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Climate 'tipping points' may arrive without warning | In a new study, a top ecological forecaster has said that climate 'tipping points' that can cause an irreparable
global disaster may arrive without any warning as such. The study, carried out by Alan Hastings from University of California, Davis, indicated that it is harder
than experts thought to predict when sudden shifts in Earth's natural systems
will occur. "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 Hastings. "Our new study found, unfortunately,
that regime shifts with potentially large consequences can happen without warning
- systems can 'tip' precipitously," he said. "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," he added. The current study focuses on models from ecology, but
its findings may be applicable to other complex systems, especially ones involving
human dynamics such as harvesting of fish stocks or financial markets. Scientists
widely agree that global climate change is already causing major environmental
effects, such as changes in the frequency and intensity of precipitation, droughts,
heat waves and wildfires; rising sea level; water shortages in arid regions; new
and larger pest outbreaks afflicting crops and forests; and expanding ranges for
tropical pathogens that cause human illness. They fear that worse is in store.
As US presidential science adviser John Holdren recently told a congressional
committee, "Climate scientists worry about 'tipping points' ... thresholds beyond
which a small additional increase in average temperature or some associated climate
variable results in major changes to the affected system." Among the tipping points
Holdren listed were: 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 6 feet or more per century;
and ocean acidification from carbon dioxide absorption, causing massive disruption
in ocean food webs. |
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