The U.S. Public Interest Research Group is warning that Utah has started to see the effects of global warming. But the state climatologist says it's too soon to know for sure.

U.S. PIRG says it supports environmental causes such as clean air, clean water and open space; opposes identity theft and political corruption; and works in favor of voting rights and safe and affordable prescription drugs.

Its report on global warming, released Tuesday, says average surface temperatures across the world have increased by more than 1.4 degrees since the second half of the 19th century. It cites a U.N. panel's report that global warming is unequivocal and that human activities are responsible for most of the rise in temperature.

"Between 2000 and 2006, the average temperature was at least 0.5 degrees ... above the 30-year average at 87 percent of the locations studied," it says.

According to the group, Utah's past seven summers included the second, third, fifth and 10th warmest summers on record. U.S. PIRG claimed this is what residents can expect "with continued global warming."

In a press release, U.S. PIRG spokesman Ruben Henriquez said, "Throw out the record books, because global warming is raising temperatures in Utah and across the country. The long-term forecast is for more of the same unless we quickly and significantly reduce global warming pollution from power plants and passenger vehicles."

The global warming idea is that power plants and vehicles emit greenhouse gases, which trap the sunlight's warmth in the atmosphere, heating the air more than normal.

But Robert R. Gillies, an associate professor of meteorology and remote sensing at Utah State University in Logan, thinks it's a bit too early to pin the blame for hotter summers on global warming.

Gillies, who is also the state climatologist, said in a telephone interview Wednesday that the changes are "within the variability of the observational data that we have."

In other words, the temperatures are not outside the norm, although they may be at the upper level of that range.

"But it does seem that we're having more hotter days in a particular month than we've seen in the past," he noted.

"Now, is that indicative of global warming? You can't say. But there is a trend there. ... To link it as cause and effect with global warming is extremely difficult."

Gillies said the scientific record goes back only about 110 years in Utah, not long enough to show much about long-term changes. A longer period would be necessary.

He added that about 60 years ago similar temperature extremes occurred in July, but they were not as frequent as those of today.