It’s no secret that humans—noisy, messy creatures that we are—are vastly altering Earth’s environments. But it’s one thing to know this in the abstract, and another to see global changes laid out in detail, as they are in comprehensive new maps published this month in the International Journal of Applied Earth Observation and Geoinformation .
Developed by geoscientist Tomasz Stepinski and his team at the University of Cincinnati’s Space Informatics Lab (SPI), the intricate visualizations reveal that 22 percent of Earth’s total landmass was altered between 1992 and 2015, mostly by humans. The most common change was forest loss due to agricultural development, and the second most common was the reverse—farms to forests. The swift urbanization of grasslands, forests, and farms was also reflected in the maps.
“There is so much talk about the change in environment,” Stepinski told me over the phone. “But surprisingly enough, there was not a map. There are maps of individual land cover issues, like forest or agriculture. But there was not a map of everything.”
To fill this gap, Stepinski and his colleagues used satellite data collected by the European Space Agency’s Climate Change Initiative, which included geospatial maps of land cover designed to monitor climate change.
The team broke these maps into 81-kilometer-squared tracts and created a legend of color-coded tiles based on nine broad types of transitions that occurred between 1992 and 2015 (agriculture gains in yellow, forest losses in maroon, etc). The tiles are shaded to reflect the degree of change, with the lightest shade corresponding to regions altered by less than 10 percent, and dark patches representing regions that shifted by 30 percent or more.
On a broad scale, the maps emphasize the massive influence of human activity on the planet. But the project has also revealed granular details about specific locations.
The stark disappearance of the Aral Sea, due to disruptions of its tributaries by irrigation projects, shows up as a visible blob on the Kazakh-Uzbek border. Forest gains in the interior of China, West Africa, and much of the Russian taiga show up in dark green. The sheer rapidity of forest loss in southeast China and massive urbanization of northeast China, represented by maroon and pink respectively, is astonishing.
The maps have obvious applications for environmental and climate science, but they could also help inform responses to social issues, like mass migrations and the emergence of climate change refugees. The deforestation of Central America, which is reflected in the maps, are among the factors motivating migrants to leave those areas. Land changes are just one of many contributing reasons to mass migrations, Stepinski said.
The project conveys the reality that humans are reshaping our world with alarming speed. The hope for the team is that these maps will become a valuable resource to interdisciplinary researchers looking to build on the findings, and perhaps anticipate future crises.
“I had two goals,” Stepinski said, describing his intent with the maps. “My first goal is not even scientific but rather for people to look at this and realize what is happening.”
“The second [goal] is that this is like a manual,” he said. “The map is not the end—for scientists, it’s the beginning. They can look at that and identify places that seem to change and they can focus on particular areas and do more research.”
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