Coastal map high­lights cli­mate change

The Prince George Citizen - - News -

A fed­eral gov­ern­ment geo­sci­en­tist has de­vel­oped fresh maps of coast­lines show­ing where flood­ing and ero­sion caused by cli­mate change are likely to in­flict max­i­mum dam­age this cen­tury.

The map­ping ef­fort led by Gavin Man­son has taken into ac­count fac­tors like the dis­ap­pear­ance of sea ice, ris­ing waves and the makeup of the shore­line.

The lat­est ver­sion of the CanCoast map has com­bined six key fac­tors to cre­ate vis­ual rat­ings of “coastal sen­si­tiv­ity” on the three oceans.

Man­son said in an in­ter­view Wed­nes­day that when you start to con­sider how wave height rises due to a lack of sea ice or the slope of the shore, it can make a ma­jor dif­fer­ence in ero­sion and flood­ing.

“It in­cludes a whole lot more in­for­ma­tion on fac­tors that af­fect the physical sen­si­tiv­ity of Canada’s coasts,” he said from the Ge­o­log­i­cal Sur­vey of Canada of­fice at the Bed­ford In­sti­tute of Oceanog­ra­phy in Hal­i­fax.

The ex­pec­ta­tion of ris­ing sea lev­els has al­ready been doc­u­mented in the Chang­ing Cli­mate Re­port Ottawa re­leased in April for large por­tions of At­lantic Canada, the Beau­fort Sea, the Fraser River low­lands and north­ern Bri­tish Columbia.

In parts of At­lantic Canada where coastal land is sinking as seas rise, the ocean is pre­dicted to be an av­er­age of be­tween 75 cen­time­tres to one me­tre higher by the end of the cen­tury – in­creas­ing flood risk dur­ing storms.

How­ever, Man­son points out that quan­ti­fy­ing coastal sen­si­tiv­ity takes the anal­y­sis fur­ther.

The na­ture of the shore­line – whether it’s beach, gravel or a hard rocky shore – is part of the mix of six vari­ables the ge­o­log­i­cal map­mak­ers have scored.

An­other factor now in­cluded in the maps is how the melt­ing of ice in the ground be­neath per­mafrost leaves coasts sus­cep­ti­ble to more ero­sion.

As the ground sinks, the oceans gain in en­ergy, tear­ing away at the shore. “In the 2090s, there’s much less in the way of sea ice, and there’s more waves,” said Man­son.

The re­searcher says the ar­eas of high­est sen­si­tiv­ity are on the north­ern coasts fac­ing the Beau­fort Sea, where bright red colours on the maps sig­nal el­e­vated risk.

“Things are get­ting much worse in that area... It’s one of the ar­eas with the high­est in­crease in sen­si­tiv­ity, and it ex­tends fur­ther east into the Arc­tic ar­chi­pel­ago than we would have ex­pected.”

Fac­tors such as melt­ing ground ice and loose ma­te­ri­als along the shore are key fac­tors along the coast fac­ing the Arc­tic Ocean, he adds.

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