A few words culled from some hacked e-mails in Britain have generated chaos in the world of climate science - throwing dark clouds over Pennsylvania State University and stirring up negative publicity for the field that shows no sign of abating.

The disturbance, now known as climategate, is threatening to damage scientists' careers, inflame cynicism over the science of global warming, and perhaps alter the course of the major U.N. climate summit in Copenhagen, which began yesterday.

The stolen and leaked e-mails that have generated the most discussion focus on the so-called hockey stick graphs created by Penn State climatologist Michael Mann and others - graphs that have famously illustrated world temperatures taking a sharp turn upward in the 20th century.

But in all the sound and fury, one inconvenient truth is emerging - the e-mails give little new information and appear to have failed to change the mind of anyone within the scientific world.

One bona fide climate expert, Richard Lindzen of MIT, has gone on the record accusing Mann and others of data rigging and outright falsification. But Lindzen is well known for expressing doubts that global warming should be a serious concern. The meteorology professor says he's thought for years that the hockey stick graphs were generated through dishonest means. The newly leaked e-mails underlined what he already believed.

Many others familiar with the issue say that at worst, the whole "scandal" reveals a few endemic problems with data sharing and perhaps bias in this field, but that any accusations of misconduct are unjustified and insult the entire scientific enterprise.

The consensus that human activity has altered the atmosphere and warmed the planet rests on much more than a hockey stick.

The controversy began last month when hackers broke into a server holding a decade of e-mails from the Climate Research Unit (CRU) at the University of East Anglia in England. The CRU is one of three institutions leading efforts to chart the climate's course over the last millennium.

The other two big players in this field, sometimes known as "paleoclimatology," include Penn State and the National Climatic Data Center in Asheville, N.C.

Reconstructing climate in the years before thermometers requires a kind of environmental forensics. Scientists search for clues in ancient tree rings, bore holes, coral bands and the composition of gas bubbles trapped deep in the ice sheets of Antarctica and Greenland.

To get those, they scuba dive off remote islands, trudge through swamps in search of ancient stumps, and brave frostbite on the ice caps.

As adventuresome as that can be, nearly all the 1,000-odd hacked e-mails communicate technical and mundane aspects of the job - details on data analysis and logistics over attending conferences, for example.

The whole controversy swirls around a small handful - most of them correspondence with or about Penn State's Michael Mann. Critics of climate research have focused on one message in 1999, which referenced a "trick" and an effort to "hide" a temperature decline.

That e-mail was written by the East Anglia climatologist Phil Jones. He wrote that he planned to use Mann's "Nature trick," referring to a paper Mann had published in the journal Nature the previous year.

That paper incorporated the tree rings, ice cores, corals, and a number of other "proxies" into a kind of formula that could approximate the world's temperature as it fluctuated over the last 1,000 years.

Also included in the graph were real temperature measurements, starting in the mid-1800s and continuing to the present.

Others before Mann had reconstructed the historical Medieval Warm Period and the Little Ice Age that gripped the world during the 1700s, but Mann's paper was the most complete to date and revealed the influential graph that became known as the hockey stick.

Many scientists were sounding the alarm over human-generated climate change well before that graph appeared.

Phil Jones, who has stepped down temporarily as CRU director, has said publicly that he never meant to imply that he or Mann had used deception. By "trick," he said he meant only a technique for highlighting data on a graph.

The trick, said Mann, who faces a Penn State inquiry, was simply a concise way of showing the two kinds of data together - clearly indicating which was which. "There's nothing hidden or inappropriate," he said. Mann said his method of combining proxy data has withstood numerous statistical tests - lining up neatly with thermometer readings during the 150 years where they overlap.