When climate study gets it wrong

Error in Nature’s paper warning that oceans were warming quicker was rectified

WALRUS SITS ON A MELTING ICESHELF IN THE CHUKCHI SEA IN THIS JULY 13, 1999 FILE PHOTO. THE EARTH'S ATMOSPHERE IS WARMING FASTER THAN EXPECTED AND EVIDENCE IS MOUNTING THAT HUMAN ACTIVITY IS RESPONSIBLE, THE UNITED NATIONS ENVIRONMENT PROGRAMME SAID JANUARY 22, 2001. THE U.N.'S INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) NOW PROJECTS THE EARTH'S AVERAGE SURFACE TEMPERATURE WILL RISE 1.4 TO 5.8 DEGREES CELSIUS BETWEEN 1990 AND 2100, HIGHER THAN ITS 1995 ESTIMATE OF A ONE TO 3.5 DEGREE RISE. SEA LEVELS ARE PROJECTED TO RISE BETWEEN NINE AND 88 CM (3.54 AND 34.64 INCHES) FROM 1990 TO 2100, POTENTIALLY DISPLACING TENS OF MILLIONS OF PEOPLE, ESPECIALLY IN LOW LYING AREAS SUCH AS THE PEARL RIVER DELTA, BANGLADESH AND EGYPT, IPCC CHAIRMAN ROBERT WATSON SAID. (NO ARK, NO SALES) REUTERS/HO-GREENPEACE/BELTRA

On November 1, AFP joined news outlets around the world in covering the release of a major academic paper warning that our oceans were warming dramatically quicker than previously thought.

The study was undertaken by some of the world’s most pre-eminent climate scientists, using state-of-the-art modelling systems reviewed by their peers, and appeared in Nature, one of the most prestigious academic journals.

There was just one problem: it was wrong.

The paper by researchers from the University of California San Diego and Princeton found that ocean temperatures had warmed 60% more than current estimates.

They concluded, with no small sense of alarm, that even the most ambitious emission cuts laid out in the global plan to prevent climate disaster would need to be slashed again by another 25%.

Soon after publication, an independent climate scientist spotted an error in the

Nature paper’s maths.

“After correction, the... results do not suggest a larger increase in ocean heat content than previously thought,” Nicolas Lewis wrote on his Climate Science blog.

With the rectified calculation, the authors quickly realised they had made a mistake.

The new results had a far larger range of possibilities in ocean temperature increases — between 10 and 70%: still warmer, but rendering the study vague even for the sometimes unknowable science of climate modelling.

“We quickly realised that our calculations incorrectly treated systematic errors in the O2 measurements as if they were random errors in the error propagation,” author Ralph Keeling wrote on climatehome.org.

The correction prompted some climate deniers to wheel out the conspiracy theory that manmade global warming is made up.

Scientists have rallied round the authors, pointing out that the process surrounding the Nature paper’s publication and correction was, really, how scientific research is supposed to work.