- Glaciers between Pakistan and China have gained mass of ice since 1998
- Survey using satellite data
- Area accounts for 3% of ice-covered area on Earth
- Gain in thickness between 1999 and 2008
- Flies in face of predictions of climate activists
By Rob Waugh
UPDATED: 18:15 EST, 10 July 2012
Huge glaciers in the area between Pakistan and China are puzzling scientists – and disproving the doom-laden predictions of some climate experts.
The glaciers in the Karakoram Range between northern Pakistan and western China have actually grown, rather than shrinking.
Unlike most mountain glaciers, the Karakoram glaciers, which account for 3 percent of the total ice-covered area in the world, excluding Greenland and Antarctica, are not shrinking.
A team of French glaciologists has recently confirmed that these glaciers on average have remained stable or may have even grown slightly in recent years.
The new study used data from satellites to study the Karakoram Range of northern Pakistan and western China.
The researchers found that the ice had actually increased in thickness by 0.11 (plus or minus 0.22) meters per year between 1999 and 2008.
Experts cautioned that the gain is so small that the glaciers might not actually be growing – but what is clear is that the glaciers are not shrinking, according to a report published in Nature Geoscience.
Etienne Berthier, a glaciologist at the Université de Toulouse in France says, ‘Not all glacial regions are changing in the same way.’
A Nasa study earlier this year using the gravity-sensing GRACE satellites hinted that ice loss in the high Asian mountains might be far less drastic than earlier predictions.
Previous estimates of ice loss in the high Asia mountains have ranged up to 50 billion tons a year, according to the University of Colorado Boulder University’s Professor John Wahr.
Previously, it had been claimed by the UN that Himalayan glaciers would have melted to a fifth of current levels by 2035, leading to sea level rises and drought.
Those predictions used ground-based measurements, whereas the new study measured the effect of gravity on twin Nasa satellites to give an accurate measure of the mass of ice being lost.
‘The results in this region really were a surprise,’ said Wahr.
‘One possible explanation is that previous estimates were based on measurements taken primarily from some of the lower, more accessible glaciers in Asia and were extrapolated to infer the behavior of higher glaciers.’
‘But unlike the lower glaciers, many of the high glaciers would still be too cold to lose mass, even in the presence of atmospheric warming.’
Around the world, melting has been overestimated. Earth’s glaciers and ice caps are shedding roughly 150 billion tons of ice annually – up to 30 per cent lower than predicted.
The researchers used satellite measurements taken with the Gravity Recovery and Climate Experiment, or GRACE,, to calculate that the world’s glaciers and ice caps had lost about 148 billion tons, or about 39 cubic miles of ice annually from 2003 to 2010.
Traditional estimates of Earth’s ice caps and glaciers have been made using ground-based measurements from relatively few glaciers to infer what all of the unmonitored glaciers around the world were doing, he said.
Only a few hundred of the roughly 200,000 glaciers worldwide have been monitored for a decade or more.
‘The strength of GRACE is that it sees everything in the system,’ said Wahr. ‘Even though we don’t have the resolution to look at individual glaciers, GRACE has proven to be an exceptional tool.’
The total does not count the mass from individual glacier and ice caps on the fringes of the Greenland and Antarctic ice sheets — roughly an additional 80 billion tons.
Launched in 2002, two GRACE satellites whip around Earth in tandem 16 times a day at an altitude of about 300 miles, sensing subtle variations in Earth’s mass and gravitational pull.
Separated by roughly 135 miles, the satellites measure changes in Earth’s gravity field caused by regional changes in the planet’s mass, including ice sheets, oceans and water stored in the soil and in underground aquifers.
A positive change in gravity during a satellite approach over Greenland, for example, tugs the lead GRACE satellite away from the trailing satellite, speeding it up and increasing the distance between the two.
A sensitive ranging system allows researchers to measure the distance of the two satellites down to as small as 1 micron- about 1/100 the width of a human hair – and to calculate ice and water amounts from particular regions of interest around the globe using their gravity fields.
‘The total amount of ice lost to Earth’s oceans from 2003 to 2010 would cover the entire United States in about 1 and one-half feet of water,’ said Wahr, also a fellow at the CU-headquartered Cooperative Institute for Research in Environmental Sciences.
According to the GRACE data, total sea level rise from all land-based ice on Earth including Greenland and Antarctica was roughly 1.5 millimeters per year annually or about 12 millimeters, or one-half inch, from 2003 to 2010, said Wahr.