Northwest Passage almost ice-free

Arctic sea ice reaches historic level

The northwest (orange line) is open, the northeast passage (blue line) only partially blocked by ice. The dark gray areas are ice-free, and the areas covered with sea ice are green. © ESA
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The Arctic ice cover has reached a new record low: summer ice in the northern polar region has shrunk as far as ever since satellite measurements began. New satellite imagery from the ESA also show that the Northwest Passage, a sea link in northern Canada that was historically considered impassable, could now be used again.

The polar regions are considered very sensitive indicators of climate change. According to the Intergovernmental Panel on Climate Change (IPCC), these areas are extremely vulnerable to rising global temperatures. Climate researchers at the IPCC predict that the Arctic could be virtually completely ice-free by 2070. Some even expect that this will already happen in 2040. However, new data from ESA's Envisat satellite show an even more alarming picture: "The ice-covered area has shrunk to just three million square kilometers, " explains Leif Toudal Pedersen of the Danish Space Center. "That's one million square kilometers less than the previous minima in 2005 and 2006."

Shrinkage rate increased tenfold

A shrinking of the Arctic ice in the northern summer is part of the natural seasons rhythm. But the satellite data collected since 1978 shows that the rate of ice loss has accelerated in recent years. Over the last ten years, the reduction rate has been around 100, 000 square kilometers per year. The jump this year to a reduction of ten times is therefore classified by the ice researchers as extreme. "The huge reduction in just one year is definitely a warning sign that the ice could disappear much faster in the summer than expected. We urgently need to better understand the processes involved, "says Pedersen.

Passable northwest passage

McClure Road: Ice-free part of the Northwest Passage © ESA

The loss of ice on the Northwest Passage, a sea route that leads from the eastern coast of Northern Canada to the Arctic Ocean to the western coast of the American continent, is particularly clear. Normally barred by sea ice, this year's route is virtually ice-free. The Northeast Passage, a sea route from northern Norway to Siberia, could, according to ESA researchers, pass much earlier than expected. Even now, the ice blockade is limited only to a small piece in the Russian Arctic Ocean.

The melting of Arctic sea ice not only changes the local conditions, it also affects the global climate. The reflection of the ice cover usually throws back part of the sunlight, thus preventing its absorption. However, when the dark surface of the sea is exposed, it absorbs the sunlight and heats up. This in turn prevents the emergence of new ice a climatic vicious cycle begins. display

(ESA, 17.09.2007 - NPO)