A grim environmental report released Tuesday highlighted some alarming global events in 2015, including a deadly heatwave in Pakistan, scorching summers in Russia and China and 101 tropical storms that hammered Equatorial countries.
But tucked among the 300-page report from the National Oceanic and Atmospheric Administration was a smaller, oft-overlooked victim of rising global temperatures: baby walruses.
In a chapter titled “Walruses in a time of climate change,” researchers analyzed the plight of two walrus subspecies, the North Pacific Arctic walrus and the North Atlantic Arctic walrus, and detailed how the move from ice to land could put walrus pups in harm’s way.
Many walrus herds live on sea ice year-round, depending on food availability, but drifting pack ice becomes increasingly important in winter when walruses mate along the ice edges. As late spring arrives, the tusked mammals typically return to the ice to give birth.
The habitat is also a known source of protection from storms and some predators.
But as sea ice melts, scientists believe walrus populations have shrunk. According to recent research, Atlantic walrus populations in the Bering Sea and Chukchi Sea likely dropped between 1980 and 2000. Pacific walruses subsequently experienced an estimated 50 per cent decline.
Researchers hypothesize that this drop could be linked to overcrowding and trampling. Pacific walrus mothers typically rear pups on ice, which allows them to avoid land-based groups where dense herds are more common.
When adults on land become spooked -- by a predator, for example -- baby walruses are at heightened risk to be crushed in the chaos. (A walrus calf is about 75 kilograms, and adults can weigh up to 1,500 kilograms.)
According to a 2007 report in National Geographic, at least 3,000 young walruses were killed in Russia during the summer as sea ice receded and walruses crowded onto a small piece of land. Russian scientists said they later noticed polar bears scavenging through the carcasses.
Researchers says that in the Bering and Chukchi Seas, female walruses are increasingly living on coastlines and islands in the summer. These particular migrations have resulted in “significant” calf mortalities in recent years, according to the report.
Shrinking sea ice also raises concerns about the availability of food for walruses. Coastal walruses must travel farther to reach offshore areas rich in food, such as fish. Researchers estimate that such trips can be as far as 180 kilometres one-way. To make matters more difficult, the lack of sea ice means walruses have fewer places to rest during their hunt.
The NOAA report released Tuesday also pointed to other animals at risk by climate change. Fish populations have begun a largescale shift in the Barents Sea, an Arctic water region shared by Russia and Norway, and several boreal species have moved further north due to rising temperatures.
