THE TOPIC OF climate change is heating up again, even though the Earth isn’t. The fifth report from the U.N. International Panel on Climate Change is due next week.

However, what is said to be a copy of its “Summary for Policy-Makers,” which is not itself a scientific document (and has been called a political one for past conclusions that varied from the official document), contains significant changes from previous versions.

The British newspaper The Mail on Sunday said it had a leaked copy of the report. According the summary, the report’s authors:

* “Make the extraordinary concession that the world has been warming at only just over half the rate claimed by the IPCC in its last assessment, published in 2007.”

That version claimed the planet was warming at a rate of 0.2 degrees Celsius every decade, corresponding with the forecasts made by computer climate models. “But the new report says the true figure since 1951 has been only 0.12C per decade — a rate far below even the lowest computer prediction,” the paper said.

* Recognize that “the global warming ‘pause’ last year, first reported by The Mail on Sunday, is real — and concede that their computer models did not predict it. They cannot explain, however, why world average temperatures have not shown any statistically significant increase since 1997.”

* “Admit that large parts of the world were as warm as they are now for decades at a time between 950 and 1250 A.D. … when the population and CO2 levels were both much lower.”

* “Admit that while computer models forecast a decline in Antarctic sea ice, it has actually grown to a new record high. Again, the IPCC cannot say why.”

* And the authors “simply dropped, without mention,” a 2007 prediction that hurricanes would become more intense. “This year has been one of the quietest hurricane seasons in history, and the U.S. is currently enjoying its longest-ever period — almost eight years — without a single hurricane of Category 3 or above making landfall.”

Despite all that, the newspaper reported, the summary says that the IPCC’s claim that human action is responsible for more than half of recently observed warming (roughly from the late 1970s to the mid-1990s) has increased in confidence from 90 percent to 95 percent.

Some scientists don’t agree. The paper quoted one of the report’s own authors, Professor Myles Allen, director of Oxford University’s Climate Research Network, as saying that “this should be the last IPCC assessment.” He accused its “cumbersome production process of ‘misrepresenting how science works.'”

Changes still can be made before the report’s final release. Nonetheless, these revelations are important, as are other recent developments:

* If warming stays at the average level predicted in the new report, the net effect will be beneficial, a Wall Street Journal columnist contended Sept. 14.

Matt Ridley said, “Most experts believe that warming of less than 2 degrees Celsius from preindustrial levels will result in no net economic and ecological damage. Therefore … there is a better than 50-50 chance that by 2083, the benefits of climate change (longer growing seasons, faster-growing crops, fewer deaths from cold weather) will still outweigh the harm.”

* A separate report recently contended that “97 percent of scientists agree” that warming is caused by humans. Prominent skeptical scientists, however, call that misleading, because nearly all of them agree that some of it is, even though they dispute its extent and predicted catastrophic effects.

* Despite earlier BBC predictions that summer Arctic sea ice could “disappear by 2013,” this year “a chilly Arctic summer has left nearly a million more square miles of ocean covered with ice than at the same time last year — an increase of 60 percent,” the Mail reported on Sept. 7.

That is still below the post-1981 average, but it proves climate predictions aren’t infallible. Indeed, total sea ice worldwide is now at a record high.

* The journal Nature Climate Change said this month that “99 percent” of 117 climate predictions made in the 1990s overestimated real warming. “On average, the predictions forecasted two times more global warming than actually occurred,” Fox News reported on Sept. 12.

* Finally, last week Australians overwhelming elected a conservative prime minister who promised to overturn expensive carbon controls, including an existing “cap-and-trade” law there that is similar to a proposal pushed by U.S. liberals.

Tony Abbot, the new leader Down Under, joins a new conservative leader in Norway in wanting to rein in the excesses of theorists who burden taxpayers with skyrocketing transportation and electricity costs, which have created “fuel poverty” for low-income consumers in Britain and Germany, among other nations.

No matter what next week’s IPCC report says, claims that “the science is settled” on climate change are demonstrably untrue.

M.D. Harmon, a retired journalist and military officer, is a freelance writer and speaker. He can be contacted at [email protected]