A wonderful new web mapping service from our colleagues at NASA SEDAC (the Socioeconomic Data and Applications Center) and CIESIN (the Center for International Earth Science Information Network, a research center within the Earth Institute at Columbia University) provides the educator and researcher with an incredibly valuable, easy-to-use, and fascinating tool to examine the distribution and demographic characteristics of the world's population. I have been a great admirer of the folks at SEDAC and CIESIN since my days at the US Census Bureau, and write about them frequently in our data blog, and this population service is the latest in a set of data and tools that can be used in multiple ways and at many educational levels and settings. It also makes use of some innovative Esri technology.
Once you access the web mapping application--(see my video for some guidance) - available without logging into anything, and available on any browser or device, you can examine global population distribution. Through toggling the maps on the right between country boundaries, roadmap, and terrain, you can examine the relationship between the distribution of population at scales from local to global and the relationship of the population density and amounts to terrain, landforms, climate zones, river systems, coastlines, and more. You can also view a layer called "settlement points" (which come from http://sedac.ciesin.columbia.edu/data/set/grump-v1-settlement-points-rev01). You also have the option to dive deeper into the population data by accessing the polygon, circle, or point tools on the left side of the map, as shown below. Note that for 2010, you have even more detail on the age breakdown.
The point buffering tool allows you to obtain population data for circular areas of the exact radius you choose, as I do below for Mumbai, India. I obtained the latitude and longitude for Mumbai by accessing ArcGIS > Map > and using the Measure--Point Location tool.
The results of my point buffer are shown below.
I can run the same procedure for other parts of the world, or simply use the polygon or circle tool, and the map holds all of my areas until I clear them. With these areas, I can then compare the number of people, age of the population, and change over time. Which areas of the world contain the fewest people? Is it southern Algeria in the Sahara, as I investigate below, or is it northern Siberia or central Australia? Why are some areas experiencing a high rate of population, growth, while other areas are experiencing slower rates, and still others are decreasing? What are the implications of growth and decline for those areas?
There is still more! One of my favorite tools as a geographer is population age pyramids. This mapping service provides these as well. For example, see the older population predominating on the Great Plains of Colorado.
This same pyramid is shown at right, below. But at left is the data for roughly the same geographic area in the southeast part of the Denver metropolitan area. The numbers in metro Denver are much higher (thousands in each age category vs. only a few dozen on the Great Plains), but also the age structure is much different--with 30- to 50-somethings raising kids, and not as many people over 65 or 20 year olds. What do these neighborhoods look like? You can change the base map to imagery, zoom in, and find out.
Where are the 20-somethings? Look at neighborhoods near light rail lines in central cities, or college towns, or, in the case below, military bases. Here I am examining Fort Riley, Kansas, a large military base; note the age structure and also the slightly higher number of males than females (though they are fairly similar in number!)
One of the key concepts when teaching with web mapping applications such as this is helping researchers and students get into the habit of examining the metadata. The values for this mapping service are calculated using Zonal Statistics on 1km rasters from the Gridded Population of the World (GPW4) data, described here: http://sedac.ciesin.columbia.edu/data/collection/gpw-v4 The GPW data has been refined, curated, and is updated with the highest attention to quality and detail with an expert staff of statisticians and rigorous methods. The age data specifically references the Basic Demographic Characteristics Dataset here: http://sedac.ciesin.columbia.edu/data/set/gpw-v4-basic-demographic-characteristics-rev10. Another way to focus attention on the data and methods is to examine the Mean Area of Geographic Units on the right side of the mapping service. This clearly shows that the data collection units are different for central Kazakhstan than for, say, Vietnam. Note that the settlement points layer referred to above are there for reference and are not used in the Zonal Stats Calculations.
This web mapping application fits nicely into the other web mapping applications that I describe here. Use these to teach about the key issues of our 21st Century world--population, natural hazards, oceans, climate, energy, water, and much more.