Rain-fed pulses of methane from East Africa during 2018-2019 contributed to atmospheric growth rate

East Africa is a key location for wetland emissions of methane (CH4), driven by variations in rainfall that are in turn influenced by sea-surface temperature gradients over the Indian Ocean. Using satellite observations of CH4 and an atmospheric chemistry-transport model, we quantified East African CH4 emissions during 2018 and 2019 when there was 3-sigma anomalous rainfall during the long rains (March-May) in 2018 and the short rains (October-December) in 2019. These rainfall anomalies resulted in CH4 emissions of 6.2 +/- 0.3 Tg CH4 and 8.6 +/- 0.3 Tg CH4, in each three month period, respectively, and represent a 10% and 37% increase compared to the equivalent season in the opposite year, when rainfall was close to the long-term seasonal mean. We find the additional short rains emissions were equivalent to over a quarter of the growth in global emissions in 2019, highlighting the disproportionate role of East Africa in the global CH4 budget.

Automated summary

The study found that during the long and short rainy seasons in 2018 and 2019, methane emissions in East Africa increased significantly, by 6.2 +/- 0.3 Tg CH4 and 8.6 +/- 0.3 Tg CH4, representing a 10% and 37% increase compared to the equivalent season in the opposite year with near long-term seasonal mean rainfall. The additional emissions during the short rainy season were equivalent to over a quarter of the growth in global methane emissions in 2019, underscoring the disproportionate role of East Africa in the global methane budget.