What could climate change mean here?

Summers as hot as Georgia's.

Maybe a salination system for your drinking water.

And imagine going for a swim at the new New Jersey coast and looking offshore to where your vacation home used to be.

Reporting on the expected long-term effects of climate change, a U.N. panel last week painted varying pictures, region by region, of devastation around the world.

If reaching agreement on how global warming would affect continents proved difficult, applying the findings locally - to, say, Pennsylvania and New Jersey - is harder still.

For now, there are "more questions than answers," said Danielle Kreeger, science director of the Partnership for the Delaware Estuary.

Given our temperate clime, we probably won't have an ecological wipeout such as the one Asia and Africa may face. But our grandchildren will be living in a different world.

Even now, researchers say they believe the data hint at changes, from plants that flower ahead of schedule to early birds that sing sooner. Recent years have seen some of the biggest floods on record on the Delaware River; with potential changes in the Gulf Stream and other factors, precipitation could increase, prompting more flooding.

"The extremes seem to be getting more extreme," Kreeger said.

Although the broad concerns are becoming clearer, outright predictions are tricky. Depending on how much greenhouse-gas emissions are reduced - or not - the scenario for the region can vary widely.

By the end of the century, according to a November report from the Union of Concerned Scientists, sea levels in the northeastern United States could rise eight inches - or three feet.

Temperatures in this region could top 100 degrees nine days a year - or 28 days.

This region is particularly vulnerable to heat-related deaths because the weather is so variable, said Laurence Kalkstein, a University of Miami bioclimatologist. Instead of the constant heat of, say, Arizona, to which people can adapt, our temperatures in the 70s and 80s often are followed by a blast in the 90s.

"Already, without climate change, we have more deaths from heat than any other weather-related cause," he said. "We can expect these numbers to only increase."

Kalkstein, who helped develop Philadelphia's noted heat-alert plan, said other urban areas needed to follow suit. "We are very unprepared, and we should be doing something about this," he said.

As for plants and animals, biodiversity almost certainly will decline, although some species will gain ground and others will lose out.

Pennsylvania forest species - such as the hermit thrush and Canada warbler, whose nesting habitats have already been damaged by deer - worry ornithologists.

And the forests themselves could change: more sweetgum, black cherry and American beech; fewer sweet birches, white oaks and black oaks. Even now in Southeastern Pennsylvania, the hemlock - Pennsylvania's state tree - is hanging on to cooler microhabitats, such as northern slopes.

Pests that are normally killed in cold winters might have a field day. And not just agricultural pests, but public-health threats such as the ticks that carry Lyme disease.

With rising sea levels, the beach-nesting piping plover could go. Intertidal feeding areas for shorebirds, which congregate in masses each spring in a spectacle that generates millions of tourism dollars, might decline substantially.

Increasing bay salinity could push the embattled Delaware Bay oyster over the edge. Likewise, if the salt line in the Delaware River is pushed far enough upstream by rising sea levels, it could threaten public water intakes and contaminate the underground aquifer much of central New Jersey depends on for drinking water.

Not all the changes are bad - at first. Longer growing seasons might lead to more productive crops. Some say warmer years could enhance tourism at the Shore - but eventually make the tourists more likely to be affected by hurricanes.

That brings up another area of concern: New Jersey's 127-mile shoreline, which Benjamin Horton, a coastal scientist with the University of Pennsylvania, said had "the highest possible vulnerability to sea-level rise."

Over the last 5,000 years, sea-level rise has been about 1.8 millimeters a year. Now, it is 3 to 4 millimeters a year - "a massive acceleration," Horton said.

Because the surrounding land is sinking, he said, Atlantic City has one of the fastest-rising sea-level rates on the Eastern Seaboard.

A January report by Rutgers University and the American Littoral Society concluded that, because of intensifying weather systems, what is considered a 100-year storm along the Jersey coast today would amount to a mere 30-year storm by 2100.

Such an event would inundate all of New Jersey's barrier islands, including about 90 square miles of primarily residential development.

Marshes that serve as teeming nurseries for fish and buffers against raging oceans would disappear.

In the Delaware estuary, Melanie Vile, a Villanova University biologist, and David Velinsky, senior scientist at the Academy of Natural Sciences, are taking a new look at the fragile freshwater tidal marshes that line the shores of many streams.

Although the ranges of some wildlife and plants are expanding northward, researchers say it's unlikely that species - let alone entire ecosystems - could migrate fast enough to keep up with climate change.

"Things just don't evolve and adapt as fast as they would need to," said Ann Rhoads, senior botanist at the Morris Arboretum.

So researchers are beginning to look at mitigation.

"Let's say you're doing a wetlands restoration or a riparian-corridor restoration," Kreeger said. "Do you want to pick trees historically found here, or would you be smarter to think about restoration trajectories? We're talking a lot about this."

The Rutgers report analyzed land use within 500 meters of salt marshes and found that 44 percent was still natural.

There's still hope, said Tim Dillingham, the littoral society's executive director.

"If we can get smart enough quick enough" - and if there's sufficient political will - "there's still an opportunity to protect some of these vital coastal ecosystems."

Contact staff writer Sandy Bauers at 215-854-5147 or sbauers@phillynews.com.