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Climate Change

Explore the long-term atmospheric conditions of Earth's climate system and learn about the different factors contributing to climate change. Discover the effects of global warming, rising sea levels, and changes in the oceans.

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Climate Change

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Presentation Transcript

  1. Climate Change

  2. Earth’s Climate System Climate – long-term atmospheric conditions in a region Different from weather! Earth’s climate includes interactions of: Atmosphere Hydrosphere Geosphere Biosphere Cryosphere

  3. Climate scientists use 3 methods: • Look at geologic records and fossil records • Build computer models • Closely monitor Earth’s current vital signs

  4. Determining Causes of Earth’s Climate Change • Paleoclimatology • Proxy data – indirect evidence using natural recorders of climate variability • Sea floor sediments • Coral deposits • Glacial ice rings • Tree rings • Pollen • Historical documents

  5. Proxy Data – Ice Cores

  6. Natural Causes of Climate Change • Solar energy changes • Variable energy from the Sun over time • Sunspots – cooler, episodic dark areas on Sun • Faculae – bright spots on Sun • Variations in Earth’s orbit • Volcanic eruptions • Movement of tectonic plates • Can change ocean circulation

  7. Natural vs. Human Caused Climate Change • Scientific consensus of large human contribution

  8. Atmosphere’s Greenhouse Effect • Global warming – increase in Earth’s global temperatures • Greenhouse effect – keeps Earth’s surface habitable • Incoming heat energy is shorter wavelengths • Longer wavelengths – some trapped, some escape, net warming effect

  9. Earth’s Heat Budget

  10. Greenhouse Gases • Water vapor • Most important • 66–85% of greenhouse effect • Carbon dioxide • Natural part of atmosphere • Released by living things as a result of respiration • However, levels have increased due to human activities • Burning of fossil fuels • Methane • Second most abundant human-caused greenhouse gas • Great warming power per molecule • Landfill decomposition • Cattle – increased human population means increase cattle due to food source • Other trace gases • Nitrous oxide, CFCs, ozone

  11. How have humans caused increased carbon dioxide in the atmosphere? • Industrial Revolution • Led to burning of fossil fuels • Burning of fossil fuels is similar to cellular respiration • Humans have altered the carbon cycle – we are releasing more carbon dioxide into the atmosphere

  12. Atmospheric Carbon Dioxide

  13. Ice Core Data

  14. Changes from Global Warming • Melting glaciers and ice caps • Shorter winters • Species distribution shifts • Global temperature rise • Sea surface temperature increases

  15. Changes from Global Warming • The 8 warmest years have occurred since 1998 • Earth’s surface temperature has risen 0.8°C (1.4°F) in past 140 years.

  16. Changes from Global Warming Predicted Changes: Earlier, hotter summers Some areas could see more extreme winters More severe droughts in some places, flooding in others Retreat of mountain glaciers Water contamination issues Ecosystem changes and extinctions

  17. Scenarios for the Future

  18. Changes in the Oceans Increasing ocean temperatures • Sea surface temperatures risen mostly since 1970 • Deep waters showing increases

  19. Changes in the Oceans Increased hurricane activity Warmer water fuels hurricanes Severity of recent Atlantic hurricanes Number of global tropical storms have not increased worldwide Intensity of storms has increased More Category 4 and 5 hurricanes

  20. Changes in the Oceans Changes in deep-water circulation • North Atlantic especially sensitive • Melting glaciers • Could change the way the ocean redistributes heat • Could change circulation patterns • Warmer surface waters

  21. Changes in the Oceans Polar Ice Melting • Arctic amplification • Loss of more than 2 million square kilometers (800,000 square miles) of Arctic sea ice in last decade • Loss of ice = enhanced warming due to lower albedo

  22. Changes in the Oceans Polar Ice Melting • Arctic ice melting affects polar bear survival. • Food sources are dwindling for human Arctic dwellers. • Marine species migration

  23. Changes in the Oceans Polar Ice Melting • Antarctica shrinking, glaciers thinning

  24. Changes in the Oceans Ocean acidity increase • Some atmospheric carbon dioxide dissolves in ocean water. • Acidifies ocean • Threatens calcifying organisms • Coccolithophores • Foraminifers • Sea urchins • Corals

  25. Organisms Threatened by Increased Marine Acidity • When we talk about ocean acidification, we don’t necessarily mean huge drops in pH • pH of ocean is ~8.6, slight decreases in pH could greatly affect organisms • pH is a measure of H+ in solution, on a log scale • Small decreases in pH can have a large effect on ocean organisms

  26. Changes in the Oceans • Rising Sea Level – already occurring • 2 main contributors: • Melting of land glaciers and ice caps • Thermal expansion of ocean water • Warmer water expands • Should we continue to build in some coastal areas?

  27. Rising Sea Level • Severely affect areas with gently sloping coastlines • U.S. Atlantic and Gulf Coasts • Models predict rise between 0.5 and 1.4 meters (1.6 and 4.6 feet) by year 2100 • Consequences: • Saltwater intrusion • Erosion • Increase storm damage • Loss of low lying areas • Loss of wetlands

  28. Changes in the Oceans Other predicted changes Sound transmission in ocean Reduced dissolved oxygen – marine dead zones Does warmer or colder water hold more oxygen? Change in ocean productivity What could happen if the polar regions had less upwelling due to change in ocean circulation? Marine organisms unable to adapt to temperature changes

  29. Reducing Greenhouse Gases Human emissions contributing excessive CO2 Global engineering – attempts to counteract human-caused climate change Reducing sunlight reaching earth Removing human-caused greenhouse gases

  30. Reducing Greenhouse Gases Ocean’s Role • Ocean’s biological pump • “Sink” for carbon dioxide • Pumps from surface to deep waters

  31. Reducing Greenhouse Gases • Ocean as thermal sponge • “heat sink” • Much of the surface of Earth is ocean, ocean water absorbs solar radiation • Unique thermal properties of water • Oceans absorb much heat without changing temperature • Oceans still warming

  32. Possibilities for Reducing Greenhouse Gases • Iron hypothesis • Fertilize ocean to increase productivity • Increase phytoplankton, increase carbon dioxide removal from atmosphere • Sequestering excess carbon dioxide in oceans

  33. Kyoto Protocol: Limiting Greenhouse Gas Emissions International agreement – 60 nations Voluntarily limit greenhouse gases Even if gas emissions stabilize, Earth will continue to warm. Commitment to warming Human activities are altering the global environment.

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