Volume 16, Number 15: 10 April 2013
Boening et al. (2012) begin their treatment of the subject of this editorial by writing that "an improved understanding of processes dominating the sensitive balance between mass loss primarily due to glacial discharge and mass gain through precipitation is essential for determining the future behavior of the Antarctic ice sheet and its contribution to sea level rise." And, hence, in the body of their report, they proceed to "describe the causes and magnitude of recent extreme precipitation events along the East Antarctic coast that led to significant regional mass accumulations that partially compensate for some of the recent global ice mass losses that contribute to global sea level rise."
Perhaps the most important finding of the four U.S. scientists was "an abrupt mass increase in East Antarctica along the coast of Dronning Maud Land in the GRACE satellite data in 2009-2011," which they were pointed to by their study of precipitation data derived from CloudSat and ERA Interim re-analysis products [Dee et al., 2011] that showed the mass increase to have been caused by "anomalously high precipitation events during the Southern Hemisphere winter." And this gain of "almost 350 Gt from 2009 to 2011," as they describe it, "is equivalent to a decrease in global mean sea level at a rate of 0.32 mm per year."
In further analyzing the precipitation data, Boening et al. found that "the mass gain primarily occurred during May of 2009 and June of 2011," and they say that "most of the accumulation in these months resulted from snowfall from only a few main events," while additionally noting that the primary drivers of the observed mass increase were "prolonged changes in pressure patterns and induced poleward wind in the two years."
Although the researchers indicate that the ERA Interim re-analysis data show that no significant change in snowfall frequency or strength occurred between 1979 and 2008, their findings of the following few years suggest that just a slight tweak of atmospheric conditions could drastically alter the ice mass balance of the East Antarctic ice sheet in a positive way and significantly slow the rate-of-rise of global mean sea level.
Sherwood, Keith and Craig Idso
References
Boening, C., Lebsock, M., Landerer, F. and Stephens, G. 2012. Snowfall-driven mass change on the East Antarctic ice sheet. Geophysical Research Letters 39: 10.1029/2012gL053316.
Dee, D.P., Uppala, S.M., Simmons, A.J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M.A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A.C.M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A.J., Haimberger, L., Healy, S.B., Hersbach, H., Holm, E.V., Isaksen, L., Kallberg, P., Kohler, M., Matricardi, M., McNally, A.P., Monge-Sanz, B.M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thepaut, J.-N. and Vitart, F. 2011. The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quarterly Journal of the Royal Meteorological Society 137: 553-597.