Rising sea levels are threatening cliffside homes and bird sanctuaries, according to a top environmentalist.

But David Wingate has urged planners not to let concern for homes lead to futile cliff strengthening which could wipe out further nests and blight the coast line.

He said some world estimates had ocean levels rising at the rate of seven inches a century but the worst case scenario would see a rise of three feet.

?Every time they come out with a new estimate they are revising it upwards ? it looks more like the worst case scenario than the least case scenario,? said Dr. Wingate.

He said global warming of one degree over the last century was to blame as it caused ice caps to melt and sea water to expand.

?It?s almost certain we will see a 1.5 foot rise in sea levels in this century. Some people predict this in less than 50 years,? he said.

A report by the Reuters news agency earlier this month revealed Greenland?s huge ice sheet could melt within the next 1,000 years and swamp low-lying areas around the globe if emissions of carbon dioxide (CO2) and global warming are not reduced.

A meltdown of the massive ice sheet, which is more than 1.8 miles thick, would raise sea levels by an average 21 feet, threatening countries such as Bangladesh, islands in the Pacific and parts of Florida.

?Any area that is less than seven metres above sea level would be flooded,? said Jonathan Gregory, a climate scientist at the University of Reading in southern England.

Coastal and environmental engineers from Smith & Warner International conducted a coastal erosion study in Bermuda last June and returned immediately after Hurricane Fabian.

They recommended coastal protection measures.

Dr. Wingate said planners needed to be even more careful about coastal zoning and homes needed to be built back further from the coast.

Efforts to shore up homes on cliff edges were futile and wiped out possible nesting sanctuaries he said. Those threatened but not destroyed by hurricanes Felix and Gert in the 1990s has succumbed to the sea during Fabian.

He said: ?At least one third of the South Shore is made ugly by these sea walls.?

Environment Permanent Secretary Brian Rowlinson agreed that large sea walls were not necessarily better as they could break up in storms and act as battering rams causing further damage.

?One of the most effective ways to protect against lost land is to set development further back,? he said.

Dr. Wingate has spent a lifetime helping to nurture threatened endemic seabirds the Cahow and the Longtail, which use tiny south shore nesting islands. ?That has absolutely convinced me that change is occurring and rapidly destroying these islands,? he said.

He said he had predicted a catastrophe for nesting sites if a category four hurricane hit but similar devastation had occurred with category three Fabian.

?The loss of Longtail nests on the south shore was staggering and the Castle Harbour islands lost about 90 percent of their nests.

?A lot of these birds face a real crisis. We are scrambling to provide alternative nests.?

Around 20 Styrofoam nests for Longtails with SKB coating of fibre board and cement have been installed at cahow nesting islands but foul weather has prevented more being put in.

However the sturdiness of the three-foot wide nests was demonstrated during Hurricane Fabian with one chick miraculously surviving water washing right over the nest.

Another 300 nests are needed to get back to the 1970s level said Dr. Wingate.

Hurricanes quickly destroyed natural nesting sites in holes in rock faces but it took a long time for natural weathering to recreate them, said Dr. Wingate.

?Over the last 12 years we have had a major hurricane destroying nests every four years. There?s no time for new nests to be created.?

He said nests for the Longtails were priority because if they were displaced they would invade the Cahow nests and were capable of killing chicks.

He said generally Bermuda?s topography rose fairly steeply from the sea meaning the threat to homes not built on fast eroding cliffs was low.

But he said the Airport, the Mill Creek/West Pembroke area, Cooper?s Island and the low lying land behind Somerset Long Bay were all vulnerable. Also at risk is Mangrove habitat including Hungry Bay in Paget.