Honors 101 - Science and the Public Good
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Climate Change

Reading:

For this topic, you will visit a series of Web sites.

Before you start, calculate your carbon footprint at Safe Climate. You will need a recent bill from your electricity/natural gas provider to use this calculator. If you don't have a recent bill, use the carbon calculator at An Inconvenient Truth instead. Print out your results and bring to class.

1. Evidence of climate change

• You will start by looking at data of changes in global temperatures.
  • Much of the data you will look at is available at http://www.ipcc.ch/graphics/index.htm. This data was collected from many sources and summarized by the Intergovernmental Panel on Climate Change sponsored by the UN and the World Meteorological Organization. Feel free to visit this Web site to look at other data not specifically linked below.
    • Global temperature change, 1861-2000 and 1000-2000
    • Many more weather graphs from NASA: http://data.giss.nasa.gov/gistemp/graphs/
    • Choose one of the NASA graphs and be prepared to explain it in class.

      What patterns to you see in the temperature data over time?

     

• We might expect to see an increase in temperatures at weather stations, because they have become more urbanized with more heat-absorbing concrete. To rule this out as a source of error in the data, scientists compare urban temperatures with nearby rural temperatures, and adjust the urban temperature downward to correct for the effect of the concrete.
  • Animation of global temperatures since 1880: the colors show variation from the average temperature at that spot. When an area is blue, it is cooler than the average temperature for that area; yellow to red colors show warmer than average.
  • Temperature change measured by satellites avoids the urbanization problem.

Did you see any spatial patterns in the data?

 

2. What causes climate change?

• If you are not familiar with the greenhouse effect and Earth's carbon cycle, please review those topics here.
• The longest continuous measurements of CO2 have been made at Mauna Loa, Hawaii.
• Other greenhouse gases are also increasing.
• Where does the CO2 come from?

• Global temperatures tend to track CO2 levels. This data was derived from Antarctic ice cores. The CO2 is from trapped air bubbles in the ice. The air temperature of the time is determined by the ration of oxygen isotopes in the trapped air. Notice that the temperature (blue) and CO2(red) rise and fall together.
  • How long ago were global temperatures as warm as they are today?
  • How high are CO2 levels today compared with the past 400,000 years?

   

• OK, so the data shows in the past that CO2 and temperature are related. But maybe any temperature change is just due to natural variations in CO2. Scientists have determined how much of the CO2 is due to human activity (anthropogenic) and how much is natural, then compared the actual increase in temperature to the amount of temperature increase we would expect from just natural sources, just human sources, and the two combined. Here are the results.

3. Impacts of global warming

Summarize each Web site in a sentence or two

• Sea level rise

• More sea level rise data

• Melting glaciers

• WARNING: this takes a little while to load. Here's the big one.This is is the Policymakers' Summary of the most recent report by the IPCC on the impacts of climate change. We are specifically using p. 11-15, but you might want to look at the highlighted conclusions on the other pages. For p. 11-18, be prepared to report to the class on your section listed below:
  • Last Name A-D: Freshwater resources & Africa
  • Last Name G-I: Ecosystems & Asia
  • Last Name J-M: Food, fibre and forest & Australia/NZ
  • Last Name P-R: Coastal systems & Europe
  • Last Name S-V: Industry, settlement and society & Latin America
  • Last Name W-Z: Health & North America
  • Everyone: Polar Regions, Small Islands, and the diagrams on p.16 and 18.

4. The future

• So what happens if we control CO2 emissions?

• Here is a comparison of different scenarios for cutting CO2 emissions.

5. Now write a little summary:

• What's the evidence?

• What are the major impacts?