Aberystwyth team's glaciers study shock
Melting mountain glaciers are contributing to sea-level rise faster than at any time in the last 350 years.
That’s the finding of new research published today, 3rd April 2011, by a team from Aberystwyth University, the University of Exeter and Stockholm University.
Writing in the journal Nature Geoscience the team undertook a survey of the 270 largest outlet glaciers of the South and North Patagonian Icefields of South America.
They mapped changes in the position of the glaciers since the “Little Ice Age”; the last time that they were much larger in the recent past.
The team calculated the volume of ice lost by the glaciers as they have retreated and thinned over the last 350 years and compared these volume losses to rates of change over the last 30 years.
They found that the rate at which the glaciers are losing volume over the last 30 years is 10 to 100 times faster than the 350 year long-term average.
The study concludes that in recent years these mountain glaciers have rapidly increased their melt rate and thus their contribution to global sea level.
Lead author Professor Neil Glasser, of Aberystwyth University, said, “Previous estimates of sea-level contribution from mountain glaciers are based on very short timescales. They cover only the last 30 years or so when satellite images can be used to calculate rates of glacier volume change.
“We took a different approach by using a new method that allows us to look at longer timescales. We knew that glaciers in South America were much bigger during the Little Ice Age so we mapped the extent of the glaciers at that time and calculated how much ice has been lost by the retreat and thinning of the glaciers”.
The second author, Dr Stephan Harrison of the University of Exeter, explains, “The work is significant because it is the first time anyone has made a direct estimate of the sea-level contribution from glaciers since the peak of the Industrial Revolution (c. AD 1750-1850). Our results show that recent (1990-2000) estimates of rates of glacier contribution to sea-level rise are well above the long-term (1650/1750-2010 and 1870-2010) average.”
The paper “Sea level contribution from the Patagonian Icefields since the Little Ice Age” is published this week (3rd April) in the journal Nature Geoscience (See www.nature.com/naturegeoscience). DOI:10.1038/NGEO1122.
How the study was conducted:
The team used remotely sensed images and fieldwork to map the former extent of the 270 largest outlet glaciers of the South and North Patagonian Icefields (SPI and NPI) of South America during their last major expansion in the Little Ice Age (around AD 1870 for the NPI and around AD 1650 for the SPI).
The total ice loss for the NPI glaciers due to ice recession and thinning around the glacier snouts is 103 ± 20.7 km3 and for the SPI glaciers it is 503 ± 101.1 km3. For the NPI this is equivalent to a volume change of -0.66 km3a-1, or a sea-level contribution of 0.0018 ± 0.0004 mma-1 (AD1870-2010). For the SPI the volume change is -1.25 km3a-1 (AD1650-2010), or a sea-level contribution of 0.0034 ± 0.0007 mma-1.
Estimates of ice-volume loss and sea-level contribution from much more recent downwasting of the Patagonian Icefields since the start of the satellite era (0.105 ± 0.011 mma-1 for the years 1995 to 2000), are two orders of magnitude higher than the long-term average over the years 1650 and 1870 to 2010.
Established in 1872, Aberystwyth (www.aber.ac.uk) is a leading teaching and research university and was awarded a Queen’s Anniversary Prize for Higher and Further Education in 2009. In 2010 the National Student Survey placed Aberystwyth in the top five institutions in the UK for student satisfaction. It is a leading centre for the study of climate change and has recently embarked on a £25m investment programme in new teaching and research facilities. Since its foundation in 1994, the Centre for Glaciology has become one of the leading British research groups concerned with the study of glaciers and their sedimentary products. http://www.aber.ac.uk/en/iges/research-groups/centre-glaciology/.
The front of San Rafael Glacier in Patagonia, one of the 270 glaciers included in this study. This glacier has retreated about 8 km since the peak of the “Little Ice Age” around AD1870. Photo credit: Neil Glasser
Satellite image of Upsala Glacier in Patagonia, one of the 270 glaciers included in this study. This glacier has retreated about 13km since the peak of the “Little Ice Age” around AD1750. Image credit: Neil Glasser
That’s the finding of new research published today, 3rd April 2011, by a team from Aberystwyth University, the University of Exeter and Stockholm University.
Writing in the journal Nature Geoscience the team undertook a survey of the 270 largest outlet glaciers of the South and North Patagonian Icefields of South America.
They mapped changes in the position of the glaciers since the “Little Ice Age”; the last time that they were much larger in the recent past.
The team calculated the volume of ice lost by the glaciers as they have retreated and thinned over the last 350 years and compared these volume losses to rates of change over the last 30 years.
They found that the rate at which the glaciers are losing volume over the last 30 years is 10 to 100 times faster than the 350 year long-term average.
The study concludes that in recent years these mountain glaciers have rapidly increased their melt rate and thus their contribution to global sea level.
Lead author Professor Neil Glasser, of Aberystwyth University, said, “Previous estimates of sea-level contribution from mountain glaciers are based on very short timescales. They cover only the last 30 years or so when satellite images can be used to calculate rates of glacier volume change.
“We took a different approach by using a new method that allows us to look at longer timescales. We knew that glaciers in South America were much bigger during the Little Ice Age so we mapped the extent of the glaciers at that time and calculated how much ice has been lost by the retreat and thinning of the glaciers”.
The second author, Dr Stephan Harrison of the University of Exeter, explains, “The work is significant because it is the first time anyone has made a direct estimate of the sea-level contribution from glaciers since the peak of the Industrial Revolution (c. AD 1750-1850). Our results show that recent (1990-2000) estimates of rates of glacier contribution to sea-level rise are well above the long-term (1650/1750-2010 and 1870-2010) average.”
The paper “Sea level contribution from the Patagonian Icefields since the Little Ice Age” is published this week (3rd April) in the journal Nature Geoscience (See www.nature.com/naturegeoscience). DOI:10.1038/NGEO1122.
How the study was conducted:
The team used remotely sensed images and fieldwork to map the former extent of the 270 largest outlet glaciers of the South and North Patagonian Icefields (SPI and NPI) of South America during their last major expansion in the Little Ice Age (around AD 1870 for the NPI and around AD 1650 for the SPI).
The total ice loss for the NPI glaciers due to ice recession and thinning around the glacier snouts is 103 ± 20.7 km3 and for the SPI glaciers it is 503 ± 101.1 km3. For the NPI this is equivalent to a volume change of -0.66 km3a-1, or a sea-level contribution of 0.0018 ± 0.0004 mma-1 (AD1870-2010). For the SPI the volume change is -1.25 km3a-1 (AD1650-2010), or a sea-level contribution of 0.0034 ± 0.0007 mma-1.
Estimates of ice-volume loss and sea-level contribution from much more recent downwasting of the Patagonian Icefields since the start of the satellite era (0.105 ± 0.011 mma-1 for the years 1995 to 2000), are two orders of magnitude higher than the long-term average over the years 1650 and 1870 to 2010.
Established in 1872, Aberystwyth (www.aber.ac.uk) is a leading teaching and research university and was awarded a Queen’s Anniversary Prize for Higher and Further Education in 2009. In 2010 the National Student Survey placed Aberystwyth in the top five institutions in the UK for student satisfaction. It is a leading centre for the study of climate change and has recently embarked on a £25m investment programme in new teaching and research facilities. Since its foundation in 1994, the Centre for Glaciology has become one of the leading British research groups concerned with the study of glaciers and their sedimentary products. http://www.aber.ac.uk/en/iges/research-groups/centre-glaciology/.
The front of San Rafael Glacier in Patagonia, one of the 270 glaciers included in this study. This glacier has retreated about 8 km since the peak of the “Little Ice Age” around AD1870. Photo credit: Neil Glasser
Satellite image of Upsala Glacier in Patagonia, one of the 270 glaciers included in this study. This glacier has retreated about 13km since the peak of the “Little Ice Age” around AD1750. Image credit: Neil Glasser
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