Tuesday, 06 December 2011

Climate Change Believers Agree — Their Models Don’t

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SunMuch of the alarmism about alleged climate change is predicated on computer models purporting to demonstrate that global surface temperatures are rising at an alarming rate and are certain to cause all manner of disaster, from droughts and frigid winters to floods and scorching summers. But how reliable are these models and their forecasts?

Not very, says the BBC’s environment correspondent, Richard Black. He maintains that the models currently in use offer wildly divergent forecasts of Earth’s climatic future, particularly when it comes to “precise indications of what the future holds for your farm, your street, your village” — so much so that, regardless of one’s climate-change persuasion, he can find data to support his position.

For instance, the United Kingdom’s national weather service, the Met Office, recently published a study based on 21 computer models that purports to show what effects climate change will have on 24 countries around the world. While the center-right Daily Telegraph reported on the study with the headline “Climate change will be good for Britain’s growers says Met Office,” the left-wing Guardian’s banner read “Met Office warns of UK climate risks,” specifically “water shortages and flooding.” Both conclusions — that farming will improve and that droughts and floods will increase — can plausibly be derived from the study, albeit with differing degrees of confidence.

Black writes:

In calculating the proportion of UK farmland likely to become more fertile, the models’ answers ranged from 60% to 99% — pretty firm stuff — and only one projected any losses in any parts of the country.

The flooding picture, however, is different, with estimates ranging from a 56% reduction in flood risk to a 180% increase.

These numbers, Black notes, “are among the most definite in the report” because of the U.K.’s “tradition of weather measurements that dates back centuries.” The forecasts become even dodgier when one looks beyond the Met Office’s jurisdiction, he adds:

The change in flood risk to Bangladesh — surely one of the most flood-prone countries in the world even without climate impacts — ranged from -59% to 557%

Dry Egypt could be better off by 100%, or worse off by 206%.

And an eagle-eyed colleague spotted that the proportion of Peruvians likely to be under more serious water shortages was calculated to be a round 0%.

The Met Office deserves credit for having acknowledged the uncertainties in its data rather than simply stating its findings as cut-and-dried facts. “But,” Black remarks, “the exercise also surely gives you an insight into the limits of current modeling when the various models, each of them supposed to be ‘state-of-the-art,’ reach such divergent conclusions.”

In other words, how can anyone take these models seriously? As The New American’s Ed Hiserodt pointed out in 2009, of the 22 computer models used by the Intergovernmental Panel on Climate Change, “none … predicted the decrease that has taken place over the last decade in the Earth’s temperature — which is now at the same level as when satellite measurements began in 1979.” All, however, “predict a hot spot” in the tropics that has failed to materialize, Hiserodt observed.

Between the models’ failure to predict current climatic patterns and their inability to agree on future conditions in any useful way, their reliability is, to say the least, highly suspect. “As a policymaker, as a business leader, as a citizen,” Black pointedly inquires, “would you make decisions on the basis of these models?”

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