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Monthly Archives: November 2017 − News & Stories


Wind: an important fac­tor for gla­cier mel­ting in Ant­arc­ti­ca

Wind may be the gre­at and so-far stron­gly unde­re­sti­ma­ted fac­tor when it comes to mel­ting of lar­ge mas­ses of gla­cier ice in Ant­arc­ti­ca. Chan­ging wind pat­terns are now recei­ving more atten­ti­on from sci­en­tists.

Rese­ar­chers have so far most­ly focus­ses on ocea­nic cur­r­ents. Warm water mas­ses are mel­ting ice shel­ves and gla­ciers from the bot­tom. This leads to enor­mous quan­ti­ties of gla­cier ice being lost – for the Tot­ten Gla­cier in eas­tern Ant­arc­ti­ca alo­ne, the loss is esti­ma­ted at an incredi­ble 63-80 bil­li­on tons of ice. Per year! Tot­ten Gla­cier is the lar­gest one, but it is not alo­ne.

The sce­n­a­rio gains even more hor­ror becau­se of the sub­gla­cial topo­gra­phy on a con­ti­nen­tal sca­le. The sur­face of the bed­rock under the ice is slo­ping down­wards as you get away from the coast and into the con­ti­nent, not upwards as with all other con­ti­nents. This is due to the hea­vy ice load. This means that war­mer sea water, as soon as it has over­co­me the ice-bed­rock-bounda­ry on the edge bet­ween the (floa­ting) ice shelf and the gla­cier (res­ting on the ground), may pene­tra­te much more easi­ly as it is actual­ly moving down­hill, and that’s what water likes to do. The pro­cess may accord­in­gly acce­le­ra­te signi­fi­cant­ly as it is pro­gres­sing.

Now, wind is com­ing in as an addi­tio­nal fac­tor, making the who­le sys­tem much more com­pli­ca­ted. But the result is most likely to be yet ano­t­her incre­a­se of ice loss due to basal mel­ting. Nor­mal­ly, the­re is a rather thin lay­er of meltwa­ter on top of the water column of the Sou­thern Oce­an near the ant­arc­tic coast. This meltwa­ter lay­er is qui­te thin, but due to its low salini­ty it has a sharp bounda­ry to under­ly­ing war­mer waters and it tends to be qui­te sta­ble. It pro­vi­des a ther­mal buf­fer bet­ween the cold atmo­s­phe­re or gla­cier ice/shelf ice mas­ses on top and war­mer waters under­ne­ath.

Strong winds can, howe­ver, dis­turb this rela­tively thin, cold lay­er of meltwa­ter, making the way free for more tem­pe­ra­te water mas­ses from grea­ter depth to come to the sur­face, whe­re they have a war­ming effect on ice and air.

Strong winds are expec­ted to incre­a­se in fre­quen­cy and for­ce in deca­des to come in the west wind zone in the Sou­thern Oce­an. This implies more fre­quent wea­ther situa­tions that may help war­mer water mas­ses to come to the sur­face, whe­re they can melt the over­ly­ing gla­cier ice inclu­ding ice shel­ves.

Robust model­ling and sub­stan­ti­al pre­dic­tion of this extre­me­ly com­plex sys­tem will requi­re a lot of fur­ther rese­arch work and com­pu­ter pro­ces­sing power. Nevertheless, it may be fair to draw the fol­lowing con­clu­si­ons, which may not actual­ly sur­pri­se you: 1) take cli­ma­te chan­ge serious­ly and get some­thing done about it ASAP 2) fur­ther rese­arch is nee­ded …

Tabu­lar ice­berg in the Ross Sea, Ant­arc­ti­ca: sym­bol of dis­in­te­gra­ting ice shel­ves.

Tabular iceberg, Ross Sea

Source: wired

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