The Arctic Ocean, a key component of our planet’s health and a regulator of global climate patterns, communicates with the Pacific and the Atlantic Oceans through various oceanic gateways.
The exchange of waters through these channels has significant implications for our climate and marine ecosystems. However, there have been distinct alterations in these exchanges over the past decade, highlighted by unusually high temperatures and exceptionally low salinities.
Researchers are now warning that additional heat will be transferred from the warming waters of the Pacific and Atlantic to the Arctic Ocean as climate change progresses. Models further anticipate an increase in low-salinity water exports from the Arctic to the North Atlantic Ocean.
This influx of warm water and the surge in freshwater exports pose potential risks to marine life and could drive significant changes in our global climate.
A group of prominent oceanographers have taken it upon themselves to compile and scrutinize current research aimed at understanding these water exchanges and the potential future shifts in temperature, salinity, and volume at these crucial junctions.
“We conducted a review of prior observational and modeling studies on Arctic-subarctic ocean linkages and examined their changes and driving mechanisms,” stated Qiang Wang, lead author of the review and senior scientist at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven, Germany.
The studies indicate that there’s been a significant increase in heat transported to the Arctic Ocean over the last decade. The warm waters flowing in from the subarctic oceans are believed to be the primary contributor to this increase. In tandem with this heat convergence, the volume of ocean inflows, which ferry warm waters into the Arctic, has also risen.
As the heat influx has escalated, the Arctic has seen a decline in sea ice formation and a boost in freshwater inflows due to increased river runoff and precipitation. A decrease in Arctic salinity is also attributed to the inflow of low-salinity water from the Pacific. These changes all echo the dire warning signs of climate change.
“Both the ocean heat convergence from lower latitudes to the Arctic Ocean and the hydrological cycle connecting the Arctic with subarctic seas were stronger in 2000-2020 than in 1980-2000 and will continue to be intensified in a future warming climate,” said Wang.
A model known as CMIP6 suggests that the Arctic Ocean’s warming rate is roughly double the global average, and it is likely to continue this way due to the ongoing increase in heat convergence.
The Barents Sea Opening, a body of water located between Bear Island, south of Svalbard, and the northernmost point of Norway, is projected to be the biggest heat contributor to the Arctic Ocean. This heat input is causing the retreat of Arctic sea ice during the colder seasons and amplifying the warming of the atmosphere.
As the heat inflow intensifies, the Arctic Ocean is also expected to receive an uptick in freshwater through increased precipitation, river runoff, and general sea ice melt. Notably, the export of this freshwater from the Arctic to the Atlantic has far-reaching impacts on the Atlantic Meridional Overturning Circulation (AMOC), a critical component of the Earth’s climate system.
Models predict an increase in this export via the Fram Strait, a channel between Greenland and Svalbard, which could disrupt large-scale ocean circulations and ultimately impact global climate.
But to accurately predict and react to these changes, we need better tools. “Both observation and modeling capabilities need to be further improved to better monitor and predict changes in Arctic-subarctic ocean linkages,” said Wang.
Understanding how forces such as wind, tides, heating, cooling, precipitation, evaporation, and river discharge affect ocean circulation and water properties is of paramount importance. Accurate representation of these effects in models is critical for developing effective mitigation strategies and policies.
However, our current monitoring tools are insufficient for accurately measuring these water exchanges across all Arctic gateways. We need to enhance the quality and quantity of our observational instruments to better understand these changes and their potential implications for global climate.
It’s clear that a comprehensive understanding of climate change requires an in-depth examination of the numerous intricate processes that govern the exchanges between the Arctic and subarctic oceans. For instance, the outflow of freshwater from the Fram Strait can influence the air-sea heat exchange in the Greenland Sea and alter ocean heat flux.
Additionally, an increased freshwater flux through the Davis Strait could potentially decrease the freshwater export in the Fram Strait. Therefore, it’s crucial to recognize that the export levels in both straits are intrinsically tied to sea level changes in the subpolar North Atlantic.
Adequately accounting for all these processes in climate modeling will greatly improve our predictions related to ocean behavior and climate change.
In essence, the current state of Arctic Ocean exchanges and their potential future changes call for concerted efforts to advance our observational capabilities, refine our models, and deepen our overall understanding of these complex systems.
The findings of this research, published in the June 1 issue of the journal Ocean-Land-Atmosphere Research, underscore the importance of continuing to observe, study, and interpret the shifts happening in the Arctic Ocean in order to effectively respond to the challenges of climate change.
Climate change is having a profound impact on the Arctic Ocean, with several effects that are already visible and others that scientists predict will happen in the future.
One of the most recognizable impacts is the dramatic reduction in sea ice. The Arctic is warming at roughly twice the rate of the rest of the globe due to a phenomenon known as Arctic amplification. As a result, summer sea ice coverage has shrunk considerably over the past few decades. This reduction in sea ice disrupts Arctic ecosystems, threatens polar species like seals and polar bears, and can alter weather patterns both regionally and globally.
The increase in global temperatures is leading to warmer ocean waters, which in turn cause more sea ice to melt in a vicious feedback loop. The loss of reflective ice cover allows more sunlight to be absorbed by the ocean, increasing the water temperature further. This can also influence the ocean currents and weather patterns.
The Arctic Ocean is absorbing a significant portion of the increased atmospheric CO2, leading to ocean acidification. This is particularly troubling for marine species that depend on carbonate ions to build shells and skeletons, such as clams and corals.
With increasing temperatures, there’s more melting of glaciers and sea ice, leading to an increase in freshwater input. This change in water composition alters the salinity (salt content) of the Arctic Ocean, potentially disrupting marine life and affecting the global ocean circulation patterns, as saltier water is denser and tends to sink, driving thermohaline circulation.
Permafrost – permanently frozen ground in the Arctic – is starting to thaw due to the warming temperatures. As permafrost thaws, it releases methane, a potent greenhouse gas that further exacerbates global warming.
All these changes impact the Arctic marine ecosystems. For instance, the loss of sea ice threatens species that rely on it for hunting and breeding, such as polar bears and seals. Changes in water temperature and salinity can alter the distribution and abundance of fish and other marine species, disrupting the food web.
The melting of the Greenland Ice Sheet and other Arctic glaciers contribute to global sea-level rise, which can lead to coastal flooding and erosion, and affect coastal communities around the world.
These changes not only affect the wildlife and people who live in the Arctic, but they also have the potential to significantly alter global weather patterns and climate due to the Arctic’s role in regulating the world’s climate. For example, changes in sea ice can influence the jet stream, potentially leading to more extreme weather events in mid-latitude regions. It is therefore critical to monitor and mitigate these changes to the Arctic Ocean and the broader Arctic region.