Human Impact

Human Population Growth

Human Population Growth Total Human Population Compared to past centuries, the human population is now growing at exponential rates!! Due to: Higher birthrates; Better medical care/sanitation ; Better nutrition/food supply; Higher survivorship/ longer life expectancy.

Overhunting: extinct/endangered bison Black rhino whales Dodo bird

Overhunting For most of human history, food was obtained through hunting. This led to the extinction of many species. Examples) North America – Woolly Mammoth, Saber toothed tigers, Giant ground sloth.

Importation of Organisms Invasive Species: those that are not native to an area. They cause major problems to ecosystems b/c they can easily out-compete native organisms; have no predators. Japanese beetle Gypsy moth

INVASIVE SPECIES More examples: Rabbits in Australia, New Zealand (from Europe) Fish like the Northern Snakehead in US Great Lakes (from Asia)

Exploitation Taking advantage of wildlife for financial gain. Example) Overfishing – by 1990, Cod fish were almost completely gone from the world’s oceans Taking advantage of wildlife for financial gain. Elephant ivory tusks at market!

Poor Land Use Management Over cropping Overgrazing No cover-crops (no crop rotation) Drain wetlands Urbanization Sprawl – Think LA or Las Vegas!

Desertification: An example of poor land use management Due to overgrazing, overfarming and drought, once productive areas have turned into desert.

Technological Oversight The rapid technological advances in the last century have contributed to unforeseen levels of… Fossil Fuel Emissions Solid Wastes Water Pollution Evidence suggests that climate change may be, in part, related to human activities that add greenhouse gases to the atmosphere. Herbicides-contaminate water supply Pesticides-DDT disrupting the food chain

CO2 Emissions by Nation

Positive Aspects (of human actions) Recycling programs Population control Legislation: The Kyoto Protocol – An international agreement to reduce Carbon emissions. Improved farming

Attempts to maintain BIODIVERSITY in entire ecosystems. Species Preservation Attempts to maintain BIODIVERSITY in entire ecosystems. . Zoos, captive breeding programs (Panda Bear). Wildlife Refuges Game Laws National Parks Endangered Species Act

Biological Control vs. Toxins Using natural solutions to get rid or nuisances or problems Use of sex hormones by trapping or immuno-contraception Natural predators/parasites Example : the use of petroleum-eating-bacteria to clean up oil spills.