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Global Warming

Global Warming. Global Warming Climate Change. Global Warming Climate Change. Climate change on a global scale is one of most severe threats to our existence in the history of the world. Global Warming Climate Change.

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Global Warming

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  1. Global Warming

  2. Global Warming Climate Change

  3. Global Warming Climate Change • Climate change on a global scale is one of most severe threats to our existence in the history of the world.

  4. Global Warming Climate Change • Climate change on a global scale is one of most severe threats to our existence in the history of the world. • Is it happening?

  5. Global Warming Climate Change • Climate change on a global scale is one of most severe threats to our existence in the history of the world. • Is it happening? • Are we causing it?

  6. Global Warming Climate Change • Climate change on a global scale is one of most severe threats to our existence in the history of the world. • Is it happening? • Are we causing it? • Are we contributing to it, and by what means?

  7. Global Warming Climate Change • Climate change on a global scale is one of most severe threats to our existence in the history of the world. • Is it happening? • Are we causing it? • Are we contributing to it, and by what means? • Can we do anything about it?

  8. The Earth’s Energy Balance

  9. The Earth’s Energy Balance Greenhouse effect Our atmospheric gases trap and return a major portion of the heat radiating from the Earth. It is a natural, necessary process.

  10. According to data taken at Mauna Loa, Hawaii since 1958, CO2 levels are on the rise.

  11. Microscopic air bubbles in ice core samples from glaciers can be used to determine changes in greenhouse gas concentrations over time.

  12. Comparing ice core data from Antarctica and Mauna Loa observations, the concentration of carbon dioxide appears to be increasing over time.

  13. The Vostok ice core shows data going back 400,000 years, while other ice cores go back even further (the inset shows data from the figure above). The current concentration of atmospheric carbon dioxide is 100 ppm higher than any time in the last million years.

  14. Average global surface temperatures have increased since 1880. The red bars indicate average temperatures for the year while the black error bars show the range for each year. The blue line is the 5-year moving average.

  15. Ice Cores as Temperature Recordings

  16. Ice Cores as Temperature Recordings

  17. Ice Cores as Temperature Recordings D D D D D D D 106°

  18. Ice Cores as Temperature Recordings Data from Wikipedia, “Heavy Water”

  19. Ice Cores as Temperature Recordings • So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water

  20. Ice Cores as Temperature Recordings • So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water • And thus in the ice in Antarctica

  21. Ice Cores as Temperature Recordings • So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water • And thus in the ice in Antarctica • And likewise, as atmospheric temperature drops, so does the concentration of heavy water in the air, and the concentration in the ice increases

  22. Ice Cores as Temperature Recordings • So, as temperatures go up, the proportion of D2O goes up in the atmosphere, and down in ocean water • And thus in the ice in Antarctica • And likewise, as atmospheric temperature drops, so does the concentration of heavy water in the air, and the concentration in the ice increases • And one can do the same for the oxygen in water • And in fossils from around the world

  23. Global temperatures for 2006 (in oC) relative to the 1951–1980 average. The most dramatic changes have been observed in the higher latitudes (dark red areas).

  24. The concentration of carbon dioxide (blue) and the global temperature (red) are well correlated over the past 400,000 years as derived from ice core data. The CO2 levels are currently higher than ANY time in the part 400,000 years!

  25. Representations of methane CH4 = molecular formula; does not express connectivity Structural formulas show how atoms are connected: Space-filling Lewis structuresshow connectivity. This Lewis structure is drawn in 3-D.

  26. Valence Shell Electron Pair Repulsion Theory Consider methane (CH4), where the central carbon atom has 4 electron pairs around it: A tetrahedral- shaped molecule has bond angles of 109.5o Four electron pairs as far from each other as possible indicates a tetrahedral arrangement.

  27. Valence Shell Electron Pair Repulsion Theory The legs and shaft of a music stand are like the bonds of a tetrahedral molecule. 3.3

  28. The 3-D shape of a molecule affects its ability to absorb IR radiation. Valence Shell Electron Pair Repulsion Theory Assumes that the most stable molecular shape has the electron pairs surrounding a central atom as far away from one another as possible.

  29. The central atom (O) in H2O also has four electron pairs around it. The nonbonding electron pairs take up more space than bonding pairs, so the H-to-O-to-H bond angle is compressed. But unlike methane, two electron pairs are bonding and two are nonbonding. The electron pairs are tetrahedrally arranged, but the shape is described only in terms of the atoms present: water is said to be bent shaped.

  30. We can use the VSEPR model to allow us to predict the shape of other molecules. Other predictions can be made based on other electron pair arrangements.

  31. Now look at the central atom of CO2: Two groups of four electrons each are associated with the central atom. The two groups of electrons will be 180o from each other: the CO2 molecule is linear.

  32. Molecular geometry and absorption of IR radiation Molecular vibrations in CO2. Each spring represents a C=O bond. (a)= no net change in dipole – no IR absorption. (b, c, d)= see a net change in dipole (charge distribution), so these account for IR absorption.

  33. The infrared spectrum for CO2 Wavenumber (mm–1) =1______ wavelength (mm)

  34. The infrared spectrum for CO2 As IR radiation is absorbed, the amount of radiation that makes it through the sample is reduced.

  35. Molecular response to different types of radiation

  36. The carbon cycle

  37. CO2 emission sources by end use:

  38. Global Warming Potential (GWP) represents the relative contribution of a molecule of an atmospheric gas to global warming.

  39. Amplification of Greenhouse Effect: Global Warming What we know: • CO2 contributes to an elevated global temperature. • The concentration of CO2 in the atmosphere has been increasing over the past century. • The increase of atmospheric CO2 is a consequence of human activity. • Average global temperature has increased over the past century.

  40. Amplification of Greenhouse Effect: Global Warming What may be true: CO2 and other gases generated by human activity are responsible for the temperature increase. The average global temperature will continue to rise as emissions of anthropogenic greenhouse gases increase.

  41. Radiative Forcings are factors that affect the balance of Earth’s incoming and outgoing radiation.

  42. Climate Models are used to predict annual global mean surface temperatures. Blue bands = predicted temperature range using natural forcings only Pink bands = temperature range with both natural and anthropogenic forcings

  43. Models can also be used to predict future global temperatures. Black line = data for the 20th century Other lines = projected 21st century temperatures based on different socioeconomic assumptions

  44. Intergovernmental Panel on Climate Change (IPCC) Recognizing the problem of potential global climate change, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. It is open to all members of the UN and WMO.

  45. Conclusions from the 2007 IPCC Report

  46. Loss of Polar Ice Cap NASA Study: The Arctic warming study, appearing in the November 1, 2003, issue of the American Meteorological Society's Journal of Climate, showed that compared to the 1980s, most of the Arctic warmed significantly over the last decade, with the biggest temperature increases occurring over North America. 1979 2003 Perennial, or year-round, sea ice in the Arctic is declining at a rate ofnine percentper decade.

  47. Loss of Polar Ice Cap 1979 As the oceans warm and ice thins, more solar energy is absorbed by the water, creating positive feedbacks that lead to further melting. Such dynamics can change the temperature of ocean layers, impact ocean circulation and salinity, change marine habitats, and widen shipping lanes. 2003

  48. Sea Level Rise • The melting of the polar ice has caused a steady rise in ocean levels • Measured as 1.5 mm per year since 1961 • Increase not uniform across the globe, so places where the rises have been seen are actually larger • Rises that large are responsible for both erosion and storm surge severity.

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