Posts Tagged ‘through’
Until the end of the 20th Century, most scientists thought they understood the nature of our climate system. As the very foundation of their science, geologists cherished the “uniformitarian principle” that held that the fundamental forces that molded the Earth’s features and climate were gradual, natural, stable processes that did not vary over time scales less than tens of thousands of years.
This idea became central to their training through a century of debate over natural catastrophes such as the biblical account of Noah’s flood. The concept of catastrophic climate change became ‘tainted by association’ with creationist zealots seeking scientific backing for fundamentalist interpretations of Bible passages. And so, such stories came to be considered as purely supernatural events, with no place within the objectivity of science.
Any evidence to the contrary…and there was, in retrospect, plenty of it… was at first readily dismissed. Sudden climate change in the Earth’s past was blurred by imperfect data and lack of refinement in early scientific methods. Where abrupt changes in the geological record were indisputable, these were written off as regional curiosities, arising from purely local impacts – such as a forest fire or the introduction of agriculture – impacts that had nothing to do with climate.
Until dating methods were perfected, chronological correlation of data collected at different locations around the globe was not possible, and even when it was possible, was not at first even pursued. Global changes in climate had different effects in different areas, further complicating the issue and obscuring the true scope of abrupt, world-wide climate shifts.
In fact, the uniformitarian climate paradigm was scarcely doubted until the 1950′s when a group of scientists set up a physical ocean system model that demonstrated that circulation could flip rapidly from one stable state to another. Scientists began to concede that change may only take thousands of years.
This view of the change-rate capacity of climate was reduced to mere hundreds of years in subsequent decades, beginning in the early 1960′s when mathematical models that incorporated climate feedback factors such as snow and ice cover (albedo effects) suggested that global climate really could change enormously in a relatively short time.
In the mid 1960′s deep sea sediment cores finally revealed that the planet had experienced several ice-age cycles of gradual glacial buildups over 90,000 year intervals, punctuated by more rapid 10,000 year de-glaciations. Because of the huge lag between global climate shifts and deep sea temperature responses, even this data belied the extreme magnitude of changes on the surface oceans, land masses and atmosphere.
However, with their old ideas now challenged by these new theories, scientists began to notice the evidence of abrupt changes in their data. Pollen records and improved carbon dating techniques in the 1970′s depicted stable climate periods interrupted by radical discontinuities that took only one or two centuries to totally change the vegetation of a region.
Since then, evidence from other studies such as cores of glacial ice and ocean sediments, has continued to accumulate as methodologies have been progressively refined. This has further built justification for heroic research, by intrepid teams braving hazardous conditions on heaving oceans or bitter, high altitude polar ice sheets, to win samples deep and distinct enough to provide an unambiguous picture of the Earth’s geological and climatic past, a picture that shows that violent, spectacular short-term shifts were common.
As a result, scientists en masse were beginning to entertain the possibility of abrupt change, this new attitude reflected in a statement from the Intergovernmental Panel on Climate Change in a 1996 report that concluded that ‘climate surprises’ were possible. The point was not emphasized at the time, and received little press attention. Many scientists also passively rejected the facts by refusing to revise their accustomed ways of thinking about climate.
Not until 2000 did paired ice-cores, extracted by competing teams in Greenland, match to show irrevocable proof of abrupt climate shifts taking effect over mere decades (see R.B. Alley’s book ‘The Two-Mile Time Machine’). Similar cores were drilled in Antarctica and revealed the global scale of the shifts. This forced the climate community to arrive at consensus.
Now respected climate scientists concur that the potential for fast climate change evidently does exist, and could surprise humanity with a climate shock within the lifetimes of you and I. However, the new paradigm has not extended beyond geoscientists to the impacts community – economists and other specialists are slow to turn their attention to the consequences of climate change, and policy makers and the public are even more ignorant of the risks humanity faces.
Because science has been late to wake up to climate change, crucial information about the potential behavior of our climate has only very recently come to light. Relentlessly emerging climate surprises have thrown into painful relief just how inadequate our understanding of the climate system remains. Like a snowball rolling down a mountain, climate change is gathering momentum, racing ahead of even the most pessimistic predictions.
Will you be ready?