Rapidly thinning sea ice on Canada's Hudson Bay will trigger a fast rate of species loss and open new access to commercial shipping and crude oil exploration, the authors of a new study suggest.
The study provides the most comprehensive look yet at how climate change will affect the Texas-sized Hudson Bay, a biologically and economically important inland sea in the country's northeast.
Summer sea surface temperatures will increase 9 degrees Fahrenheit in the southeastern Hudson Bay and 5.4 degrees Fahrenheit in the central portion before mid-century, spelling disaster for sea ice formation and the polar bears and other wildlife that depend on the ice to survive, according to the study.
The bay's western edge is home to one of the world's largest clusters of polar bears.
The scientists calculate that within 30 years the 316,000-square-mile water body could lose 31 percent of its total volume of ice. Since the 1950s, Canada's average temperatures have been steadily increasing from the rise in emissions of carbon dioxide and other heat-trapping gases.
Their findings have been published in the May issue of Climate Dynamics.
The study says that air temperatures could increase by as much as 7 degrees Fahrenheit on average in the bay year-round. Frigid temperatures in the coldest months will persist decades in the future, meaning sea ice will still form across nearly all of its original extent with only a 2.6 percent loss by the 2040s. But the ice will be thinner and remain frozen for less time.
Due to warmer water temperatures in the summer months, it will take more time for the water to get cold enough to freeze, delaying the formation of sea ice by nearly a month — from November and December to as late as January — said Sylvain Joly, lead author of the paper and a climate researcher at the University of Quebec.
With less time to form, the sea ice will be roughly 50 percent thinner than today's levels in some areas such as the Hudson Strait and Ungava Bay. Thinner ice also means the frozen cover will break up in May or June compared to July.
Overall, the Hudson Bay will lose 7 to 9 weeks of ice coverage by the 2040s.
The impact will be felt beyond the bay region, Joly said. Previous studies show that the Hudson Bay marine system plays a significant role in the regional climate variability of Canada — to such an extent that "a change in sea-ice season over the Hudson Bay might affect climate in the southern part of the country," he said.
His team's research joins a number of studies that have documented dwindling sea ice, one of the bellwether indicators of global warming. NASA and European Space Agency satellites have recorded a rapid thinning of sea ice in the Arctic, up to 7 inches a year, or 19 percent annually, from rising levels of carbon dioxide emissions.
First Polar Bears Driven Extinct?
Scientists have also repeatedly shown that thinning ice and shorter ice seasons have dire effects on species such as polar bears, whales, walruses and seals due to a loss of habitat, protection and resources, as well as on the native communities that depend on them.
The U.S. Geological Survey predicted in 2007 that two-thirds of polar bears could disappear by 2050 from shrinking summer ice based on moderate projections, though newer research published in Nature shows their decline could be controlled by aggressive cuts in greenhouse gas emissions. Scientists estimate the current polar bear population is between 20,000 and 25,000.
The bears come to land when sea ice melts and fast until it forms again. In the Hudson Bay and elsewhere they now have to fast longer, endangering their health, said Shaye Wolf, climate science director at the Center for Biological Diversity, a nonprofit conservation group based in Arizona.
Currently, there are about 900 polar bears living in the western part of the bay.
"Polar bears in western Hudson Bay are already starving, giving birth to fewer cubs and declining in number as they lose the ice they need to hunt and find mates," Wolf told SolveClimate News. "If current trends persist, western Hudson Bay will likely be the first polar bear population driven extinct by global warming" by 2050.