For decades, humans have been the undisputed champions of changing the U.S. landscape - building cities, expanding farms, and logging forests with the enthusiasm of a toddler with a crayon. But a new NASA-funded study published in *Nature Geoscience* suggests that nature is finally fighting back, and it's winning.
The researchers, led by former Landsat science team member Zhe Zhu, analyzed nearly 35 years of data from NASA/USGS Landsat satellites to see what's been shaping the continental U.S. They found that “human-directed disturbances” like logging, agriculture, and construction are on the decline, while “wild disturbances” like wildfires and hurricanes - disasters that may be influenced by human activity but are definitely not under our control - are rising in frequency and intensity.
Robert Emberson, associate program manager for the NASA Disasters program (who was not involved in the study, because apparently one disaster program is enough), said understanding these forces is critical for planning. “If you know what’s causing them, you can begin to plan around disasters,” he said, adding that any understanding of causal factors impacts the adaptation strategy. In other words, knowing a wildfire is coming is better than just standing there with a garden hose.
Between 1988 and 2022, 18 percent of the land area in the continental U.S. was disturbed at least once. Factor in repeated disturbances, and the cumulative area rises to almost 700,000 square miles - roughly one-third of the continental U.S. Humans drove more than half of that change, clearing or developing over 446,000 square miles, an area bigger than Texas and California combined. (Yes, we paved paradise and put up a parking lot, but it turns out nature is now setting that parking lot on fire.)
Meanwhile, wild disturbances transformed more than 165,000 square miles. The trend lines are moving in opposite directions: human-caused disturbances decreased by nearly 232 square miles (600 square kilometers) each year, thanks to policy changes, technological improvements, and the 2008 financial crisis putting the kibosh on construction. Wild disturbances increased by more than 77 square miles (200 square kilometers) per year, driven by fire, drought stress, and wind - likely fueled by climate warming and other environmental factors.
“What this study basically tells me is that what we've been doing is not working,” said retired NASA scientist and co-author Ramakrisna Nemani, perhaps understating the situation like a man who just discovered his house is on fire and says, “Hmm, this seems suboptimal.”
The study used a new machine-learning algorithm trained on 40 years of land-change data, manually inspected at 50,000 locations. After a decade of work, the algorithm achieves more than 75 percent accuracy across most disturbance types - which, in the world of AI, is basically a straight-A student.
The takeaway? “The USA is entering a new era of disturbance,” the authors wrote. “The challenge now is to transform our relationship with disturbance from one of control to one of coexistence.” In other words, we can't just tell wildfires to knock it off. We might have to, you know, actually do something.