Improving our understanding of methane emissions in Brazil
Concentrations of methane in our atmosphere are rising faster than predicted. Why?
Methane is a potent greenhouse gas and one of the most significant contributors to our planet’s climate warming. Despite challenging targets set by nations as part of their Paris Agreement commitments to reducing human-made greenhouse gas emissions, the growth in atmospheric concentrations of methane is outstripping the trajectories used for climate modelling – much more so than the pathways for carbon dioxide.
We know relatively little about methane’s increased presence in the atmosphere, and there’s no scientific consensus about what may be driving the unexpected rate of change. As a result, it’s difficult to understand the causes of methane variations and tough to anticipate their future levels. We need better knowledge about the sources of methane emissions in order to make more accurate predictions about our changing climate.
What we're doing
We’re combining multiple data sources to improve how we quantify methane emissions. Our project focuses on Brazil, a country with a complex mix of emission sources, and collects findings from both ground-level and satellite sensors.
A satellite measures the methane in a column of air between its position and the ground by detecting the amount of sunlight reflected back at it. Methane is distinguishable from carbon dioxide and nitrous oxide, for example, because each greenhouse gas absorbs radiation in a different wavelength.
Satellites orbit the globe and come back to the same point every few days, so our data from 2010 shows how methane concentrations change over the seasons. By combining that data with atmospheric models showing how air circulated over the same period, we can pinpoint the origin of emissions.
This analysis is particularly useful in Brazil where significant emissions stem from not only human activity but also wetlands and biomass burning. Crucially, we’re able to determine the sources from which emissions emanate.
How it helps
The climate models that guide science, policy and efforts to mitigate warming don’t currently reflect the higher-than-expected trajectory of atmospheric methane concentrations, and there’s no consensus on why the discrepancy exists.
At the same time, as nations signed up to the Paris Agreement submit their greenhouse gas emissions reports to the UN Framework Convention on Climate Change, they only provide estimates of human-made methane.
Our research captures other relevant natural sources too. It’s the starting point for understanding what’s driving rising concentrations and provides more accurate predictions for methane concentration levels, helping to improve climate modelling and inform future decision-making.
Dr Anita Ganesan, Senior Research Fellow and Proleptic Senior Lecturer, School of Geographical Sciences
Dr Rachel Tunnicliffe, Research Associate and Lecturer, School of Chemistry