As Arctic temperatures rise, polar bears face increasing threats from bacteria, viruses, and parasites at levels not seen since the '90s. Melting ice and rising temperatures may be exposing these majestic animals to dangerous diseases, and experts warn that the impact could ripple up the food chain—potentially affecting humans too. Explore the details of how climate change is reshaping the Arctic and posing unprecedented risks to wildlife and ecosystems alike.
The warming global climate is making survival increasingly difficult for polar bears. However, the challenges they face don’t stop there. Polar bears—and the Arctic itself—are now confronted with an increasing threat from microorganisms and parasites.
Karyn Rode, a wildlife biologist at the Alaska Science Center of the U.S. Geological Survey in Anchorage, explains, “Warming allows pathogens to thrive in environments where they couldn’t survive before.” The extent of warming’s impact on the Arctic isn’t fully understood, which is why Rode and her colleagues are examining the polar bear immune system.
Studies show that these bears, native to the waters between Alaska and Russia, are spending longer periods on land in the summer due to the dramatic melting of sea ice. This prolonged time on land increases their exposure to pathogens.
These samples were screened for antibodies against bacteria, viruses, and parasites. The findings indicated “the presence of antibodies aimed at fighting specific pathogens.” This data was then compared to analyses from samples collected from 115 bears between 1987 and 1994. Rising antibody levels signal an increase in diseases!
Since the 1990s, the prevalence of exposure to the parasite Neospora caninum and to bacteria causing diseases like brucellosis and tularemia has at least doubled among polar bears. Additionally, more bears in the current cohort have antibodies against canine distemper virus, and exposure to the parasite Toxoplasma gondii has surged from about 2% to 14%, a sevenfold increase!
For example, in recent years, ringed seals—a primary prey species for polar bears—have been observed dying from an unknown disease. Given these concerning trends, scientists have broadened their research efforts.
Rode also highlights that some polar bears are hunted and consumed by humans, underscoring the need for more research to determine whether these pathogens pose a risk of infecting people.