Guest post by Dr Jonathan Day, Department of Meteorology, University of Reading
What is going on with the Antarctic sea ice?
March 2017 was an interesting month for sea ice. Both northern and southern hemispheres experienced record breaking low extents for the time of year. The extent of Arctic sea ice reached the maximum area of its seasonal cycle on March 7th coming in at 14.42 million km2. This was a fraction below the previous record, set in 2015 and is in line with what we expect to see in a warming climate. Meanwhile the other side of the planet Antarctic sea ice continues to confound expectations. Continue reading
Here is, hopefully, an informative and hopefully entertaining A to Z of all things Antarctic!
- A – Antarctica. The 5th largest continent in with world, with 26.5 million km3 of ice.
- B – Beaker [slang]. A scientist who visits Antarctica to undertake research.
- C – Cold. Antarctica has the coldest average temperature of any continent. The coldest temperature ever recorded on Earth was at Vostok: -89.2°C on 21st July 1983. Continue reading
A new paper by Levermann et al. in PNAS uses the record of past rates of sea level rise from palaeo archives and numerical computer models to understand how much sea level rise we can expect per degree of warming in the future. These data suggest that we can expect a global sea level rise of 2.3 m per 1°C of warming within the next 2000 years: well within societal timeframes. A 2°C of warming would result in a global sea level rise of 4.8 m within 2000 years. This would inundate many coastal cities in Europe alone, and cause untold economic and societal damage.
Holt, T.O., Glasser, N.F., Quincey, D. and Siegfried, M.R., 2013. Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula. The Cryosphere, 7: 797-816.
George VI Ice Shelf
George VI Ice Shelf, Alexander Island, showing ice flowing onto the ice shelf from both the Antarctic Peninsula and Alexander Island
Alexander Island and George VI Ice Shelf is an area I’m particularly interested in (see our project details), and the ice shelf is worth investigating for several reasons. For a start, it’s unusual, being trapped between the mainland and Alexander Island, and secondly, because it’s right on the -9°C mean annual air temperature isotherm (like a contour, but of mean annual air temperatures). Some people have argued that this mean annual air temperature is the critical threshold above which ice shelves may dramatically collapse, which has implications for accelerated flow of glaciers and ice-sheet thinning. Ice shelves are also susceptible to warming from below by warm currents penetrating onto the continental shelf. So, research into this important part of the peninsula is always welcome. Holt and colleagues have just completed a study (open access) that investigates the response of George VI Ice Shelf to environmental change (i.e., oceanic and atmospheric temperature variations), and offer an assessment as to its future stability (Holt et al., 2013). Continue reading