How It Works - UK (2020-02)

ENVIRONMENT

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G

laciers form in areas of snowfall where

conditions are cold enough to allow

snow to lie until it has frozen into ice.

Ranging in size based on climate conditionsand

snowfall levels, many are the remnants of the

last ice age, when frozen peaks covered over 30

per cent of all land.

Referring to them as remnants gives the

impression that these frozen spectacles are

declining. Currently these thick ice blocks

dominate 15 million square kilometres of our

planet, but as human activ it y continues to

increase global temperatures, glaciers are

reverting back to water at a faster rate than they

wou ldn at u r a l l y.

Find out how some of Earth’smostimpressivefrozenfeaturesare disappearing

Why do glaciers retreat?

Glaciers in the US cover over

75,000 square kilometres

©Getty

Melting Alaska’s

mightiest

Glaciers form high in snowy mountains,

so it is no surprise that Alaska is an area

bountiful in these colossal ice blocks. In

fact, Alaska is home to the world’s

thickest glacier, the Taku Glacier.

Towering a mighty 1,480 metres from its

surface to the ground, scientists studying

the block have stood in awe of its ability

to appear unsettled by global warming.

That was until recently. Glacial

developments have always been used as

a visual representation of our impact on

Earth’s climate, but the world’s thickest

was not only surviving, but thriving. The

icy giant continued to expand, as it had

been doing for nearly 50 years, seemingly

unphased by the shrinking of its glacial

neighbours. But now, by comparing aerial

photos taken by NASA in August 2014 and

then in August 2019, the glacier’s size is

visibly reduced.

In most natural glacier cases studied,

they stop advancing for at least a

few years before beginning their retreat,

so this case has come as a surprise to

many glaciologists.

An aerial shot of Taku Glacier, imaged by the

Landsat 8 satellite

© NASA Earth Observatory

Discover how different

sections of glaciers

contribute to their

changing size

Glacier

anatomy

It’s not unusual for glaciers to be subjected to

melting during their lifetime, but they run on a

continuous snow budget. If they lose ice quicker

than they receive their income of fresh snow,

their mass begins to diminish and glaciers begin

to retreat.

Glaciologists analyse the activ it y of glaciers

year on year. Study ing indiv idual glaciers can

prov ide insight into which are grow ing, which

are sustaining their mass and which are

retreating. This being said, specific locations

come w ith their ow n patterns, and a glacier’s

state depends heav ily on its surroundings.

To an extent, glacial retreat is natural, and the

causes of this can var y from temperature and

evaporation to w ind scouring. The build of these

structures can often be season dependent,

meaning a slight summer decrease is nothing to

worr y about, as the w inter snowfall w ill make

up for any mass lost as the season continues.

Determining global glacier patterns for

unnatural retreating requires long-term data to

be analysed over a variet y of locations.

Meltingice

Towardsthebottomoftheglacier,

meltinganderosionoccursata faster

ratethanaccumulation.Thefresh

meltwateris oftenusedfordomestic

andcommercialwatersupplies.

Bedrock

Inthesummer,melted

glacialicecanexposethe

rockbelowin crevasses.

Glacialretreat

Asiceis lostthroughmelting

andabrasion,theperimeter

oftheglacierretreatsandits

massdecreases.