Urgent 1

Winter 2019 PBPL 28728 Instructor: Amir Jina Homework 1 Due: Wednesday 29th January, 2020

Directions: Please submit a PDF write-up with your answers to questions and any required figures. For data analysis, also submit the file containing your analysis. For example, submit the code / output of your coding language of choice (e.g., a Stata “log file”, or R-script, or Excel sheet). Using Excel is okay, but not preferred - it is often hard to replicate work done in Excel, and it’s easy to make mistakes and not be able to track them down. The next assignment will need more work in R, so it’s a good idea to attempt these simple exercises for this assignment. There’s a sample R-script for question 4 on canvas. See note about R at the end of this problem set. This problem set looks longer than it is!

Greenhouse effect with a transparent atmosphere

1. In class, we derived the Earth’s surface temperature using a simple energy balance model with a one-layer atmosphere. Now, you’ll derive the energy balance with a partly transparent atmosphere.

(a) Draw a diagram like the one on slide 52/130 in “L1” lecture slides (b) Write out the energy balance equations for an atmosphere with an emissivity1, � (c) Solve the equations for TS , the temperature of the Earth’s surface (d) Assume the following values and calculate TS : S = 1370 Wm−2; � = 0.78; A = 0.3 (e) One of our neighbours, Mars, has an average solar constant of SM = 589 Wm−2, an albedo

of AM 0.24, and a surface temperature of -46◦C. What would its atmospheric emissivity, �M , need to be to achieve that surface temperature?

CO2 trends

2. Watch this video produced by NASA using a high-spatial-resolution model of CO2 emissions. I want you to think about various patterns, natural and human-caused, that are evident through this video. Total answer length will be about one paragraph.

(a) Write a brief (∼ 3-4 sentence) description of the features of CO2 throughout a single year. (b) What might explain the pulsating emissions intensity (about once every second in the video)

in lower latitudes? (c) In class, we discussed how CO2 is “well-mixed”. Why does it appear that there is so much

variation, particularly in the northern hemisphere near the start of the video? (d) CO2 has an annual cycle. Comment briefly (∼ 1-2 sentences) on this, explain when it peaks,

and explain why it changes throughout the year. (e) What areas appear to be the major CO2 sources? Why? (f) What accounts for the horizontal(-ish) line in emissions over the Sahel region that appears in

some parts of the video? (g) Look at the Keeling curve data. What is the approximate magnitude of the annual cycle of

CO2? How does this compare to the heterogeneity at any point in time across space as seen in the video?

1Th emissivity is defined as the ratio of the energy emitted by a body to the energy emitted by a “blackbody” at the same temperature. Essentially, it tells you how close to being a perfect emitter you are.

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Australian climate data analysis

3. In late 2019 and early 2020, Australia has witnessed some of the worst bushfires in history. There has been concern that precipitation has been gradually decreasing in many parts of Australia over the last 60 or so years. Not all such beliefs are necessarily supported by actual data. Download the file perth airport.csv from Canvas. the monthly total precipitation (in mm) and temperature (in ◦C) records at Perth Airport (station ID: IWMO 94610), in southwestern Australia.2 You are going to explore some trends. The data are available from 1944 to 2019. Such a long station history makes possible a wealth of statistical experiments. Perth is known to have a “Mediterranean climate” - most of its precipitation is in the winter, very little is during summer.

(a) Confirm this climate pattern by finding the precipitation climatology (mean rainfall for 1981- 2010) for Perth. What is the rainiest month?

(b) Plot the July rainfall for each year (since 1944) in the dataset. Interpret the trend. (c) Rainfall may occur over all winter months. Take the average across May-August and plot the

trend in average winter rainfall (since 1944). Interpret the trend.

Climate change and inequality

4. Now we are going to begin examining the intersection of climate and inequality. Download the datasets hw1 us counties incomes.csv and hw1 us counties temperature.csv from Can- vas. If you want to try to analyze these in R, there is also a sample R-script to help you get started. These datasets contain information on annual average temperatures for every county in the United States, starting with the average from the end of the last century. Then there are averages over 20 year periods, projected using RCP 8.5 emissions, up to the end of this century, using all models in the CMIP5 (IPCC) set of climate models. In addition to that, there is data on incomes per capita in 2018, and income deciles.

(a) Plot a histogram of county temperatures for 1981-2010. Plot (on the same figure if you can) a histogram of county temperatures under RCP8.5 emissions from 2080-2099.

(b) Calculate the average temperatures per income decile group for each of the time periods. (c) Plot these average temperatures against the income decile group for 1981-2010 and for 2080-

2099. (d) Interpret these plots. What does this imply about who will feel the impacts of climate change? (e) Now create a variable that is the change in county temperature between the 1981-2010 period

and the 2080-2099 period. Which income decile will experience the most change? Look at latitudes. What is the spatial pattern of those changes?

(f) If you were a policy-maker and saw all of these patterns, what would your main considerations be for making an equitable climate adaptation policy in the US? Be brief (∼ 2-3 sentences).

Climate change communication

5. Climate change has been subjected to a vast amount of scientific, political, media, and popular skepticism over the past few decades. Out of this, climate change communication has become a field of study in its own right. There are now many resources and practical guides that aim to

2Data for Perth Airport, obtained from NOAA Climate Data Online.

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help communication across different stakeholder groups. The IPCC’s Climate Outreach Handbook3 gives six principles for effectively communicating climate change. You’re going to use these to think through communicating a common misconception or myth about climate change.

(a) Select one of the following climate change myths based on the first letter of your last name:

(A-C) Myth 1: Climate’s changed before (D-G) Myth 2: It’s the sun (H-K) Myth 3: The temperature record is unreliable (M-Z) Myth 4: It’s not going to be bad

(b) Go to Skeptical Science (or just click any of the links above) and find an explanation of the relevant myth, as well as answers at various levels of detail. Intermediate should be a good level.

(c) Write one paragraph (including visuals taken from wherever you can find good visuals on the issue) and summarize the scientific argument that dispels the myth or misconception. This is just to get the science right.

(d) Choose any two hypothetical audiences from the list below. Write another paragraph that explains how you would target this message for that audience, and the different strategies you might take to approach this. Be sure to include a sentence or two that indicate some exact phrasing you would use. Pay close attention to the six principles on page 5 of the IPCC communication handbook when answering.

• Financial manager at large asset management firm who has been feeling pressure from the divestment movement. However, they dislike talking about climate change because the discussion is always about “green bonds” and they are skeptical of how much of risk there is from climate change.

• Journalist from local Texas newspaper, writing an article after Hurricane Harvey in Hous- ton. They understand climate change is a risk, but are not well informed about the science. Their last article on the subject got many negative comments repeating common climate myths. They want advice on engaging with their audience.

• You visit a friend’s house in suburban Chicago for Thanksgiving. Their uncle or aunt politely says that they are open-minded about climate change, but have heard things that make them doubt the science.

• A well-known think tank has produced a report that includes the climate myth you have chosen. At an event with a prominent climate-denying politician, they cite this fact from the report and you have been given a chance to respond.

Installing and using R

In this class we’ll be doing a reasonable amount of data analysis. R is a coding language and set of associated platforms that is one of the dominant data analysis tools in the world. It’s also free and open source. One of the easiest ways to get started is to download R and RStudio, and install the “Tidyverse” package. There are thousands of R resources online, including many on how to install R and RStudio for the first time.

Excel will suffice for these problems, but R will make your life easier in the long-run.

3Available here: Principles for effective communication and public engagement on climate change: A handbook for IPCC authors

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