Climate could tip without warning, study finds

Posted by Emma Woollacott

A top ecological forecaster says it is harder than experts thought to predict sudden shifts in Earth's natural systems - the so-called tipping point.

"Many scientists are looking for the warning signs that herald sudden changes in natural systems, in hopes of forestalling those changes, or improving our preparations for them," said UC Davis theoretical ecologist Alan Hastings. "Our new study found, unfortunately, that regime shifts with potentially large consequences can happen without warning — systems can ‘tip’ precipitously.

"This means that some effects of global climate change on ecosystems can be seen only once the effects are dramatic. By that point returning the system to a desirable state will be difficult, if not impossible."

The mathematical study examined how nonlinear systems combined with environmental variability could lead to situations where sudden change occurred without warning.

The researchers numerically examined the dynamics of several model ecological systems under slowly changing conditions. The results offeedr a cautionary note about the generality of forecasting sudden changes in ecosystems, finding that there is likely to be a class of natural systems for which there will be no forewarning of a regime change.

These tipping points include the complete disappearance of Arctic sea ice in summer, leading to drastic changes in ocean circulation and climate patterns across the whole Northern Hemisphere; acceleration of ice loss from the Greenland and Antarctic ice sheets, driving rates of sea-level increase to six feet or more per century; and ocean acidification from carbon dioxide absorption, causing massive disruption in ocean food webs.

The full article appears in Ecology Letters.