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  1. Return to Home Page Introduction to GEOG 495: The Geographies of Climate Change February 18, 2014

  2. Source: John Houghton, Global Warming, 4th edit., 2009, p. 127.

  3. Websites to use today What are the 7 common misconceptions about global warming? • Questions: • Why is it important for everyone to become informed on climate science? • What are the essential principles of climate science? • Describe the primary ways to improve understanding of the climate system. • Describe how climate varies over space and time.

  4. Websites continued • Questions: • What did you learn about human impacts to the carbon cycle? • What are the major causes of climate change? • What does the term amplified warming mean? • Describe possible responses to global warming? • How are carbon dioxide emissions expected to change between 2000 and 2500?

  5. Climate Change Evidence • Carbon dioxide concentration now over 400 PPM, now growing ~ 3x rate of 1990s, currently highest concentration since the Miocene Epoch (15 million years ago) when sea level is estimated to have been 25 to 40 m (82-131 ft) higher and global temperature 3°C to 6°C (5°F to 10°F) warmer than present • In 2010 the average temperature of Earth’s surface ties with 2005 as the warmest year since record keeping began in 1880. The year 2011 was 9th warmest (but warmest year on record under the cooling influence of La Niña, and 9 of the 10 warmest years are in the 21st century, the only exception being 1998, which was warmed b y the strongest El Niño of the past century. • According to NASA, GISS (Goddard Inst. of Space Studies) and NOAA, 2009 was only fraction of a degree cooler than 2005 and it tied with a cluster of other years – 1998, 2002, 2003, 2006 & 2007-as 2nd warmest year since record keeping began • First decade of 21st Century was warmest decade since instrumental records began • Over past 3 decades, Earth’s surface temperature has trended upward about 0.2°C (0.36°F) per decade

  6. Figure 2.1 (Fletcher)

  7. Fig 2.2 (Fletcher)

  8. Future Changes Fletcher • Future abnormally hot days and nights and heat waves are very likely to become more common. • Cold days and cold nights are very likely to become much less common. The number of days with frost is very likely to decrease. • Future sea ice extent will continue to decrease and could even disappear entirely in the Arctic Ocean in summer in summer in coming decades. Sea ice loss has increased coastal erosion in Arctic Alaska and Canada because of increased exposure of the coast line to wave action. • Future precipitation is likely ato be les frequent but more intense, and precipitation extremes are very likely to increase. • Future droughts are likely to become more frequent and severe in some regions (e.g., U.S. Southwest, Mexico), leading to a greater need to respond to reduced water supplies, increased wildfires, and various ecological impacts. • Future hurricanes in the North Atlantic and North Pacific are likely to have increased rainfall and wind speeds; for 1C (1.8F) increase in tropical sea-surface temperature, rainfall rates will increase by 6% to 18% and wind speeds of the strongest hurricanes will increase 1% to 8%. • Future strong cold-season storms in both the Atlantic and Pacific are likely to be more frequent, with stronger winds and more extreme wave heights.

  9. Climate Changes Resulting from Global Warming • Glaciers are melting. • Air temperature ovef land is rising. • The global percentage of land area in drought has increase by about 10% • Snow cover is shrinking. • Regions of Earth where water is frozen for at least one month each year are shrinking with impacts on related ecosystems. • The southern boundary of North Hemisphere permafrost is retreating poleward. • Tree lines are shifting poleward and to higher elevations. • Spring is coming earlier. • Plants are leafing out and blooming earlier each year. • The lower atmosphere (troposphere) is warming. • The tropics gave expanded. • Species are migrating poleward and to higher elevations. • Atmospheric humidity is rising. • The global water cycle has accelerated. • Air temperature over the oceans is rising.

  10. Climate Changes Resulting from Global Warming, p. 2. • Sea surface temperature is rising. • Ocean water is more acidic from dissolved CO2, and this is negatrively affecting marine organisms. • Dissolved oxygen in the oceans is declining because of warmer water. • Deep ocean temperature is rising. • Continental ice sheets are shrinking. • Arctic sea ice is shrinkng as a result of global warming. • Storm tracks are shifting poleward. • Extreme weather events are more frequent • Daily record high temperatures occur twice as often as record lows. • Sea level is rising and rhte rish has accelerated. • Global wind speed has accelerated. • Extreme warm events in winter are much more prevalent than cold events. • Extreme weather is increasing. • Global warming is changing on Earth on a global scale.