Is the biosphere nearing a ‘tipping point’? A new study written by over 20 major scientists, published in Nature this month, suggests that irreversible, planet-scale biological changes are plausible– and probably likely– unless society makes significant changes.
The study cites over 100 papers on environmental tipping points, and explains how the phenomenon occurs both in local ecosystems and globally. When an ecosystem reaches a tipping point, or critical threshold, it can change quickly and dramatically. The Sahara Desert, for example, was a fertile grassland just 5,500 years ago.
The planet has undergone global ‘state shifts’ several times– most recently, in the transition from the most recent ice age into the current interglacial state. Before that, there were five mass extinctions, when at least 75% of Earth’s species became extinct and other species slowly became dominant over hundreds of thousands (or millions) of years.
Now, the scientists say, the changes that humans are causing (from resource consumption, to habitat transformation, to climate change) far exceed the changes that caused the end of the last ice age. And the pressures from humans will continue to increase, as our population reaches 9.5 billion by 2050, and as much as 27 billion by 2100 (if fertility rates remain at today’s levels, though they note it’s not thought to be possible to support that population size).
It’s extremely difficult to forecast when a planetary-scale shift may occur, though the scientists point out that many of the changes in the shift from the last glacial age are already occuring: extinctions, drastic changes in species distributions, and changes in diversity. Understanding how many complex factors work together, and how certain problems may magnify others, is part of the challenge.
Despite the scale of the challenge, the study ends on a hopeful note, suggesting that we can work toward sustainability. We need innovation, in fields from food production to energy to ecosystem management, and we need massive social change.
Main image credit: Flickr Creative Commons by DonkeyHotey; secondary image from Nature.