climate change

Healthy ecosystems provide Ecosystem Services

  • Purify air and water

  • Decompose wastes

  • Recycle nutrients

  • Example: wetlands buffer coastal populations against hurricanes, reduce the impact of flooding rivers, and filter pollutants


The expanding human population threatens

  • The loss of natural ecosystems

  • Biodiversity

  • Humans overexploit resources

    • Ecological footprint - the amount of land required to provide the raw materials (food, fuel, water, housing, waste disposal) that an individual consumes

    • How much land area each country needs to support its current lifestyle…many countries require more land than is available

    • The ecological footprint of the U.S. is 23 acres/person 

The ecological impact of affluent nations is a problem of overconsumption, not overpopulation

  • The world’s richest countries have 20% of the global population and use 86% of the world’s resources

  • The rest of the world has 80% of the global population but use just 14% of global resources

  • Biodiversity is the variety of life on Earth


  • Maintaining biodiversity is important, since all organisms interact


  • Biodiversity is threatened worldwide

  • Habitat destruction and fragmentation by agriculture, urban development, forestry, and mining

  • Invasive species compete with native species, prey upon native species, and parasitize native species

  • Population growth – human population size is increasing exponentially

  • Pollution of terrestrial and aquatic ecosystems by toxic chemicals and nutrients

  • Overexploitation by people that harvesting organisms at rates that exceed the ability of populations to rebound (examples: tigers, whales, American bison, Galápagos tortoises)

The impact of human activities on freshwater ecosystems may pose an even greater threat to life on Earth 

  • Las Vegas’ water resources are increasingly stressed by drought and overuse

Lake Mead is a reservoir formed by the Hoover Dam

  • The water level in Lake Mead has dropped drastically due to droughts and diversion of water to Las Vegas

  • Parched cities and farms farther downstream

  • Sustainability- the goal of developing, managing, and conserving Earth’s resources in ways that meet the needs of people today without compromising the ability of future generations to meet their needs

  • Average global temperatures have risen 0.8°C (~1.4°F) over the past century, mostly over the last 30 years 

  • Global climate patterns are changing because of rising concentration in the atmosphere of greenhouses gases 

    • Include CO2, water vapor, and methane

    • Are transparent to solar radiation

    • increase global temperatures

Effects of Climate Change on Ecosystems

  • In many plants and animals, life cycle events are triggered by

    • Warming temperatures 

    • Day length

  • As global temperatures warm, and day length remains steady, natural interactions may become out of sync

    • Plants may bloom before pollinators have emerged

    • Eggs may hatch before dependable food sources are available

Ice is melting worldwide, especially at the Earth’s poles

  • Glaciers have declined in Montana's Glacier National Park from 150 to < 30 in the past century

  • Global sea levels are rising 0.13 inches/year, and are expected to rise at least 10 inches by the end of the century

  • Less freshwater will be available

    • Glaciers store 75% of the world’s freshwater 

  • Vanishing ice has driven species to the brink of extinction, such penguins and polar bears

    • unable to adapt fast enough

Some species—including mosquitoes, ticks, jellyfish, and crop pests, are thriving

  • Bark beetles have an extra reproductive cycle per season

  • They have devastated millions of acres of spruce and pine trees in the U.S.

As temperatures change, many species are on the move 

  • Some butterflies, foxes, and alpine plants have migrated farther north or to higher, cooler areas


New weather patterns

  • Precipitation has increased across the globe on average

  • Some regions are experiencing more severe drought

    • increasing the risk of wildfires, lost crops, and drinking water shortages 

  • Hurricanes and other storms are likely to become stronger

  • Floods and droughts will become more common 


Some diseases will spread

  • such as mosquito-borne malaria