Climate change is transforming the Arctic Ocean in ways that could permanently alter the food chain and impact ocean species, according to a new study.
The study, published in the journal Science Advances, looked at the concentration of the chemical element radium-228 in the central Arctic Ocean and found that between 2007 and 2015 the concentration doubled.
Though radium-228 doesn’t have a large impact on ocean life, it is transmitted into the water through the ocean’s shelf. So if the water has a high level of radium, then it’s been in frequent contact with the shelf.
The shelf also contains carbon, nutrients and trace metals, which do have an impact an ocean life. Therefore, the authors of the study infer that if there’s an increase in radium in the Arctic Ocean, then there also must be an increase in those other elements, because they come from the same source.
“[The doubling of radium] is a relatively dramatic change in a relatively short period of time,” said Matthew Charette, a senior scientist at the Woods Hole Oceanographic Institution and a researcher on this study.
“So based on those changes in radium we inferred there had been a significant change in shelf input to the central Arctic Ocean in that time period. And so with that change in radium we infer that there are probably also significant changes in nutrient and carbon inputs.”
Researchers took dozens of samples from the Chukchi Sea Shelf to the North Pole in summer 2015. The study says coastal erosion and permafrost thaw could be contributing to the significant amounts of radium between the shelf sediments and overlying waters.
According to Charette, there’s no way to know at this point what the impact of the added carbon and nutrients will be, but there’s a few possibilities.
One possibility is the creation a more productive Arctic Ocean, because carbon and other nutrients provide fuel for sea life.
“The species that live in the surface ocean, like tiny plankton, they need these carbon and trace metals to survive, just like people need iron to transport the oxygen in our blood,” said Lauren Kipp a graduate student at the Massachusetts Institute of Technology and the lead researcher of the study.
“These species need different metals to make different enzymes work, to make their metabolisms work, so if they have more of those and more food, basically, then they could be happier and thrive in this region.”
Kipp said something that is potentially problematic is that the added carbon, nutrients and trace metals can change which species are best suited to live in the Arctic Ocean, which can cause a disruption to the food chain.
“This will most likely first affect the tiniest species that live in the surface ocean that make up the base of the food chain, but eventually this might have ramifications up the food chain and affect fisheries, which could affect people that live in the Arctic and also the other megafauna that live there, like polar bears or whales,” she said.
According to Kipp, one of the most important aspects of this study is that it shows the prevalence of climate change in the Arctic.
She said the warming climate and melting sea ice are most likely the reasons for these changes in the Arctic Ocean.
“The retreat of ice beyond the shelf has allowed for more mixing to occur over the shelf, because there’s no longer that barrier of the ice preventing the wind from affecting the water,” she said.
“So you can have increased mixing and turbulence and this mixing basically stirs up the dissolved materials that are in the sediments and brings them into the water column and then they can be carried out into the central Arctic,” she said.
Kipp said she hopes this study brings attention to the fact that climate change is happening now and that it’s not an “abstract phenomenon.”
Source : cbc