It is important to quantify the size of sources and sinks of greenhouse gases and ozone depleting substances to understand our changing climate and inform policy makers. It is impossible to measure all global sources and sinks directly and so we have to use measurements of atmospheric concentrations combined with models to inform us instead.

One approach to this is solving an ‘inverse problem’ where we track a gas backwards from the measurement site to a location to quantify its emissions. Another is simulating the global flow of gases and observing how well this matches measurements. As no model or measurement is perfect, we robustly quantify the uncertainty using a variety of statistical methods.