Environmental Engineering Reference
In-Depth Information
tica melted, the sea level would rise another 61 meters. (However, extreme melting in Antarctica is unlikely as
the mean air temperature of -37°C is still much below the melting point of water at 0°C.)
Biodiversity
Humans are not the only organisms affected by global warming. A decrease in polar ice in the Northern Hemi-
sphere has decreased both the food supply and the hunting areas of polar bears. Plants and animals have moved
their ranges towards the poles. Grasses have become established in Antarctica for the first time. Bird migration
patterns have changed, with migrations starting an average of two days earlier per decade. As the thermal tem-
perature of the water increases, phytoplankton, krill, and fish populations have been affected, changing popula-
tion size and location. It is interesting to note that many migratory patterns have evolved with codependence on
other species. For example, a migratory bird population may depend on the timing of seasonal food sources
along its route. With global climate change, many of these coevolved behaviors are altered. Birds may arrive to
find plant or animal food sources nonexistent, which, in turn, can impact reproduction and offspring. Current
research is exploring the ways in which interdependent populations are likely to be affected by continuing cli-
mate change.
Global warming and the resultant rise in sea levels will affect not only land ecosystems, but also sea life. Cor-
als are dependent on a narrow temperature range for survival and are sensitive to temperate variations. There-
fore, small increases in temperature can kill corals. In recent years, we have seen this happen, as corals die in
warmed seas. Also, increasing acidification of the oceans due to changing CO
2
concentrations can harm and
kill coral. Other marine life may be forced to migrate northward or southward to find the same water temperat-
ure. These displaced animals may find that, while their migration allows them to keep a constant water temper-
ature, many of the habitats and food sources on which they depend are scarce.
Sea water circulation patterns also are disturbed by global warming. Cold water moves along the sea floor to-
ward the equator, and warm water around the equator moves toward the poles across the surface of the ocean.
This is known as
thermohaline circulation.
One result of this circulation process is the delivery of oxygenated
water to the sea floor and nutrient-rich waters to the surface. Without this circulation, oxygen levels in the
deeper parts of the ocean and on the sea floor would be depleted and nutrient upwellings on the surface would
decrease.
Fish, such as salmon, are also sensitive to water temperature. During the summer, when the water is warm, sal-
mon have a higher metabolic rate. During the winter months, their metabolism slows down, an adaptation that
allows them to survive longer on less food (like a bear's hibernation when food is scarce). With global warming
and increased water temperatures, salmon would be forced to maintain a higher metabolic rate, even in the
winter months of food shortage. Many salmon would starve.
Reducing Climate Change
In the 1990s, CO
2
emissions increased 1.3 percent per year, but with the current rate of global growth and in-
dustrialization, scientists predict that the annual growth rate of CO
2
emissions is likely to climb to approxim-
ately 1.9 percent to 2.5 percent annually. According to the EPA, total emissions from the developing world are
expected to exceed those from the developed world by the year 2015. Asia is leading the way in the growth
rate of CO
2
emissions, with an increase in a consumer-oriented economic middle class and new coal power
plants. The rise in carbon dioxide is also due to the inability of natural
carbon sinks
such as plants and oceans
to absorb carbon dioxide at the rate at which it is being produced.
