Chapter 23 Environmental Science

23.1 Humans and the Environment  Environmental science is the study of the relationships between humans and the Earth  Since all life is interconnected, it is important to develop it is important to develop ways to correct global ways to correct global problems from humans problems from humans

A Global Connection  Warming and cooling air form loops called convection cells in Earth’s atmosphere  Convection cells determine climate and create climate and create oceanic circulation oceanic circulation patterns patterns

Convection Cells  The sun’s rays heat air molecules near Earth’s surface  The less dense, warm molecules rise  Eventually they cool and sink back toward Earth

Upwelling  Cold water rises from the ocean depths and carries nutrients upward  More nutrients support more plankton which leads to large populations of fish

El Nino  Occurs when the warm surface water prevents upwelling from occurring  Causes fish populations to decline (anchovy exports decrease)

Declining Ozone  O 3 is a naturally occurring gas that protects living things from harmful UV rays  CFC’s are ozone- destroying chemicals

Chlorofluorocarbons  Used as coolants in refrigerators and air conditioners and as propellants  Banned in 1992  As long as we don’t use CFC’s, the ozone layer will continue to recover

Increasing CO 2  Carbon dioxide is a byproduct of cellular respiration and a component of photosynthesis  It is also released when fossil fuels are burned

The Greenhouse Effect  Greenhouse gases form a blanket around Earth and keep it at a temperature suitable for life  When the layer gets thicker, it traps too much heat which causes global warming

Evidence About Global Warming  Ice-core samples show there is a correlation between rising temperatures and CO 2 temperatures and CO 2 concentrations concentrations  Global temperatures are expected to rise 2°C (4°F) within the next century  Can affect rainfall patterns, soil moisture, sea level, crop growth, biodiversity, human diseases, etc.

Future Population Growth  The U.N. estimates that human population will be at 12.5 billion by 2050  This would result in more fossil fuels being burned and higher global temperatures

23.2 The Biodiversity Crisis  Biodiversity: the variety of organisms in a given area  Genetic diversity: the amount of genetic variation (the most important measure of biodiversity)

Measuring Biodiversity  There are 3 million species that have been identified on Earth  It is estimated that there are million species  Tropical rainforests have many undiscovered species

Earth’s Biodiversity

Extinction  Extinction is forever!  Rapid destruction of habitats is driving many species to extinction each day  More than half of all tropical rainforests have already been destroyed

Ways to Save Biodiversity  Conservation strategies! (Ecotourism)  Debt-for-nature swap: richer countries or private organizations pay off some of the debts of a developing country in exchange for them not cutting down their rainforest

The Importance of Biodiversity  Utilitarian Value: considers the economic benefits that biodiversity provides for humans (food, medicine, etc.)  Nonutilitarian Value: All life-forms deserve to exist (intrinsic value)  Need for a “Declaration of Interdependence”

Conservation and Restoration Biology  Conservation biology: identify and maintain natural areas to preserve biodiversity  Restoration biology: convert damaged areas back into viable habitats

Conserving Migratory Birds  Migratory birds spend spring and summer in Tundra and northern forests (abundant insects for food)  In the Fall, they migrate to warmer climates where there will be enough food to last until their next breeding season

Flyways  There are four major flyways in North America

Saving Critical Habitat  Wildlife refuges must be established along the flyways to allow birds a place to rest and eat during their long migrations  They also need protection in their wintering grounds  Conservation efforts need to be international! to be international!

Magee Marsh

Reintroduction of the Wolf  The gray wolf is an endangered species because they were killed by people  There has never been a documented case of a human being attacked by a healthy wolf!  They will occasionally kill livestock

Wolves in Yellowstone  Without wolves in the park, the elk population exploded  In 1995, 14 wolves were released

The Florida Everglades  Drainage canals were built to divert water away from the everglades so people could use the land for homes  More than 50% of the wetland was destroyed

Wetlands  Wetlands are important habitats for wildlife  They also purify drinking water and help replenish groundwater  Coastal wetlands prevent flooding and beach erosion

Everglades Restoration  Currently, a restoration plan is being implemented to remove some of the drainage canals  40,000 hectares (100,000 acres) will be set aside for protection  Melaleuca trees will be cut down (non-native species) down (non-native species)

Get Involved!  Learn about your local environment  Get involved in your own community to preserve local biodiversity  Recycle  Urban ecology: increasing biodiversity in heavily developed areas