After completing this chapter, students will be able to:
- download, combine, and analyze data sets from NCAR's GIS Climate Change Portal;
- work with models that are used as predictors of possible future conditions;
- visualize one of the components of climate change, that of variations in mean air temperature;
- make predictions based on the analysis of single variables for future conditions; and
- describe how temperature anomalies can affect human health.
This chapter only deals with the air temperature anomaly portion of the tutorial. The user is invited to review the complete tutorial for the additional statistical (standard deviation and t-test) analysis.
This chapter demonstrates how to analyze climate projections from a Global Climate Model (GCM) in a Geographic Information System (GIS) using climate datasets generated by the Community Climate System Model (CCSM) for the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment Report. The data is distributed through the NCAR GIS Initiative Climate Change Scenarios portal in a GIS format. Many atmospheric and land variables are available from the CCSM and the GIS Climate Change portal.
- Variable: Air Temperature (tas)
- Region: Global
- Analysis: Summer months' temperature anomaly in 2030 with respect to the average summer temperatures of present-day climate.
- CCSM model runs:
- 20th Century Experiment; Ensemble Average; months June, July, August; years 1980-1999
- Scenario A2; Ensemble Average; months June, July, August; years 2021-2040
This is a comparison of the most current climate available from the CCSM runs with an ensemble average, the 20th Century Experiment to the SRES A2 scenario ensemble average for 2030. An ensemble average is composed of many ensemble members or model runs that have been averaged and used for climate projections. This method tends to discriminate between the real climate "signal" and "noise" which is inherent in the internal variability of individual model runs. One of the final outputs in this chapter is an anomaly map of future projected temperature compared to the present-day climate. In climate science, an anomaly is a deviation of a meteorological variable from the normal (mean) value. Determining this anomaly is best accomplished by taking an average over multiple ensemble members, and also by averaging over multiple years within each ensemble average.
In climate models, internal variability in the climate system is expressed both as year-to-year variability and as differences between ensemble members. It is helpful to have a large number of data points included in the average for both the present-day and future climates when computing an anomaly. For this chapter, there are nine ensemble members available for the present-day climate simulation and five ensemble members for the future climate scenario. In order to reduce the year-to-year variability within the ensemble runs, an average was calculated over 20 years using the period from the present-day simulations (1980-1999) and the period from the future scenario (2021-2040). For each year, a mean temperature was calculated for the Northern Hemisphere summer, as a weighted average for June, July, and August.
For purposes of this chapter, it was determined that the final 20 years of the 20th Century Experiment was the most appropriate choice for comparison to the A2 Scenario ensemble average. Initial consideration was given to the Present Day Control Run model run which is also available from the GIS Climate Change Portal. This model run was performed by the CCSM model community to show that the model could obtain a stable and appropriate representation of current climate conditions. However, because the Present Day Control run does not contain multiple initial starting conditions (e.g., ensemble members)so it is difficult to compare its' climate signal to a model run that does have multiple starting conditions (e.g., ensemble average)...
For further information on the CCSM, ensembles, and IPCC SRES scenarios, please refer to the GIS Climate Change Portal
Listed below are four additional sources of information on climate change.
- Weather and Climate Basicsbackground information from UCAR
- About Climate ResearchNCAR
- Earth Lab: Degrees of ChangeInteractive from Koshland Science Museum
- Short webcasts about climate changeNCAR Scientists Discuss Global Warming and its Impacts
Key Terms and Prerequisite KnowledgeStudents who use this chapter will need to be familiar with the following key terms. It is important to stress the difference between Global Warming and Climate Change, as these terms have incorrectly been used interchangeably in most popular media.
- Anomaly: A deviation from the common rule; an extreme.
- Climate Change: A long-term change in the Earth's climate or of a region on Earth.
- Climate Model: Climate models are a mathematical representation of the earth's climate system and climate modelers employ a technique called ensembling to capture the range of possible climate states.
- Climate forcing: A variable that impacts climate, usually the focus of the climate experiment. It sets into motion the change.
- Ensemble: A climate model run ensemble consists of two or more climate model runs made with the exact same climate model, using the exact same boundary forcings, where the only difference between the runs is the initial conditions.
- Global Warming: the increase in Earth's average surface temperature due to rising levels of greenhouse gases.
This chapter is intended for advanced students of climate change. It can be used as a lab activity or homework assignment. In order for users to grasp the concepts described in the chapter, background reading and discussions should precede the GIS analysis.
Conveying the relationship between increases in mean summer temperatures and the probability of extreme events, such as heat waves, is central to this analysis. Two resources along these lines include the following.
- Change in Mean Temperature as a Predictor of Extreme Temperature Change in the Asia-Pacific Region, (Acrobat (PDF) 3.7MB Jan31 09) Griffith et al 2005
- Extreme climatic events and their evolution under changing climatic conditions (Acrobat (PDF) 637kB Jan31 09) Martin Beniston and David B. Stephenson 2004
It is important for users to understand that scientific studies demonstrate that even small changes in the mean state of climate can result in the large change in the probability of extreme events (Griffith et al 2005) (Acrobat (PDF) 637kB Jan31 09). By analyzing the anomaly of mean summer temperatures, offered in this chapter, users can identify potential regions at risk to increased probability of extreme heat events.
The Frequently Asked Questions (FAQs) of the IPCC deal with this question of climate change and extreme events as well.
In a warmer future climate, there will be an increased risk of more intense, more frequent, and longer-lasting heat waves. The European heat wave of 2003 is an example of the type of extreme heat event lasting from several days to over a week that is likely to become more common in a warmer future climate.
This chapter uses ESRI's ArcGIS 9.3 software which requires a Windows operating system. ArcGIS 9.3 System Requirements. It is possible to run ArcGIS on a Apple Intel-based computer using emulation software such as Parallels or VMware Fusion.
If your school or institution doesn't already have ArcGIS 9.x installed in your classroom or computer lab, you can request an evaluation DVD from ESRI by filling out the form at Request Evaluation DVD.
Note: It can take from 10-14 business days to receive the evaluation DVD after submitting your request so be sure to plan accordingly.
The following National Science Education Standards are supported by this chapter:
- Formulate and revise scientific explanations and models using logic and evidence.
Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.
- Use technology and mathematics to improve investigations and communications.
A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.
- Scientists rely on technology to enhance the gathering and manipulation of data.
New techniques and tools provide new evidence to guide inquiry and new methods to gather data, thereby contributing to the advance of science.The accuracy and precision of the data, and therefore the quality of the exploration, depends on the technology used.
The following U.S. National Geography Standards are supported by this chapter:
- How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective
- How to analyze the spatial organization of people, places, and environments on earth's surface
- The physical processes that shape the patterns of earth's surface
- How human actions modify the physical environment
- Technology productivity tools. Students use technology tools to enhance learning,increase productivity, and promote creativity.
- Technology problem-solving and decision-making tools. Students use technology resources for solving problems and making informed decisions.
Optional DownloadsThe following shapefiles and/or project files contain all the data layers needed for this chapter.
Part 1. Step 5. Folder of zipped data flies from CCSM Data Portal (Zip Archive 23.5MB Feb3 09)
The most time-consuming steps in this chapter are the calculation of the Summer Air Temperature Averages for both 1980-1999 and 2021-2040 in Part 2. Below are the completed shapefiles for the steps. These can be downloaded and provided to students. Students will still need to calculate the 20-year Average for both these time periods in Steps 3 and 5.
Part 2. Summer Air Temperature Averages
Step 2. Calculate Summer Averages for 1980-1999
tas_JJA_1980_1999_20th_Century_Experiment_completed (Zip Archive 8.1MB Jan10 09)
Part 2. Summer Air Temperature Averages
Step 4. Calculate Summer Averages for 2021-2040
tas_JJA_2021_2040_Scenario_A2_completed (Zip Archive 8.1MB Jan10 09)
Completed project files with data
Part 2. Folder containing completed project file with data at the end of Part 2. NCAR Climate Change Part 2 complete (Zip Archive 21.2MB Feb3 09)
Part 3. Folder containing completed project file with data at the end of Part 3. NCAR Climate Change Part 3 complete (Zip Archive 27.4MB Feb3 09)
- IPCC Homepage
- Climate Change 2007: Synthesis Report Summary for Policymakers (PDF file)
- Climate Change 2007: Synthesis Report (PDF file)
- United State Global Change Research Program has up to date reports on global climate change impacts as well as educator resources, including an image gallery.
- Increase in Urban Population
- NWS Heat Wave Information