Methane plays a central role in the atmosphere, affecting the atmospheric oxidising capacity through its reaction with the hydroxyl radial (OH), air quality through its role as an ozone precursor, and climate through its greenhouse gas properties.
I'm interested in modelling methane, its processes, feedbacks and their effects on other parts of the Earth system. I use a new methane emissions-driven version of the UK Earth system model (UKESM1-CH4). This is an important update from the current standard treatment of methane, where the concentration of methane is fixed at the surface.
The first part of my PhD involved evaluation of the model performance compared to historical data and previous models. Some of these results can be found in the model description and evaluation paper (see Publications below).
I am now using the new capability of UKESM1-CH4 to change emissions directly and to vary their spatial distribution.
To estimate the maximum impact of future anthropogenic methane emissions, I set up a zero anthropogenic methane emissions scenario (ZAME) where the emissions of methane were instantaneously stopped from 2015 onwards. The Earth system response was rapid and the methane concentration fell to below pre-industrial levels within 12 years. I studied the impacts on climate such as on surface temperature and precipitation, and also considered air quality by looking at ozone, OH and nitrogen oxide (NOx) concentrations. For more details see Publications below.
In an extension of the ZAME study, I am modelling carbon monoxide (CO) and NOx emissions reductions in tandem with methane mitigation, and exploring the sensitivity of ozone and OH to changes in CO and NOx on a regional level.
I'm also interested in methane policy and potential future mitigation pathways. The Global Methane Pledge was launched at COP26 in 2021, where countries agreed to "take voluntary actions to contribute to a collective effort to reduce global methane emissions at least 30 percent from 2020 levels by 2030". I am currently modelling this scenario using UKESM1-CH4, and am interested in the potential climate and air quality impacts.