The Changing Geographic Distribution of Malaria with Global Climate Warming

General questions:

• Should we worry about a re-emergence of malaria in the United States because of climate changes?
• If so, can trends in climate data with time be used to predict where malaria might first appear?
• Do all climate parameters show the same trends? Where are the ambiguities and uncertainties?
• Do climate trends based on instrumental records match predictions of malaria based on analysis of global climate models?

Geoscience Goals:

• Working with instrumental records of climate
• Comparing analysis of instrumental records to results of GCM models
• Analyzing possible human health impacts of global climate change
• Determining and comparing climate trends
• Analyzing the interaction of climate and socio-economic conditions

Quantitative Skills emphasized:

• Making and interpreting graphs and maps
• Descriptive statistics
• Use of moving averages
• Time series analysis
• Trend analysis
• Thinking about risk probabilistically
• Assumptions, uncertainty and error analysis

This activity was designed for an introductory level environmental science class, Geology and Human Health. It can be adapted for use in other introductory environmental science, environmental studies, geology and geography classes.

The activity sheet includes these sections, most done by a pair of students:

• Characterization of general climate at station;
• Histogram and descriptive statistics of average monthly minimum temperatures;
• Moving averages of average monthly minimum temperature and total precipitation data;
• Interpretation and analysis of graphs through a powerpoint presentation;
• Peer review of powerpoint presentations;
• (Formal) powerpoint presentation;
• GIS analysis of combined class data;
• Written report (individual) on the project.

Depending on the nature of the class and assignment, these can be combined in various ways.

• Activity Handout (Microsoft Word 76kB Jun14 12)
• Data Sheet for Mexia, TX site (Excel 100kB Jun23 05)
• Data Sheet for Alpine, TX site (Excel 142kB Jun24 05)
• Data Sheet for Fairhope, AL site (Excel 83kB Jun24 05)
• Data Sheet for Glennville, GA site (Excel 98kB Jun24 05)
• Data Sheet for Grand Canyon, AZ site (Excel 100kB Jun24 05)

Time needed for activity:

Short answer: About two weeks.
Long answer: We start this activity by assigning reading for the students (see references below). In a follow-up lecture period we raise the larger issues of climate change and human health, examine maps of malaria occurrence in the U.S. and elsewhere, discuss the climate controls on the malaria parasite and brainstorm with students about what indications in the climate records might be best suited to answer the questions. During the lab period, we demonstrate the use of EXCEL and start students working on the individual data sets they analyze in pairs. Student pairs need three to six hours to analyze their data and prepare their powerpoint presentations. A peer review step (two pairs examining two data sets) and revision will take approximately another two hours. Finally, depending on the class size, two hours or more will be needed for students to make their powerpoint presentations to the whole class.

Accessing climate data:

For the sample files included on the web site, we used two data sources, both from the US Historical Climatology Network. For minimum temperatures, we used sites that had been corrected for changes in location, for time of day of readings and for the "urban heat island" effect. These are available on the USHCN fps server in a file called urban_min_fahr. Precipitation data come from FILENET at the USHCN site. These data have several rows for each year; use the data with the "A" flags which have been corrected for location and time of day.

Preparing climate data for student use:

Depending on the level of the course and how much experience students have had with EXCEL, you may want to ask them to find and download their own data files or (in advance) prepare the data in EXCEL workbooks and as templates. In an introductory level course, students may become stymied even before analysis starts by the process of finding files on the web, opening large files (try Wordpad or another simple text editor), choosing the data, copying datainto EXCEL and using a "text-to-columns" command to parse data, checking for missing data, converting from English to metric units, etc. Students experienced in EXCEL and working with large data sets probably will have fewer problems.

EXCEL quirks:

In addition to EXCEL help, one source of information on basics of EXCEL is described in the activity sheet; as an instructor, you probably have your own list of EXCEL tips that deal with common student frustration. These might include: manually setting the scale and the major units on graphs, entering text for the "series," adding additional data to a graph, changing the background, adding a line to a scatter plot, choosing the set of cells to copy, etc. Some of these are described in the activity sheet, generally in the text blocks with blue background; you may want to add your own. Feel free to expand, change or contract these instructions as you work with students whose spreadsheet experience varies.

Samples for students:

I generally do a sample analysis and powerpoint presentation for a station the students haven't chosen, to give them an example of the kind of analysis I'm looking for.

More stations:

With more time for this exercise, it would probably be advantageous for each pair of students to analyze a second station's data once they have finished a first set.

Cautions:

As described for students in the activity sheet, analysis of the climate data provided in this exercise will not answer the question of whether malaria will return to the southern U.S. This is partly because of the difficulty establishing an algorithm to connect the average values of temperature with the viability constraints of the mosquitoes and parasites. Partly, too, it is because malaria (and other diseases) are highly dependent on socio-economic factors not explicitly considered in the exercise.

Students work in groups through a number of steps, culminating in a PowerPoint presentation, oral report and individual paper on the results of their research. Each of these steps can be independently assessed. In particular, student presentations in all these media should show that they have good understanding of the meaning of the statistics and graphs they generate and the limitations of these statistics.

• Malaria - Information page on Malaria from the US Centers for Disease Control and Prevention.
• Rogers DJ and SE Randolph, 2000, The global spread of malaria in a future, warmer world: Science, v. 289, 1763-65. HTML
• Epstein, P. R., 2000, Is Global Warming Harmful to Health?: Scientific American, v. 283, p. 50-57.
• Simon I Hay, Carlos A Guerra, Andrew J Tatem, Abdisalan M Noor, and Robert W Snow, 2004, The global distribution and population at risk of malaria: past, present, and future: THE LANCET Infectious Diseases, Vol 4, p. 327-336. PDF
• L. Joseph Melton III, M.D., 1998, Malaria in Minnesota: Past, Present, and Future: Minnesota Medicine, v. 81.
• Miller, Jane E., 2004, The Chicago Guide to Writing About Numbers: Chicago, University of Chicago Press, 304 p.
• Teaching Statistics Using Climate Data - Uses rainfall data from a station in Kenya to show different kinds of graphs and statistical analyses suitable for undergraduates. By Parin Kurji and Roger Stern