OSLO, Feb.5 (Reuters) - The United Nations defended on Friday its panel of climate scientists from criticisms that an error about the thaw of Himalayan glaciers undermined its wider findings that global warming is man-made.

The panel "remains without doubt the best and most solid foundation" for assessing climate change, said Achim Steiner, head of the U.N. Environment Program (UNEP), which sponsors the Intergovernmental Panel on Climate Change (I.P.C.C.).

Mr. Steiner said criticisms of the I.P.C.C. and its chairman Rajendra Pachauri had reached "almost witch-hunting proportions in some quarters" as some dismissed "climate change as a hoax on a par with the Y2K computer bug."

"The time has really come for a reality check," Mr. Steiner wrote in an opinion article after the I.P.C.C. last month regretted exaggerating the pace of thaw of Himalayan glaciers in a report that wrongly said they could all melt by 2035.

Mr. Steiner said it was right to expose errors and re-check sources and also right that the panel had acknowledged a need for tougher controls. The I.P.C.C. was set up in 1988 by UNEP and the U.N.'s World Meteorological Organization.

"But let us also put aside a myth that the science of climate change is holed below the water line and is sinking fast on a sea of falsehoods," he wrote in the article, distributed by international nonprofit group Project Syndicate.

Mr. Steiner said a "typographical error" was at the root of the glacier error. One original source had spoken of the world's glaciers melting by 2350, not 2035. "The I.P.C.C. is as fallible as the human beings that comprise it," he wrote.

But the error – and exposure of poor checks and reliance on "grey literature" outside peer-reviewed journals – has damaged the I.P.C.C., which shared the 2007 Nobel Peace Prize with former United States Vice President and climate campaigner Al Gore.

The I.P.C.C. concluded in 2007 that it is more than 90 percent certain that mankind is the main cause of global warming by burning fossil fuels. Climate change could cause more droughts, floods, disease, species extinctions and rising sea levels.

I.P.C.C. findings are far from merely academic - following up to shift toward cleaner energy such as wind or solar power would cost the world trillions of dollars.

Mr. Pachauri has said he will not quit.

A U.N. summit in Copenhagen in December agreed a plan to limit warming to below 2 degrees Celsius with the prospect of $100 billion a year to help developing nations. It fell far short of many nations' hopes for a binding treaty.

Mr. Steiner said the I.P.C.C. had been guided by "caution rather than sensation" over the years. He noted that the panel had been criticized since 2007 for being too conservative in projecting the likely rate of sea level rise this century.

-   Reuters