This writer usually prefers news items about remarkable technological innovations and inspiring, newly discovered species over those portending environmental doom and gloom. But a paper published today in Nature is enough to get me to wince and face the cold, hard facts. According to “Approaching a State Shift in Earth’s Biosphere,” we Earth dwellers may be very close to a planetary “tipping point” in which irreversible change will be upon us. The culprits: a warming climate and expanding global population and economic growth that rapidly deplete energy and food and consume natural landscapes. Acknowledging inherent uncertainties, the scientists who authored the paper in advance of Rio+20, the June follow-up to the Earth Summit held two decades ago, nevertheless describe warning signs that a “state shift” on a planetary scale “could arrive within a few human generations, if not sooner."
The authors concluded that global ecosystems can react just like small-scale ecosystems: Once 50 to 90 percent of an ecosystem is altered, the ecological web can collapse. Humans have already converted 43 percent of the ice-free bits of our planet to farming or habitation. Extrapolating from current trends, we’ll reach the 50 percent mark by 2025. Uh-oh.
“The situation scares the hell out of me,” said report co-author James H. Brown, macroecologist at the University of New Mexico and a member of the National Academy of Sciences.
Photo by iStock/MichaelUtech
Reed McManus is a senior editor at Sierra. He has worked on the magazine since Ronald Reagan’s second term. For inspiration, he turns to cartoonist R. Crumb’s Mr. Natural, who famously noted: “Twas ever thus.”
