‘Surprisingly high’ temps beneath West Antarctica causing ice to melt

Mount Erebus Aerial 2" by jeaneeem - Flickr. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mount_Erebus_Aerial_2.jpg#/media/File:Mount_Erebus_Aerial_2.jpgMount Erebus Antarctica’s active volcano by jeaneeem – Flickr. Licensed under CC BY 2.0 via Wikimedia CommonsA new study published Friday in the journal Science Advances reveals what some geologists have known all along: geothermal heat flowing toward the base of the West Antarctic Ice Sheet is causing the ice to melt, and it has nothing to do with warmer oceans or atmosphere. For the very first time, geothermal heating has been directly measured beneath the West Antarctic Ice Sheet (WAIS) and the UC/Santa Cruz researchers found the amount of subglacial heat was “surprisingly high.” Direct measurements of geothermal heat flowing at the base of the WAIS, below subglacial Lake Whillans, showed an extremely high heat flux, which is “significantly higher than the continental and regional averages” that used traditional measuring methods.

Since satellite measurements began in 1979, Antarctic sea ice extent around the continent has been growing year after year and leaving many researchers puzzled, since because climate models have completely missed the mark and predicted rapid ice loss from both poles. This new research shows that, at least in West Antarctica, the continent is a geologically active area that sits on one of the world’s largest Rift Systems. Altered heat and fluid release from the WAIS has been hidden from scientific investigation because the primary heat release was in hitherto unreachable areas.

Instrumental readings from beneath the subglacial Lake Whillan showed a very high upward heat flow through the WAIS, and that this high geothermal heat flow “may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.” According to the study’s lead author, Professor Andrew Fisher, “this is a region where there is volcanic activity, so this measurement may be due to a local heat source in the crust.” The team used a special thermal probe “to measure temperatures in sediments below subglacial Lake Whillans, which lies beneath half a mile of ice.”

Once drilling was completed, the UC/Santa Cruz-built probe was lowered through the “borehole until it buried itself in the sediments below the subglacial lake.” What the probe found was rather astonishing: temperatures at different depths in the sediments were roughly five times higher than what is typically found on continents. This indicated that a geothermal heat flow was melting the bottom of the ice sheet. Once melted, the water would flow into a “network of subglacial lakes and wetlands that underlies a large region of the ice sheet.” Much of this freshwater eventually makes its way to the surrounding ocean via underground funnels and natural drainage systems.

After contacting geologist James Kamis about this study, who has been writing about this subject for many years, he indicated this geothermal activity beneath the WAIS can “melt significant amounts of the Antarctic glacial ice sheet in a relatively short period of time, and it certainly has a very strong affect on the Antarctic climate.” He also says it can influence other parts of the planet by increasing worldwide sea level rise, change selective deep-ocean currents, and modify significant portions of our global climate patterns.

Another author of this research, Professor Slawek Tulaczyk, notes, “It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic Ice Sheet will behave in the future, how much of it is melting, how quickly ice streams flow, and what the impact might be on sea level rise. I waited for many years to see a directly measured value of geothermal flux [flow] from beneath this ice sheet.”

All of this may be mute if the source of the geothermal heat turns out to be from an anecdotal measurement caused by a specific, localized heat source. That seems unlikely, Kamis said, as the WAIS sits atop one of the Earth’s most geothermally active regions. Hidden beneath West Antarctica’s thick glacial ice cover is a myriad of currently active rifts and volcanoes that are all located along the West Antarctic Rift System. He pointed out a research project by the University of Texas that concluded the glaciers in the Amundsen Embayment Area were melting in response to geothermal sources.

While some believe that ice sheet melt is the “canary in the coal mine” as far as global warming is concerned, ice-core analysis from Antarctica shows that nothing unusual is occurring in terms of melting. Another study, using deep ice cores drilled from the WAIS to reconstruct records going back 2,000 years, shows that melting in that area is, in fact, normal. And still another major study published in Nature showed similar conclusions regarding the “much-discussed Antarctic Peninsula” previously reported here.