MapLab: Why More Americans Are Moving Toward Wildfire

06 October 2021

Published by https://www.bloomberg.com/

USA – Climate change is making wildfires more frequent, severe and hard to predict — not to mention more costly, as governments, insurers and local residents pay to pick up the pieces after a blaze. Yet Americans are flocking to areas at high risk for burning, and the pandemic accelerated that trend: During the first year of Covid-19, the number of U.S. households moving into areas with a recent history of wildfire increased 21% over the previous year. Areas without that recent history saw net moves fall by 15%. 

Those shocking statistics were among the many findings made by my colleague Marie Patino and me in our investigation of recent U.S. migration into the wildland-urban interface, or the edge between highly developed areas and flammable forests and mountains. Between affordability pressures and cultural ideals, our story explores the motivations for why so many people are settling there — in many cases, within the literal footprints of recent wildfires — as well as the staggering cost of this long-term trend. We paired the narrative with rich visuals, including photographs, data visualizations, and maps, with the help of our graphics colleague Jackie Gu. To explain how we approached the cartographic elements, here’s Marie:

We started with detailed data on moves nationwide from global data intelligence and address analytics company Melissa. This data, an enriched version of changes of address filed with the U.S. Postal Service, allowed us to compare moves over time by census tract, a granular level of U.S. geography. We then set out to identify which of these tracts were at high fire risk. As a proxy, we decided to look at all the census tracts that have been touched by fire since 2010 by looking at fire perimeters, provided by the National Interagency Fire Center (NIFC)

These were the building blocks for the map below, which overlays the number of net moves during the first year of Covid with these fire perimeters. As you can see, migration into these fire-risky areas soared.

Our article explores the causes of this phenomenon, from affordability to a desire for more space, and an under-appreciation of fire risk. One factor that’s allowed more people to move into flammable areas is that development is expanding in and near fire zones. Using satellite maps, we show how this has played out in the Barber Valley area of Boise, Idaho, where construction is getting closer to the edge of the 2016 Table Rock fire.

Here we again used the fire perimeters from the NIFC, which are already encoded with geographic information. We overlaid these on current and historical satellite images from Google Earth, and drew in by hand the spots for planned future developments in Barber Valley. Because Google Earth images and hand-drawn maps don’t come with geographic data encoded in them, we georeferenced these images in a free, open-source mapping software called QGIS

Another eye-catching map in the piece showed shaded relief in California using elevation data, QGIS and an open source 3D software called Blender.  

If you’d like to try it for yourself, here’s the most helpful tutorial graphic journalist Jackie Gu found on the topic, put together by mapmaker Daniel Huffman. (And my favorite thing is watching Huffman’s playlist of map labeling; it’s so soothing.)

— Marie Patino

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