As a follow-up to last week’s visualization of Old Light and New Light, I wanted to make a single map, of the whole world, comparing NASA’s new 2016 Earth At Night image to the 2012 version. Using a simple pixel-difference math bot, this map isolates places where lights have come on (or increased) and where they have gone off (or decreased) in the past five or so years.
To explore this map in more detail, with a closer look at interesting locations and the presumed causes of changing nighttime lights, including a walk-through the creation process, visit this story map.
New light is blue and extinguished light is pink. Places that haven’t changed (lots of places have no nighttime light to begin with, and others, like the center of big cities, were bright before and after) are transparent so you just see right through to the satellite background.
There are lots of interesting changes to the nighttime sky in these last recent years. Some optimistic and exciting, and others terribly sad.
In the map’s text I lay out some hunches for what might cause lights to come on in some places and some reasons I suspect for lights that have been extinguished.
Some reasons for new nighttime illumination are suburban growth rings around existing urban centers, the new electrification of rural areas, wellhead fires in areas of new petroleum extraction, or waters newly popular with fisheries.
Some reasons for dimmed or extinguished nighttime illumination are the preventative measures taken to reduce nighttime light pollution, the contraction of populations from economically struggling areas, the abandonment of petroleum fields or fisheries, or the collapse of population or infrastructure due to war or social upheaval.
Here are some areas I thought were particularly interesting. Each has a story. Please do let me know if you have insights into the reasons for any of these changes in nighttime illumination. I’d love to learn more about the causes.
If you’re a mapping nerd like I am, you’ll want to know how these were made. Check out the specific how-to process here.
Happy mapping, John