Glaciers in northern Antarctic Peninsula melting faster than ever despite increased snowfall

An international team of researchers, led by Dr Bethan Davies, from Royal Holloway, University of London, has discovered that small glaciers that end on land around the Antarctic Peninsula are highly vulnerable to slight changes in air temperature and may be at risk of disappearing within 200 years.

Temperatures are currently rising rapidly in the Antarctic Peninsula. Because warmer air holds more moisture, the amount of snowfall has also increased. Some researchers have suggested that this may offset the melting of the glaciers, however this study found that just a small rise in air temperature increased melting so much that even large amounts of extra snowfall could not prevent glacier recession.

"These small glaciers around the edge of the Antarctic Peninsula are likely to contribute most to rising sea levels over the coming decades, because they can respond quickly to climate change," said Dr Davies, from the Department of Geography at Royal Holloway. "This study is the first to show how glaciers in this vulnerable region are likely to respond to climate change in future. Our findings demonstrate that the melting will increase greatly even with a slight rise in temperature, offsetting any benefits from increased snowfall."

The researchers carried out extensive fieldwork on James Ross Island, northern Antarctic Peninsula, to map and analyse the changes to a glacier, which is currently 4km long, over the past 10,000 years. They used a combination of glacier and climate modelling, glacial geology and ice-core data.

Dr Davies added: "Geological evidence from previous studies suggests that the glacier grew by 10km within the last 5,000 years, before shrinking back to its current position. It was argued that this occurred during a warmer but wetter period, suggesting that increased precipitation in the future would offset the melting of the glaciers. However, our study shows that this growth occurred during the colder 'Little Ice Age', reaching its largest size just 300 years ago."

Researcher Dr Nicholas Golledge, from Victoria University of Wellington, in New Zealand, said: "This glacier, though small, is typical of many of the small glaciers that end on land around the Antarctic Peninsula. This research is important, because it helps reduce some of the uncertainties about how these glaciers will react to changing temperature and precipitation over the next two centuries."

Professor Neil Glasser, from Aberystwyth University, added: "We found that this glacier remained roughly the same size for thousands of years until it started to grow again 1,500 years ago. However, it is now melting faster than anything seen before, and over the next 200 years will become far smaller than at any point over the last 10,000 years. This unprecedented glacier recession, in response to climate change, will result in significant contributions to sea level rise from this and similar Antarctic Peninsula mountain glaciers and ice caps."
http://www.sciencedaily.com/releases/2014/09/140914211024.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28Latest+Science+News+--+ScienceDaily%29
14/9/14
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WMO annual climate report confirms 2012 as among top 10 warmest

GENEVA, May 2 (Xinhua) 
-- The World Meteorological Organization (WMO) said Thursday that the year 2012 was the ninth warmest on record despite the cooling influence of a La Nina episode early in the year.
The WMO's Statement on the Status of the Global Climate said that the global land and ocean surface temperature in 2012 was estimated to be 0.45 degrees Celsius above the 1961-1990 average of 14.0 degrees.
This was the ninth warmest year since records began in 1850 and the 27th consecutive year that the global land and ocean temperatures were above the 1961-1990 average, according to the statement.
It said that during 2012, above-average temperatures were observed across most of the globe's land surface areas, most notably North America, southern Europe, western Russia, parts of northern Africa and southern South America.

Nonetheless, cooler-than-average conditions were observed across Alaska, parts of northern and eastern Australia, and central Asia.
WMO Secretary-General Michel Jarraud said that although the rate of warming varies from year to year due to natural variability caused by the El Nino cycle, volcanic eruptions and other phenomena, the sustained warming of the lower atmosphere is a worrisome sign.
"The continued upward trend in atmospheric concentrations of greenhouse gases and the consequent increased radioactive forcing of the Earth's atmosphere confirm that the warming will continue," he said.
Jarraud said that the record loss of Arctic sea ice in August-September, 18 percent less than the previous record low of 2007 of 4.17 million square kilometers was also "a disturbing sign of climate change".
"The year 2012 saw many other extremes as well, such as droughts and tropical cyclones. Natural climate variability has always resulted in such extremes, but the physical characteristics of extreme weather and climate events are being increasingly shaped by climate change," he said.
"For example, because global sea levels are now about 20 cm higher than they were in 1880, storms such as Hurricane Sandy are bringing more coastal flooding than they would have otherwise," Jarraud said.
The WMO's annual statements gather the key climate events of each year, which is an internationally recognized authoritative source of information about temperatures, precipitation, extreme events, tropical cyclones, and sea ice extent. 
 .cntv.cn
2/5/13
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• Πενταπλασιάστηκαν τα ρεκόρ υψηλών θερμοκρασιών στον πλανήτη

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New satellite data reveals sea-level rise

The city of Venice is investing billions in a new flood defence system to protect against sea level rises

(CNN) -- Sea-levels are rising unevenly around the world, with Pacific countries in particular suffering significant increases over the past two decades, according to accurate new satellite data.

On average, global sea-levels have been rising at about three millimeters (mm) a year, however, this masks large differences between regions of the world.

While some regions have seen sea-level rises of 12 mm a year, others have actually seen decreases of about 12 mm a year.

The results are based on radar readings from the European Space Agency (ESA) over an 18-year period from October 1992 to March 2010.

ESA used its satellites to send radar pulses to the sea surface below, recording the time delay in its return and creating a precise measurement of their height above the surface.

Special report: Sea-level rises

Scientists say sea-level rises are the result of the expansion of water due to rising temperatures, melting of glaciers and the melting of polar ice sheets.

Annual mean global sea-level changes 1992-2010 (ESA)

 

The worst hit regions over the past two decades, according to the ESA data, have been the Pacific countries of Indonesia, Papua New Guinea, Philippines and vulnerable Pacific islands like the Solomon Islands.

The Philippines for one is already frequently subjected to flooding and landslides caused by heavy rain, with seasonal monsoon rains in August killing at least 11 people.

Scientists suggest regions that have seen high sea level rises over the past 20 years will not necessarily continue to see higher than average sea-level rises in the future.

"We suspect that the bigger the differences get, the more they will tend to level out in the future," says Robert Meisner, a spokesperson for ESA.

However, a recent study of coastal cities still predicted the Philippines' capital Manila would see its vulnerability to flooding double by the end of the century, due to sea-level rises.

In some regions of the world, the increasingly accurate sea level data is being used by planners to mitigate against the risk of flooding.

See also: Five cities battling flooding, heats and storms

In Venice, where the sea-level data was released, engineers are constructing a new set of tidal barriers to protect the historic city.

The city, which attracts millions of tourists every year, is seeing sea-level rises of around 2 mm per year, together with slow, mostly natural, subsidence of about another 2 mm every year.

The new $7.9 billion-barrier system will see giant barriers placed on the sea floor around Venice. When the water levels rise, air will be pumped into the barriers raising them up to block the tidal flow and protect the city from flooding.

The system is due to be completed in 2014 and is expected to be able to protect the city for the next 20 years.

http://edition.cnn.com/2012/10/02/tech/satellites-sea-level-rise/index.html

3/10/12