Climate Change Study Warns of Tipping Points that Could Lead to Significant Human Impact

A new report by the National Research Council augments the threats of sudden climate change by reporting that even a steady and gradual change in climate can have abrupt impacts on ecosystems and human infrastructure if certain thresholds are crossed.

The report, which was released Tuesday, calls for the development of an early warning system to be used to help society better anticipate the impacts brought forth by changes in the physical climate system.

The current rate of warming is one not seen in the past 65 million years. The rising temperature will not only place stress on the environment in a way it has not seen in eons, but will also usher in an unprecedented level of stress on humans. One of the issues the report addresses is food security.

"By end of the century, average summers are supposed to be hotter than the hottest we're already seeing," Richard Alley, a geoscientist at Penn State and one of the report's authors, said in an interview with The Associated Press. "Our food is already heat stressed. If we move to unprecedented levels (of warmth), what does that do for eating?"

James W.C. White, a professor of geological sciences at the University of Colorado, Boulder, and chair of the committee that wrote the report, said in a statement that the research has numerous implications.

"Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century," he said. "Evaluating climate changes and impacts in terms of their potential magnitude and the likelihood they will occur will help policymakers and communities make informed decisions about how to prepare for or adapt to them."

Among the abrupt climate changes already underway, the study cites the disappearance of late-summer Arctic Sea ice and the increase of extinction rates of marine and terrestrial species. Some additional scenarios, such as the destabilization of the west Antarctic ice sheet, are not expected to occur within the next century. However, the report notes these scenarios are not yet well enough understood, despite their potential consequences. The report cites these unknowns as a reason to continue climate research.

Other high-impact climate scenarios not likely to happen this century include the shutdown of Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice.

However, the researchers note, even climate-related effects that happen slowly, even if over decades, can have an abrupt and potentially devastating impact on humans once a critical tipping point is reached.

The report uses the example of slow, gradual sea-level rise, which can have an effect on infrastructure such as roads, airports, subways and pipelines if a levee were suddenly breached.

"Right now we don't know what many of these thresholds are," White said. "But with better information, we will be able to anticipate some major changes before they occur and help reduce the potential consequences."