Landsat shows us the home planet, warts and all.
- By Linda Shiner
- Air & Space magazine, April 2013
(Page 2 of 4)
Loveland points out that the image of Beijing in the mid-1970s shows a compact urban center. Surfaces like roads and rooftops appear blue or gray, surrounded by the green of vegetation. In a 1990s image, the blues and grays have sprawled outward; three concentric circles are visible, the outer beltways of Beijing. Says Loveland: Once the economic engagement with the West began, with the 1972 visit to China by U.S. President Richard Nixon, the satellites began to see the city’s massive growth.
Landsat has recorded surface change not only on the most populated continent, but also on the least populated. In Antarctica, there is simply no way other than satellite remote sensing to keep track of what’s going on, says glaciologist and NASA scientist emeritus Robert Bindschadler. “Satellites can guide field researchers to the places where things are happening,” he says. “Without them, we’d just be flailing in a dark room.” Data from Landsat and other satellites, for example, indicated that the Pine Island Glacier on the continent’s west coast was thinning and accelerating seaward. “We could see that the trigger was at the coast,” says Bindschadler, “and that led to the NASA IceBridge flights,” which made headlines in 2011 with the discovery of a 19-mile-long crack in the glacier, which has by now extended several more miles.
In 2007, Bindschadler led a team to create, from more than 1,000 Landsat 7 images made between 1999 and 2003, the first, true-color, high-definition map of Antarctica. With the Landsat Image Mosaic of Antarctica, anybody with a laptop can cruise around Earth’s emptiest place. Bindschadler got a surprise when the first scientific use of the map turned out to benefit not glaciologists but biologists: Scientists with the British Antarctic Survey used LIMA to find Emperor penguin rookeries. The recorded spectral signatures allowed the biologists to differentiate the penguin guano from ice, snow, and rock.
Nowhere on Earth has change been more obvious than in the planet’s tropical rainforests, and Brazil has been the world leader in measuring deforestation and publishing the results. “Brazil decided not to wait for the world to tell them what’s going on,” says Tom Loveland. Every year, Brazil’s National Institute for Space Research collects images from Landsat and other satellites, creates a map of Amazonian forests, and reports the statistics to the world. With these results, says Loveland, the institute has evidence of the effectiveness of their policies for protecting timberland; recent statistics show they’re starting to work.
That means that the loss of forests is being slowed, not that the forests are being replaced. “That’s all you can do,” says Matt Hansen. “How long does it take to re-establish a primary rainforest, with all of its richness? All you can do is lose it. When it’s cleared, it’s cleared. That’s the way we treat it, and that’s the way Brazil treats it.”
If the world’s forests are to survive, local governments must devise equitable plans for managing the competing demands on them. In the Democratic Republic of the Congo, almost 50 million people, two-thirds of the population, live in rural areas and rely on the land for livelihood. Because villagers clear forestland for farms and depend on firewood for fuel, the forests are gradually declining.
Since 2004, the African Wildlife Foundation has led a program that involves local communities in plans to protect forests from loss in the north central part of the country, home to a large population of bonobo apes as well as other species. Working with the project, Janet Nackoney, a research assistant professor at the University of Maryland, visited the Maringa-Lopori-Wamba Landscape and helps create maps to be used for land-use planning there. Combining Landsat imagery and GPS data with the villagers’ hand-drawn maps of roads, farms, rivers, the locations of chiefs’ houses, and village boundaries, Nackoney and her team help the villagers delineate natural resource management zones that the national government will make formal.