and ammonia) that may have important effects but are difficult to quantify without long-term (e.g. decade long) experiments. Our approach will treat the numerous studies that have monitored CH4 emission from a wide range of wetlands, spanning existing pollution gradients, as a regional/global experiment where the long-term impacts of pollution are more accurately represented.