For anyone interested in how human activity is altering the planet, a new study published Tuesday in Nature Communications has some good news, and some bad news.
The good news: Despite the fact that both economic activity and human population increased at near-breakneck speeds between 1993 and 2009 — growing at 153 percent and 23 percent respectively — the human footprint has increased at just 9 percent, a significantly slower rate than either population or economic activity. And that, the researchers conclude, is reason for some optimism.
“We are becoming more efficient in how we use natural resources.”
“Seeing that our impacts have expanded at a rate that is slower than the rate of economic and population growth is encouraging,” Oscar Venter, an associate professor at the University of Northern British Columbia and lead author of the study, said in a statement. “It means we are becoming more efficient in how we use natural resources.”
The bad news, however, is that despite the fact that the human footprint has grown at a relatively slow rate, compared to economic and population growth, almost three-quarters of the world is still under measurable pressure from human activity.
To get a detailed sense of how human activities have left their mark on the planet, the researchers relied on satellite data to map eight factors: the extent of built environments, crop land, pasture land, human population density, night-time lights, railways, roads, and navigable waters. The researchers then compared the impact that each of these categories had on the environment, relative to the other categories, for every square kilometer of land on Earth (they excluded Antarctica). What they found was that about 75 percent of the planet is under pressure from human activity, with areas that harbor high levels of biodiversity facing the most intense pressure.
That’s consistent with a growing body of scientific literature, which argues that humans have changed the Earth to such an extent that they have actually created an entirely new geologic time period, known as the Anthropocene.
“In the context of the Anthropocene, this sort of measure of how the Earth is changing is another facet,” Jan Zalasiewicz, a professor of palaeobiology at the University of Leicester and chair of the Anthropocene Working Group, who was not involved in the study, told ThinkProgress. “All the changes that are talked about will leave some sort of track in the fabric in the Earth.”
Zalasiewicz cautioned that while the findings that humanity’s footprint is increasing at a rate slower than both economic or population growth is certainly means for optimism, the metrics with which the researchers measured the human footprint are fairly narrow in scope. The researchers did not, for example, look at the increase in atmospheric carbon dioxide created by human activity in their calculation of the human footprint — something scientists like Zalasiewicz is certainly a large part of how humans are changing the environment.
“Looking at the parts of the planet that are still wild and finding ways of keeping them as they are…should be something that we’re really thinking about.”
“Some key aspects of the Earth system are not being taken into comparison, simply because of the methodology that they are using,” he said. “Clearly that rise in CO2, when it translates to a rise in temperature, is going to amplify the human footprint effect globally.”
Relying on satellite data — even the increasingly fine data provided by improved satellite technology — misses other human-driven impacts, like water pollution from agriculture or air pollution from cars, power plants, and other pollutants. And while some of these pressures — like pollution, excessive hunting, or invasive species — might be closely associated with factors that the researchers did measure, like urban sprawl or agriculture, the researchers do note that their exclusion does generally limit the study.
The report also notes that human activity is not having an equal impact on all parts of the world, and while some wealthier places have exhibited a decrease in their human footprint, other places — especially most species-rich places on Earth— face an increase in pressure.
“They’re quite unique, and once they’re gone, they’re really gone,” study leader Venter told National Geographic. “I think looking at the parts of the planet that are still wild and finding ways of keeping them as they are, keeping them free of humans, should be something that we’re really thinking about.”