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Cool maps: Measuring growth from outer space

For many of the world’s poorest countries, figures measuring economic growth are unreliable, and in some cases they don’t exist at all.  In an NBER working paper, Brown University professors J. Vernon Henderson, Adam Storeygard, and David N. Weil came up with an interesting proxy for GDP growth: the amount of light that can be seen from outer space.

Lights at night, 2008. The paper's authors used data from several US Air Force weather satellites that circle the planet 14 times each day. Click for larger image.

Of course, the light intensities pictured in this world map reflect both income and population density. The authors explain:

In the United States, where living standards are fairly uniform nationally, the higher concentration of lights in coastal areas and around the Great Lakes reflects the higher population densities there. The comparison of lights in Western Europe and India reflects huge differences in per capita income, as does the comparison between Brazil and the Democratic Republic of Congo.

While GDP figures are almost always reported at the national level, the night lights allow us to see the growth of cities and regions too. The lights may be better able to show activity in the informal economy, and can be captured far more frequently, and with less of a time lag, than GDP figures.

Growth in light intensity not only “gives a very useful proxy for GDP growth over the long term;” the authors also found that it “tracks short term fluctuations in growth.” One example shows the dramatic contrast in long term growth between North and South Korea, and gives a picture of how quickly South Korea has developed over the last two decades:

The Korean peninsula. Click for larger image.

Another example illustrates how genocide literally darkened Rwanda in 1994:

Rwanda, before, during and after the 1994 genocide. Click for larger image.

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9 Comments

  1. christian wrote:

    Very interesting. In order to foster these type of analyses, the authors’ data source is on http://www.ngdc.noaa.gov/dmsp/downloadV4composites.html.

    Might be good to spread an easy explanation on how to get map informations into econometric software like Stata. Especially for economists who have high search costs.

    Posted January 25, 2011 at 3:02 am | Permalink
  2. Ed Carr wrote:

    This is interesting . . . geographers/GIScientists have been playing with this sort of thing for a while, but what might be really innovative here is using the concentration information to overcome the national scale problem of GDP – that is, the smoothing of the national income across the entire space of the state, when we all know that development is uneven and some places have a lot more wealth than others. If they can develop a robust proxy (probably at the country level) for growth via night lights, they might also be able to develop a decent proxy for the unevenness of development – a hugely useful tool for rapidly assessing what is happening at the sub-national level.

    Posted January 25, 2011 at 9:54 am | Permalink
  3. A very interesting thing about the paper is that has both, Jeffery Sachs and Paul Krugman as references. Finally an acknowledgement that both do (or did) related research. Sure my college thesis wasn’t enough for that. :)

    Posted January 25, 2011 at 9:55 am | Permalink
  4. Matt Richmond wrote:

    @christian

    As a poor graduate student, I’m willing to teach anyone who wants to know… for a price

    ($10, or free pizza?)

    Posted January 25, 2011 at 9:57 am | Permalink
  5. Phil wrote:

    Inspired by this blog post I’m proud to announce my new initiative:

    Lights For Zambia – lightupzambia.org !!!!!

    It has recently been proven that the amount of light visible from space is an accurate indicator of development in a region, so we’re taking the most direct approach to developing this poor country possible: donate all your old lamps, and lights. We’re also taking batteries and generators too to power them, and investigating the possibility of solar energy storage to power the lights.

    We’ll go and air-drop all the lights, ready to go. Then, when the satellites fly over, they’ll see the brightest country in Africa shining up at them, proving how much better off Zambia will be.

    After our assured success in Zambia we plan on scaling up to the rest of the country of Africa. This is the silver bullet people! Get ready to see Africa transformed into the most-developed country IN THE WORLD! We believe we can do this at just a fraction of the current global aid budget!

    Donate today! Everything helps! The dying children in Zambia need light!

    lightupzambia.org

    Posted January 25, 2011 at 1:07 pm | Permalink
  6. Rachael wrote:

    I think there is some merit behind the idea of this study in terms of innovative ways to look at economic growth. However, there are two sides to this coin. The brighter the glow in this map, the more energy that is being used. Energy may be a symbol of industrial growth, but the important question here is, “should we place such an emphasis on this type of growth in relation to development?”
    Personally, if small businesses are growing and community-based organizations are making small changes within their community, development is going in the right direction. Yes, of course economic growth is essential to development, but there is only so far we should really “light up” the map before the consequences outweigh the positive effects of development.

    Posted January 25, 2011 at 5:10 pm | Permalink
  7. Asif Dowla wrote:

    @Rachael:

    You raise an important point. However, a small community using kerosene for lighting is not good development either. Indoor pollution is a major health issue for women and children in poor countries.The community based arrangement of land use will require more land and hence emission of methane and Co2 to feed ever increasing number of people. In other words, there is “community failure.”

    Posted January 26, 2011 at 10:33 am | Permalink
  8. One possible objection to this method is that past a certain point in development, reduction of light pollution becomes an environmental issue. That said, even the most advanced countries are only beginning to tackle that issue, so this objection remains mostly theoretical for now.

    Posted January 27, 2011 at 8:34 am | Permalink
  9. au war cam wrote:

    This technology has an incredibly long list of uses in the world. For instance, Countries could use this to see what land is being developed on a day to day basis. For instance, when you look at the United States in the first picture, a large part of the mid-west is in relative darkness. If I were involved in development in the US, I would see this as an opportunity, as there is plenty of land and resources waiting in our country’s backyard. The image of Rowanda is also very interesting. Researchers could use this technology to keep track of disasters and conflict in countries that do not have the information highways that more developed countries use to measure these.

    Posted January 28, 2011 at 10:29 am | Permalink

11 Trackbacks

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