National Geographic: Six Degrees Could Change the World Page #3

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of Tuvalu are lost

beneath the rising tides

of global warming.

This could be our world

plus-two degrees.

At two degrees of warming,

the impacts in the marine ecosystem

are going to be much more severe.

The oceans are the planet's

largest "carbon sink,"

nature's primary mechanism

for absorbing CO2

out of the atmosphere.

But lately there are indications

these systems are breaking down.

Under normal conditions,

tiny sea creatures like forams

and coccolithophores

absorb carbon out of the water

and use it to build

their shells and skeletons.

But there is a tipping point,

when too much CO2 in the oceans

turns the water

increasingly acidic.

Acidification dissolves

the creatures' shells and skeletons

and prevents them from absorbing

more CO2 out of the water

to build new ones.

Some of these tiny animals

at the bottom of the food chain

measure only one millimeter.

But the fate of all sea creatures,

of all shapes and sizes,

larger and larger,

hangs in the balance.

Alter the ocean's chemistry,

and nature's primary mechanism

for controlling the climate

begins to break down.

You lose a coral reef,

you lose perhaps 500,000 species.

You lose those little coccolithophores,

these little algae,

and you start to lose things

that are very important

to life on this planet.

We're losing some of the most vital

elements of the way the world works.

And that's got us all concerned.

Scientists half a world away

share those concerns.

They're investigating global warming

at the climate's opposite extreme.

It took nature 150,000 years

to make the great Greenland ice sheet

that's now melting into the sea

faster than at any time in history.

As it disappears, rising oceans

will flood coastal cities

around the world.

Greenland's Jakobshavn Glacier

is the fastest moving ice field

on the planet,

more than 40 meters per day,

melting into the sea

twice as fast as a decade ago.

Rising temperatures

are transforming

one of the Earth's harshest climates,

disrupting the way people have lived

in Greenland for hundreds of years.

For as long as anyone can remember,

sled dogs have been

a symbol of wealth here

and a necessity for survival,

especially for hunting

across the winter sea ice.

When the winter ice started thinning,

dogs became an expense

most islanders couldn't afford.

In this town of 4,500 people,

there are 4,000 dogs,

with very little to do these days.

Many are starving.

Some are being put down.

Marit Holm is one of Greenland's

five veterinarians.

As she patrols the town of Ilulissat,

she sees the impact of climate change

in every sled dog

without a sled to pull.

So, what I do, I drive

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