A new analysis shows that humans had transformed most of earth’s land-based ecosystems by the early part of the 20th century, according to a paper by Erle Ellis, a professor in UMBC’s department of Geography and Environmental Systems, and collaborators in Canada and Europe.
The researchers classified ecosystems based on human residence and land-use in 1700, 1800, 1900 and 2000, finding in the most recent year that only 22 percent of earth’s ice-free land surface had living systems that were not directly influenced by human populations and activities such as agriculture and forestry.
“We can now point our finger at a time when earth was no longer a wild planet,” Ellis said. The findings, he continued, have clear implications for ecologists, land managers and the general public: “Once we accept that this is a used planet, we can move from discussion about ‘saving’ the planet to talk about the best ways to live on it.”
The research is described in the latest issue of the journal Global Ecology and Biogeography, published Aug. 5. The journal’s cover photo, taken by Ellis in 1999, shows terraced slopes near Pohkara, Nepal, that were shaped by centuries of rice production.
Ellis said the research stemmed from his attempt to answer a question posed by an audience member at his 2007 American Geophysical Union presentation on “anthromes” (a word Ellis developed to describe anthropogenic biomes, or ecosystems reshaped by human activities): “So how did the biosphere become anthropogenic anyway?”
Ellis’ answer is that it did so gradually prior to the Industrial Revolution, with changes accelerating in the 20th century as urbanization, agriculture and forestry activities spread to greater portions of the earth’s surface and intensified within areas used only lightly in the past.
According to his team’s analysis, 40 percent of all ice-free land in 2000 was being used directly for agriculture or urban settlements, with an additional 37 percent of the ice-free land area classified as “novel ecosystems” that had been reshaped by becoming embedded within these used landscapes.
Ellis said the research provides a clearer understanding that we are living in the Anthropocene, a geological epoch defined by an atmosphere and climate permanently altered by humans.
“Our findings,” he said, “demonstrate the extent to which we humans have permanently transformed the patterns of life on land.”
Ellis' blog post on the research, along with a link to maps showing anthrome classifications, can be found here.
Posted: August 5, 2010, 12:00 PM