Friday, January 18, 2013

Glaciers continue losing mass adding to sea level rise

Figure 2: Mean cumulative mass balance of all reported glaciers (blue line) and the reference glaciers (red line), from glaciers in the Americas and Eurasia.

Preliminary figures for glacier mass balance for 2010/2011 have just been released and show that data from more than 100 mountain glaciers from around the world continue a strong trend of losing mass. The melt water from glaciers flows into the oceans and adds to sea level rise.

The report says:

"The average mass balance of the glaciers with available long-term observation series around the world continues to be negative, with tentative figures indicating a further thickness reduction of one metre water equivalent (m w.e.) during the hydrological year 2011. The new data continues the global trend in strong ice loss over the past few decades and brings the cumulative average thickness loss of the reference glaciers since 1980 at more than 15 m w.e."

Figure 1: Mean annual mass balance of reference glaciers from glaciers in the Americas and Eurasia.

I reported in January 2011 on research from Canada that most mountain glaciers are on the retreat. Many glaciers in Europe, New Zealand, Africa and the US Rocky Mountains will lose up to 75 per cent of their mass by the end of the century. The melt from mountain glaciers will contribute up to 12 centimetres of sea level rise by 2100.

Himalayan Glaciers

Himalayan glaciers are more complex with most retreating, some stable, and a very few advancing. Glaciologists have been paying particular attention to trends in Himalayan Glaciers after the Glaciergate! error in the IPCC 4th assessment report.

A recent study found that Himalayan Glaciers Will Shrink by Almost 10 Percent, Even If Temperatures Hold Steady Study author Brigham Young University geology professor Summer Rupper said that "These particular glaciers have seen so much warming in the past few decades that they're currently playing lots of catch up,"

She predicts that almost 10 percent of Bhutan's glaciers would vanish within the next few decades. More concerning, the amount of melt water coming off these glaciers could drop by 30 percent.

A National Research Council report from September 2012 found that Himalayan Glaciers Retreating at Accelerated Rate in the Hindu Kush region.

Glaciers in the northwestern Himalayas and especially in the Karakoram Range are subject to surges and are the exceptions to the overall trend of decreasing glacier extent and volume in the region. A comprehensive study by glaciologists from the University of Zurich found that State of Himalayan Glaciers Less Alarming Than Feared


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