The event will convene an array of scientists, economists, statisticians and libertarian commentators holding a dizzying range of views on the changing climate  from those who see a human influence but think it is not dangerous, to others who say global warming is a hoax, the sun’s fault or beneficial. Many attendees say it is the dawn of a new paradigm. But many climate scientists and environmental campaigners say it is the skeptics’ last stand.

Michael E. Schlesinger, an atmospheric scientist at the University of Illinois, Urbana-Champaign, said that any focus on the last few months or years as evidence undermining the established theory that accumulating greenhouse gases are making the world warmer was, at best, a waste of time and, at worst, a harmful distraction.

Discerning a human influence on climate, he said, “involves finding a signal in a noisy background.” He added, “The only way to do this within our noisy climate system is to average over a sufficient number of years that the noise is greatly diminished, thereby revealing the signal. This means that one cannot look at any single year and know whether what one is seeing is the signal or the noise or both the signal and the noise.”

The shifts in the extent and thickness of sea ice in the Arctic (where ice has retreated significantly in recent summers) and Antarctic (where the area of floating sea ice has grown lately) are similarly hard to attribute to particular influences.

Interviews and e-mail exchanges with half a dozen polar climate and ice experts last week produced a rough consensus: Even with the extensive refreezing of Arctic waters in the deep chill of the sunless boreal winter, the fresh-formed ice remains far thinner than the yards-thick, years-old ice that dominated the region until the 1990s.

That means the odds of having vast stretches of open water next summer remain high, many Arctic experts said.

“Climate skeptics typically take a few small pieces of the puzzle to debunk global warming, and ignore the whole picture that the larger science community sees by looking at all the pieces,” said Ignatius G. Rigor, a climate scientist at the Polar Science Center of the University of Washington in Seattle.