Image caption Victoria Hill spent six weeks on the ice, carrying out research in temperatures as low as -40C

A scientist hopes that a better understanding of what is happening beneath the Arctic ice will offer an insight into why summer sea ice is melting at rate that is alarming experts.

Victoria Hill, an oceanographer from Old Dominion University, US, was one of five scientists who spent six weeks in the barren, frozen landscape where temperatures fall to -40C (-40F).

"As a scientist, the reason I am prepared to come out here and be cold is because of the desire to learn and answer burning questions I have about what is going on up here, why the ice is melting as fast as it is," she told the Earth Reporters programme.

Arctic summers are projected to be free of sea ice by the middle of the century, with some studies warning that it could occur in the next decade.

Professor Hill explained that the Arctic played a key role in regulating the Earth's climate.

"The Arctic drives global circulation and therefore our global climate."

Ocean currents transport vast volumes of water around the planet. They are known as "thermohaline" circulations because they are affected by variations in salinity and temperature.

As warm water evaporates, the salinity increases and temperature falls resulting in a mass of denser water, which sinks and drives the current.

"If the Arctic gets a lot warmer, we will see a slowing down of the current," she said.

"If that happens, we'll see the climate in places like England change subtly, getting colder because the warmer waters from the south won't be pushed north."

Heart of the matter

Professor Hill said her work focused on how the Sun's energy is absorbed, accelerating the ice melt.

Image caption A team of five scientists set up camp 1,000 miles north of the Arctic Circle

"In early Spring, small particles of organic matter are seen in Arctic waters, and also found in sea ice - I called it 'ocean tea' and I think it may be formed from algae," she suggested.

"My theory is that this organic matter absorbs the Sun's energy, making the ice melt faster."

In order to test her idea, Professor Hill collects samples of water from depths of up to 500m beneath the ice, as well as ice core samples.

When examining the samples, she finds "a lot of algal material".

"This is really exciting," she explains. "What that means is that as ice melts from the bottom, that material will come into surface water, absorbing light and heating up the water."

She added that the next question was to identify the source of the organic matter.

"Is it coming from ice algae, phytoplankton, rivers? How much of it is there and how is it affecting heating?

"They are small questions; but when you link tall these questions together, we end up with an answer to why sea ice is melting so fast."