IPCC predictions: then versus now

Eight examples of where the IPCC has missed the mark on its predictions and projections

Scientists will tell you: There are no perfect computer models. All are incomplete representations of nature, with uncertainty built into them. But one thing is certain: Several fundamental projections found in Intergovernmental Panel on Climate Change reports have consistently underestimated real-world observations, potentially leaving world governments at doubt as to how to guide climate policy.

Ocean Acidification

To its credit, the IPCC admits to vast climate change unknowns. Ocean acidification is one such impact.

Projection: Unmentioned as a threat in the 1990, 1995 and 2001 IPCC reports. First recognized in 2007, when IPCC projected acidification of between 0.14 and 0.35 pH units by 2100. “While the effects of observed ocean acidification on the marine biosphere are as yet undocumented,” said the report, “the progressive acidification of oceans is expected to have negative impacts on marine shell-forming organisms (e.g. corals) and their dependent species.”

Reality: The world’s oceans absorb about a quarter of the carbon dioxide humans release annually into the atmosphere. Since the start of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale is logarithmic, this change represents a stunning 30 percent increase in acidity.

Why the miss? Scientists didn’t have the data. They began studying acidification by the late 1990s, but there weren’t many papers on the topic until mid-2000, missing the submission deadline for IPCC’s 2001 report. Especially alarming are new findings that ocean temperatures and currents are causing parts of the seas to become acidic far faster than expected, threatening oysters and other shellfish.

National Oceanic and Atmospheric Administration chief Jane Lubchenco has called acidification the “equally evil twin” to global warming.

Glenn Scherer, The Daily Climate, 6 December 2012. Full article.

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