Many scientists believe that the Earth is losing animal and plant species at a more rapid rate than in past millennia, in part because of the effects of humans on complex ecosystems. For example, human activities such as building cities and highways, clearing and tilling land for food crops, and diverting water resources for our own use all affect the habitats of specific species. But now scientists report that humans may also increase the rate of species extinctions through our effect on carbon dioxide emissions and global warming.
In an article published online in Proceedings of the Royal Society. B, Biological Sciences (doi:10.1098/rspb.2007.1302), British ecologists report that four out of five periods of mass extinctions of species over the last 520 million years coincided with periods of warmer world climate. And according to climate scientists, Earth is now on track to reach similarly warm temperatures within 100 years unless global emissions of carbon dioxide are reduced soon. Fully 20-30% of all species assessed so far “are likely to be at risk of extinction” if temperatures rise just 3-4 degrees Fahrenheit, according to the highly respected and authoritative Intergovernmental Panel on Climate Change (IPCC).
A big issue of the century will be what, if anything, to do about it.
