
Recent studies based on tree ring measurements near the tree line indicate a trend of steady warming over the last 100 years, and current conditions are warmer than those in the past three centuries. This steady change in the climate has resulted not only in warmer temperatures on average, but also in changes in the timing of the seasons, and increases in the frequency of unusual weather events. Recent research is documenting the disruptive influence of these changes in day-to-day and month-to-month weather patterns.
For example, artificial temperature-raising experiments at Spitsbergen, Norway, resulted in dramatic increases in the number of aphids living on plants. There was an eleven-fold increase in the number of overwintering eggs following a prolonged growing season. Their effect on the plants the following season are not yet known. The International Tundra Experiment (ITEX) being carried out at 25 sites in the eight circumpolar countries
has found that as warming persists there is a loss of plant diversity in undisturbed tundra ecosystems, with potentially drastic consequences for animal populations. The area of pack ice will decrease and have potentially disastrous effects on marine species, particularly the polar bear (which is entirely dependent on pack ice). Changes in the area of sea ice along the coast of the North East Greenland National Park, the largest protected area in the world, could affect the resident polar bears and ringed seals. If enough ice is lost, polar bears will become extinct.
The Arctic is a land of seasonal contrasts, and the annual life cycles of plants and animals often follow a tight schedule. In their annual spring migration to the coastal plain of the Arctic National Wildlife Refuge, female caribou in the porcupine herd closely track the pulse of vegetation growth as it progresses northward. They eventually concentrate in small and highly productive areas of the plain where they are able to obtain the nutritious forage they need to raise their calves. The problem, however, is that over the last several decades, spring has been arriving earlier and earlier on the coast and the caribou are hard-pressed to arrive in time to take advantage of the period of maximum plant growth. The 1990 spring was the earliest in nearly 40 years, and by the time the caribou had reached the plain their principal food plant (Eriophorum vaginatum) had already gone to seed. Warming creates other potentially serious problems for the caribou. Mosquito harassment will increase directly with anticipated increases in summer temperatures, and the caribou can be expected to expend more and more time and energy escaping the persistent clouds of insects. Detailed energetics models suggest that future climate conditions may prevent the females from successfully raising calves, thereby leading to herd declines. Or perhaps even worse, freezing rain in the spring or fall can prevent caribou and other herbivores from reaching their food supplies. Destructive weather of this sort is happening with greater frequency in the Arctic at a time when dramatic caribou die-offs are being observed and herds are declining. Although Arctic species are following their age-old strategies, they are increasingly finding themselves in the wrong place at the wrong time.
Back to The Arctic contents