Something for everyone this weekend: a few podcasts to grab, ice news from both ends of the planet, interesting reading, and a great interview with Noam Chomsky. Audio first: Radio NZ National’s Bryan Crump interviewed Prof Jean Palutikof, Director of the National Climate Change Adaptation Research Facility at Griffith University in Queensland at the beginning of the week. It’s a wide-ranging discussion: Palutikof is an engaging speaker and frank about the dangers we confront. Grab the podcast now, because it’ll disappear from the RNZ site on Monday.
The 2010 ice melt season on the Greenland ice sheet (see video) set new records, according to Marco Tedesco, director of the Cryospheric Processes Laboratory at the City University of New York. The melt season was “exceptional”, Tedesco said. Melting in some areas lasted as much as 50 days longer than average, starting very early at the end of April and ending later than usual in mid-September. During the summer, temperatures over large parts of Greenland were as much as 3ºC above average, snowfall was below average, and the capital, Nuuk, had its warmest spring and summer since records began in 1873.
Tedesco is lead author of a paper published today, The role of albedo and accumulation in the 2010 melting record in Greenland(*), which integrates weather, satellite and ground data with modelling to build a detailed picture of the melt season. Here’s the abstract:
Analyses of remote sensing data, surface observations and output from a regional atmosphere model point to new records in 2010 for surface melt and albedo, runoff, the number of days when bare ice is exposed and surface mass balance of the Greenland ice sheet, especially over its west and southwest regions. Early melt onset in spring, triggered by above-normal near-surface air temperatures, contributed to accelerate snowpack metamorphism and premature bare ice exposure, rapidly reducing the surface albedo. Warm conditions persisted through summer, with the positive albedo feedback mechanism being a major contributor to large negative surface mass balance anomalies. Summer snowfall was below average. This helped to maintain low albedo through the 2010 melting season, which also lasted longer than usual.
Jason Box will be posting more on the extraordinary warmth of last summer in Greenland at his meltfactor.org blog soon.
Meanwhile, the summer warmth seems to be persisting through the depths of winter — even become more extreme — as this temperature anomaly map for the last month from an excellent article by Bob Henson of UCAR discusses. Those positive anomalies (in red) are as much as 21ºC above average for the time of year:
[…]Let’s take a look at Coral Harbour, located at the northwest corner of Hudson Bay in the province of Nunavut. On a typical mid-January day, the town drops to a low of –34°C (–29.2°F) and reaches a high of just -26°C (–14.8°F). Compare that to what Coral Harbour actually experienced in the first twelve days of January 2011, as reported by Environment Canada […].
After New Year’s Day, the town went 11 days without getting down to its average daily high.
On the 6th of the month, the low temperature was –3.7°C (25.3°F). That’s a remarkable 30°C (54°F) above average.
On both the 5th and 6th, Coral Harbor inched above the freezing mark. Before this year, temperatures above 0°C (32°F) had never been recorded in the entire three months of January, February, and March.
The unseasonal warmth is associated with what Henson describes as ” a vast bubble of high pressure” which formed near Greenland in mid-December. The high was associated with record-breaking 500mb heights, a measure of the “thickness” of the atmosphere and associated with warmth below. This high helped to direct the atmospheric flows that brought Europe’s December cold spell.
With the delayed freeze-up in Hudson Bay and a warm winter on the fringes of the Greenland ice sheet, it may that 2010′s record for ice melt will not last long. And that’s not good news.
(*)Marco Tedesco, X Fettweis, MR van den Broeke, RSW van de Wal, CJPP Smeets, WJ van de Berg, MC Serreze, and Jason Box, The role of albedo and accumulation in the 2010 melting record in Greenland, Environmental Research Letters DOI: 10.1088/1748-9326/6/1/014005. My thanks to Jason Box for the details.
Northern hemisphere winter, that is — we’re still in a nice warm autumn down here. Before I disappear for a couple of days of hectic activity (vintage 2010 tomorrow, bottling the ‘09 on Monday), I just wanted to draw attention to a couple of articles I read over my Saturday morning toast (fine bread from the farmer’s market). The first is the review of the northern hemisphere winter by Bob Henson at UCAR: an interesting overview of how El Niño and the Arctic Oscillation combined to bring cold and snow to the US and Europe, but record breaking warmth to Canada, Greenland, North Africa and the Middle East. Henson draws on a fascinating statistical analysis of the winter by Geert Jan van Oldenborgh of the Netherlands Meteorological Institute(KNMI), putting the combination of cold, snow and warmth into the context of a changing climate.
Van Oldenborgh assesses the the likelihood of the various temperature and snowfall anomalies in the context of an unchanging climate, and on the change that current trends indicate has already occurred. The map above left (click to see the original via KNMI) shows how often winters as cold as 2010 would be expected in the current (changing) climate: 10-50 year return periods are common, stretching out to 100-500 years in parts of Siberia. The map at right shows the warm extremes. Even in a warming climate, winter 2010 was a 10,000 year event — extremely unusual — in parts of the Middle East. Egypt’s winter, for instance, was a full 1ºC above the previous record, and 3ºC above the mean. Southern Greenland was also exceptionally warm. Compared with an unchanging climate (assuming that the probabilities for 1971-2000 still apply), the cold anomalies are less extreme because cold events were more common in the past, and the heat extremes were greater. But however you analyse the situation, the warmth experienced in Canada and the Middle East was more unusual than the US and European cold spells. It’s well worth reading van Oldenborgh’s article, even if you’d rather be eating chocolate eggs.
PS: Also noteworthy: David Appell takes a look at why current sea ice extent/areas don’t tell us the ice is “back to normal”, as some would have us believe. In the words of the old joke, sceptics are asserting “never mind the quality, feel the width.”
May all your buns be cross, and hot. Happy Easter.