Highlighting errors you made almost a decade ago isn’t often a good way to raise your credibility — but it might help the U.N. panel of climate scientists after controversy over mistakes in its most recent 2007 report.

In 2003, I was at a conference in Moscow at which Bert Bolin of Sweden, the first chairman of the Intergovernmental Panel on Climate Change (IPCC), was trying to persuade a largely sceptical audience of Russian experts that the fight against global warming was affordable.

His problem: a key part of the IPCC evidence he presented exaggerated the costs to the world economy by a mind-boggling 1,000 times.

The cost “has negligible impacts on the projected economic growth”, he assured the audience, under a giant slide showing that the costs, in the worst case, would be almost $18,000,000,000,000,000 this century. (… it was wrong — such an amount would cripple the world economy).

Bolin was a persuasive debater, with wit and deep knowledge, but you could feel from the muttering around the audience that he wasn’t winning that one. He (wrongly) acknowledged that the costs could run to the ”quadrillions” of dollars, and produced other data (rightly) showing that the estimated costs — mostly of shifting from fossil fuels towards renewable energies — could easily be absorbed by an expanding world economy. 

Bolin was under a lot of fire at that conference – especially from Andrei Illarionov, a former aide of then President Vladimir Putin, who said that IPCC scenarios for combating climate change would wreck the Russian economy. Moscow was at the time undecided about whether to ratify the Kyoto Protocol, the U.N. plan for curbing greenhouse gas emissions by 2012 (it eventually did, despite Illarionov’s objections).

A while after the Moscow conference, the IPCC quietly fixed the graph in the 2001 assessment as an “important correction”, cutting three zeroes.  It now shows that it could cost up to $18,000,000,000,000 - that is still a huge amount but only a few percentage points of world GDP by 2050.

A review is now under way to recommend reforms for the IPCC after errors in the latest 2007 climate assessment including an exaggeration of the thaw of the Himalayas and the amount of the Netherlands that is under sea level. The results of that review, and how to bolster the work of the IPCC, will be presented to U.N. Secretary-General Ban Ki-moon in New York on Aug. 30.

Another report in July by the Netherlands Environmental Assessment Agency found “no errors that would undermine the main conclusions” of the 2007 report, but said the IPCC had to improve quality controls.

Some opponents of the IPCC have this year portrayed the panel as having a bias to exaggerate the negative aspects of climate change to put pressure on governments to act. The Himalayas are in no danger of melting by 2035 as one sentence in the report said, before it was corrected. 

But remembering Bolin (he was chairman of the IPCC from 1988-97 and passed away in 2007) trying to fend off Illarionov, with a faulty graph that grossly overstated the costs, shows that the IPCC has also made errors that badly undermine the case that fighting global warming is affordable.

Maybe the IPCC, like most people,  has just made the occasional mistake? Those are much easier to avoid with better checks – reforms would be far more complex if there was a consistent bias.

Photos: Top: Russia’s then President Vladimir Putin at the World Climate Conference in Moscow, Sept. 29, 2003. Below: A tourist looks at a view towards Mount Everest from the hills of Syangboche in Nepal (Gopal Chitrakar, Reuters)

BP’s vast and spreading oil disaster is killing ever more birds and other wildlife in the Gulf of Mexico — but one of the worst spills for birds was a harmless-sounding 5 tonnes of oil in the Baltic Sea in 1976.

That spill from a ship killed more than 60,000 long-tailed ducks wintering in the area after they fatally mistook the slick for an attractive patch of calm water, according to Arne Jernelov, of the Institute for Futures Studies in Stockholm, writing in today’s edition of the journal Nature.

By contrast, he writes that fewer than 1,200 birds have  so far been recorded killed after the explosion of the Deepwater Horizon rig, which has led to a leak of a gigantic 250,000 to 400,000 tonnes of oil in the Gulf of Mexico.  About 60,000 birds were killed off Alaska in 1989 by the accident usually known as the Exxon Valdez spill (…Exxon’s website calls it The Valdez Oil Spill ), previously the biggest spill off the United States at 37,000 tonnes.

By my maths, the Baltic Sea spill killed one bird for about every 80 grams of oil (…an amount easily spilt when filling up a car), the BP spill (so far) one per 200-330 tonnes. Even tiny amounts of oil can mean that birds’ feathers stick together and let chill water, like in the Baltic Sea, get to their bodies through what is normally a layer of insulation. They can then die of cold.

Jernelov gets backing from the Global Marine Oil Pollution Information Gateway, linked to the U.N. Environment Programme.

“There is no clear relationship between the amount of oil in the marine environment and the likely impact on wildlife. A smaller spill at the wrong time/wrong season and in a sensitive environment may prove much more harmful than a larger spill at another time of the year in another or even the same environment. Even small spills can have very large effects,” it says.

“In a cold climate an oil spot the size of 2-3 square centimetres can be enough to kill a bird,” it says.

It also says that penguins give another example of a how small spills can cause big problems for birds.

A collision of two oil tankers off South Africa in 1977 released 31,000 tonnes of oil and polluted just 47 African penguins, it says. But a far smaller spill of 1,000 tonnes of oil after the sinking of the Treasure in 2000 oiled 20,000 penguins and another 20,000 were removed from their breeding colonies on Dassen and Robben islands to avoid getting them soiled.

The conclusion: don’t spill oil.