The Arctic is losing ice and at record speed, as temperatures continue to grow. While the direct effect usually mentioned is sea-level rise, other consequences are also starting to be discovered, such as the spread of diseases among marine mammals.
A study published in Scientific Reports showed that artic ice reduction could allow pathogens infecting sea mammals to spread more regularly between the North Atlantic and North Pacific oceans. This is linked to the opening of new water routes that allow contact with previously distinct populations.
Lead author Tracy Goldstein and her research team specifically looked at the Phocine distemper virus (PDV). The disease affected marine mammals for decades and killed 51.000 of European harbor seals in the North Atlantic in 2002, which represented 51% of the population.
But, only two years later, it was discovered that northern sea otters in Alaska had contracted the virus. This confused experts back then, as the Arctic sea ice was blocking routes between the species and made impossible any connection.
“How did a virus that had previously been seen in the Atlantic Ocean end up in the Pacific Ocean?” said Goldstein, a scientist at the University of California Davis who investigates how pathogens move through marine ecosystems.
Goldstein and her team searched studies and records of biological samples taken from 2,530 live and 165 dead seals of species that spend at least part of their years on Arctic ice. They then looked at data showing the reach of sea ice at a given time of year, called Arctic ice extent
Finally, they figured out the reason for the expansion of the virus between non-related species.: it was ice melt. The study concluded that melting sea ice brought on by the Earth’s warming climate created a way for the virus to move into a new region and infect a new population of sea life.
Goldstein and her team found that sea ice opens up new migration routes for marine mammals, allowing them to more easily cross from the Atlantic to the Pacific by way of the Arctic Circle. The added stress of needing to forage farther for food can even weaken the animals’ immune systems, making them easier targets for the virus.
“The loss of sea ice is leading marine wildlife to seek and forage in new habitats and removing that physical barrier, allowing for new pathways for them to move,” Goldstein said. “As animals move and come in contact with other species, they carry opportunities to introduce and transmit new infectious disease, with potentially devastating impacts.”
Of all regions in the world, the Arctic is one of the most affected by climate change, making the results specifically worrying. In 2019, a study by researchers at the University of Cincinnati found that the Arctic could soon be completely free of sea ice during its transition from summer to winter, due to climate change.
Nevertheless, a lot of uncertainty remains about the disease and how it will evolve as climate change continues. While vaccination is a possibility, doing so at a scale large enough to prevent the disease from spreading would be difficult, Goldstein and her team said.
Across the globe, many animals are being forced out of their normal habitats because of climate change, pushing them to go out and seek out cooler areas to live in. Butterflies, birds, reptiles, and many are moving away from the equator, either to the north or to the south. Unfortunately, not all animals can adapt to environmental changes in this way.
Animal health may be affected by climate change in four ways: heat-related diseases and stress, extreme weather events, adaptation of animal production systems to new environments, and emergence or re-emergence of infectious diseases, especially vector-borne diseases critically dependent on environmental and climatic conditions.
According to Defenders of Wildlife, some of the wildlife species hardest hit by global warming include caribou (reindeer), arctic foxes, toads, polar bears, penguins, gray wolves, tree swallows, painted turtles, and salmon.
The Intergovernmental Panel on Climate Change (IPCC), said on a recent report that climate change is doing “widespread and consequential” harm to animals and plants, which are struggling to adapt to new conditions. As a consequence, many life-forms are moving north or into deeper waters.
But concurrent human population growth means that many land areas that might be suitable for the move are not available. A report by the Pew Center for Global Climate Change suggests that creating “transitional habitats” or “corridors” could help migrating species.