Chapter 21 Part 1 Global Warming

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Chapter 21 - Part 1Global Warming
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Overview

• 1. Case Study on El Nino as a climate phenomenon
• 2. Some atmospheric basics
• 3. Long-term climate change
• 4. The Greenhouse Effect (causes, evidence)
• 5. The Global Warming controversy
• 6. Projected effects of global warming

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Some important supporting concepts

• The Carbon Cycle (ch 4)
• Human Population Growth (ch 5)
• Feedback Loops (ch 3)

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A Climate Case Study El Nino

• What Is El Nino
• A build-up of warm water along the West coast of
  South America along the Equator

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El Nino (under the surface)
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Some Atmospheric BasicsLayers of the Atmosphere
(Fig 21.3a p 442)
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Some Atmospheric BasicsHadley Cells (fig 21.3b,
p 443)
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What is Climate

• Climate is a representative set of atmospheric
  conditions over a period of time.
• Weather (a contrast) means right now So on some
  days in SoCal it is raining (weather) but that
  doesnt mean the climate is rainy.

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Climatograms (see p 445)

• Show annual patterns of rainfall and temperature
  averaged over 300 years (usually)

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Microclimate

• Variations in climate within a larger climate
  region
• An important case is the urban heat island
  effect

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Long term climate changeat several timescales

• See figures in book.

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Greenhouse Gases

• H2O vapor - 85 of warmth captured by atmosphere
• H20, small particles - 12 of warmth captured by
  earth
• Anthropogenic - CO2, CFCs, Methane, nitrous
  oxides, ozone. see table 21.2 for details

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Atmospheric Window

• See figure 21.8, p449

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CO2

• 50 - 60 of anthropogenic warming attributed here
• Pre industrial level was 200-300ppm
• Currently around 370ppm
• Main sources - Fossil fuel burniung and
  deforestation (we will so other effects
  elsewhere)
• A CO2 sink?
• The crazy correlation game p451 and453

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Methane

• 12-20 of anthropogenic effects
• Natural sources - termites, wetlands
• Anthropogenic sources burning biomass, coal and
  natural gas production, agriculture

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CFCs

• Usually associated with ozone depletion
• 15 - 25 of anthropogenic warming
• Absorb in atmospheric window
• Each molecule may absorb up to 100 times as much
  heat energy as CO2

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Nitrous Oxide N2O