Rain-fed pulses of methane from East Africa during 2018–2019 contributed to atmospheric growth rate
Mark F. Lunt, Paul I. Palmer, Alba Lorente, Tobias Borsdorff, Jochen Landgraf, Robert J. Parker, Hartmut Boesch
Abstract
Abstract East Africa is a key location for wetland emissions of methane (CH 4 ), driven by variations in rainfall that are in turn influenced by sea-surface temperature gradients over the Indian Ocean. Using satellite observations of CH 4 and an atmospheric chemistry-transport model, we quantified East African CH 4 emissions during 2018 and 2019 when there was 3- σ anomalous rainfall during the long rains (March–May) in 2018 and the short rains (October–December) in 2019. These rainfall anomalies resulted in CH 4 emissions of 6.2 ± 0.3 Tg CH 4 and 8.6 ± 0.3 Tg CH 4 , 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 CH 4 budget.