Antarctica has been referred to as the “last place on Earth.” It has recently been in the news because of a gigantic rift in the Antarctic Peninsulas’s Larsen C ice shelf. Some scientists have suggested that if part of the shelf breaks off, it could be an iceberg the size of the state of Delaware. The Larsen B ice shelf did something similar in 2002. While such calving processes are often naturally-occurring, climatologists are also watching the region for signs of climate change.
Antarctica is often misunderstood, and you commonly see people mischaracterize ice gains and losses in Antarctica compared to the Arctic. It is typically a region known for being cold. The South Pole’s annual mean temperature is -76F (-60C) in winter and -18 (-28.2C) in summer according to data at Woods Hole Oceanographic Institute. In a previous Forbes discussion, I explained why the polar regions are so cold. However, the World Meteorological Organization (WMO) announced today new verified record high-temperatures for the region, and they may surprise you.
WMO announced in a press release,
The highest temperature for the “Antarctic region” (defined by the WMO and the United Nations as all land and ice south of 60-deg S) of 67.6 F (19.8 C) , which was observed on Jan. 30, 1982 at Signy Research Station, Borge Bay on Signy Island. The highest temperature for the Antarctic Continent, defined as the main continental landmass and adjoining islands, is the temperature extreme of 63.5 F (17.5 C) recorded on Mar. 24, 2015 at the Argentine Research Base Esperanza located near the northern tip of the Antarctic Peninsula. The highest temperature for the Antarctic Plateau (at or above 2,500 meters, or 8,200 feet) was 19.4 F (-7 C) made on Dec. 28, 1989 at an automatic weather station site D-80 located inland of the Adelie Coast.
These records are quite impressive when you consider that average yearly temperature ranges from about about 14 F on the coasts to -76 F at the highest points in the interior. The ice sheet contains about 90% of the planet’s freshwater supply and is about 3 miles thick in places. While unlikely to happen, if the entire ice sheet melted it would raise sea levels by around 200 feet (60 meters) according to the WMO.
Randy Cerveny is an Arizona State University professor of geographical science and urban planning and also serves as the the Rapporteur of Climate and Weather Extremes for the WMO. He stated in this morning’s press release,
The temperatures we announced today are the absolute limit to what we have measured in Antarctica…The polar regions of our planet have been termed the ‘canary’ in our global environment…because of their sensitivity to climate changes, sometimes the first influences of changes in our global environment can be seen in the north and south polar regions.
If you commonly read my discussions in Forbes, you know that I use them to increase weather and climate literacy. An intriguing aspect of the Antarctic records is that they were likely associated with “Foehn-type winds” often referred to as “Chinook winds” here in the Rocky Mountain region of the United States. The American Meteorological Society glossary defines Foehn winds as,
The specific reference to the Alps provides clues about the origin of the word, but the winds exist in Antarctica as well. Though not as well-studied, a 2010 research paper published in the Journal of Climate concluded that Foehn winds resulting from modified air flow in the lee of mountain barriers in the Mcmurdo Dry Valleys are fairly frequent. Why are these types of winds so warm? It has to do with something called adiabatic compression. Adiabatic means no heat is exchanged between a thermodynamic system and the surrounding environment. On the lee side of mountains, air descends and is compressed (think about your hand pressing down on a sponge). Such compression also leads to “adiabatic warming” of the air. Though targeted at kids, the KidsGeo website actually has a pretty simple explanation of this fairly rigorous scientific progress.
The next time you head to Antarctica, pack your shorts (just kidding). However, in all seriousness, we must continue to monitor and study the polar regions carefully. I should also mention that due to the remoteness of polar regions, satellite based observations like those provided by NASA’s Earth Sciences program are vital for doing so and should be maintained.
Dr. Marshall Shepherd, Dir., Atmospheric Sciences Program/GA Athletic Assoc. Distinguished Professor (Univ of Georgia), Host, Weather Channel’s Sunday Talk Show, Weather (Wx) Geeks, 2013 AMS President
Highest Recorded Temperatures In Antarctica Announced And They May Surprise You – Forbes