PORT-OF-SPAIN, Trinidad and Tobago -- Caribbean nations face "very, very scary" rises in sea level and intensifying hurricanes, and Florida, Louisiana and even northern California could be overrun with rising water levels due to global warming triggered by carbon-based greenhouse gases, Energy Secretary Steven Chu said Saturday.

Chu's comments followed meetings with environmental ministers attending the fifth Summit of the Americas. He did not shy away from the most perilous predictions about the potential effects of global warming.

He said global temperatures have already risen by 0.8 degree Centigrade, that another 1 degree increase was certain to occur and "there's a reasonable probability we can go above 4 degrees Centigrade to 5 and 6 more."

Chu painted a dire picture of the implications.

"So imagine a world 6 degrees warmer. It's not going to recognize geographical boundaries. It's not going to recognize anything. So agriculture regions today will be wiped out," Chu said. 

"I think the Caribbean countries face rising oceans and they face increase in the severity of hurricanes. This is something that is very, very scary to all of us. The island states in the world represent -- I remember this number -- one-half of 1 percent of the carbon emissions in the world. And they will -- some of them will disappear," he added.

Chu said the United States would not be spared, either.

"Let me state what the official IPCC (the United Nations Intergovernmental Panel on Climate Change) prediction is: It (sea levels) could go up as much as three-quarters of a meter in this century, but there is a reasonable probability it could be much higher than that," Chu said. 

He said a rise in levels of one meter, coastal areas around Florida around Louisiana would move much farther inland. 

"Lots of area in Florida will go under. New Orleans at three-meter height is in great peril. If you look at, you know, the Bay Area, where I came from, all three airports would be under water. So this is -- this is serious stuff. The impacts could be enormous," he said.

Conservative climate change skeptics immediately denounced Chu's assessment of the threat and potential consequences of global warming.

"Secretary Chu still seems to believe that computer model predictions decades or 100 years from now are some sort of 'evidence' of a looming climate catastrophe, said Marc Morano, executive editor of ClimateDepot.com and former top aide to global warming critic Sen. Jim Inhofe, R-Okla. 

"Secretary Chu's assertions on sea level rise and hurricanes are quite simply being proven wrong by the latest climate data. As the Royal Netherlands Meteorological Institute reported in December 12, 2008: There is 'no evidence for accelerated sea-level rise.'"

Morano said hurricane activity levels in both hemispheres of the globe are at 30 years lows and hurricane experts like MIT's Kerry Emanuel and Tom Knutson of the National Oceanic and Atmospheric Administration  "are now backing off their previous dire predictions."

He said Chu is out of date on the science and is promoting unverified and alarming predictions that have already been proven contrary.