Tuesday, November 8, 2011

Climate Change, NOT Overkill Hypothesis may have Greater Effect on Biodiversity

Climate change and past extinction events have shown to have a significant correlation. When examining the most recent extinction event, the Late Pleistocene Extinction, there are two comparable theories for its cause. One of which, the “overkill hypothesis” states that overhunting by humans caused the extinction of hundreds of genera of megafauna throughout the world. The second theory is that the mass extinction was due to warming temperatures on the Earth’s surface that resulted from the ending of the ice age. Generally, the overkill hypothesis is accepted as the more likely theory given that human populations increased drastically at around the same time the extinctions occurred.

Mammoths and horses are two species that used to be highly abundant in Alaska and the Yukon Territory. Their extinction roughly 12,000 years ago correlates with the arrival of humans as well as the increasing global temperatures. Dale Guthrie states that the increasing temperatures in this area allowed for a drastic shift in the vegetation in this environment. Horses and mammoths thrived in the previous habitat, as they were able to efficiently extract their nutrients from consuming a large amount of less efficient food. The warming temperatures allowed for the growth of the current tundra biome, consisting of forests and shrubs (Guthrie 2006). This new environment favored animals such as the moose and bison, which are now widely abundant in that area. This evidence suggests that the climate change was the underlying reason for the extinction of these two animals, and allowed for other species to prosper. This is in opposition to the more widely accepted overkill hypothesis, and has significant implications regarding the current global warming problem.

This paper reveals evidence that climate change has a direct effect on certain species existence. Given that the current climate change is happening fifty times faster than the previous global warming period after the last ice age, a real, imminent danger exists for all species on Earth. We can expect to see similar habitat shifts like that seen in the tundra 12,000 years ago except on a far greater scale. There is reason for concern because drastic climate changes could have detrimental effects on species if they do not have time to adapt or are not capable of migration due to fragmented habitat. This will have significant effects on all species on Earth, and green house gas emissions will need to be drastically slowed in order to decrease global warming effects. We have to be aware that the current mass extinction that we are in is likely to increase at an alarming rate in the coming decades, and it will take a huge effort on the part of all humans to save what species we still can.

Dale Guthrie, R. "New Carbon Dates Link Climatic Change With Human Colonization And Pleistocene Extinctions." Nature 441.7090 (2006): 207-209.Academic Search Complete. Web. 4 Nov. 2011.

New carbon dates link climatic change with human colonization and Pleistocene extinctions.

-AJ Mells

No comments: