As fall sets in here in the northern hemisphere, our changing global climate is lining up to render yet another unprecedented summer along the Antarctic Peninsula. Arguably the most rapidly rising temperatures anywhere on earth, mid-winter temperatures along the Peninsula have risen 10 degrees Fahrenheit over 60 years. The impacts are hard to miss. The annual sea ice has retreated dramatically with its seasonal duration and extent offshore reduced by some 40 percent over the past 30 years. The Wilkins Ice Shelf, a floating ice sheet several hundred feet thick the size of Connecticut, may sever its tenuous grip on the peninsula and join eight other large ice shelves that have departed since 1980. And as the ice shelves separate from the mainland, they deprive it of an important bulwark and make it easier for glaciers to flow into the sea and melt. We might joke about building sea walls around real estate in Florida and Manhattan, but with melting glaciers along the Antarctic Peninsula and Greenland contributing increasingly to sea level rise, this is no longer a laughing matter.
Yet more is at risk than ice shelves and rising seas as the Antarctic Peninsula shifts from a cold and dry climate to a warmer, moister, climate. The peninsula's fragile marine ecology, from the smallest bacterium to the largest baleen whale, is being challenged. As the seas warm and the climate changes, communities of tiny floating plants called phytoplankton are becoming less common and shifting from larger to smaller varieties that are less nourishing. Along the northern peninsula, the phytoplankton no longer provide sufficient sustenance for krill, the shrimp-like zooplankton that are the biggest ingredient of Antarctic food webs -- they feed fish, seals, penguins, and whales. Younger krill are finding it more difficult to find a meal. They gorge on phytoplankton that grows on the underside of the annual sea ice. As the annual sea ice is disappearing so are the krill.
Additional ecosystem changes are underway along the western Antarctic Peninsula, including the dramatic 35-year decline of the iconic Adélie penguin whose eggs perish in unseasonably late snow storms, the result of a warmer moister climate. Eighty-percent of the Adélie penguins along the central Antarctic Peninsula are now gone. The Peninsula is also facing a pending invasion of king crabs that are no longer being held at bay by low temperatures. Antarctic seafloor animals have evolved in the absence of crushing predators and their thin weak skeletons will be no match for the large, clawed crabs. And ocean acidification, "the other CO2 problem" caused by the ocean's absorption of atmospheric CO2 from fossil fuels, will uniquely challenge marine life in the Southern Ocean as carbon dioxide dissolves more easily in cold water and thin-shelled marine life is vulnerable. Antarctica will become a global laboratory for studying the impacts of future ocean acidification closer to home.
There are more tangible losses to consider as the austral summer approaches the Antarctic Peninsula. Antarctic seafloor invertebrates including sponges, soft corals, starfish, and sea squirts are fine-tuned to live at constant low polar temperatures and studies indicate many may be unable to adapt to rapid warming. The loss of these animals is tantamount to losing an investment portfolio of genetic diversity that may harbor cures to human disease including cancer, AIDS, cystic fibrosis, and infectious diseases. For example, an Antarctic sea squirt the size and shape of a soft ball has been discovered to harbor chemicals that scientists at the National Cancer Institute found kills melanoma, the deadliest form of skin cancer. With the Antarctic sea floor boasting a marine biota equivalent to that of the Great Barrier Reef of Australia its myriad invertebrates represent a priceless resource.
Also at risk is the esthetic value of this vast untamed wilderness. Over my twenty expeditions to Antarctica, I continue to be dazzled by the poetic grandeur of the landscape, the stunning colors of the ice, and the rocky shores teeming with nesting, braying penguins. Tourists that visit Antarctica return home transformed -- ambassadors for a remote continent. Here, politics takes a back seat. The Antarctic Treaty recognizes no sovereignty, but rather Antarctica remains a global commons for the pursuit of scientific knowledge and the preservation of our last great wilderness. What a fitting context for a diminishing Antarctic Peninsula to serve as a clarion call for a sustainable planet.
James B. McClintock is an author and the Endowed University Professor of Polar and Marine Biology at the University of Alabama at Birmingham. His book Lost Antarctica: Adventures in a Disappearing Land was just released.
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