Max Mayfield, director of the U.S. National Hurricane Center, says there's plenty of potential for a storm worse than Hurricane Katrina which killed 1,339 people along the U.S. Gulf coast and caused some $80 billion in damage last August.

"People think we have seen the worst. We haven't," Mayfield told Reuters in an interview at the fortress-like hurricane center in Florida.

"I think the day is coming. I think eventually we're going to have a very powerful hurricane in a major metropolitan area worse than what we saw in Katrina and it's going to be a mega-disaster. With lots of lost lives," Mayfield said.

"I don't know whether that's going to be this year or five years from now or a hundred years from now. But as long as we continue to develop the coastline like we are, we're setting up for disaster."

Looking back nearly a year to the costliest natural disaster in U.S. history, and the third-worst hurricane in terms of American lives lost, Mayfield said Katrina itself could have been a greater disaster.

By Friday night, more than two days before the storm struck the Gulf coast on Aug. 29, the hurricane center had predicted its future track accurately and also warned it could become a powerful Category 4 storm on the five-step Saffir Simpson scale of hurricane intensity.

New Orleans was squarely in the danger zone, and emergency managers and residents had plenty of time to prepare.

"One of my greatest fears is having people go to bed at night prepared for a Category 1 and waking up to a Katrina or Andrew. One of these days, that's going to happen," Mayfield said.

Katrina went just to the east of New Orleans, sparing the city the worst of a massive storm surge and the strongest winds. But still the city's protective levees failed.

VULNERABLE CITIES

The worst-case hurricane scenario? Mayfield has many in mind. A stronger hurricane closer to New Orleans. A direct hit on the vulnerable Galveston-Houston area, the fragile Florida Keys or heavily populated Miami-Fort Lauderdale.

Or how about a major hurricane racing up the east coast to the New York-New Jersey area, with its millions of people and billions of dollars of pricey real estate?

"One of the highest storm surges possible anywhere in the country is where Long Island juts out at nearly right angles to the New Jersey coast. They could get 25 to 30 feet (7.6 to 9.1 metres) of storm surge ... even going up the Hudson River," Mayfield said.

"The subways are going to flood. Some people might think 'Hey, I'll go into the subways and I'll be safe.' No, they are going to flood."

Mayfield, a silver-haired, 34-year veteran of the hurricane center who became its public face in 2000, is a tireless campaigner for hurricane preparation, warning the 50 million people who live in U.S. coastal counties from Maine to Texas that they are all in the path of a future storm.

He is mystified by a study that found 60 percent of people in hurricane-prone U.S. coastal areas have no hurricane plan -- which to disaster managers means up to a week's worth of food and water squirreled away, a kit with flashlights and other gear and an established evacuation route to higher ground.

"After Katrina and after the last two hurricane seasons you can't understand why more people are not taking hurricanes seriously," Mayfield said.

Katrina, he says, killed people who stayed in their homes with confidence because they had lived through 1969's Hurricane Camille. Camille was a much stronger storm than Katrina when it crashed ashore in Louisiana and Mississippi as one of only three Category 5s to hit the United States in recorded history.

"There were a lot of people who lost their lives because they thought that they had already lived through the worst they could possibly live through," Mayfield said.

"Experience isn't always a good teacher."

Emergency services did not report any victims or damages.

The quake, however, was felt by residents of the capital and in the eastern part of the country.

The depression that formed Monday was centred 480 kilometres west of the southernmost Cape Verde islands and was moving toward the west-northwest at speeds of near 30 km/h, the National Hurricane Center said.

The storm had maximum sustained winds near 105 km/h, with some strengthening forecast for the next 24 hours.

Cape Verde is about 560 kilometres off the African coast.

Long-range forecasts show the storm nearing Bermuda in about a week. But it was still too early to tell if it would hit land, senior hurricane specialist James Franklin said.

It is the fourth named storm of the 2006 Atlantic hurricane season.

The U.S. National Weather Service's outlook through October saw persistent drought from eastern Montana to Minnesota and on down through Nebraska, Kansas, Oklahoma and Texas -- the main spring-wheat and winter-wheat growing areas of the United States as well as its main cattle and beef production region.

"Relief for water supplies will likely need to wait until next winter's snow season, at the earliest, since snow melt is the major source for water in the West," the National Weather Service's Drought Outlook said last month.

IRRIGATION

The region under the greatest stress is the Great Plains, an area from North Dakota to Texas dubbed the Great American Desert by early explorers but turned into a garden spot in the last century thanks to a single innovation: irrigation.

But farmers from Nebraska through northern Texas are now growing more water-thirsty crops, like corn, that offer them better cash returns due to changing trends such as the boom in ethanol and biodiesel fuels.

That is only accelerating the depletion of ground water faster than it can be replenished by rain. In some cases, farm land is already being idled to conserve water.

"My sense in looking at these issues for 20 years, we're going to need at least a doubling of water productivity in agriculture if we're going to have an opportunity to meet food demand in a way that is somewhat environmentally sustainable," said Sandra Postel with the Global Water Policy Project, a group in Amherst, Massachusetts that analyzes water policies.

NOT JUST A PROBLEM FOR U.S. FOOD PRODUCTION

Experts say water scarcity will be a growing dilemma for world farmers. Most projections put world population at about 8 billion people by 2025, or another 2 billion mouths to feed.

But those people and their industries will also need more water. A 2002 study by the International Food Policy Research Institute estimated that farmers' use of irrigation water worldwide will rise only 4 percent from 1995 to 2025, partially because the water won't be available.

Meanwhile, non-irrigation water use could rise 62 percent.

"In the face of water scarcity, farmers will find themselves unable to raise crop yields as quickly as in the past, and by 2025 their irrigated cereal production will be 300 million metric tons less than it would have been with adequate water -- a difference nearly as large as the U.S. cereal crop in 2000," the study said.

But U.S. water problems have the greatest implications for world food supplies. The United States for decades has been the planet's "food reserve," the top exporter of wheat, corn and soybeans and the largest single provider of food aid to other nations.

The squeeze on water for U.S. farms is pushing innovation, such as a trend away from flood irrigation to center pivot sprinklers or state-of-the art, localized drip irrigation.

"Just the changing of irrigation techniques can save a lot of water. That's the first place to start," said Thomas Kimmell, executive director with the Irrigation Association.

Such technology is what arid Texas is banking on to maintain crop production. But further north, water costs and conflicts over the vast but shrinking Ogallala aquifer have already prompted restrictions on irrigation.

The aquifer is an 800-mile-long (1,287-km-long) underground pool that stretches from Texas to South Dakota and feeds one-fifth of all the irrigated land in the United States. But Nebraska has put a moratorium on new wells and taken farmland out of production in the Platte River Valley to limit the draw on the Ogallala.

"Farmers who constructed an irrigation well here 20 years ago did that believing that they'd never have to experience regulation of their wells," said Michael Jess, former director of Nebraska's water resources department.

"Changing the rules will adversely affect their economic situation," he said.

Professor Edmund Penning-Rowsell, head of the Flood Hazard Research Centre at Middlesex University, warned that government cuts indicated official complacency over a risk that could only increase with time. "The maintenance of flood defences should not be subject to political machinations and the reversal in funding sends out a dangerous sign of uncertainty," Professor Penning-Rowsell said. "People enjoying the beach this summer are probably not aware that our coast is in crisis. It is where the risks and dangers of flooding are increasing."

Last month the Department for Environment, Food and Rural Affairs (Defra) told the Environment Agency to cut its £400m flood protection budget by £15m, which will affect future mapping for floods and improved warning systems. "I think it's to be regretted. It sends a signal that flood defence is an area that's liable for volatile budgets in the future," Professor Penning-Rowsell said at the Science Media Centre in London. "That's quite dangerous when you have to build and plan things for the next 50 years. Really what we need is certainty, long-term planning, and a secure financial framework," he said.

"We're playing catch-up to a certain extent and the trends to the distant future don't look at all promising. There is unease in the profession as to whether we are spending enough money to deal with the kind of problems climate change will create in 20 or 30 years."

The risk of flooding will be heightened by two exceptionally high tides, with the highest on 9 October. If they coincide with storm surges, severe coastal flooding is almost inevitable.

Jean Venables, vice-president of the Institution of Civil Engineers and former chairman of a regional flood defence committee, said that three years ago the Government indicated that it would increase its investment in flood defences. "It's extremely disappointing for the Government to be reducing the budget for flood-risk management," Dr Venables said. "We need to look very hard at doing proper maintenance of flood defences. I'm very concerned that Defra has gone in the wrong direction." Rising sea levels and the increasing risk of heavy downpours or storm surges have raised the probabilities of severe flooding. Building on floodplains, such as the Thames Gateway scheme, was exacerbating the situation, the scientists said.

Professor Penning-Rowsell said that there were three major flooding threats. The first was to low-lying areas of the east coast of England, which was affected by rising sea levels. The second was to the Thames Valley, which was largely unprotected from flooding, and the third was to London, which was vulnerable to exceptionally heavy summer downpours that can overwhelm the city's Victorian drains.

A Defra spokesman said cuts to the Environment Agency's spending on floods only affected resources such as training and maintenance. It did not erode the capital budget used to build new flood defences.

Now a team led by Domenico Patanè at Italy's National Institute of Geophysics and Volcanology in Catania, Sicily, has used seismic data to peek inside the volcano. From variations in the seismic waves from local earthquakes that passed through Mount Etna before and after the 2002 outburst they were able to build up a 3D picture showing magma rising within the volcano a few months before the eruption (Science, vol 313, p 821). "We used a technique similar to a medical CAT scan," Patanè says.

The monitoring exercise was helped by the existence of a dense grid of seismic stations around the volcano. Patanè hopes that such networks will be placed around other volcanoes too. "This could be a powerful tool for forecasting highly explosive eruptions," he says.

From issue 2565 of New Scientist magazine, 23 August 2006, page 16-17

Greenland hosts the second-largest icecap on Earth, holding 10 per cent of the global ice mass. If the whole thing melted, global sea level would rise by 6.5 metres. Earlier this year Eric Rignot of the California Institute of Technology in Pasadena and his team used satellite radar interferometry to determine that Greenland's glaciers were melting more and more each year, with about 220 cubic kilometres lost in 2005.

Now Jianli Chen and colleagues at the University of Texas at Austin have confirmed the scale of the problem using independent data from the twin satellites that make up the Gravity Recovery and Climate Experiment (GRACE). These satellites monitor shifts in water and ice over a particular spot on Earth every 30 days by measuring slight changes in the gravitational field. Chen's team devised ways to home in on areas the size of Greenland and found that the massive island is losing about 239 cubic kilometres of ice per year, mainly from the eastern parts (Science, DOI: 10.1126/science.1129007).

The ice loss corresponds to 0.6 millimetres of sea level rise per year. "That's a very big number," says Chen. It's about 20 per cent of the total sea level rise that is occurring each year. Large outflows from east Greenland could also disrupt the North Atlantic current that warms much of northern Europe, says team member Byron Tapley.

Though Chen's findings agree remarkably well with Rignot's, not everyone is convinced. "Based upon our analysis of satellite data, including ICESat and GRACE, we believe the melting rate is only one-third of what they have reported," says Jay Zwally of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

That doesn't mean Zwally isn't worried. His own previous work showed no significant loss of ice prior to 2002, so he agrees that melting is accelerating. "There's no question that Greenland has changed in the last five years from being close to balanced to being imbalanced," Zwally says.

While it would take millennia for all of Greenland's ice to melt at the rate calculated by Chen, positive feedback mechanisms could accelerate the process. For instance, melt water is lubricating the bases of the glaciers, speeding up their calving rate. So a threshold exists beyond which the melting of the whole sheet is irreversible. That could happen within the century, says Zwally.

John Church of the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart, Australia, agrees. "It is possible that by the end of this century the Greenland ice will have melted to a sufficient extent to cross the threshold."

Worse still, one of the possible safety nets appears not to be working as expected. Climate models predicted that as the world warms, Antarctica might mitigate sea-level rise by accumulating 15 to 20 per cent more snow, since warmer air can hold more moisture. However, Andrew Monaghan of Ohio State University in Columbus and his team studied ice cores from Antarctica and found that no such increase has occurred over the last 50 years (Science, vol 313, p 827).

Rising seas from Greenland's melt alone would be catastrophic. Huge parts of the world would be inundated, especially low-lying areas such as Bangladesh and the Nile delta. Great tracts of Florida would go underwater, and London and Manhattan would be threatened, along with the world's coastal infrastructure of ports, power plants and refineries.

"The world can't afford it," says climate change scientist John Harte of the University of California, Berkeley. "Even the most outrageously high estimates of what it would cost to do something about this are way, way less than what it would cost if it happened. It's frightening."

From issue 2565 of New Scientist magazine, 19 August 2006, page 8-9