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  • A further new result is that weather patterns now show the influence of greenhouse gas forcing. Analyses of global sea level changes indicate that READ TOP. The figure shows a schematic diagram of the Northern Annular Mode, which is affected by changes in circulation and favors its positive phase. It shows lower pressure over the poles, enhanced westerly circulation in midlatitudes of the Northern Hemisphere. This affects storm tracks, winds and regional temperatures as shown in this schematic from the TS. The finding of changes in variables other than temperatures is a new and important development since the TAR Important details of all these findings will be given in the science presentation on attribution
  • Globalwarming

    1. 1. GLOBAL WARMING An Inconvenient Truth or A Convenient Lie
    2. 16. Global Warming Intro <ul><li>What is it? Read PDF p.30 </li></ul><ul><li>What causes it? </li></ul><ul><li>Is it real? </li></ul><ul><li>What do opponents of Global Warming say? </li></ul>
    3. 17. “ Intergovernmental Panel on Climate Change” Findings The Upcoming Slides are taken from IPCC Report, 2-2007 <ul><li>About IPCC </li></ul>
    4. 18. <ul><li>Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. </li></ul>Direct Observations of Recent Climate Change
    5. 19. Direct Observations of Recent Climate Change Global mean temperature Global average sea level Northern hemisphere Snow cover
    6. 20. <ul><li>At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include: </li></ul><ul><ul><li>Changes in Arctic temperatures and ice, </li></ul></ul><ul><ul><li>Widespread changes in precipitation amounts, ocean salinity, wind patterns </li></ul></ul><ul><ul><li>and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones </li></ul></ul>Direct Observations of Recent Climate Change
    7. 21. Global mean temperatures are rising faster with time Period Rate Years  /decade 100 0.074  0.018 50 0.128  0.026 Warmest 12 years: 1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999, 1990 ,2000
    8. 23. Warming in the Arctic is double that for the globe from 19 th to 21 st century and from late 1960s to present. Warmth 1925 to 1950 in Arctic was not as widespread as recent global warmth. Note different scales Arctic vs Global annual temperature anomalies (°C)
    9. 24. Further Changes in Artic and Frozen Ground <ul><li>Annual average Arctic sea ice extent shrunk by 2.7 % per decade, decreases in summer 7.4 % </li></ul><ul><li>Temperatures at the top of permafrost layer have generally increased since the 1980s by up to 3°C </li></ul><ul><li>The maximum area covered by seasonally frozen ground has decreased by about 7% in Northern Hemisphere since 1900, in spring of up to 15%. </li></ul>
    10. 25. Changes in Precipitation, Increased Drought <ul><li>Significantly increased precipitation in eastern parts of North and South America, northern Europe and northern and central Asia. </li></ul><ul><li>The frequency of heavy precipitation events has increased over most land areas - consistent with warming and increases of atmospheric water vapour </li></ul><ul><li>Drying in the Sahel, the Mediterranean, southern Africa and parts of southern Asia. </li></ul><ul><li>More intense and longer droughts observed since the 1970s, particularly in the tropics and subtropics. </li></ul>
    11. 26. <ul><li>Widespread changes in extreme temperatures observed </li></ul><ul><li>Cold days, cold nights and frost less frequent </li></ul><ul><li>Hot days, hot nights, and heat waves more frequent </li></ul><ul><li>Observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures </li></ul>Other changes in Extreme Events
    12. 27. Regions of disproportionate changes in heavy (95 th ) and very heavy (99 th ) precipitation Proportion of heavy rainfalls: increasing in most land areas
    13. 28. The most important spatial pattern (top) of the monthly Palmer Drought Severity Index (PDSI) for 1900 to 2002. The time series (below) accounts for most of the trend in PDSI. Drought is increasing most places Mainly decrease in rain over land in tropics and subtropics, but enhanced by increased atmospheric demand with warming
    14. 29. Circulation change <ul><li>Climate change is affecting storm tracks, winds and temperature patterns </li></ul>
    15. 30. N. Atlantic hurricane record best after 1944 with aircraft surveillance. Global number and percentage of intense hurricanes is increasing North Atlantic hurricanes have increased with SSTs SST (1944-2005) Marked increase after 1994
    16. 31. Snow cover and Arctic sea ice are decreasing Spring snow cover shows 5% stepwise drop during 1980s Arctic sea ice area decreased by 2.7% per decade (Summer: -7.4%/decade)
    17. 32. Glaciers and frozen ground are receding Area of seasonally frozen ground in NH has decreased by 7% from 1901 to 2002 Increased Glacier retreat since the early 1990s
    18. 33. <ul><li>Some aspects of climate have not been observed to change: </li></ul><ul><ul><ul><li>Tornadoes </li></ul></ul></ul><ul><ul><ul><li>Dust-storms </li></ul></ul></ul><ul><ul><ul><li>Hail </li></ul></ul></ul><ul><ul><ul><li>Lightning </li></ul></ul></ul><ul><ul><ul><li>Antarctic sea ice </li></ul></ul></ul>Direct Observations of Recent Climate Change
    19. 34. CO 2 , CH 4 and N 2 O Concentrations - far exceed pre-industrial values - increased markedly since 1750 due to human activities Relatively little variation before the industrial era Human and Natural Drivers of Climate Change
    20. 35. Understanding and Attributing Climate Change <ul><li>Continental warming </li></ul><ul><li>likely shows a significant contribution over the past 50 years </li></ul>
    21. 36. Understanding and Attributing Climate Change <ul><li>Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. This is an advance since the TAR’s conclusion that “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations”. Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns </li></ul>
    22. 37. Projections of Future Changes in Climate <ul><li>Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century. </li></ul><ul><ul><li>Best estimate and assessed likelihood range for future temperature projections for first time </li></ul></ul><ul><ul><li>Broadly similar to the TAR but not directly comparable </li></ul></ul>
    23. 38. Projections of Future Changes in Climate <ul><li>For the next two decades a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. </li></ul><ul><li>Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. </li></ul><ul><li>Earlier IPCC projections of 0.15 to 0.3 o C per decade can now be compared with observed values of 0.2 o C </li></ul>
    24. 39. Projections of Future Changes in Climate Best estimate for low scenario (B1) is 1.8°C ( likely range is 1.1°C to 2.9°C), and for high scenario (A1FI) is 4.0°C ( likely range is 2.4°C to 6.4°C). Broadly consistent with span quoted for SRES in TAR, but not directly comparable
    25. 40. Projections of Future Changes in Climate Projected warming in 21st century expected to be greatest over land and at most high northern latitudes and least over the Southern Ocean and parts of the North Atlantic Ocean
    26. 41. Projections of Future Changes in Climate Precipitation increases very likely in high latitudes Decreases likely in most subtropical land regions
    27. 42. <ul><li>Snow cover is projected to contract </li></ul><ul><li>Widespread increases in thaw depth most permafrost regions </li></ul><ul><li>Sea ice is projected to shrink in both the Arctic and Antarctic </li></ul><ul><li>In some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century </li></ul>PROJECTIONS OF FUTURE CHANGES IN CLIMATE
    28. 43. <ul><li>Very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent </li></ul><ul><li>Likely that future tropical cyclones will become more intense, with larger peak wind speeds and more heavy precipitation </li></ul><ul><ul><li>less confidence in decrease of total number </li></ul></ul><ul><li>Extra-tropical storm tracks projected to move poleward with consequent changes in wind, precipitation, and temperature patterns </li></ul>PROJECTIONS OF FUTURE CHANGES IN CLIMATE
    29. 44. <ul><li>Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized. </li></ul><ul><li>Temperatures in excess of 1.9 to 4.6°C warmer than pre-industrial sustained for millennia…eventual melt of the Greenland ice sheet. Would raise sea level by 7 m. Comparable to 125,000 years ago. </li></ul>PROJECTIONS OF FUTURE CHANGES IN CLIMATE
    30. 45. What Global Warming?
    31. 48. <ul><li>What follows is a very brief summary </li></ul><ul><li>of the science that the former Vice </li></ul><ul><li>President promotes in either a wrong </li></ul><ul><li>or misleading way: </li></ul><ul><li>He promoted the now debunked “hockey stick” temperature chart in an attempt to prove man’s overwhelming impact on the climate </li></ul><ul><li>He attempted to minimize the significance of Medieval Warm period and the Little Ice Age </li></ul><ul><li>He insisted on a link between increased hurricane activity and global warming that most sciences believe does not exist. </li></ul>
    32. 49. <ul><li>He asserted that today’s Arctic is experiencing unprecedented warmth while ignoring that temperatures in the 1930’s were as warm or warmer </li></ul><ul><li>He claimed the Antarctic was warming and losing ice but failed to note, that is only true of a small region and the vast bulk has been cooling and gaining ice. </li></ul><ul><li>He hyped unfounded fears that Greenland’s ice is in danger of disappearing </li></ul><ul><li>He erroneously claimed that ice cap on Mt. Kilimanjaro is disappearing due to global warming, even while the region cools and researchers blame the ice loss on local land-use practices </li></ul><ul><li>He made assertions of massive future sea level rise that is way out side of any supposed scientific “consensus” and is not supported in even the most alarmist literature. </li></ul>
    33. 50. <ul><li>He incorrectly implied that a Peruvian glacier's retreat is due to global warming, while ignoring the fact that the region has been cooling since the 1930s and other glaciers in South America are advancing </li></ul><ul><li>He blamed global warming for water loss in Africa's Lake Chad, despite NASA scientists concluding that local population and grazing factors are the more likely culprits </li></ul><ul><li>He inaccurately claimed polar bears are drowning in significant numbers due to melting ice when in fact they are thriving </li></ul><ul><li>He completely failed to inform viewers that the 48 scientists who accused President Bush of distorting science were part of a political advocacy group set up to support Democrat Presidential candidate John Kerry in 2004 </li></ul>
    34. 51. Kyoto Protocol <ul><li>The Kyoto Protocol is an agreement made under the United Nations Framework Convention on Climate Change (UNFCCC). </li></ul><ul><li>Passed in 1997 </li></ul><ul><li>Countries that ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases. </li></ul>
    35. 53. US Refuses To Join <ul><li>Why? </li></ul><ul><ul><li>US is #1 emitter of carbon dioxide </li></ul></ul><ul><ul><li>By ratifying, US GDP would seriously decline </li></ul></ul><ul><ul><li>Kyoto Protocol exempts China which upsets US </li></ul></ul><ul><ul><li>Questions global warming’s real threat to the world and whether US ratifying would really help stop it </li></ul></ul><ul><ul><li>US does believe in the Kyoto principles and does a lot to help out the cause </li></ul></ul>
    36. 57. What can you do? <ul><li>Discuss </li></ul><ul><li>Handout </li></ul>