Massey University computer engineering scientists Tom Moir and Fakhrul Alam have been contacted by more than 30 people, most in Auckland and the North Shore, who claim to have heard a humming noise.

The symptoms are similar to those suffered by people with tinnitus, commonly associated with a prolonged high-frequency ringing in the ear.

The scientists are visiting people who can hear the humming, and trying to measure the noise in the hope they will be able to identify its source.

People from central Auckland to Kaiwaka in Northland have reported the sound, as have residents from the North Shore suburbs of Torbay, Browns Bay, Murrays Bay, Birkenhead and Beach Haven, and Stanmore Bay on Whangaparaoa.

The scientists are measuring the frequency by playing a second low frequency to someone who can hear the humming. When the person can no longer hear the hum, the frequency they are playing is the same as the humming noise.

Dr Moir said people could definitely hear a sound. "It's quite serious to them, it's driving them bonkers. I was there at the same time and I couldn't hear anything."

He said the sound was well within the average hearing range for people.

Most people can hear between 20 hertz and 20 kilohertz and the humming is around 56 hertz, according to Dr Moir's research.

Not everyone could hear the sound, because of its low volume, he said.

"We're all born differently - some people are better runners, some people are better hearers."

An Auckland woman who heard the sound described it as a "low drone or rumble".

The woman, who asked not to be named or have her suburb identified, said the noise had become so bad she was thinking about selling her home.

"I absolutely love my home but last night I couldn't get to sleep before 5am. In desperation I even tried to put Blu-Tack in my ears," she said.

But nothing works. The noise is louder inside and during the night when there are no other sounds to mask it.

The woman said there was no point telling people who could not hear it because they thought she was "stark raving mad".

The founder, patron and counsellor of the New Zealand Tinnitus Association, Joan Saunders, said some of the people who contacted Dr Moir did have tinnitus, but not all of them.

She could not diagnose everyone without meeting them, she said.

Dr Moir could not hear the sound himself but his wife, Jude, could.

She described the sound as an "awful noise and sensation".

"It feels creepy. It's not a place I'd like to live regularly," Mrs Moir said.

Author Rachel McAlpine based her 2005 novel The Humming on her experiences of a mysterious humming in Puponga, near Farewell Spit.

The book featured an unknown humming noise that plagued only certain people in a small town.

Western Power and the British Geological Survey have carried out checks in the area.

Pc Baxter Proven of Devon and Cornwall Police said an investigation was under way into the cause.

He said: "One theory being considering is perhaps a military aircraft has broken the sound barrier a little too close to the land and that has caused this sonic boom and this, in turn, caused some light damage around the north Cornwall area."

'Physically shook'

One resident in Bude said a crack in her kitchen had widened as a result, and others reported experiencing their properties "shaking".

A BBC Radio Cornwall listener said: "The stables physically shook. It sounded like Concorde used to sound when it broke the sonic barrier. But much louder. It went 'boom, boom'."

A crack that was left at one home
Experts ruled out the possibility of an earth tremor

Western Power Distribution said engineers had completed checks and found no faults with its systems.

The Ministry of Defence and the RAF said there were no records of their aircraft flying over the area.

The Civil Aviation Authority said it was also unaware of the cause.

David Galloway from the British Geological Survey said the organisation checked its readings for the area after receiving several phone calls about the bang.

He said: "We've not got any signals at all from any instruments, and in fact we have instruments nearby at Hartland Point."

He added it was possible that it might have been a sonic boom, but although the equipment was geared towards detecting ground movement, it would sometimes pick up such disturbances as well.

He said: "Typically we'd register any ground movement but we have been known to have signals of a sonic nature to register."

The nightmare scenario of a shutdown in the meridional ocean current which drives the Gulf stream was dramatically portrayed in The Day After Tomorrow. The climate disaster film had Europe and North America plunged into a new ice age practically overnight.

Although no scientist thinks the switch-off could happen that quickly, they do agree that even a weakening of the current over a few decades would have profound consequences.

Warm water brought to Europe's shores raises the temperature by as much as 10C in some places and without it the continent would be much colder and drier.

Researchers are not sure yet what to make of the 10-day hiatus. "We'd never seen anything like that before and we don't understand it. We didn't know it could happen," said Harry Bryden, at the National Oceanography Centre, in Southampton, who presented the findings to a conference in Birmingham on rapid climate change.

Is it the first sign that the current is stuttering to a halt? "I want to know more before I say that," Professor Bryden said.

Lloyd Keigwin, a scientist at the Woods Hole Oceanographic Institution, in Massachusetts, in the US, described the temporary shutdown as "the most abrupt change in the whole [climate] record".

He added: "It only lasted 10 days. But suppose it lasted 30 or 60 days, when do you ring up the prime minister and say let's start stockpiling fuel? How can we rule out a longer one next year?"

Prof Bryden's group stunned climate researchers last year with data suggesting that the flow rate of the Atlantic circulation had dropped by about 6m tonnes of water a second from 1957 to 1998. If the current remained that weak, he predicted, it would lead to a 1C drop in the UK in the next decade. A complete shutdown would lead to a 4C-6C cooling over 20 years.

The study prompted the UK's Natural Environment Research Council to set up an array of 16 submerged stations spread across the Atlantic, from Florida to north Africa, to measure flow rate and other variables at different depths. Data from these stations confirmed the slowdown in 1998 was not a "freak observation"- although the current does seem to have picked up slightly since.

Jean Ziegler, a UN expert on food rights, said that some 852 million people were "gravely, permanently undernourished on this planet" at the end of 2005, an increase of 11 million from the year earlier.

Much of that increase came in Africa, where drought, climate change and poor farming practices are spreading the Sahara Desert further southward into once-fertile lands, Ziegler told a news conference.

He also said that unfair trade practices by rich nations hurt food production in Africa, where excess food from rich nations can be dumped in local markets, undercutting local producers.

Africa is seeing hunger increases in both absolute and relative terms, meaning the rate of increase of hungry people is greater than the overall increase in the population, he said.

Still, "only the absolute figures are important, because these are human beings," said Ziegler. "They are living people who die from hunger.''

Ziegler, a university professor and former politician representing Switzerland's socialist party, said solutions to end hunger exist - but not the political will.

Fast-growing trees can be planted to secure fertile lands against encroaching Saharan sands, irrigation canals can be built to help farmers and pesticides can be employed early to kill crop-ruining insects, like the locusts that ruined farms two years ago in many West African countries, he said.

Dr Eleanor Burke, with colleagues from the Met Office Hadley Centre for Climate Change, has undertaken the first-ever projections of global drought, which was published yesterday (Thursday 26th October) in the Journal of Hydrometeorology.

Results show that areas under extreme drought could increase to 30 percent from today's figure of 3 percent and up to half of the land surface might be influenced by moderate drought at any one time.

The scientists have used a method known as the Palmer Drought Severity Index (PDSI) to calculate the extent of drought. This determines dryness from rainfall, evaporation and run-off.

Dr Burke's paper also concludes that human influence, through greenhouse gas emissions, is detected in the observed increase in global drought conditions during the period 1952-1998.

Speaking of her findings, Dr Burke said: "These results are very sobering but it must be pointed out that further research is required to substantiate what is the first look at this issue. However, it does indicate the potential seriousness of future climate change impacts if CO2 emissions continue to increase substantially."

The research shows that the climate model reproduces the global observed trend in drought very well, but is less good at capturing regional variations. Further research using other climate models from other Climate Centres is needed to substantiate these results and provide regional detail.

Drought poses a very real threat to business continuity. It can have many impacts, including:

1) The most obvious impact is upon businesses which rely upon industrial quantity water supplies for their day-to-day activities - agricultural and manufacturing companies for example. Such businesses are often seriously impacted by drought conditions in their regions.

2) Power shortages: in areas where hydroelectricity is an importance source of power generation, drought can result in power shortages and power rationing.

3) Increased risk of fire damage: perhaps the most wide-ranging impact of drought is the huge fire-risk increase it engenders. This not only creates a direct physical threat to businesses, but also to critical infrastructures upon which businesses depend.

4) Evacuations: whether linked to shortages of drinking, cooking and sanitation water, or to the increased fire risk, drought can lead to the requirement to evacuate away from affected areas, for potentially long periods of time. This can have a direct impact on businesses, with business premises becoming inaccessible; employees unable to travel to work; or employees having to take extended periods of absence to care for their own families and properties.

The prediction came as Prime Minister John Howard said the "big dry" would put pressure on prices and said an interest rate hike might be best to contain inflation.

The drought will slash the gross value of farm production by 35 percent, or 6.2 billion dollars (4.7 billion US) in 2006-07, hurting Australia's stellar economic growth, the country's top commodities forecaster said.

In a revised crops estimate, the Australian Bureau of Agricultural and Resource Economics (ABARE) predicted wheat growers would face their smallest crop since 1994-95 as their harvest falls to 9.5 million metric tonnes.

"The drought is estimated to reduce economic growth in Australia in 2006-07 by around 0.7 percentage points from what would otherwise have been achieved," said ABARE's Executive Director Karen Schneider.

The forecast wheat crop of 9.5 million tonnes would be less than one third the size of the 2005-06 crop of 25 million tonnes, as a devastating drought that has plagued farmers for the past six years tightens its grip on economy.

It comes after the nation's monopoly wheat exporter ABB Ltd. this week slashed its production forecast by up to 40 percent to nine to 11 million metric tonnes from 12-15 million predicted last month.

ABARE said Production of barley and canola is also tipped to suffer, with the barley crop forecast to be 3.6 million tonnes this year, down 64 percent on a year ago, with canola tipped to fall to 440,000 tonnes, or 69 percent.

But Howard said the dry stretch would not have a major impact on overall economic growth.

"The aggregate impact on our gross domestic product will not be all that great," the prime minister told Southern Cross Broadcasting after around half the country's farming land was officially declared drought-stricken.

The reduction in agricultural output would be offset by other sectors of the economy, he said.

But Howard conceded the drought was already impacting prices and warned an expected interest rate rise next month may be justified to contain a bigger increase in the future.

Inflation came in at a higher-than-expected annual rate of 3.9 percent this week, ratcheting up expectations of a rate rise when the Reserve Bank meets in early November.

"I think an interest rate rise is entirely possible given inflation," Howard said, stressing that the decision was entirely up to the central bank.

"What you have to consider is that if you don't have an interest rate rise then it is possible there will be a further boost in inflation because of the strength of the economy and a bigger rise might be needed further down the track to contain the inflation."

Despite the drought, Australia enjoyed a "very strong, even exuberant economy" and that activity had contributed to inflationary pressure, he said.

"The Reserve Bank may well say that the best thing it can do for Australia is dampen that inflationary exuberance a little now, rather than to let it run, and if it does it may have to lift interest rates by a much bigger amount in order to dampen inflation," he said.

But later on in the day, Howard insisted he had not endorsed another interest rate rise.

"I'm simply acknowledging that the Reserve Bank will make the decision and I also make the point that controlling inflation is very important and the Reserve Bank has to keep that very much in mind," he told reporters.

Vidale and two colleagues, Katie Boyle of Lawrence Livermore National Laboratory and Peter Shearer of the University of California, San Diego, examined data from 83 Japanese earthquake swarms over about 2½ years. Their findings confirmed work they published earlier this year that looked at data from 72 events in southern California during a 19-year span.

Both studies examined data collected from swarms in which at least 40 earthquakes were recorded in a few-mile radius over two weeks. The swarms did not follow the well-recognized pattern of an earthquake burst that begins with a main shock and is followed by numerous smaller aftershocks.

"We saw a mix of the two kinds of events, swarms or earthquakes and aftershocks, wherever we looked," Vidale said. "It confirms what people have suspected. There are earthquake swarms and they are responses to factors we can't see and don't have a direct way to measure."

The Japanese research is being published tomorrow in the online edition of Geophysical Research Letters.

The scientists suspect that "swarminess" in volcanic and geothermal zones might be driven by hot water or magma pushing fault seams apart or acting to reduce friction and enhancing the seismic activity in those areas.

Away from volcanic and thermal regions, it is unclear what triggers swarms that don't include main shocks and aftershocks, Vidale said. It is possible that swarms are driven by tectonic movements so gradual that they take many minutes to weeks to unfold but still are much more rapid than normal plate tectonic motions.

The researchers also found that, contrary to expectations, swarms occurring within 30 miles of Japan's volcanoes lasted perhaps twice as long as swarms in other types of geological formations. It was expected that earthquake episodes would have been briefer in hotter rock formations.

The results help to provide a clearer picture of how seismic swarms are triggered and give a better means of assessing the danger level for people living in tectonically active regions where earthquake swarms might occur, Vidale said.

The statistical analysis led by University of California-Santa Barbara Associate Professor Bradley Cardinale concludes both the number and varying types of species are needed to maintain ecological balance and "services."

"By combining the results of more than a hundred studies performed over two decades, we were able to conclusively show the extinction of species from our planet will change the way pests and diseases are controlled, organic wastes are broken down and recycled, food is produced by ecosystems, and water is purified," Cardinale said.

Cardinale said a third to half of all the species now on the planet are expected to be lost during the next 100 years, primarily due to the cutting of rainforests, development and pollution.

The research appears in the journal Nature.

A mother and her son and daughter, who had also been aboard the canoe, managed to swim to shore and were rescued by police.

A huge search for the man, a 40-year-old German, was called off at 5pm last night. The four had gone out fishing without life jackets in the Canadian-style canoe.

An RAF helicopter from Prestwick spotted it upturned at the southern end of Loch Freuchie, Perthshire.

Police, who managed to haul the canoe ashore, will resume their search today at first light.

Police divers will be on standby at the loch, which is near Dunkeld.

The mother and her two children are from Meigle, near Coupar Angus, Perthshire.

Locals described the conditions on the water as the worst they had seen "for some time".

One said: "The winds had been gale-force since about lunch time and, as soon as that happens, the waves on the loch quickly pick up.

"It would be suicide to go out there in a small boat without lifejackets.

"The water is freezing at this time of year. If you get swamped and go in, you have little or no chance.

"It's a miracle that some of them managed to get to shore at all."

The three family members were checked by a doctor at the scene.

But they were taken to Perth Royal Infirmary after showing signs of mild hypothermia.