EES 3310/5310

Climate Models

Class #16 (Wed., Feb 23)

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Required Reading (everyone):

  • Climate Casino, Ch. 3–4.

Reading Notes:

Chapter 3 treats global warming as a scientific consequence of an economic problem. As you read, consider the following questions. Some have clear answers while others are beyond the knowledge of experts and I ask them to challenge you to think about hard problems. On p. 30, Nordhaus describes three components that drive CO2 emissions: population, per-capita GDP, and the carbon intensity of the economy. A mathematical expression for this relationship is known as the Kaya identity, and we will study this in great depth on Mar. 21–28 and in the lab project on decarbonizing the energy supply.

  • Why don’t free markets manage greenhouse gas emissions well?
  • Are CO2 emissions going up or down? Why?
  • What is carbon intensity? Is it going up or down in the US? Why?
  • When Nordhaus writes about models for predicting future climate change, he distinguishes between predictions and projections. What is the difference and why is it important?
  • Table 1 on p. 31 shows two projections of future CO2 emissions. Why are they different? How can we tell which is a better prediction?
  • What is an integrated assessment model (IAM)?
  • What are the biggest sources of uncertainty in predicting future CO2 emissions?
  • How much can we trust models of future climate change? What should we consider when deciding how much to trust a model?

Chapter 4 looks at what we do and don’t know about future climate change.

  • Pages 37–42 are largely a review of material we studied in much greater depth in the first few weeks of the term. You can read through it quickly.
  • What is the difference between transient and equilibrium response to CO2 emissions? What would we expect to happen to the global temperature if everyone around the world completely stopped burning fossil fuels this afternoon?
  • Figure 9 shows several different projections for how temperature might change over the rest of this century. What is the biggest reason the projections don’t all agree with each other?
  • Pay close attention to the bullet points on pp. 47–48.
  • How does Nordhaus recommend that we think about the uncertainties in predictions about the climate?
  • Given these uncertainties, can we trust climate models and can they be useful?