The Impact of the Extreme 2015–2016 El Niño on the Mass Balance of the Antarctic Ice Sheet

Interannual variations associated with El Niño‐Southern Oscillation can alter the surface‐pressure distribution and moisture transport over Antarctica, potentially affecting the contribution of the Antarctic ice sheet to sea level. Here, we combine satellite gravimetry with auxiliary atmospheric data sets to investigate interannual ice‐mass changes during the extreme 2015–2016 El Niño. Enhanced precipitation during this event contributed positively to the mass of the Antarctic Peninsula and West Antarctic ice sheets, with the mass gain on the peninsula being unprecedented within GRACE's observational record. Over the coastal basins of East Antarctica, the precipitation‐driven mass loss observed in recent years was arrested, with pronounced accumulation over Terre Adélie dominating this response. Little change was observed over Central Antarctica where, after a brief pause, enhanced mass‐loss due to weakened precipitation continued. Overall, precipitation changes over this period were sufficient to temporarily offset Antarctica's usual (approximately 0.4 mm yr−1) contribution to global mean sea level rise. Plain Language Summary Given that the Antarctic Ice Sheet has the potential to raise sea level by over 50 m if completely melted, it is crucial that we fully understand the factors controlling its stability. Presently, changes in rates of mass loss and mass gain over the ice sheet vary from short (seasonal/interannual) to long (decadal) timescales. Previous research has shown that one potential factor influencing Antarctica on interannual timescales is the El Niño‐Southern Oscillation, a large‐scale interaction between the Pacific Ocean and the overlying atmosphere that fluctuates between warm (El Niño) and cold (La Niña) states every 2–7 years. Here, we show an unprecedented increase in accumulation over the Antarctic Peninsula and West Antarctic sectors during the extreme 2015–2016 El Niño, along with a brief stabilization in mass loss over East Antarctica. Overall, precipitation changes during this event were sufficient to temporarily offset Antarctica's usual (approximately 0.4 mm yr−1) contribution to global mean sea level rise. Key Points Precipitation‐derived mass anomalies are estimated for the Antarctic Ice Sheet over the GRACE period An unprecedented increase in accumulation over the Antarctic Peninsula and West Antarctica coincides with the extreme 2015–2016 El Niño This was sufficient to temporarily offset Antarctica's usual (≈0.4 mm yr−1) con