Fiona's work aims to gain a better understanding of the sources and sinks of atmospheric methane; the interannual variability of methane emissions and atmospheric concentrations, and the potential feedbacks in the climate system which may affect future concentrations of atmospheric methane. She is also interested in modelling and understanding the role of short-lived atmospheric trace gases, such as ozone and methane, in climate change.

A key aspect of her work is developing and running the UKCA model on a global scale and on a decadal-to-centennial timescale. In particular, she implemented atmospheric chemistry in the latest version of the Met Office Hadley Centre's climate model, HadGEM2, which will be run as part of the Coupled Model Intercomparison Project Phase 5 integrations for the International Panel on Climate Change (IPCC) 5th Assessment Report.

She is also working towards implementing UKCA in the Met Office Hadley Centre's regional climate model, so that the interactions between climate and air quality on a more regional scale can be explored.