"It would keep on warming even though we have stopped the cause, which is greenhouse gases from the combustion of fossil fuels," David Jhirad of the Washington-based World Resources Institute said on Wednesday.
The rate of warming would be slower, Jhirad said in a telephone interview, but a kind of thermal inertia would ensure that global temperatures continue their upward trend.
He referred to a report released by the nonprofit institute this week that analyzed research reports on climate change for 2005.
"Taken collectively, they suggest that the world may well have moved past a key physical tipping point," the institute wrote.
Jhirad said there were actually two tipping points. The first is that there is no doubt human activities cause global warming; a more physical tipping point is that the effects of global warming are evident now.
The report, based on research published in journals including Science and Nature, also found the effects of climate change were so severe they should spur urgent action to prevent more damage and to combat damage that has already occurred.
"We can't assume this change is so far in the future that we can afford to delay," Jhirad said.
The World Resources Institute, founded in 1982, is a nonpartisan environmental think tank that works with industry and other ecological groups around the world.
In other news the increased planetary temperatures are producing stronger hurricanes, according to a new study.
Rising ocean surface temperatures are the primary factor fueling a 35-year trend of stronger, more intense hurricanes, scientists report in a new study.
The finding backs up the results of two controversial papers published last year that linked increasing hurricane intensity to rising sea-surface temperatures, said Judith Curry, an atmospheric scientist at the Georgia Institute of Technology in Atlanta.
"Global warming is sending sea-surface temperatures up, so we're looking at an increase in hurricane intensity globally," Curry said.
She added that in the North Atlantic Ocean basin—where hurricanes that affect the U.S. form—the number of hurricanes may also increase.
"Other ocean basins don't show an increase in [the] number [of hurricanes], but the North Atlantic does," she said.
Curry is a co-author of the new study, which appears in tomorrow's issue of the journal Science.
She also co-authored a study published last September in Science, that found the yearly number of hurricanes that reach Category Four and Five—the strongest storms on the hurricane intensity scale—has doubled since 1970.
This finding coincides with a 1°F (0.5°C) rise in global sea-surface temperature over the same time period.