5.Global.Warming.11

5.Global.Warming.11 - Special Topic: Global Warming and the...

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Unformatted text preview: Special Topic: Global Warming and the Carbon Cycle Introduction: earth’s atmosphere Global Warming – the “Greenhouse Effect” the Carbon Cycle and Atmospheric CO 2 Aerosol’s Effects on Global Warming How to Reduce Global Warming? I. Introduction: Earth’s Atmosphere Gases (99.99999%) ASA, the blue marble tp://visibleearth.nasa.gov/view_rec.php?id=2429 Dust, sea salt, soot, ammonium sulfate, nitrates, organic particles … 0.00001% Aerosol particles (0.00001%) Atmosphere: extends upwards ~ 100 km, but ~75% of the mass within 11 km. Functions: Acts as a freshwater distillery. Absorbs cosmic rays and UV radiation. II. Global Warming – the “Greenhouse Effect” Slightly different but closely related In a greenhouse, UV radiation readily passes through glass. Absorbed by surfaces, it is converted to longwavelength IR radiation (heat). IR radiation cannot pass through glass easily and is trapped, heating up the greenhouse. The greenhouse effect Solar Radiation Energy Balance of the Earth Longwave Radiation http://www.sc.doe.gov/ober/Atmospheric%20System%20Research%20Science%20Plan.pdf Only about 48% of sunlight energy is absorbed by the earth’s surface – the rest is lost to space. The Natural Greenhouse Effect UV radiation readily passes through the atmosphere. Absorbed by surfaces, it is converted to IR radiation. IR radiation cannot pass through the atmosphere. IR radiation is trapped, and thus heats up the earth. w/o GHG with GHG Greenhouse Gases – Triatomic or Larger Carbon dioxide, water vapor, ozone, nitrous oxide, methane, halocarbons (CFCs), NOx, SOx, etc. Need a central atom from which to vibrate. o Keep global mean annual temperature at 15 C. Most atmospheric gases are diatomic (99%). The Rise of CO and Warming IPCC 2001 http://www.grida.no/publications/other/ipcc_tar/ Many Greenhouse Gases Have Increased Since 1750 AD atmospheric CO2 has increased dramatically. Increased Gases Mean Increased In 1900, Arrhenius estimated that a doubling of Temperatures 2 o CO would increase temperature by 5-6 C. Since 1900, CO2 levels have increased by 25%, o causing a rise in temperature of 1 C. The Consequences of Global Warming In recent years there has been an increased melting of polar pack ice as temperatures have increased. Sea ice thickness has decreased by 21% in the past 50 years. Since 1880 sea level has risen over 12 cm (approx. 5”). As we see ice melting, the ocean is risen By 2100, the rise may be as much as 100 cm (approx. 40”). Glaciers and Snow Packs In 1910, there were 150 glaciers in Glacier National Park – now fewer than 30. Just the past 100 years Most remaining have shrunk by 2/3, and within 30 years they may all disappear. The snow pack on Mt. Kilimanjaro has melted by more than 80% since III: The Carbon Cycle and Atmospheric CO The basic carbon cycle has historically been balanced between photosynthesis and respiration. The cycle represents the conversion of light energy into chemical bond energy, then metabolic energy. Combustion and Carbon Dioxide Combustion adds to the reservoir of CO2 in the atmosphere. Deforestation prevents a rebalancing via photosynthesis to account for combustion. The imbalance results in a surplus 2 of CO in the IV: Aerosol’s Effects on Climate Change (Global Warming) Indirect effect on climate Direct effect on climate Aerosols (PM) • Aerosols are counteracting the warming effects from green house gases V: How to Reduce Global Warming Reducing emissions of greenhouse gasses can reverse the current situation. However, with long half lives reversal will take time. The life time of aerosol is < 1 month Reduce Atmospheric CO Concentration Reduce fossil fuel combustion for energy. Switch to renewable sources of energy. Enhance global photosynthetic capacity. Plant trees 2 Sequester CO in deep oceanic sites or geologic formations. http://www.arb.ca.gov/research/fieldstudy2010/noaascienceplan. Conclusions 2 The atmosphere is the reservoir for CO . Triatomic gases trap IR – the “greenhouse effect.” Increased triatomic gases result in global warming. The result is an increase in global mean annual temperature. Increased temperature results in ice cap melting and increased sea levels. Atmospheric aerosol particles play very important roles in global warming ...
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This note was uploaded on 03/10/2011 for the course ETX 102A taught by Professor Ronaldtjeerdema during the Winter '10 term at UC Davis.

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5.Global.Warming.11 - Special Topic: Global Warming and the...

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