It was a troubling site. In September 2004, US Minerals Management Service researchers found four dead polar bears floating in the Beaufort Sea. The scientists concluded that as many as 40 polar bears likely drowned as they swam between ice floes—their traditional hunting grounds. Though polar bears are skilled swimmers, as the floes retreat due to warming air and ocean temperatures, the greater distances they must travel have proven to be deadly.That same month, the polar ice cap was reported to have retreated 160 miles north of the northern coast of Alaska. This was not an anomaly. As the arctic temperature rose 5 degrees Fahrenheit over the past several decades, the total amount of sea ice was reduced by 250 million acres, and ice thickness declined from 10 to only 6 feet. With an annual loss of approximately 14,000 square miles of sea ice, it is of no surprise that many scientists predict polar bears could become extinct within the next century.
Despite the plight of the polar bear and other evidence of global warming, no serious steps have been taken to stop or at least slow the buildup of heat-trapping greenhouse gases in the atmosphere. These gases—primarily carbon dioxide, methane and nitrous oxide—are emitted mostly as a result of human activities, particularly the burning of fossil fuels. They have led to a 0.6 to 1.2 degrees F temperature increase since the late 19th century, ten of the warmest years on record since 1990 and up to a 10-inch rise in sea levels due to melting polar ice. Unfortunately, scientists affiliated with the Intergovernmental Panel on Climate Change now predict that global temperatures may rise up to 8.1 degrees F by 2100. And while polar bears may be the most noticeable and charismatic species to be first to fall victim to climate change, they will certainly not be the last. Not a single species, including humans, will be spared the impacts of this warming climate. Coastal flooding, prolonged droughts, more ferocious and unpredictable storms and climate patterns, fresh water shortages and increased disease will become commonplace as the mercury continues to rise.
While scientists have known for years that the warming temperatures melt the ice floes, few imagined how dramatic and rapid the loss would be. The annual loss of Greenland's ice sheet, according to scientists from the National Aeronautics and Space Administration (NASA) and the University of Kansas, has risen from 21.6 cubic miles in 1996 to 36 cubic miles in 2005. In Alaska, scientists estimate the summertime Arctic could be ice-free within 70 years. Responding to the significant loss of polar ice in Antarctica, top NASA climate scientist James Hansen has predicted that without a dramatic cut to emissions, the sea level could rise 80 feet by the time today's children reach middle age.
The potential consequences to the world's oceans are dramatic. In the Arctic, crabs and other bottom dwelling species will either have to move north with the retreating sea ice or perish. In the Antarctic, the number of krill (the primary food source for whales, seals and penguins) has already declined by 80 percent since the 1970s as global warming causes the species' food supply to diminish. As the oceans warm, they also are becoming more acidic due to escalating rates of carbon dioxide input into the sea. Increasing ocean acidity threatens the very existence of crabs, oysters and mussels by dissolving their shells or preventing shell formation. Such changes, including alterations in the abundance and distribution of plankton— a critical food species in an ocean ecosystem—will have dramatic impacts on the health of our oceans. This means disastrous consequences for a wide variety of species, including crabs, salmon, seals and whales.
Climate change is causing enormous impacts to the world's coral reefs, which provide critical habitat to a cornucopia of marine organisms and are already under threat from unsustainable and illegal fishing practices, coastal development and pollution. Global warming exacerbates these impacts by causing coral bleaching, a phenomenon that occurs when stressed or diseased coral expel the algae that give them their vibrant colors. Bleaching incidents, particularly if they are prolonged, can kill coral. In October 2000 at a symposium in Bali, Indonesia, scientists warned that over 25 percent of the world's coral reefs have already been destroyed, mainly because of global warming.
In 2002, 60 percent of Australia's Great Barrier Reef suffered bleaching, with 90 percent of coral bleached in the worst affected areas. More recently, an unprecedented die-off of coral was documented in the US Virgin Islands by National Park Service biologists, with ancient corals that existed during the voyages of Columbus found dead over the past few months. Described by the Global Coral Reef Alliance as an "underwater holocaust," the die-off was caused by increasing water temperatures that caused bleaching and made the coral more susceptible to disease. Indeed, 90 percent of coral reefs around the Maldives and Seychelle Islands in the Indian Ocean have been killed over the past two years as a result of global warming. Such losses have caused some scientists to claim that the world's existing reefs may be dead within 50 years because coral cannot recuperate in a hostile environment.
For many animals and plants, surviving in a warming world may simply not be possible. Scientists estimate that to survive a 5.4 degree F increase, plant and animal species will have to move north more than 300 miles or travel over 1600 feet up a mountain in order to find a suitable habitat. Because such extreme movements are often unlikely due to both natural dispersal limitations and a lack of available habitats, scientists are predicting an impending extinction crisis. Already, scientists believe that a warming climate is responsible for the extinction of almost half of the 80 herds of desert bighorn sheep in California, the near extirpation of a moose population in northwest Minnesota and a loss of 60 percent of collared lemming habitat in Canada. The population of over 5 million ducks who nest in the prairie pothole region of the central United States and Canada may be halved by 2060 because of harsher, more frequent droughts. Habitat for freshwater fish species, including brook, rainbow and cutthroat trout and the invertebrates they feed on, will shrink significantly as streams and rivers warm and their depth decreases. Forests like the Sierra Nevada mountains in California have already shifted their tree lines as much as 100 feet upslope, as they attempt to escape the heat and drought that have increased the frequency and ferocity of forest fires.
And even if suitable habitat can be found, as the climate warms, various diseases—including those that threaten human health—will become more prevalent in all wildlife, from those living in reefs to those who dwell in tropical rainforests. As winter and summer temperatures rise, viruses, bacteria and fungi increase in number and range. Their deadly consequences grow as host species, weakened by the stress of climate change, become more susceptible to disease. In Maine, eastern oysters have fallen victim to a parasite whose range was previously limited by colder temperatures. The last populations of boldly colored honeycreeper songbirds in Hawaii have been afflicted by malaria as increasing temperatures allow disease-carrying mosquitoes to move higher up the mountains. In Central and South America, entire populations of frogs have been killed, with some species going extinct, because of a deadly fungus triggered by the higher temperatures. Warming has also caused an expansion in the range of insects with damaging ecological consequences. In the Rocky Mountains, the mountain pine beetle is devastating whitebark pine ecosystems, while in Canada, the same species has devastated lodgepole pines across an area three times the size of the state of Maryland.
To put it simply, global warming is a global crisis that requires immediate solutions. Though it is home to less than 5 percent of the Earth's human population, the United States produces a quarter of the world's carbon dioxide emissions—which affects the entire planet. Instead of waiting for the US government to take action, individuals must do what they can to reduce energy use and emissions. Simple steps such as replacing standard light bulbs with compact fluorescent bulbs, driving less, using recycled paper products, unplugging unused electronic devices, setting the household thermostat a few degrees cooler in winter and warmer in summer, taking shorter showers, purchasing minimally packaged goods and buying locally grown and produced products are all steps in the right direction. Animals, the environment and future generations are all depending on your help.