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Gradual Climate Change Can Have Abrupt Impacts

A National Research Council report is raising concern about the increased potential for abrupt climate changes in the near future, meaning change in a few years or decades - rather than centuries - leaving little time for society and ecosystems to adapt.

University of Colorado Geological Sciences Professor Jim White led the scientific committee assessing the risk.


"It is important to recognize that not only does climate change itself, but there are impacts, on human systems and on natural eco-systems, and the report looked not only at those rapid changes in the climate system itself, like changes in temperature, precipitation, but also looked at the fact that a slowly changing system can push other parts of the system past thresholds."

He says such effects can be seen in the dramatic decrease in the amount of summer ice cover in the Arctic. While that opens up more shipping opportunities, it also allows more sunlight to penetrate the water, promoting the growth of algae, changing and impacting the Arctic food chain from the bottom up.

As the number of frost-free days and the length of the growing seasons change, committee member Tony Barnosky, of the University of California, points to the increased extinction pressure on plant and animal species.


"What is happening is the planet is going to be warmer than most species living on earth today have seen it, including humans, by the year 2070. The pace of change that takes us there is actually orders of magnitude higher than what species have experienced in past tens of millions of years. As a result, habitats are shifting and changing in ways that species just can not adapt to fast enough or move fast enough."

In its report, the committee calls for the development of an abrupt change early warning system. It would monitor temperatures and greenhouse gas emissions, use improved computer models for predictions, -synthesize and analyze the information, and communicate it to policymakers and the public early enough to give them time and flexibility to deal with the problem.

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