Science, climate change, and Arctic amplification
As the world seeks solutions to the global climate crisis, many eyes are turning north — to the Arctic Ocean.
Climate scientists say Arctic regions are a key indicator of the changes that have already occurred worldwide and those yet to come. The Arctic has already warmed at least 3 degrees C in the past 50 years, more than most other parts of the world. Openings in the ocean ice pack are allowing the sun to directly warm the waters there, causing a warming feedback within the region’s ice cover.
Mary-Louise Timmermans, the Damon Wells Professor of Earth and Planetary Sciences in the Faculty of Arts and Sciences, is a leading investigator of the dynamics and variability of the Arctic Ocean, sea ice, and climate. YaleNews spoke with Timmermans, who recently gave a presentation about her research to a Yale Planetary Solutions Project symposium, about the role Arctic regions play in addressing climate change.
Why have Arctic regions become such a focal point for climate change?
A number of reasons. The loss of Arctic sea ice is now really well documented by satellites. This general trend of less sea ice covering the Arctic Ocean with each passing summer is a striking picture of ongoing climate change. The iconic images of polar bears straddling small ice floes are dramatic symbolism for our changing planet, and this also resonates with the public.
Changes in the Arctic are big. Scientists even have a term for it: Arctic amplification. If we look at global maps of air temperature changes since pre-industrial times, they show a lot of warming everywhere. But these temperature increases are twice as large in the Arctic compared with other regions. That’s where the term “amplification” comes from.
How much do we know about the causes of such dramatic warming in the Arctic, compared with other parts of the world?
The answer to this question is very complicated and is an area of active research. It involves relationships between the sea ice, ocean, atmosphere, and land. One simple mechanism relates to the fact that sea ice is much more reflective than the ocean. So as we lose sea ice, less of the sun’s energy is reflected back to space, and more is absorbed, leading to warming. The oceans play a role too. The warmer ocean waters can stick around in the Arctic after summer is over.
There are added complications that relate to different cloud patterns that arise over sea ice-covered regions versus those that have no sea ice. And clouds can either trap heat or reflect solar energy back to space. And these changes in the atmosphere can have larger scale influence and affect how much atmospheric heat is being transported to the Arctic from the rest of the world. There are many open questions and complicated factors to tease out.
What are the challenges of gathering information and finding answers in this region?
The harsh, extremely cold weather throughout most of the year, as well as 24-hour winter darkness, coupled with the presence of sea-ice make data collection difficult. Even in summer, it’s expensive and logistically challenging to mount ice-breaker expeditions, which can require navigationally tricky transits through the Northwest Passage, for example.
What sorts of relevant information and mechanisms do we still not know, or fully understand?
There are parts of the Arctic that we can’t get to easily, and that we can’t sample autonomously with drifting buoys. These include the broad shallow ocean regions of the continental shelves, which change rapidly depending on the season and have energetic ocean currents. We have very little information about these regions in winter, for example, when they are completely inaccessible. For this reason, we don’t fully understand how they work, and we also can’t pin down how they’re changing.
We’re also lacking observations where the land meets the ocean, including wetland regions and changing river inflows, for example. So in general, the coastal boundaries of the Arctic Ocean basin are notoriously under-sampled. To some extent, these problems are geopolitical with many different exclusive economic zones, and data sharing between nations that is often deficient.
How much more change do you expect to see in the Arctic climate over the next 10 to 20 years?
There’s no reason to expect the Arctic won’t continue to undergo substantial changes over the coming years and decades. With every passing year, the Arctic Ocean is generally showing warmer temperatures, and lower sea-ice extents. While there are regional patterns of air and ocean temperature changes that show year-to-year fluctuations, the overall theme of a warming Arctic continues. Along with reduced sea ice, we’ll see other changes like bigger waves, continued coastal erosion, and possibly increased storminess. Here I’m only talking about changes to the physical system. A whole host of ecosystem changes are also underway in this interconnected system.