THE BLOG
01/21/2015 04:31 pm ET Updated Mar 23, 2015

Scientists' Surprising Use of Cold War Spy Photos

As we have all become acutely aware over the past few years, the United States government loves to collect data. Lots of data. In the present, that can seem like a troubling manifestation of unchecked surveillance powers. Forty years down the track, however, governmental surveillance efforts that were once cutting-edge start to seem quaint, and information that was once top-secret ceases to be sensitive. Upon declassification, such information becomes an invaluable resource for scientists and other researchers who, for one reason or another, need to reconstruct the past.

An example of how declassified data can be repurposed is described in this new video and blog post produced by the E.O. Wilson Biodiversity Foundation in cooperation with Gorongosa National Park, a spectacular nature reserve in Mozambique. Josh Daskin, a Ph.D. student in my lab at Princeton University, is using old CIA spy satellite imagery from the 1970s to understand how the amount of tree cover has changed in the park over the last 30-40 years.

Tree cover is an existential issue for savanna ecosystems, which are defined as areas where grasses and trees coexist, somewhere midway on the spectrum between open grassland and closed forest. The drivers of tree cover in savannas are therefore of great interest to ecologists. In Gorongosa, the question is whether the near-extinction of many large wildlife species during the Mozambican Civil War from 1977-1992 may have shifted the tree-grass balance.

Elephants in particular eat a lot of trees. In 1972, Gorongosa's elephant population was estimated at 2,500; thirty years later, less than 200 remained. Today, thanks to the dedicated efforts of the Gorongosa Restoration Project, the elephant population is increasing again. In the meantime, however, the ecosystem may have changed, and understanding those changes is an important step in figuring out how to ensure the continued recovery of this iconic African savanna.

So what is Josh's research revealing? Click through to find out!