Could turning up the heat inside cause plummeting temperatures outside?

Energy is thought by some to be the biggest contributor to climate change, what's sending most industrial greenhouse gases in the United States into the air. Greenhouse gases can build like a thick blanket between the earth and space, causing temperatures to warm and, according to some, potentially bringing about harsher winters.

The amount of carbon dioxide in the air since 1860 has steadily grown, according to an Intergovernmental Panel on Climate Change chart on the United Kingdom Environmental Change Network web site. Florida Keys lodging facilities are working to improve energy efficiency, major rental car companies now offer hybrids, airlines are working also to reduce carbon emissions.

In the United States, petroleum and natural gas account for more than 80 percent of harmful gases, the U.S. Energy Information Administration web site notes. Energy providers in Florida offer alternative forms of energy, such as solar power. One island in the Florida Keys has long been powered entirely by solar energy.

About Historic Walking Guides: Florida Keys

Historic Walking Guides: Florida Keys takes readers back in time as they travel off the beaten path from the edge of Florida's mainland to Key West. In Key West, readers can embark upon a series of historic walking tours, each centered around themes such as treasure hunting, commercial fishing, literary luminaries and, of course, two of the best known residents of all -- Ernest Hemingway and Jimmy Buffett. Historic Walking Guides: Florida Keys is available in print through Destinworld Publishing and Amazon.com. It's expected to be in digital format in early 2011.

Enjoy the warmth. Winters could be colder thanks to . . . Key West?

It has to do with a current known as Florida's Gulf Stream.

The Gulf Stream is borne between Key West and Cuba, and it's probably better known for transporting warmth to the Northeastern United States, Canada and Europe. This single current carts some 90 trillion tons of water an hour, according to a 1930 Popular Mechanics report that described it, at its birthplace, as a “rushing torrent larger than 10 Mississippi rivers.”

If the Gulf Stream stalled or stopped flowing, some say, an ice age – or “little ice age” could set in. That was the premise of the 2004 movie, "The  Day After Tomorrow."

Warming and cooling periods throughout the world happen naturally and in cycles that are gradual, in part as a result of the earth's rotation and the sun's energy, experts suggest. Continents naturally shift, and cooler eras seem to happen after they collide, according to Kirk A. Maasch, a University of Maine Geological Sciences Professor. But ice ages happen about every 200 million years and last millions of years, Maasch notes.

The ocean, on the other hand, holds the majority of the earth's heat – and it could cause noticeable climate changes in as few as 10 years that could go on for centuries, according to the Woods Hole Oceanographic Institute in Massachusetts.

Winds move tepid waters near the top of the Gulf Stream, while cool, salty waters sink and become a lower river, according to NASA and Woods Hole Oceanographic. The warmer seas become, the more moisture and evaporation results, Woods Hole information suggests.

For northern regions, that could mean more showers that are lighter than salt water. If they don't sink the way their thicker, salty counterparts do, the Gulf Stream could stall or stop moving, Woods Hole suggests. Seas deepened from the rain, along with melted glaciers, could in turn become colder, the organization notes.

The Gulf Stream, and current weather patterns, might have once been vastly different.

That's because the Gulf Stream is part of a “conveyor belt” of waters that generally begin with those said to be from the fresher, deeper and cooler Indian and South Pacific oceans. Waters from these oceans trek toward South Africa, slip up into the Caribbean Sea, loop around the Gulf of Mexico and head down along Florida's west coast before they funnel in to the Gulf Stream, an American Meteorological Society map shows.

A “Continental Divide” keeps conveyor belt waters on track. But at one point, a wide seaway between North and South America allowed waters to flow between the warmer, saltier Atlantic and the cooler, fresher, Pacific, according to a 2008 Florida Museum of History study. Then, millions of years ago, the continents collided, and Panama began blocking that flow, the museum study noted. With the Americas joined, ocean currents changed and ushered enough moisture northeast that glaciers were able to form, the Florida Museum researcher contends.

It was during a glacial period, archaeologists say, that seas receded and the former reefs and shoals that are the Florida Keys emerged.

Dangling south west from mainland Florida, they gently curve around the Gulf Stream.

About Historic Walking Guides: Florida Keys

Historic Walking Guides: Florida Keys takes readers back in time as they travel off the beaten path from the edge of Florida's mainland to Key West. In Key West, readers can embark upon a series of historic walking tours, each centered around themes such as treasure hunting, commercial fishing, literary luminaries and, of course, two of the best known residents of all -- Ernest Hemingway and Jimmy Buffett. Historic Walking Guides: Florida Keys is available in print through Destinworld Publishing and Amazon.com. It's expected to be in digital format in early 2011.

If the weather gets colder, blame it on . . . Key West?

Winters could be a lot longer and colder, according to some scientists, who indirectly point toward Key West.

It has to do with a mighty current known as Florida's Gulf Stream. The Gulf Stream is part of a “conveyor belt” of waters that travel from the Indian and South Pacific oceans into the Caribbean Sea and Gulf of Mexico.

The Gulf Stream is borne in a slender passage between Key West and Cuba and travels northeast, ushering some 90 trillion tons of water an hour and carrying 27,000 times the total output of all the power stations in Britain, according to a 1930 Popular Mechanics report and a more recent article in the United Kingdom's Independent newspaper.

Typically, the Gulf Stream transports warmth to North America and western Europe.

If this current were to stall or stop moving, the Massachusetts-based Woods Hole Oceanographic Institute suspects, it could bring about an ice age – or a “little ice age,” as some say could have happened during Revolutionary War-era winters.

Well before the Revolutionary War, before continents shifted and Panama formed a land bridge uniting North and South America, waters between the Caribbean Sea and Pacific Ocean flowed freely. With Panama to block the flow after the Americas collided, a Florida Museum researcher suggests, water was forced northeast, allowing glaciers to form.

It was during a glacial period, archaeologists say, that seas receded and the former reefs and shoals that are the Florida Keys emerged. They gently curve around the Gulf Stream.

As glaciers to the north melt and seas deepen, they become colder, Woods Hole suggests, and conditions become more ripe for the Gulf Stream to stall.

That was the premise behind the 2004 movie, “The Day After Tomorrow.”

About Historic Walking Guides: Florida Keys

Historic Walking Guides: Florida Keys takes readers back in time as they travel off the beaten path from the edge of Florida's mainland to Key West. In Key West, readers can embark upon a series of historic walking tours, each centered around themes such as treasure hunting, commercial fishing, literary luminaries and, of course, two of the best known residents of all -- Ernest Hemingway and Jimmy Buffett. Historic Walking Guides: Florida Keys is available in print through Destinworld Publishing and Amazon.com. It's expected to be in digital format by January.

Florida Keys were once like Pennekamp Park: Under water

The bronze Christ of the Deep statue guarding the coral reef off Key Largo didn't start out under water, but the island itself is thought to have once been there. The Florida Keys are believed to have been coral reefs and shoals that, with glaciers forming to the north, surfaced in receding seas and came to be islands.

Ice ages, scientists say, happen naturally and ever so gradually as the earth orbits the sun and as lands shift, in some instances uniting and in others drifting apart. Now that glaciers are melting -- and, according to some, melting more quickly than anticipated as a result of human activity -- what does that mean for the Florida Keys, where elevations are said to average 4 feet above sea level? Are we drowning these American islands?

About Historic Walking Guides: Florida Keys

Historic Walking Guides: Florida Keys takes readers back in time as they travel off the beaten path from the edge of Florida's mainland to Key West. In Key West, readers can embark upon a series of historic walking tours, each centered around themes such as treasure hunting, commercial fishing, literary luminaries and, of course, two of the best known of all -- Ernest Hemingway and Jimmy Buffett. Historic Walking Guides: Florida Keys is available in print through Destinworld Publishing and Amazon.com. It's expected to be in digital format by January.

Happy Anniversary, Pennekamp Park

There was a time, historians say, when trucks could be seen hauling piles of precious coral out of the Florida Keys, where one of the most productive coral reefs spans Biscayne National Park off Miami to the Dry Tortugas west of Key West. That began to change in December 1963, when John Pennekamp Coral Reef State Park was established as a means of preserving the reef. Pennekamp Park is now part of the much more expansive Florida Keys National Marine Sanctuary. On Saturday, Dec. 11, admission to the park is free as it celebrates its 50th anniversary with special exhibits and activities. It's named for the late John Pennekamp, a former Miami newspaper editor who helped secure the land for it. Most of its sites, however, are beneath the sea. They include:

~ The bronze Christ of the Deep statue, a replica of Italy's Christ of the Abyss that was an Italian dive group's gift to the Underwater Society of America and the society's gift to the park.

~ The City of Washington, a 360-foot passenger and cargo vessel that survived the 1898 Havana Harbor explosion of the battleship USS Maine and, years later, grounded on the coral reef and sank.

~ The 510-foot landing ship dock, Spiegel Grove, which landed on its side after being intentionally scuttled in 2002 and was then found righted after Hurricane Dennis passed through in 2005.

About Historic Walking Guides: Florida Keys

Historic Walking Guides: Florida Keys takes readers back in time as they travel off the beaten path from the edge of Florida's mainland to Key West. In Key West, readers can embark upon a series of historic walking tours, each centered around themes such as treasure hunting, commercial fishing, literary luminaries and, of course, two of the best known of all -- Ernest Hemingway and Jimmy Buffett. Historic Walking Guides: Florida Keys is available in print through Destinworld Publishing and Amazon.com. It's expected to be in digital format by January.

About Historic Walking Guides: Florida Keys

Beyond stylish Miami’s southern edge, coral forests and planes are believed to have surfaced from vast waters and, with help from Midwest Wisconsin, came to form sultry islands with a rich and enchanting past. On and around the mangrove-fringed isles, pirates plundered passing vessels, rum runners slipped in illicit booze and treasure hunters reaped wealth from the belly of commanding seas.

These are the Florida Keys -- more than 800 in all. Some 30 or so are united by bridges, the Gulf of Mexico on one side, the Atlantic Ocean on the other. Many people visit these American islands to escape frigid winters. Few realize that a warm waterway borne between Key West and Cuba prevents them from having to endure permanent winters.

Historic Wallking Guides: Florida Keys takes readers back in time and off the beaten path from Homestead and Florida City to Key West and then on a series of themed walks throughout the southernmost American City. The guidebook is available through Destinworld Publishing and on Amazon.com. This blog is designed to keep readers up to date, and your comments and updates are welcome.