Senator Lieberman and members of the subcommittee, thank you for the opportunity to testify today on the impacts of climate change on Arctic wildlife. For the past 30 years, I have studied Arctic wildlife, primarily ice-associated marine mammals (whales, seals, and walruses). My studies have benefited by collaboration with colleagues in the scientific community and with Yupik and Inupiaq Eskimos who generously shared their knowledge and observations. Over millennia, Eskimo people evolved a rich culture around the seasonal sea ice and the plant and animal life that, in turn, had adapted to sea ice.
In the late 1800s, immediately following the decimation of bowhead whale and walrus populations by commercial whalers, approximately 50% of the Eskimo population in the Bering Strait region starved to death. One hundred years later, I began learning about ice-associated animals from Native hunters such as Mr. Alex Akeya, a descendant of the survivors of the famine. By that time, the walrus population had recovered, the whales were recovering, but the Eskimo population remained below its historical size.
The plants and animals that Alex and his kin depend on exist, of course, not in isolation but as part of an ecosystem. This particular ecosystem is dominated by seasonal sea ice which strongly influences the climate, oceanography, and biology of the Arctic Ocean and surrounding lands.
Sea ice influences not only Arctic climate but, in fact, global climate in several ways, most notably through a mechanism first described to me by Mr. Akeya. He told me, as we traveled around St. Lawrence Island in his walrus skin boat, that in his language (Siberian Yupik) the island is named Savouqaq, a reference to the shape of the island. The island looks like something that has been wrung out like a wet rag. A Yupik creation story described raven diving to the bottom of the Bering Sea, taking mud in its beak, and, back at the surface, wringing out the mud to form the island. How, I asked Mr. Akeya, did his ancestors know that shape of this large island without benefit of an aerial view? His answer was that in the autumn, when the island is snow covered and the surrounding sea is not yet ice covered, an image of the island occasionally is reflected up on to the cloud cover due to the high reflectivity of the snow in contrast to the low reflectivity of the water. Indeed, it is now known scientifically that sun and ice reflect over 90% of the incoming sunlight, while sea water absorbs over 90% of the sunlight. That differential reflection explains not only how ancient Yupiks knew the shape of Savouqaq, but it also contributes strongly to the faster rate of climate change experienced today in polar regions. One consequence of our warming climate is the melting of sea ice. Once that melt begins, it is accelerated by the resulting change in reflectivity. As the ice changes to water, the reflectivity of the surface goes from more than 90% to less than 10% resulting in further warming, more ice melt, and yet a further decrease in reflectivity. The importance of this polar amplification effect to global climate can be appreciated when the surface area of the polar seas - as much as 34,000,000 km2 in the recent past – is taken into account.
Sea ice strongly influences winds and water temperature, both of which are key determinants of upwelling, the oceanographic phenomenon whereby nutrient rich water is brought up to depths at which there is sufficient sunlight for phytoplankton to make use of those nutrients.
The Bering Sea produces our nation’s largest commercial fish harvests as well as supporting subsistence economies of Alaskan Natives. Ultimately, the fish populations depend on plankton blooms controlled by the extent and location of the ice edge in spring. Naturally, many other organisms, such as seabirds, seals, walruses, and whales, depend on primary production, mainly in the form of those plankton blooms. As Arctic sea ice continues to diminish, the location, timing, and species make-up of the blooms is changing in ways that appear to favor a different kind of ecosystem. While much of Bering Sea’s production ends up in a bottom-dwelling community of clams, crabs, and other organisms favored by walruses, gray whales, bearded seals, and eider ducks, the altered ecosystem may instead favor organisms living in the water column. The result would be a radically altered community of organism favoring a different suite of upper level consumers. The subsistence and commercial harvests of fish could be altered radically.
Ecosystem changes, of course, will be profound and effect more components than the fish. Many changes already have been observed and are predicted to accelerate along with the rates of climate change. The changes to the Arctic sea ice ecosystem will be especially rapid and profound. In my thirty years studying that system, we already have lost over 25% of the summer ice cover.
My colleagues in the scientific community are working diligently to understand the manifold impacts of our changing climate. There is a real sense of urgency given the pace of change and the tremendous economic and social impacts that will ensue. Many of the changes will not be obvious or, seemingly, even counterintuitive. Two examples involving marine mammal species may be illustrative.
Walruses feed on clams and other bottom-dwelling organisms. Over a nursing period of two or more years, the females alternate their time between attending a calf on the ice and diving to the bottom to feed themselves. The record ice retreats observed in recent summers increasing are extending beyond the continental shelf such that the ice is over water too deep for the female walruses to feed. Thus, the habitat suitable for adult feeding is becoming disconnected from the suitable nursing habitat. The prediction is for walrus populations to once again decline.
Counter-intuitively, ringed seals, the major prey of polar bears and an important resource to Arctic Eskimos, face the prospect of freezing deaths as a consequence of global warming. Ringed seals give birth in snow caves excavated above breathing holes they maintain in the sea ice. The snow caves protect the pups from extreme cold and to a large extent from predators. As the climate warms, however, snow melt comes increasingly early in the Arctic, and the seals’ snow caves collapse before the pups are weaned. The small pups are exposed without the snow cover and die of hypothermia in subsequent cold periods. The prematurely exposed pups also are more vulnerable to predation by arctic foxes, polar bears, gulls, and ravens. Furthermore, gulls and ravens are arriving increasingly early in the Arctic as springs become warmer, further increasing their potential to prey on the seal pups.
The net effect of climate change inevitably will be major changes to the ecosystem. Some species will become extinct, others will adapt to new habitats. Indeed, the history of the earth has involved many ecosystem changes and extinctions. Whether the changes underway today will be survived by walruses, seals, Eskimo culture, our economies and ways of life, will depend critically on the pace of change. Adaptation – biological or social – requires time for adjustment. The current rates of change, however, are very steep.