Researchers have found evidence that warmer water in the Arctic has penetrated deep into the interior of the region. This heat is still trapped just below the surface. But it can melt Arctic's ice pack as it comes up and touches the surface.
"We are documenting a striking global warming in one of the main catchment areas of the inland Arctic Ocean, the Canadian basin." Lead author Mary-Louise Timmermans of Yale University said.
The main reason for the change is temperature rise. Rising temperatures have widespread effects on ecosystems around the world, but the effects are more pronounced in the Arctic. As the Arctic warms up, the ice melts. The exposed surface absorbs more of the sunlight instead of reflecting it back into space. As a result, the temperature rises further and causes more melting.
Researchers have followed the changes in Canada's basin over the past 30 years and have witnessed a two-fold increase in heat over that period. They also found a warm layer of water about 50 meters below the surface that had formed hundreds of kilometers away in the south. But Arctic winds drive the warmer water to the north and catch it under the surface.
The detrimental effect is caused by the different water layers of the North Pole. Less dense low fresh water is at the top, while salt stays closer to the bottom of the water. The hot water is kept at that depth by the layer of colder, fresh water overhead. When these two layers begin to mix, they will speed up the ice loss.
"This means that the effects of sea ice loss are not limited to the ice-free areas themselves, but also lead to an increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well into the summer season," said Timmermans. "At the moment, this heat is stuck under the surface layer, and when it is mixed at the surface, there is enough heat to completely melt the ice pack that covers this region for most of the year."