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Prince Charles Island, recorded by the Earth observation satellite "Landsat 8"
Photo by Joshua Stevens / US Geological Survey / NASA Earth Observatory
Prince Charles Island is a cool and calm corner of the world. The almost oval island is located north of Canada's Hudson Bay, right next to Baffin Island and already within the Arctic Circle. And it belongs to the Nunavut Territory, an area where the Inuit enjoy special rights. But people rarely get lost on the island, which was named after the British heir to the throne. Although the Inuit had known Prince Charles Island for a long time, it was not officially discovered until 1948, the year Charles was born.
The island is 130 kilometers long and 90 kilometers wide and offers a barren landscape, criss-crossed by ponds and ponds.
The permafrost soil bears the typical vegetation of the tundra - only a few grasses, lichens and mosses grow here.
At most, they are trampled flat by a few polar bears, arctic foxes and, above all, by herds of caribou who come here via the frozen Foxe Basin, the sea basin north of Hudson Bay.
But when scientists flew over the island in the summer of 2016, the experts were faced with a disturbing sight.
The remains of dozens of caribou cadavers lay scattered across the flat tundra.
Such an accumulation of dead animals seemed unusual.
What happened here
Some of the animals had apparently died lying down, others just appeared to have collapsed.
A look at the state of decomposition of the internal organs allowed an estimate of the time of death of the animals.
It was probably a few weeks ago, possibly towards the end of winter.
Apparently the animals had not been shot.
The researchers collected samples and, together with the Nunavut Ministry of the Environment, hoped to find out soon.
But it was only now that the sequence of events was tracked down - with a combination of satellite data and sensors on the ground.
The image that NASA has now published comes from June 2016 and was taken by the Earth observation satellite "Landsat 8".
Race against winter
Caribou feed on lichens and plants. In autumn and spring they break through the snow with their hooves to get food. In winter they rarely find anything edible and also use mushrooms and mosses. Caribou are actually adapted to the harsh conditions of their environment and manage their energy reserves very efficiently. But when the animals no longer have enough reserves, they are running out of time. Apparently the spring that would have allowed them to break through the snow again came too late.
In fact, meteorological information from the island suggests an unusually violent weather event that occurred in April of that year. Heavy storms had come - and at a time when the reserves of the animals were gradually coming to an end. The wind and snow from these storms created an unusually thick blanket of snow, according to data from the military weather satellite program DMSP (Defense Meteorological Satellite Program). That can only mean: At the end of the long winter, the exhausted caribou must have starved to death because the weather conditions prevented them from cracking the thick layer of snow and ice.
But that didn't stop the case. Because the events on the Canadian island are not an isolated incident. They reminded the scientists of an event that happened many years ago, more than 6,800 kilometers to the west, on St. Matthew Island, an Alaskan island in the Bering Sea. Reindeer, the European and Asian representatives of the caribou, were released there in the 1940s
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Around 6000 animals were counted at the beginning of the 1960s. But in 1966, biologists experienced a similarly creepy scene as on Prince Charles Island: there were just over three dozen grazing animals between the carcasses of the entire herd. All the others were dead. The cause of the mysterious death could not be determined at the time.
But now the researchers had the same suspicions as at the crime scene in Prince Charles Island.
They scoured the weather data from the 1960s for similar events - and found what they were looking for.
Unusually harsh winter weather had hit St. Matthew Island too.
The winter of 1963/64 was one of the toughest ever recorded on the Bering Sea Islands.
The reindeer had to withstand storms with gusts of hurricane strength and temperatures of -57.5 degrees Celsius.
There was also a record amount of snow.
Here, too, the hard crust of the snow cover made it difficult for the huge herd of reindeer to access essential food.
Almost 6000 animals died, only 42 survived.
Using the satellite data, the scientists were finally able to solve this old case as well - half a century apart.
Looking for reindeer by helicopter
However, it is the milder winters caused by climate change that are causing problems for the animals in the north polar region.
Because if rain falls instead of snow, this leads to ground ice in winter due to the lower ground temperature.
The animals often cannot break that.
Even on the snow, ice sometimes forms due to rainfall - these hard ice sheets sometimes make it impossible for the animals to get food.
In addition, due to the effects of climate change, the animals are increasingly having to travel long distances south in search of food.
This sometimes makes it very difficult for reindeer herders to find their animals.
Some even use helicopters for this.
Over the past few decades, wild reindeer populations have declined by around 40 percent globally, reports the WWF.
Canada's caribou herds were also severely decimated, and by 2015 had been decimated by 52 percent over three generations.
joe
