Geology Essay Example | Topics and Well Written Essays - 3500 words

Geology - Essay Example Because of these concerns, the prominent changes, at least many of it, occur so in the arctic region. The basis for this is strong positive feedback associated with occurs with ice and snow melt. As a fact, ice and snow are highly reflective and white, for this reason, when the ground or ocean beneath is revealed more absorption occurs. This leads to further warmingfurther melting etc Clearly the level of warming currently occurring in the arctic is having an enormous impact on the region and the magnitude of further warming is set to be disastrous for the region. Thus, the Arctic Climate Impact Assessment (ACIA) states: "The reduction in sea ice is very likely to have devastating consequences for polar bears, ice-dependant seals, and local people for whom these animals are the primary source of food." The polar bear (Ursus maritimus) is the world's largest species of bear and the largest land predator. There is a great difference in size between male and female polar bears, with the males (350-800 kg) weighing more than twice as much as the females (150-300 kg). Their body weight varies considerably during the season - especially female bears which can often double in weight between early spring and late summer. Compared to other bear species, the polar bear has a relatively small, long and narrow head, smaller and shorter fur-covered ears, and shorter, more powerful claws. Its longer predatory teeth and sharper molars have helped polar bears adapt to the arctic climate and its almost exclusively carnivorous lifestyle. The polar bear is the youngest species of bear and is closely related to the brown bear (Ursus arctos) and grizzly bear (Ursus arctos horribilis). In the wild, polar bears normally live to be 20-30 years old. Both males and females mature at the age of four to five years. Females often give birth to their first litter of cubs when they reach maturity, while males do not usually start mating until they are between eight to ten years old. Mating takes place in April-May, but delayed implantation (the fertilised egg stops developing at an early stage) means that foetal development does not commence until September-October. During late autumn, females go into hibernation and remain there for approximately four months. At about the beginning of January, between one and three cubs are born (depending on the mother's age and condition). The newborn cubs are extremely small, weighing only about half a kilo, but they grow rapidly due to the high fat content of their mother's milk. The cubs stay with the mother until they are two-and-a-half years old. The cub infant mortality rate is high and can exceed 70%. Only about a third of cubs r each the age of two. The polar bear is a circumpolar species and is found in arctic regions where there is access to sea ice throughout much of the year. Polar bear populations are found in Canada, Alaska (USA), Greenland, the Russian Arctic, the Norwegian Arctic and on the ice surrounding the North Pole. The global population of polar bears consists of roughly 20,000-25,000 individuals spread between 19 sub-populations. However, polar bears wander across enormous distances, so there are no major genetic differences between these populations. The distribution of polar bears in their habitat is far from even and is highly dependent on the availability of their prey. In the central areas of the polar icecap there is only very limited access to prey, and the density of polar bear