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using the most advanced earth observing

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laser instrument nasa has ever flown in

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space scientists have made precise

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detailed measurements of how the

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elevation of ice sheets in greenland and

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antarctica have changed over 16 years

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we can actually see some processes at a

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scale that's almost long enough to tell

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us about the climate in those two places

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scientists took ice sheet elevation

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measurements from 2003 overlaid data

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from 2019

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and analyzed where the data sets

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intersected in order to see where ice

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was lost or gained for example the study

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definitively shows that the east

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antarctic ice sheet the largest of all

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the ice sheets is growing but more

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importantly what we find is that growing

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is more than offset by increased losses

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coming from the west antarctic ice sheet

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which is thinning very rapidly as it

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responds to warmer ocean temperatures

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specifically in the amundsen sea in

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bayman area the west antarctic side

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we're seeing strong thinning on the ice

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shelves which is causing draw down on

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the inland ice um on the grounded ice

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upstream most of that is being caused

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because of changes in ocean heat flux

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underneath the ice shelves which is

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causing them to thin and then

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consequently the buttressing force is

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being lost against the grounded ice and

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the graded ice is then flowing faster

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into the ocean and causing sea level

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rise

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in greenland we're seeing different

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signatures again in the center of the

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ice sheet in the plateau we're seeing

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increased accumulation so there is a

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slight increase in mass in the center

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but the overall signal for greenland is

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one of thinning and that is being caused

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by ocean and atmospheric signals acting

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all around the edges of greenland so

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we're seeing 200 gigatons per year of

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ice flowing into the oceans which is

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enough to raise sea level by about

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two-thirds of a millimeter per year

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combine that with the almost 118

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gigatons lost in antarctica and sea

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level has risen a total of 14

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millimeters over the 16-year period due

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to ice sheet melt

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it may seem small but the small changes

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add up what we expect by the end of the

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century is you know on the order of two

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three maybe four feet of sea level rise

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and because we have all of our

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infrastructure that is

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built around the coast we have a lot of

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vulnerability to a meter change in sea

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level rise

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is one critical motivation for the

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continued study of the mechanics driving

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the changes in the ice sheets if we can

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understand those mechanisms and how

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they've played out over the last 30

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years well then we can start to look and

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and think about how will those ice

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sheets respond to what we project the