Sudden 'ecosystem flips' imperil world's poorest regions, say wat...(ifficult or even impossible to reverse. ...)

According to Peterson, recent outbreaks of toxic algae blooms in Quebec lakes and off Swedens Baltic Sea coast are prime examples of ecosystem flips, the consequence of nutrients from fertilizers permeating the soil and running off into streams, lakes and oceans.

As you get more and more nutrients in the soil you eventually get to a point where you can even completely stop farming and all the nutrients will still be there, explained Bennett, an assistant professor at McGill's Department of Natural Resource Sciences and the School of Environment. You go past a tipping point where its very difficult to reverse.

Ecosystem flips can have significant and sometimes devastating effects on human well-being, as global populations suddenly lose resources they are dependent on, said the researchers. Some of the most vulnerable areas on Earth are places like the drylands of sub-Saharan Africa.

In some of these regions we risk two types of ecosystem flips, one that causes rapid soil degradation with dramatic effects on yields and farmers' livelihoods, and another that affects rainfall and therefore also vegetation growth, Gordon said.

These are the places where populations are growing the fastest, people have the least amount of water per capita and are the poorest of any of the biomes of the world. They are also the regions most likely to be affected by climate change, Peterson added.

As global demands for agriculture and water continue to grow, concluded the authors, it is increasingly urgent for scientists and managers to develop new ways to build resilience by anticipating, analyzing and managing changes in agricultural landscapes. Managing the green water component of the hydrological cycle is also important, as well as encouraging more diverse agricultural practices.