Nearly half of Earth’s environmental systems have been compromised by human activity in the last 100 years, putting human civilization beyond “safe operating space”, an international research study has found. An 18-member research team published their findings in the journal Science.
[caption id="attachment_191" align="alignright" width="300"] Earth's western hemisphere on October 2nd, 2007. Image credit: NASA/Goddard Space Flight Center/Reto Stöcklit.[/caption]
The team found that four out of nine boundaries indicating the stability of Earth’s environment have become unstable as a result of human activity in the last century. Of particular interest is the damage done to the planet’s Nitrogen-Phosphorus cycle, two elements over-used in farming, which are responsible for contaminating water leading to algae blooms and fish kills.
Dr Stephen Carpenter, director of the University of Wisconson-Madison Center for Limnology, says “We've changed nitrogen and phosphorus cycles vastly more than any other element. (The increase) is on the order of 200 to 300 percent. In contrast, carbon has only been increased 10 to 20 percent and look at all the uproar that has caused in the climate.”
Another side-effect of excessive phosphorus-based fertilisers draining into water supplies is the release of toxins. Professor Elena Bennett, of McGill University’s School of the Environment, added “This kind of problem is likely to become much more common. We will see more lakes closed, will have to pay more to clean our water, and we will face temporary situations where our water is not cleanable or drinkable more and more frequently. That's what it means to have crossed this planetary boundary. It's not a good thing for any of us.”
Besides the Nitrogen-Phosphorus cycle, the other boundaries deemed to have been breached were climate change, species extinction, and land-system change. These boundaries have remained stable for 11,700 years, in which time human civilisation has evolved to the point it’s at today. However, in just the last 100 years, much instability has occurred.
Dr Carpenter hopes this international study will not be ignored by politicians, “we're running up to and beyond the biophysical boundaries that enable human civilization as we know it to exist,” he points out, adding “It might be possible for human civilization to live outside Holocene conditions, but it's never been tried before. We know civilization can make it in Holocene conditions, so it seems wise to try to maintain them.
The results of the study will be discussed in detail at the World Economic Forum in Davos, Switzerland next week.