Con­fir­ma­tion of ris­ing seas

Kapi-Mana News - - NEWS - By JIM CHIPP

Core sam­ples from deep in the Antarc­tic ice ob­tained by a Welling­ton­based re­search team have con­firmed cli­mate change mod­els that pre­dict rapidly ris­ing sea lev­els.

Fur­ther­more, a re­search pa­per re­leased by the Uni­ver­sity of Cal­i­for­nia, San Diego, on March 26 sup­ported the lo­cal re­searchers’ work and found that the Antarc­tic ice melt has ac­cel­er­ated rapidly since 2003.

Dr Nancy Bertler is the ice core leader of the multi- na­tional Roo­sevelt Is­land Ice Core re­search project, which is based at GNS in Grace­field.

Cores up to 70,000 years old were taken down to 764 me­tres be­low the ice sur­face.

Wa­ter and air sam­ples from suspended bub­bles have shown sci­en­tists what global air and ocean tem­per­a­tures were in dif­fer­ent pe­ri­ods, as well as how much car­bon diox­ide was in the air, and how ice and sea lev­els re­sponded.

Bertler said the In­ter­na­tional Panel on Cli­mate Change pre­dicted in 2010 that global sea lev­els would rise about 50cm dur­ing this cen­tury, but that had changed.

‘‘Now we think it will be sig­nif­i­cantly more than 50cm,’’ she said.

In­creased fre­quency and in­ten­sity of storms had al­ready been ob­served. The se­vere storm of 2013 was a onein-100-year event, but with a sea level rise of 50cm, storms of that sever­ity were likely to be an­nual.

‘‘Storms we think of as ‘the storm of the year’ would be­come a daily event,’’ she said.

The project is also in­ves­ti­gat­ing an­other spec­tre – the pos­si­bil­ity that a ‘‘ melt- wa­ter’’ pulse has be­gun. Th­ese have oc­curred twice in the past 14,000 years.

For a pe­riod of be­tween 100 and 200 years, sea lev­els rise one me­tre ev­ery 25 years.

Th­ese melt pulses orig­i­nate at the West Antarc­tic Ice Shelf, which feeds the Ross Ice Shelf, where Roo­sevelt Is­land is.

The news from the Uni­ver­sity of Cal­i­for­nia two weeks ago added more weight to the re­search.

Satel­lite radar al­time­ter read­ings found that West Antarc­tic ice was melt­ing at a rapidly ac­cel­er­at­ing rate.

Be­tween 1994 and 2003, 25 cu­bic kilo­me­tres of ice dis­ap­peared ev­ery year, but from 2003 un­til 2012, it was melt­ing at 310 cu­bic km per year.

Ap­par­ent growth in the mas­sive East Antarc­tic Ice Shelf has also stopped and some ice shelves have lost 18 per cent of their thick­ness over 20 years.

Sci­en­tist Dr Nancy Bertler with an ice core from 656 me­tres be­low the sur­face of the Antarc­tic ice sur­face. The stor­age freezer is main­tained at mi­nus 36 de­grees Cel­sius.

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