Реферат: Climate Change And Evolution Essay Research Paper

Climate Change And Evolution Essay, Research Paper


The ecological consequences of global climate change are expected to be drastic although not much is known as to how individual species will react to these changes. Irrespective of the causes of climate change, whether anthropogenic or natural, it is imperative that we address these concerns, as they will have widespread impacts on the human species, both directly and indirectly through forcings on other species. The climate is not expected to shift evenly and the ways in which certain species adapt or migrate due to these changes could be erratic and unpredictable. The rate at which the earth’s climate is currently changing is unprecedented and has not been seen in the past 450,000 years. Although many species have simply migrated northward or vertically up mountainsides to escape warming habitats, others do not have this luxury or cannot migrate fast enough to survive. The earth’s temperature has risen by over one degree Fahrenheit over the past century, based on land and sea level measurements. The temperature is expected to continue rising at a faster pace over the next century, possibly increasing by as much as seven degrees Celsius. In comparison, the earth’s average global temperature was only twelve degrees cooler than it is now during the last great ice age. A vast majority of species now living do so within a narrow spectrum of temperature ranges and will not be able to adapt to a warming climate on such a large scale. If humans are the cause of a warming climate we will ultimately be responsible for the destruction of millions of species.

Indicator Species

Polar bears are one species that are currently feeling the effects of a warming climate. Over the past twenty years, NASA satellite data has shown a 2.9 percent decline per decade in Arctic sea ice, resulting in shorter feeding seasons for polar bears. The species’ main food source, ringed seals, which live on the ice of Hudson Bay are becoming increasingly inaccessible due to earlier ice melts. “We’re wrong if we think that climate change is something that will happen far off in the future. Polar bears are starving now and we need to act now to stop climate change,” said Kevin Jardine, Greenpeace climate impacts specialist. A recent study by Canadian polar bear researchers showed that the species have less time to hunt during the season and are forced to return to land undernourished. The study reports a decline in weight of both male and female bears as well as a noticeable decline in offspring. As the Hudson Bay bears fast for six to eight months out of the year, sustaining themselves on nourishment from the hunting season, they are increasingly unable to survive the rest of the year due to limited food resources. Polar bears are not the only species currently under stress form a warming climate however.

Masses of orange-and-black Monarch butterflies that travel on a 3,000-mile annual migration from the United States and Canada covered an area of 42 acres two years ago. Now, however, the butterflies that winter in the area cover a mere 13.5 acres. Monarch butterflies are very sensitive to climate change; the smallest temperature change can have drastic impacts on their populations. Monarchs have developed various adaptations in order to avoid being caught and eaten by predators. These adaptations range from their colorful wings to chemical secretions used to repel predators. Many of these adaptations are ineffective in areas outside of their native habitat however and as the species is forced to migrate to more suitable areas, they are forced to further adapt to their new surroundings. At the rate at which the climate is warming, they simply cannot make these phenotypical and morphological changes fast enough and eventually perish. Numbers of Monarch butterflies are currently declining in North America in trends that concur with what climate models predict.

Agriculture and plant species will also be greatly impacted by global climate change. The biggest concern for plants is that they cannot just get up and move. Based on current computer models depicting future trends in climate change, many plant species in the northern hemisphere, mainly Russia and Canada, would have to migrate by up to one kilometer per year, a rate that many plants just cannot accomplish. Complicating the process further is the interference of humans in migratory paths. Plants will have to overcome physical barriers established by man such as roads, cities and neighborhoods. Furthermore, plants considered weeds or regarded as intrusive will move into populated areas only to be exterminated with herbicides and other chemical intensive processes. With the deck stacked against them, many species simply will not be able to adapt or migrate and will go extinct.

Sea Level Rise

As the climate warms, the water in the oceans is expected to rise through the process of thermal expansion and the melting of polar ice caps and mountain glaciers. Rising seas would inundate low-lying deltas and other coastal areas, erode beaches and contaminate inland water supplies and aquifers. The sea level is expected to rise by up to one meter over the next century and continue to rise over the next few centuries. As the seawater forces wetlands to move further ashore, many species will have to make the shift as well. Wetlands are delicate ecosystems however and cannot regenerate themselves fast enough to withstand the rising seas. This will cause massive loss of habitat over the next century. Wetlands that do successfully move into areas previously considered dry lands will eventually meet with obstacles such as seawalls, dikes, cliffs and cities and will not be able continue their onshore shift. This loss of habitat could signal the extinction of many shorebirds, amphibians, insects and various forms of aquatic life that rely on coastal wetlands for survival.


Beyond taking steps to reduce greenhouse gas emissions that are thought to contribute to an increase in global temperatures, there exist various other ways in which humans can reduce the loss of habitat and species due to climate change. Humans are the most invasive species to ever inhabit this planet and we can take steps to reduce our fingerprint on the environment. This would at least give other species a fair shot at adapting to a changing climate without the added stress of overcoming anthropogenic barriers. We could resist the urge to build seawalls and dikes in the interest of human property and allow coastal areas to naturally expand as the climate warms. Given the freedom to adapt without human barriers, many wetland areas will be able to survive a warming climate, although not much is known about the resulting influences on surrounding areas (forests, estuaries and marshes.) Other anthropogenic influences cause stress for species as well, such as deforestation, pesticides and herbicides, introducing invasive non-native plants and building dams for hydroelectric power. Combined with the pressure of a warming climate, many species just cannot survive. It is time we address the health our planet and our own ecology on a more holistic level. A place for everything and everything in its place.

Indicator species such as polar bears and butterflies are signaling us that we are treading into uncharted waters. We must cautiously move forward taking preventative measures where possible and reducing our fingerprint on our climate and environment in general or we will be yet another species unable to adapt, and eventually, suffer extinction.


Ian Stirling, Nicholas J. Lunn and John Iacozza, 1999. “Long-term trends in the population ecology of polar bears in western Hudson Bay in relation to climate change”, Arctic 52(3):294-306. September 1999.

Markham, Adam and Malcolm, Jay. September 2000.

Speed kills: rates of climate change are threatening biodiversity.


Antipredator Adaptations by Monarch Butterflies

Kim A. Pike


Intergovernmental Panel on Climate Change: Special Report

The Regional Impacts Of Climate Change: An Assessment Of Vulnerabilities

(Summery For Policy Makers.) 1995


Stevens, William K. 1999. The Change In The Weather: People, Weather and the Science of Climate. New York, New York. Delecorte Press.

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