The sea level along the San Diego County coast may be a foot and a half higher, temperatures may be 4.5 degrees hotter and the region may have 18 percent less water than it needs in 2050, all a result of climate change, according to a report released Monday by the San Diego Foundation.

The rising ocean would put popular beaches and seaside communities at risk, even as the air is choked with increasingly thick smog fueled by three times as many heat waves as now, the report warned.

And the county that boasts more endangered species than any other in the nation could wake up to a backcountry where many native plants and wildlife have been pushed into extinction.

"It's really an unprecedented threat," said Bill Kuni, chairman of the foundation's climate change committee, in a telephone interview Monday.

The report, titled "San Diego's Changing Climate: A Regional Wake-up Call," examines what the region will look like a little more than four decades from now if measures are not taken to slash emissions of greenhouse gases, such as carbon dioxide, that are believed to be heating up the planet.

About 40 scientists contributed to the analysis, including several from the widely respected Scripps Institution of Oceanography at UC San Diego.

The foundation is a charitable group that has awarded hundreds of millions of dollars in grants over three decades for reports and projects aimed at improving the region's quality of life. The foundation paid $173,000 for the report.

The study represents local scientists' first attempt to go beyond the general impacts of global warming statewide and determine what specific consequences might be in store for San Diego County.

And it follows the release in September of a first-ever report quantifying the region's contribution to global warming. That report found that 46 percent of local carbon emissions come from cars and trucks.

The latest report issued a call for action to county residents and elected officials.

Kuni said the foundation wants all 18 area cities and the county government to develop their own plans to slash greenhouse gas emissions from their neighborhoods, business districts and municipal operations.

Not everyone believes there is urgency in heeding the call to action.

A global-warming skeptic maintains that sea level and temperature rises between and now and 2050 won't come close to the report's projections.

"That's complete and total nonsense," said Gary Sharp, scientific director for the Center for Climate/Ocean Resources Study in Salinas, a group that exists to debunk the idea of climate change.

Kuni said, however, that the foundation report is backed by solid science and is, if anything, on the conservative side in its predictions.

And Kuni said that if the atmosphere is allowed to continue to fill up with increasing amounts of carbon, the quality of life will suffer in every corner of the county.

"In the inland areas, we are going to see temperatures over three figures for a significant period of the year," he said. "Meanwhile, folks in places like Solana Beach and Encinitas are going to watch their homes fall into the ocean. They're going to watch their streets and their beaches go under water."

That is, he said, unless the region does something about global warming.

"The good news is that there is still time to act now, and we can have a positive impact on our future," said Emily Young, director of the foundation's environmental program.

The report asks each resident to:

- Commit to making three personal lifestyle changes to help the environment.

- Call mayors, city council members and county supervisors, and press them to develop local climate action plans.

- Call state and federal lawmakers and ask them to pass laws to accelerate efforts to curb emissions.

- Get involved in community programs that aim to conserve natural resources and build a more sustainable region.

- Share the report with family, friends and others.

Among the potential lifestyle changes, Kuni said people could conserve electricity, cover buildings with light-colored roofs, drive more fuel-efficient vehicles, take public transportation to work and switch out lawns for drought-tolerant landscaping.

"We do live in a desert," he said.

According to the report, the county will become even more desertlike as rainfall totals shrink and temperatures climb by 1.5 degrees to 4.5 degrees.

"We will have three times as many heat waves, and they're likely to start earlier in the year and be drawn out later in the year," Young said.

The hotter weather, in turn, will reverse the current long-term trend toward cleaner air as the sun bakes exhaust from cars and creates more smog.

Some disagree, however, with the report's dire predictions.

While hotter weather may well erase air-quality gains, Bill Brick, a meteorologist with the San Diego County Air Pollution Control District, said his agency still expects smog levels to be lower in 2050 than today.

"Ozone levels might be higher with global warming than without, but we should still be in (compliance with federal standards)," Brick said.

Sharp, the skeptic, said the temperature may increase, but by a small amount.

If it does, he said, "it won't have a damn thing to do with … the globe." Instead, he said, it will be a result of what has been widely called the "urban heat island effect," by which the expanding mass of concrete buildings and asphalt highways warms cities over time.

Sharp maintained that the sea level isn't likely to climb any faster than it did last century, when it rose 7 inches along the Southern California coast.

The report is available at http://www.sdfoundation.org/news/pdf/Focus2050glossySDF-ClimateReport.pdf.

Contact staff writer Dave Downey at (760) 745-6611, Ext. 2623, or ddowney@nctimes.com.