In Africa, drought continues for the sixth consecutive year, adding terribly to the toll of famine victims. During 1972 record rains in parts of the U.S., Pakistan and Japan caused some of the worst flooding in centuries. In Canada's wheat belt, a particularly chilly and rainy spring has delayed planting and may well bring a disappointingly small harvest. Rainy Britain, on the other hand, has suffered from uncharacteristic dry spells the past few springs. A series of unusually cold winters has gripped the American Far West, while New England and northern Europe have recently experienced the mildest winters within anyone's recollection.

As they review the bizarre and unpredictable weather pattern of the past several years, a growing number of scientists are beginning to suspect that many seemingly contradictory meteorological fluctuations are actually part of a global climatic upheaval. However widely the weather varies from place to place and time to time, when meteorologists take an average of temperatures around the globe they find that the atmosphere has been growing gradually cooler for the past three decades. The trend shows no indication of reversing. Climatological Cassandras are becoming increasingly apprehensive, for the weather aberrations they are studying may be the harbinger of another ice age.

Global warming fears aside, all students of climate science know that the Earth is presently in an Ice Age and has been for approximately the past 2 to 2.5 million years. This Ice Age has been characterized by successive advances and retreats of a glacial ice sheet, originating in Greenland and extending across the northern portions of the North American and Eurasian continents. Just 12,000 years ago, the undisputed geological evidence shows that New York, Chicago, and all of North America up to the Arctic regions were under a sheet of ice, estimated to have been from 1 to 2 miles thick. Mountain glaciers also extended downward from the Rocky Mountains and the Appalachians in regions further to the south than the main glacial mass. A similar situation prevailed over most of Germany, northern France, the British Isles, Scandinavia, Poland and other parts of eastern Europe, and Russia.

Such had been the state of things on Earth for probably at least 100,000 years. Before that, a short period known as an interglacial had allowed for a warm climate somewhat like the present, and before it another extended period of glacial advance. The thaw which produced our present geography--the Great Lakes, the southward flowing Ohio River, and much else we take for granted--was not completed until about 8,000 to 9,000 years ago, according to the best estimates of geologists and climatologists. Not only were there changes in the internal geography, but the continental boundaries were also greatly changed during the glacial period. Calculations of the volume of water that must have been contained frozen in the continental glaciers, indicate that the global sea level, was lower by as much as 300 to 400 feet at times of glacial advance. A glaciation does not mean sea level rise, but a sharp fall in sea level exposing the continental shelf for miles out to sea. Much of the coastal-dwelling civilization of the past 100,000 or more years, thus lies buried offshore beneath hundreds of feet of ocean.

Can this happen again? The most plausible theory of the causes of the ice ages, the theory of astronomical determination, suggests that the time is ripe for it to happen sometime soon. A Jan. 11 article in the online edition of the Russian daily Pravda was titled "Earth on the Brink of an Ice Age."

Scientists say evidence in the ice of Antarctica and Greenland shows a volcanic eruption, probably near the equator, contributed to global cooling early in the 19th century.

Global warming may be making some people nervous now, but from 1810 to 1819, people worried because the Earth was colder than usual.

For an entire decade, the Earth cooled almost a full degree Fahrenheit. In fact, 1816 was known as the year without a summer. And until recently, scientists weren't quite sure why everyone was shivering.

The chill of 1816 has long been blamed on an Indonesian volcano called Tambora, which erupted the year before. But no one could figure out why the years before Tambora's eruption were also colder than usual.

In the film, The Day After Tomorrow, the world gets gripped in ice within the span of just a few weeks. Now research now suggests an eerily similar event might indeed have occurred in the past.

Looking ahead to the future, there is no reason why such a freeze shouldn't happen again - and in ironic fashion it could be precipitated if ongoing changes in climate force the Greenland ice sheet to suddenly melt, scientists say.

Starting roughly 12,800 years ago, the Northern Hemisphere was gripped by a chill that lasted some 1,300 years. Known by scientists as the Younger Dryas and nicknamed the "Big Freeze," geological evidence suggests it was brought on when a vast pulse of fresh water - a greater volume than all of North America's Great Lakes combined - poured into the Atlantic and Arctic Oceans.

This abrupt influx, caused when the glacial Lake Agassiz in North America burst its banks, diluted the circulation of warmer water in the North Atlantic, bringing this "conveyer belt" to a halt. Without this warming influence, evidence shows that temperatures across the Northern Hemisphere plummeted.

It wasn't quite The Day After Tomorrow but it's closer than we thought. An analysis of mud from Lough Monreagh, a lake in Co Clare, has revealed that Europe was struck by a sudden mini ice age 12,800 years ago, suggesting the kind of rapid climate change previously seen only in Hollywood disaster movies.

It was believed that the "Big Freeze" took about a decade to set in. Based on an analysis of Greenland's ice cores, scientists have estimated that the Younger Dryas, as the event is also named, occurred gradually.

However, after analysing mud deposits from Lough Monreagh, William Patterson of the University of Saskatchewan in Canada, has found that the freeze took only months to take hold.

Using a very precise robotic scalpel, Patterson and his colleagues shaved 0.5mm layers from the lake bed, each representing up to three months of sediment. Carbon isotopes in the samples recorded changes to biological activity in the lake, while oxygen isotopes revealed temperature and rainfall patterns.

The tiny mud deposits showed for the first time that temperatures in Ireland dropped suddenly in the space of several months at the time of the Big Freeze.

Just months - that's how long it took for Europe to be engulfed by an ice age. The scenario, which comes straight out of Hollywood blockbuster The Day After Tomorrow, was revealed by the most precise record of the climate from palaeohistory ever generated.

Around 12,800 years ago the northern hemisphere was hit by the Younger Dryas mini ice age, or "Big Freeze". It was triggered by the slowdown of the Gulf Stream, led to the decline of the Clovis culture in North America, and lasted around 1300 years.

Until now, it was thought that the mini ice age took a decade or so to take hold, on the evidence provided by Greenland ice cores. Not so, say William Patterson of the University of Saskatchewan in Saskatoon, Canada, and his colleagues.

The group studied a mud core from an ancient lake, Lough Monreagh, in western Ireland. Using a scalpel they sliced off layers 0.5 to 1 millimetre thick, each representing up to three months of time. No other measurements from the period have approached this level of detail.

Carbon isotopes in each slice revealed how productive the lake was and oxygen isotopes gave a picture of temperature and rainfall. They show that at the start of the Big Freeze, temperatures plummeted and lake productivity stopped within months, or a year at most. "It would be like taking Ireland today and moving it up to Svalbard" in the Arctic, says Patterson, who presented the findings at the BOREAS conference in Rovaniemi, Finland, on 31 October.

Researchers here have discovered the pivotal role that volcanoes played in a deadly ice age 450 million years ago. Perhaps ironically, these volcanoes first caused global warming - by releasing massive amounts of carbon dioxide into the atmosphere. When they stopped erupting, Earth's climate was thrown off balance, and the ice age began.

The discovery underscores the importance of carbon in Earth's climate today, said Matthew Saltzman, associate professor of earth sciences at Ohio State University.

The results will appear in the journal Geology, in a paper now available online.

Previously, Saltzman and his team linked this same ice age to the rise of the Appalachian Mountains. As the exposed rock weathered, chemical reactions pulled carbon from Earth's atmosphere, causing a global cooling which ultimately killed two-thirds of all species on the planet.

Hunting has been banned in parts of Austria after freak storms with tennis ball-sized hailstones killed up to 90 per cent of the wild game population.

Sepp Eder, the hunting chief, said : "Animals sought shelter in farms, in fields of grain but the hail was so heavy it smashed right into them. It may take five years for animal numbers to recover, if they ever do so."

Farmers are believed to have suffered more than £60 million in damages to crops and buildings.

Hundreds of deer were discovered either dead or so badly injured they had to be put down by wildlife experts.

In the country's rural Salzburg province, 90 per cent of pheasants and 80 per cent of hares were killed in the hail storms.

In a new research, scientists have found evidence on the Martian terrain that points towards a recent ice age on the Red Planet.

The research, by Samuel C. Schon and James W. Head from the Department of Geological Sciences, Brown University, was carried out to explain the distribution of ice in the near subsurface at middle to high latitudes on Mars.

Two hypotheses emerged out of the research.

While one theory suggested diffusion of water vapor into porous regolith, the other indicated atmospheric deposition of ice, snow, and dust during recent ice ages.

To determine which of these hypotheses is correct, Schon and his team used data from the High Resolution Imaging Science Experiment (HiRISE) to examine the structure of exposed subsurface mid-latitude Martian terrain.

The researchers observed that the terrain is characterized by layered deposits multiple meters thick that stretch over many hundreds of meters.

A team of researchers says it has largely put to rest a long debate on the underlying mechanism that has caused periodic ice ages on Earth for the past 2.5 million years - they are ultimately linked to slight shifts in solar radiation caused by predictable changes in Earth's rotation and axis.

In a publication to be released Friday in the journal Science, researchers from Oregon State University and other institutions conclude that the known wobbles in Earth's rotation caused global ice levels to reach their peak about 26,000 years ago, stabilize for 7,000 years and then begin melting 19,000 years ago, eventually bringing to an end the last ice age.

The melting was first caused by more solar radiation, not changes in carbon dioxide levels or ocean temperatures, as some scientists have suggested in recent years.

"Solar radiation was the trigger that started the ice melting, that's now pretty certain," said Peter Clark, a professor of geosciences at OSU. "There were also changes in atmospheric carbon dioxide levels and ocean circulation, but those happened later and amplified a process that had already begun."