Are we overlooking potential abrupt climate shifts?
Most of the studies and debates on potential
climate change, along with its ecological and economic impacts, have focused on
the ongoing buildup of industrial greenhouse gases in the atmosphere and a gradual
increase in global temperatures. This line of thinking, however, fails to
consider another potentially disruptive climate scenario. It ignores recent and
rapidly advancing evidence that Earth’s climate repeatedly has shifted abruptly
and dramatically in the past, and is capable of doing so in the future.
Fossil evidence clearly demonstrates that Earth’s climate can shift gears within a decade, establishing new and different patterns that can persist for decades to centuries. In addition, these climate shifts do not necessarily have universal, global effects. They can generate a counterintuitive scenario: Even as the earth as a whole continues to warm gradually, large regions may experience a precipitous and disruptive shift into colder climates.
This new paradigm of abrupt climate change has been well established over the last decade by research of ocean, earth and atmosphere scientists at many institutions worldwide. But the concept remains little known and scarcely appreciated in the wider community of scientists, economists, policy makers, and world political and business leaders. Thus, world leaders may be planning for climate scenarios of global warming that are opposite to what might actually occur.
It is important to clarify that we are not contemplating a situation of either abrupt cooling or global warming. Rather, abrupt regional cooling and gradual global warming can unfold simultaneously. Indeed, greenhouse warming is a destabilizing factor that makes abrupt climate change more probable. A 2002 report by the US National Academy of Sciences (NAS) said, “Available evidence suggests that abrupt climate changes are not only possible but likely in the future, potentially with large impacts on ecosystems and societies.”
The timing of any abrupt regional cooling in the future also has critical policy implications. An abrupt cooling that happens within the next two decades would produce different climate effects than one that occurs after another century of continuing greenhouse warming.
Fossil evidence clearly demonstrates that Earth’s climate can shift gears within a decade, establishing new and different patterns that can persist for decades to centuries. In addition, these climate shifts do not necessarily have universal, global effects. They can generate a counterintuitive scenario: Even as the earth as a whole continues to warm gradually, large regions may experience a precipitous and disruptive shift into colder climates.
This new paradigm of abrupt climate change has been well established over the last decade by research of ocean, earth and atmosphere scientists at many institutions worldwide. But the concept remains little known and scarcely appreciated in the wider community of scientists, economists, policy makers, and world political and business leaders. Thus, world leaders may be planning for climate scenarios of global warming that are opposite to what might actually occur.
It is important to clarify that we are not contemplating a situation of either abrupt cooling or global warming. Rather, abrupt regional cooling and gradual global warming can unfold simultaneously. Indeed, greenhouse warming is a destabilizing factor that makes abrupt climate change more probable. A 2002 report by the US National Academy of Sciences (NAS) said, “Available evidence suggests that abrupt climate changes are not only possible but likely in the future, potentially with large impacts on ecosystems and societies.”
The timing of any abrupt regional cooling in the future also has critical policy implications. An abrupt cooling that happens within the next two decades would produce different climate effects than one that occurs after another century of continuing greenhouse warming.
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