Drowning polar bears and crumbling coastal communities are the most visible effects of melting glaciers and sea ice in the polar regions, and now scientists are learning about less obvious but still alarming results of this shift: the wider spread of wildlife disease and contaminants. The COVID-19 pandemic has also hindered researchers’ efforts to perform 2020 fieldwork and collect data, potentially complicating further studies on the topic
As melting ice allows pathways to open up in the Arctic, people and animals can use these routes to access previously inaccessible areas. Corporations and governments are making plans to use a more open Arctic for shipping routes and development, which could end up releasing more contaminants into the ecosystem. Animals, meanwhile, may already be traversing these open passageways to travel to new locations and spread disease.
Less ice in Arctic equals more spread of disease
“By altering animal behavior and removing physical barriers, loss of sea ice may create new pathways for animal movement and introduction of infectious disease into the Arctic,” says a paper published by researchers, including Tracey Goldstein, an associate director of the One Health Institute at the UC Davis School of Veterinary Medicine.
She and her colleagues published the study in the journal Scientific Reports. It explores how melting sea ice may be facilitating the spread of a disease called Phocine distemper virus (PDV) among marine mammals.
PDV, a highly infectious virus, can afflict marine mammals with respiratory and neurological problems, and also make affected animals more susceptible to secondary infections. In 1988, an outbreak of PDV killed over 23,000 European harbor seals, and a 2002 epidemic killed over 30,000.
In 2004, scientists found the same disease was affecting otters in Alaska, and they’ve indicated they believe melting sea ice may be to blame. Previously, North Atlantic and North Pacific populations of otters were not known to interact – experts believed sea ice prevented them from reaching one another, and they are not known to travel far. But they now are suggesting melting ice could have created a pathway for the animals to make contact and spread the disease, perhaps with other species acting as intermediaries.
Ice melt + COVID-19 … ‘perfect storm’
To examine the topic, the researchers analyzed samples from 2,530 live and 165 dead animals in the North Pacific Ocean collected between 2001 and 2016. The study included samples from northern sea otters, northern fur seals, Steller sea lions, and a variety of ice-associated seals.
They found evidence PDV was widespread in the North Pacific Ocean – both in terms of infection and exposure – beginning in 2003. “Openings in the sea ice along the Russian coast were linked to the increased likelihood of PDV exposure or infection,” the researchers wrote. “And peaks of viral exposure in 2003 and 2009 occurred after a year with low sea ice extent and open water along the Russian coast, suggesting that multiple introductions may have occurred.”
“This is the first example in the Arctic, and I think that with the sea ice it’s really making us think a little bit more about it,” Goldstein said. “As animals are changing their behavior because the ice is changing, they’re moving further, maybe looking for food or other things.”
The researchers have been planning to explore the topic further, but the COVID-19 pandemic is interfering with 2020 fieldwork plans. They had expected to collect data this year after record low Arctic sea ice in 2019, but many projects are now being canceled or postponed.
“It’s kind of the perfect storm,” Goldstein said. “This is one of the years we really need to understand what’s happening up in the Arctic and, of course, this outbreak is changing all of our lives.”
More contaminants crossings more national borders
Diminished sea ice may also allow contaminants to travel between nations via ice, potentially with serious geopolitical consequences. Ice can transport a wide variety of contaminants ranging from anthropogenic pollutants like oil, lead, mercury, and microplastics, to dust, sediments, aerosol deposits, algae, and even biological communities.
Sea ice historically could last 10 years, persisting through summers and building layers over time. Now, the ice is thinner, it moves faster, and in many places it completely melts during the summer, releasing any contaminants in it wherever it ends up. As the Arctic melts, increased shipping and oil drilling in the region are expected to boost the risk of contamination.
Researchers including Patricia DeRepentigny, a PhD candidate at the University of Colorado in Boulder, examined how a melting Arctic may lead to an international exchange of pollutants. They published their findings in AGU’s Earth’s Future.
Using the Sea Ice Tracking Utility, which DeRepentigny helped develop, they found that by mid-century the time it takes ice to travel between regions will decrease by around half, and the exchange of ice between nations will “more than triple.” The scenario with the least likelihood of spreading contaminants between nations was actually the most dire scenario: the end-of-century highest emissions scenario. Under this scenario, the ice would melt so quickly after forming that it wouldn’t have a chance to transit between nations and would melt close to where it was formed, likely releasing any contaminants back into the country of origin’s waters.
Arctic geopolitical issues
Five nations have “exclusive economic zones” in the Arctic Ocean – the U.S., Canada, Russia, Norway, and Denmark (Greenland). No nation has exclusive economic rights in the Central Arctic Ocean, so this polar shortcut would be attractive for shipping, which in turn would open up the potential for pollution and increased movement of ice. It also raises questions about how countries will handle transnational ice exchanges in the Arctic and any potential exchange of contaminants.
“As these pollutants cross nations’ boundaries, they can also cross different environmental protection laws,” DeRepentigny says. Nations already are dealing with transnational exchanges of air and water pollution, but the possibility of faster moving sea ice bridging borders could increase concerns.