TOPICS IN BIODIVERSITY LOSS
 
Does Biodiversity Change? Is Biodiversity Changing Now? Biodiversity Loss and Humans
Future for Biodiversity What if Loss Occurs? What Can Be Done? Biodiversity Hotspots
     
 
Current extinction rates are up to 100 times greater than natural, background extinction rates, because of the effect of humans on other organisms and ecosystems. We impact the world around us in many ways, some of which are more destructive than others. Here are some of the ways in which humans are causing other life forms to go extinct:
   
Overfishing
   
   
Overhunting
   
   
Habitat Destruction & Conversion
 
Habitat destruction occurs whenever humans change a landscape and alter the ecosystem that resides there. This occurs whenever a forest is cut down for pasture or a wetland is filled in to build a parking lot. Tropical rainforests are at high risk for this, as they are frequently cut down to create cropland and pasture for cattle.
   
Invasive Species Introductions
 
Introduction of invasive species can do irreparable damage to an ecosystem that is not prepared to cope with the intruders. A foreign plant might be able to out-compete all others in a given environment, driving out the other species and replacing them with a monoculture. Humans introduce microbes and soil particles relatively easily and unknowingly when they travel, and we have also introduced foreign species as pest controls at times.
   
Climate Change
 
Biodiversity is threatened by climate change largely because of loss of habitat. As sea levels and temperatures rise, plants and animals, just like humans, will be forced to relocate, to leave the places where they live and move into new areas. This graphic illustrates the effects of climate change on one type of habitat, mountains, as temperature and precipitation increase:
 
See UNEP/GRID Arendal Maps and Graphics Library, Climate Change Impact on Mountain Vegetation Zones
 
As the climate warms, the various habitat zones move up the mountain, and along the way species and ecosystems are invariably lost. The most vulnerable species are those that can only survive in a narrow zone of climate, such as within a certain temperature or precipitation range. If individuals cannot move quickly enough to stay within their required climate zone, they will perish.
 
See UNEP/GRID Arendal Maps and Graphics Library, African Wildlife Under Threat from Climate Change
 

This graphic shows the numbers of threatened and endangered animal species in Africa. The group of bars on the far left shows totals for all of Africa’s different categories of animals (mammals, birds, reptiles, etc.), and the other four sets of bars are broken down by region within Africa. This shows the current status of threatened and endangered animals in Africa; climate change will only make this worse.

Closer to home, a March 19, 2007 article in the Washington Post described one likely effect of climate change on a familiar bird: the Baltimore Oriole. The state bird of Maryland will likely be driven out of that state within a century, as climate change shifts its range north and towards Philadelphia.

 
     
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