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| Ice sheets losing volume at increased levels http://www.envirolink.org/forum/viewtopic.php?f=3&t=24700 |
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| Author: | Wayne Stollings [ Fri Aug 22, 2014 7:40 am ] |
| Post subject: | Ice sheets losing volume at increased levels |
http://www.awi.de/en/news/press_release ... bbd97480fe “The new elevation maps are snapshots of the current state of the ice sheets. The elevations are very accurate, to just a few metres in height, and cover close to 16 million km2 of the area of the ice sheets. This is 500,000 square kilometres more than any previous elevation model from altimetry”, says lead-author Dr. Veit Helm, glaciologist at the Alfred Wegener Institute in Bremerhaven. For the new digital maps, the AWI scientists had evaluated all data by the CryoSat-2 altimeter SIRAL. Satellite altimeter measure the height of an ice sheet by sending radar or laser pulses in the direction of the earth. These signals are then reflected by the surface of the glaciers or the surrounding waters and are subsequently retrieved by the satellite. This way the scientists were able to precisely determine the elevation of single glaciers and to develop detailed maps. On the basis of further CrysoSat-2 the scientists also documented how the elevation has changed over the 2011–2014 period. Ice sheets gain mass through snowfall and lose it due to melting and accelerating glaciers, which carry ice from the interior of the ice sheet to the ocean. “We need to understand where and to which extent the ice thickness across the glaciers has changed. Only then can we can analyse the drivers of these changes and find out how much ice sheets contribute to global sea level rise”, says Veit Helm. The team derived the elevation change maps using over 200 million SIRAL data points for Antarctica and around 14.3 million data points for Greenland. The results reveal that Greenland alone is reducing in volume by about 375 cubic kilometres per year. “When we compare the current data with those from the ICESat satellite from the year 2009, the volume loss in Greenland has doubled since then. The loss of the West Antarctic Ice Sheet has in the same time span increased by a factor of 3. Combined the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest speed observed since altimetry satellite records began about 20 years ago,” says AWI glaciologist Prof. Dr. Angelika Humbert, another of the study’s authors. |
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| Author: | Milton Banana [ Sun Aug 24, 2014 2:31 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
This again? Really? |
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| Author: | Wayne Stollings [ Sun Aug 24, 2014 2:51 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
Yes, that again. The results reveal that Greenland alone is reducing in volume by about 375 cubic kilometres per year. “When we compare the current data with those from the ICESat satellite from the year 2009, the volume loss in Greenland has doubled since then. The loss of the West Antarctic Ice Sheet has in the same time span increased by a factor of 3. Combined the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest speed observed since altimetry satellite records began about 20 years ago,” says AWI glaciologist Prof. Dr. Angelika Humbert, another of the study’s authors. |
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| Author: | Wayne Stollings [ Sun Aug 24, 2014 2:54 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
One cubic kilometer is equal to about 264 billion gallons of water. The two major sheets are losing about 500 cubic kilometers per year. Thus, there is 132,000,000,000,000 gallons of water being added to the oceans every year. That by itself is ~1.4 mm per year in sea level rise. |
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| Author: | Milton Banana [ Sun Aug 24, 2014 3:13 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Wayne Stollings [ Sun Aug 24, 2014 5:40 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Wayne Stollings [ Sun Aug 24, 2014 5:46 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
http://en.wikipedia.org/wiki/Sublimatio ... transition) Water Snow and ice sublime, although more slowly, at temperatures below the freezing/melting point temperature line at 0 °C for most pressures; see line below triple point.[1] In freeze-drying, the material to be dehydrated is frozen and its water is allowed to sublime under reduced pressure or vacuum. The loss of snow from asnowfield during a cold spell is often caused by sunshine acting directly on the upper layers of the snow. Ablation is a process that includes sublimation and erosive wear of glacier ice. |
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| Author: | Milton Banana [ Sat Aug 30, 2014 10:54 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Wayne Stollings [ Sat Aug 30, 2014 11:18 pm ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Milton Banana [ Sun Aug 31, 2014 12:46 am ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Wayne Stollings [ Sun Aug 31, 2014 6:44 am ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
| Author: | Wayne Stollings [ Sun Aug 31, 2014 7:00 am ] |
| Post subject: | Re: Ice sheets losing volume at increased levels |
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