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

Abstract

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.As the dominant and most far-reaching mode of interannual climate variability, the impact of ENSO on the AIS is of particular interest. El Niño's influence in the Southern Hemisphere's high latitudes has been associated with blocking events induced by Rossby wave trains that alter surface-pressure distribution and

Accelerated Climate Changes in Weddell Sea Region of Antarctica Detected by Extreme Values Theory

“…As mentioned before, the disagreement with EVT we evidenced can be interpreted as the acceleration of warming in some regions of the Antarctic, perhaps much faster than the warming recorded through global averages [16], as results from the return plots. If confirmed, this opens up new scenarios concerning local, possibly abrupt accelerations of climate change, thus strongly influencing and constraining the alert that signals the tipping point in the world's greatest repository of ice.…”

“…In particular, it is evident that the maximum value T (min) M of minimum temperature registered to date has a high probability to be rapidly surpassed in a few years at the Halley Met station, while this is not so obvious for the Rothera Met station. In other words, the system seems to be particularly sensitive to local factors of the climate system, which affect the dynamics [16]. In particular, in our case, this results in a local acceleration of the increase in minimum temperatures at Halley Met rather than at Rothera Met.…”

“…In particular, in our case, this results in a local acceleration of the increase in minimum temperatures at Halley Met rather than at Rothera Met. This could be due to the effect of El Niño Southern Oscillation, which influences the mass changes from region to region [16].…”

Inter-Annual Variability in the Antarctic Ice Sheets Using Geodetic Observations and a Climate Model

“…ENSO also causes simultaneous high and low pressure systems leading to larger cloud formation and precipitation. This often leads to fluctuations in the normal mass change trends [12] and can influence the nominal mass change patterns in Antarctica [9,13]. Similar anomalies were detected in surface mass and elevation change estimated from space-borne geodetic techniques which had a periodicity of 4 to 6 years and circle the AIS in 9 to 10 years [14].…”

“…As Gao et al (2019) [31] suggest, combined analysis using multiple data sets give better estimates rather than from a single technique or data set. Multiple studies talk about the influence of climate processes and presence of climate process signature in the ice sheet mass balance at multiple scales [9,[12][13][14] but have not explored it based on mass balance estimates from a climate model to establish a possible climate origin. A recent study using surface mass balance estimates and GRACE data by Zhang et al (2021) [32] finds correlation between interannual ice mass variations on a regional scale and ENSO index.…”