Doug, we could add in nearly every prediction made by Treasury and Government about budget surpluses/ deficits, revenues etc.

How about the Crown of thorns starfish that was going to destroy the barrier reef?!
Coral bleaching that would kill off the reef
Peak oil
most forecasts on currencies

Computers in the future may weigh no more than 1.5 tons.”
– Popular Mechanics, forecasting the relentless march of science, 1949

“I think there is a world market for maybe five computers.”
– Thomas Watson, chairman of IBM, 1943

“I have traveled the length and breadth of this country and talked with the best people, and I can assure you that data processing is a fad that won’t last out the year.”
– The editor in charge of business books for Prentice Hall, 1957

“But what … is it good for?”
– Engineer at the Advanced Computing Systems Division of IBM, 1968,commenting on the microchip.

“There is no reason anyone would want a computer in their home.”
– Ken Olson, president, chairman and founder of Digital Equipment Corp., 1977

“This ‘telephone’ has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us.”
– Western Union internal memo, 1876.

“The wireless music box has no imaginable commercial value. Who would pay for a message sent to nobody in particular?”
– David Sarnoff’s associates in response to his urgings for investment in the radio in the 1920s.

“”We don’t like their sound, and guitar music is on the way out.”
– Decca Recording Co. rejecting the Beatles, 1962.

“Heavier-than-air flying machines are impossible.”
– Lord Kelvin, president, Royal Society, 1895.

“If I had thought about it, I wouldn’t have done the experiment. The literature was full of examples that said you can’t do this.”
– Spencer Silver on the work that led to the unique adhesives for 3-M “Post-It” Notepads.

“So we went to Atari and said, ‘Hey, we’ve got this amazing thing, even built with some of your parts, and what do you think about funding us? Or we’ll give it to you. We just want to do it. Pay our salary, we’ll come work for you.’ And they said, ‘No.’ So then we went to Hewlett-Packard, and they said, ‘Hey, we don’t need you. You haven’t got through college yet.’”
– Apple Computer Inc. founder Steve Jobs on attempts to get Atari and HP interested in his and Steve Wozniak’s personal computer.

“Professor Goddard does not know the relation between action and reaction and the need to have something better than a vacuum against which to react. He seems to lack the basic knowledge ladled out daily in high schools.”
– 1921 New York Times editorial about Robert Goddard’s revolutionary rocket work.

“Airplanes are interesting toys but of no military value.”
– Marechal Ferdinand Foch, Professor of Strategy, Ecole Superieure de Guerre.

“Everything that can be invented has been invented.”
– Charles H. Duell, Commissioner, U.S. Office of Patents, 1899.

“Louis Pasteur’s theory of germs is ridiculous fiction”.
– Pierre Pachet, Professor of Physiology at Toulouse, 1872

“The abdomen, the chest, and the brain will forever be shut from the intrusion of the wise and humane surgeon”.
– Sir John Eric Ericksen, British surgeon, appointed Surgeon-Extraordinary to Queen Victoria 1873.

“640K ought to be enough for anybody.”
– Bill Gates, 1981

“$100 million dollars is way too much to pay for Microsoft.”
– IBM, 1982

“Who the h_ll wants to hear actors talk?”
– H.M. Warner, Warner Brothers, 1927.
thx to http://wilk4.com/humor/humore10.htm for the above “predictions”

Others may like to add to the list

Wishful thinking is clouding proper judgement it seems to me.

Jim Hansen, director of the Nasa God-dard space centre and a renowned critic of global measures to combat climate change, believes carbon trading is a “terrible” approach. “Carbon trading does not solve the emission problem at all,” he says. “In fact it gives industries a way to avoid reducing their emissions. The rules are too complex and it creates an entirely new class of lobbyists and fat cats.”

http://www.timesonline.co.uk/tol/news/environment/article5257602.ece

A physicist from Harvard Uni has spent 20+ years on his own research project, looking hard at forecasting results over a wide range of issues (nothing to do with physics per se, he is just interested in hard measurements).

Results ?

over 80% of such forecasts have been 180 degrees wrong, with the remaining 20% so vague as to be just silly.

He interviewed or questioned those who had been demonstrably wrong (a large task, actually).

Excuses ?

1) “I was misquoted”. This lie was nailed with an accurate history of the actual forecast
2) “Circumstances changed”. Since the point of prediction is to account for future change, this excuse shows the bathos of the forecasters
3) “I’ve got it right now”. Always after the event – hindsight is the lawyers’ tool.

Still people yearn for certainty and safety. A human trait of course, but one that allows constant repitition of the cycles described above.