Climate alarmists gleefully surfed a 2005 Nature study that claimed greenhouse gas emissions would slow Atlantic Ocean circulation and cause a mini ice age in Europe. Their ride now seems headed for a gnarly wipeout.

An international team of researchers just reported in the journal Science (Aug. 17) that the intensity of the Atlantic circulation may vary by as much as a factor of 8 in a single year. The decrease in Atlantic circulation claimed in the Nature study falls well within this variation and so is likely part of a natural yearly trend, according to the new study.

The media release for the 2005 Nature study ominously read, “The ocean currents that help to maintain Northern Europe's relatively clement climate are weakening, according to a new survey carried out in the Atlantic Ocean. The new data shows that the system of currents that moves warm waters north and returns cooler waters to more southerly latitudes has weakened by 30 percent since 1957.”

Researchers aboard a 2004 voyage led by the UK National Oceanography Centre’s Harry Bryden surveyed the strength of currents at various depths at latitude of 25 degrees north. Although Bryden found no change to the Gulf Stream — the northward flow of warm water near the surface — he reported a 50 percent reduction in the amount of cold, deep waters flowing southwards and a 50 percent increase in the amount of water recirculating within subtropical regions without reaching higher latitudes. These changes, according to Bryden, showed that less water is completing a full circuit of the entire Atlantic current system.

The Nature study spawned a tidal wave of scary headlines around the world that December, including “Scientists Say Slow Atlantic Currents Could Mean a Colder Europe” (New York Times); “Fears of Big Freeze as Scientists Detect Slower Gulf Stream” (The Independent, UK); “Shifting Currents Renew Fears of Freezing” (The Gazette, Montreal); “Europe Faces Feal Day After Tomorrow” (Courier Mail, Australia); and “Ocean Flow Findings Indicate Harsher Winters for Europe” (Press Trust of India).

Even the anti-Kyoto Protocol, non-alarmist magazine The Economist fell for the Atlantic Panic.

“Dr. Bryden’s data indicate that what [geologic] history and the [climate] models describe may actually be happening at the moment to currents in the north Atlantic … Dr. Bryden’s result is about as robust as can be expected … Dr. Bryden’s finding … provides a reason to think more clearly about the whole issue of climate change.”

Nine months later, in an editorial entitled, “The Heat Is On” (Sept. 9, 2006), The Economist moved squarely into the alarmist camp. “The uncertainty surrounding climate change argues for action, not inaction. America should lead the way,” is how the editorial opened. “Mr. Bush has got two years left in the job. He would like to be remembered as a straight shooter who did the right thing. Tackling climate change would be one way to do that,” is how the article closed.

Bryden’s line of thinking also found its way into the most recent report of the United Nations’ Intergovernmental Panel on Climate Change (IPCC) — a report that includes him as one of its reviewers. Although the report didn’t endorse Bryden’s claimed magnitude for the Atlantic slowdown, it did conclude that such a slowdown was “very likely” during the 21st century.

But now Bryden’s finding has been exposed as a nothing burger — although this should have come as no surprise.

Bryden worked with only very limited oceanic data — five sets of ship-based temperature and salinity measurements from the north Atlantic collected during research cruises between 1957 and 2004. His prediction of a much larger slowdown of the Atlantic current than made by climate model simulations is the sort of extreme outlier result that often occurs with the use of incomplete and inadequate data.

In contrast, the new result is based on bottom pressure, temperature and salinity data for the full water column on either side of the Mid-Atlantic Ridge collected continuously since March 2004. The ocean-interior measurements were complemented by sea cable and satellite measurements of the northward flow of the Gulf Stream and surface-driven wind transport, respectively. What a difference high-quality data makes.

Even though Bryden wisely backed off his alarmist claims by mid-2006 after reviewing a year’s worth of the new measurements, his retraction garnered virtually no media attention. The New Scientist’s “No New Ice Age for Western Europe” (Nov. 4, 2006), New Zealand National Business Review’s “Scientists Debunk Gulf Stream Failure Scenario” (Jan. 26, 2007) and a passing mention on National Public Radio (Jan. 29, 2007), hardly begin to undo the media hysteria launched in December 2005.

Despite the new Atlantic data, however, there is still much uncertainty about the variation in Atlantic current. A recent study in the Journal of Climate estimated that it will take several decades of data to detect trends in Atlantic circulation. A news article accompanying the new Science study observed, “Similarly, it will take decades of monitoring to determine which (if any) of the models analyzed by the IPCC most accurately reflects reality.”

Several decades, you say? But we’re being stampeded into global warming regulation now. The Atlantic Panic underscores our limited knowledge of how the climate system functions. Does it really make sense to regulate first and ask questions later?

Steven Milloy publishes JunkScience.com and DemandDebate.com. He is a junk science expert, an advocate of free enterprise and an adjunct scholar at the Competitive Enterprise Institute.