Researchers eye global warming thresholds
By Summit Voice
FRISCO — Climate researchers say more should be done to develop an early warning system for ecological tipping points that could be reached as the ocean, land and atmosphere gradually warm.
Some large and rapid changes could happen in a relatively short time as critical thresholds are breached, the scientists said in a new report from the National Research Council.
“Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century,” said James W.C. White, professor of geological sciences at the University of Colorado, Boulder, and chair of the committee that wrote the report. “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.”
“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.” The report identifies several research needs, such as identifying keystone species whose population decline due to an abrupt change would have cascading effects on ecosystems and ultimately on human provisions such as food supply.
The report outlines how some abrupt climate change impacts are already under way, including the disappearance of late-summer Arctic sea ice and increases in extinction rates of marine and terrestrial species.
Other scenarios, such as the destabilization of the west Antarctic ice sheet, have potentially major consequences, but the probability of these changes occurring within the next century is not well-understood, highlighting the need for more research.
Some changes pose a long-term concern, including a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice, the researchers wrote, explaining that those scenarios are unlikely this century.
But even gradual changes in the physical climate system that happen gradually over many decades or centuries can cause abrupt ecological or socio-economic change once a “tipping point” is reached. For example, relatively slow global sea-level rise could directly affect local infrastructure such as roads, airports, pipelines, or subway systems if a sea wall or levee is breached. And slight increases in ocean acidity or surface temperatures could cross thresholds beyond which many species cannot survive, leading to rapid and irreversible changes in ecosystems that contribute to further extinction events.
Further scientific research and enhanced monitoring of the climate, ecosystems, and social systems may be able to provide information that a tipping point is imminent, allowing time for adaptation or possibly mitigation, or that a tipping point has recently occurred, the report says.
An effective searly warning system would need to include careful and vigilant monitoring, taking advantage of existing land and satellite systems and modifying them if necessary, or designing and implementing new systems when feasible. It would also need to be flexible and adaptive, regularly conducting and alternating between data collection, model testing and improvement, and model predictions that suggest future data needs.
The study was sponsored by the National Oceanic and Atmospheric Administration, National Science Foundation, U.S. intelligence community, and the National Academies. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, independent nonprofit institutions that provide science, technology, and health policy advice under a congressional charter granted to NAS in 1863. The Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering. For more information, visit http://national-academies.org.