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The Greenhouse Effect

The Greenhouse Effect. Global Warming 101. Huge Amount in the Media and the Political Realm on this Issue. Inconvenient Truth: Basically Accurate But Contains Some Errors. Downplays Global Warming. The Day After Tomorrow: Global Warming Causes Ice Age: Complete Nonsense.

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The Greenhouse Effect

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  1. The Greenhouse Effect

  2. Global Warming 101

  3. Huge Amount in the Media and the Political Realm on this Issue

  4. Inconvenient Truth: Basically Accurate But Contains Some Errors

  5. Downplays Global Warming

  6. The Day After Tomorrow: Global Warming Causes Ice Age: Complete Nonsense

  7. In contrast, others hold that the lack of warming of the planet over the past ten years indicates that global warming is no real threat George Will

  8. ..and that scientific consensus is a myth

  9. …but thousands of scientists from around the world have written a series of reports indicating the imminent threat of global warming due to mankind’s influence

  10. IPCC Reports

  11. Some ask:How can scientists predict climate when they can’t get the next week’s weather forecast right?

  12. What is the truth? What is biased and wrong? What do we know for sure? What are the uncertainties? What will happen here?

  13. “Greenhouse Warming” Makes Earth Liveable

  14. The Earth With No Atmosphere (infrared) Earth’s surface would be 60F cooler than today…no life.

  15. But the Earth has an atmosphere! • Dominated by gases such as nitrogen and oxygen • Also includes greenhouse gases.

  16. What is a Greenhouse Gas? • Greenhouse gas is a gas that that is relatively transparent to solar radiation, but absorbers and emits in the infrared…the type of radiation the earth and clouds emits. • Some examples: • Water vapor • Carbon dioxide • Nitrous oxide • Methane • Chlorofluoromethanes

  17. Earth With An Atmosphere That Includes Greenhouse Gases Partly (infrared)

  18. Greenhouse Gases Warm the Earth in a Similar Way That Blankets Warm Us at Night

  19. The Problem: Rapidly Rising Greenhouse Gases Due to Mankind

  20. Gases Trapped in Ice Gives Us a History of the Gases in the Atmosphere

  21. The Problem:greenhouse gases have increased but will continue to increase

  22. But it is worse than that… • There are a number of natural “amplifiers” of mankind’s emission of greenhouse gases. • The warming due to increased carbon dioxide, methane, and other greenhouse gases will cause more water to be evaporated from the earth’s oceans.

  23. Why? • The amount of evaporation increases with temperature. • The amount of water vapor air can contains increases rapidly with temperature • Water vapor is the most potent greenhouse gas and thus causes even MORE warming. • This is caused a positive feedback.

  24. But it gets even worse… • Warming temperatures melt snow and ice. • Snow and ice help cool the planet because they reflect much of the sun’s radiation….that is why you need sun glasses while skiing. • As the snow, melts less radiation is reflected to space and more is absorbed. • Thus, the earth gets warmer, which melts more snow. • Another positive feedback!

  25. The Technology of Climate Prediction • Atmospheric scientists use complex climate prediction models…called General Circulation Models…to predict the future climate. • These models are similar to weather forecast models, but allow the gases in the atmosphere to change. • They also simulate the evolution of the oceans. • Have to assume the future emission of greenhouse gases by mankind…a major uncertainty. • These models are not perfect and cannot exactly replicate the current climate….but they are close and getting better each year.

  26. Use some of the largest supercomputers in the world

  27. Details on Current Study: GCM • Which Scenario Will Mankind Follow? IPCC Report, 2001 IPCC Report, 2001

  28. How good are are climate models? • The technology is constantly being tested and improved in our weather prediction models. • But even more important, how well can we duplicate the climate of the past hundred years?

  29. IPCC.AR4.2007

  30. Range of Global Warming

  31. Sample Climate Model Output for 2100

  32. Projections of Future Changes in Climate Projected warming in 21st century expected to be greatest over land and at most high northern latitudes

  33. Precipitation Subtropics Drier, Midlatitudes/Polar Regions/Tropics Moisten Summer Winter

  34. Global Warming is NOT Uniform • Arctic warms up the most for a number of reasons, including the melting of sea ice. • Continents warm up more than oceans. • Eastern oceans up less than western oceans. • In general, the dry areas (e.g., the SW) will get drier and wet areas (e.g., British Columbia) will get wetter.

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