Chapter 6 Sustainability
extra worksheet 4: Changing climate of Antarctica
Science Understanding Verbal/Linguistic
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In 2009 it was reported by the U.S. Geological Survey that the ice sheets in the southern part of the Antarctic Peninsula (Figure 1) were disappearing and that the change in the amount of ice was significant. Since 1998 approximately 4000 square kilometres of ice has been lost from one area. This area of ice lost is about one and a half times the size of the Australian Capital Territory (ACT). This loss of ice is regarded as very strong evidence of the effects of global warming on the planet.
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Effect on plants and animals
Antarctica is home to only two species of flowering plant and both these grow on the Peninsula. The range (area over which they are found) and abundance (number of plants in an area) have both increased in the last few decades.
Krill are tiny shrimp-like crustaceans that are a very important food source for animals in the Antarctic. Krill numbers in Antarctica have declined by as much as 80% since the 1970s. Krill feed on algae that live just under the surface of sea ice. Where the amount of sea ice is decreasing, so too does suitable habitat for krill.
Krill feed the fish of Antarctica and are the main food source for baleen whales. In the years 1925 to 1975 baleen whales were hunted and their numbers decimated. Without krill it will be difficult for baleen whale numbers to recover to pre-hunting levels.
With the shrinking sea ice in western Antarctica, the Adélie penguins (Pygoscelis adeliae) have declined in numbers over the last 20 to 25 years. In other parts of Antarctica the colonies are stable or increasing in numbers. Adélie penguins feed only on krill. The penguins nest on land and parent birds go out to the sea ice to find food for their chicks. A reduction in the amount of sea ice not only reduces the Adélie penguins’ food supply, it also increases the distance the parent birds have to travel to find food.
Some penguins are benefiting from the changes taking place in Antarctica. Gentoo penguins (Pygoscelis papua) (Figure 1a) are nesting on the Antarctic Peninsula. Studies of the bones and other remains found in penguin colonies indicate that Gentoo penguins did not nest in this area before 1950. These penguins feed on fish and squid as well as krill.
Chinstrap penguins (Pygoscelis antarctica) (Figure 1b) are also benefiting from the changes. Where...