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Earth Science:

Earth Science:. A study in Change - Natural Resources: Our Climate. Global Warming vs. Greenhouse Effect. Weather NOT the same as climate! They are DIFFERENT! (Weather = short term conditions, Climate = long term pattern)

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Earth Science:

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  1. Earth Science: A study in Change - Natural Resources: Our Climate

  2. Global Warming vs. Greenhouse Effect • Weather NOT the same as climate! • They are DIFFERENT! (Weather = short term conditions, Climate = long term pattern) • Greenhouse effect: a natural warming of the surface of the Earth and lower atmosphere • Caused by stratospheric ozone • Also caused by trace gases: CO2 (.039%) & H2O • These are the MOST important gases to the greenhouse effect.

  3. Greenhouse Effect Process • Greenhouse gases let solar radiation inwithout reflecting/absorbing it, then absorb radiation from the earth. • Two heat sources for the atmosphere, 1 = sun and 2 = earth. • Bottom sandwich bun • Longer wavelength • Life on Earth CANNOT exist without the greenhouse effect! It would be too cold.

  4. Global Warming • Global Warming: the overall increase in global temperatures due to manmade increase of carbon dioxide levels. • Caused by burning fossil fuels • Same process as greenhouse effect • Results in changing the RATE of global climate changes. • Keep in mind: Global Mean (average) Temperature does naturally change. • Called Global climate change • Due to a combination of orbit, rotation, precession, solar activity, &. . . &. . . .&. . . • This is what caused the ice ages • Life is messy! We know we can affect the atmosphere, but by how much?

  5. Global Mean Temerature NOAA (updated 5/2011)

  6. Global Temperature Variations in perspective Book diagram starts here. Industrial revolution starts here.

  7. Carbon Dioxide Levels(pg 602)

  8. CO2 Levels • CO2 naturally varies annually due to tilt of planet. • majority of plant life located in Northern hemisphere. • 6CO2 + 6H2O C6H12O6 + 6O2 • Summer in north = more photosynthesis = lowering of CO2 LIGHT

  9. Historic CO2 levels -measured many ways. . . • Measured using isotope data from glaciers • Thousands of years old • Trap gas bubbles • Ice cores taken and analyzed • From this data (800,000 yrs), CO2 never rose above 290 ppm until after the industrial revolution. • 1ppm= one credit card on a football field • 1ppm = one step on a walk of 568 mi • 1ppm = 726 people (150 lbs. ea.) sharing one chocolate bar. • 1ppm =one minute in 2 years • 290ppm = 4hrs 48min

  10. CO2 Levels • CO2 also changes by approximately 100 ppm every one million years. (.0001 ppm/yr) • Man made rate of change = approximately 2 ppm/yr. • Do the math! Humans overwhelm natural variations (20,000 X natural rate of change). • Began during industrial revolution, one cause is the burning of fossil fuels.

  11. Carbon Dioxide and Temperature

  12. CO2 and temperature • Global temperatures closely follow CO2 levels. • From glacial studies we know that global temperatures are sensitive to changes of about 1oC. • This means that lots of “stuff” happens when global temperatures change even a little. • Current rate of CO2 increase means an approximate 2-11oC rise of global temperature by 2100.

  13. Trends and projections • Minimum temperatures are increasing at a faster rate than maximums. • “squeezing” the habitable zone • Nighttime lows show greater warming trend than daytime highs • CO2 emissions reduced = 2.2oC-3.3oC(4oF-6oF) increase. • CO2 emissions same = 3.9oC-6.1oC(7oF-11oF) • Polar regions tend to have greater effects. • In US, for example, Colorado annual temperature increase = .9oF, North Dakota = 2.9oF, since 2011

  14. Effects of Temperature Increase • Thermal inertia - latent heat/specific heat of water: water heats & COOLS slower than land/atmosphere. • Even if we made all necessary changes today, will still see effects until at least 2100! • Water and CO2 in atmosphere increases with temperature. • Due to increased capacity. • When water and CO2 increase, so does temperature = positive feedback loop

  15. Global and Regional effects: DIFFERENT • Precipitation changes patterns • Increased annual precipitation due to heavy downpours. (US increase = 5%) • Regionally: Ne decreased annual snowfall • Northern regions = wetter, South/West = drier • Therefore, LOCAL effects are NOT THE same as GLOBAL effects. • Increased evaporation = more irrigation = less water in Ogallala Aquifer

  16. Greenland & Antarctic land ice sheets • In Greenland, 70 meters of ice lost in the last 5 yrs. • Approximately 150 km3/yr • Translates to a rise in sea level of 3 cm/yr • This is double the rate of the last 15 yrs.

  17. Ice sheet loss • If continues at this rate = irreversible • Ice = high albedo (reflectivity) • Recall: 30% of all incoming solar radiation is reflected! • Ice loss means lower reflectivity and increase of absorption. • Positive feedback loop • 3oC of global warming = 25 m higher sea level • Florida, Japan, Bangladesh, • All under water! • Since 1900 the San Francisco Bay Tide Station has recorded an 8 in. rise in sea level.

  18. USGS estimations http://cegis.usgs.gov/video/1Km/sealevel_us.avi

  19. Impact on Species • Habitats will change altitudes. • Cooler climates at higher altitudes will warm • Species will migrate up to higher altitudes. • Species that prefer cool climates migrate. . where? • Increase of invasive species • Current rate of ~3oC = ~25-50% of species lost (Nobel 2008) • Nobel 2012 = rate of change more like last global warming event that had 92% species lost. • Slow to <1oC = ~<10% of species lost • Lowers diversity and subjects survivors to extinction.

  20. Impact on Humans • Water shortage • Huh? Water for much of Tibet and California comes from snow pack melting or glacial melting. (decrease in preciptiation = less snowfall) • Increased evaporation = more irrigation for food production = less water in Ogallala Aquifer • Change in ocean chemistry/currents • Impact on local climates = changes precipitation globally • Fishing and trade routes change • Food shortage due to decreased nutrient supply(fishing), decreased pH harms hard shelled organisms.

  21. Impact on Humans (cont.) • Coastal communities & Sea level rise • Approx 10% of world population lives below 33ft elevation. (Omaha elevation = 1,090 ft) • Tundra thawing • Increases erosion & methane release • Damages towns/homes/water lines/etc • Physiology • What range can our bodies function well in? (Tuna hearts)

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