One of the more interesting results from recent research into climate is that for the past million years or so, the earth's climate has shown a distinct 100,000 cycle of long ice ages punctuated by a brief, warm intergalacials. We are in one of those brief warm periods, an interglacial period that is called the Holocene.

This cycle can be seen in the temperature graph below taken from publicly available Vostok ice core data. The ice cores are very long sections of ice in which ancient climates can be worked out by careful analysis of atomic isotopes of layers of ice, where each wafer thin layer represents a year. Although there are other ways to determine past climatic conditions the Vostok cores (the site is in Antarctica but run by Russian scientists) are remarkable in being a connected track of temperatures of several hundred thousand years.

As you can see climate changes by about 14 degrees C from the top of the interglacial to the bottom of the ice age, but even the 420,000 or so years covered by the Vostok cores is just a moment in earth's geological history. As noted, the 100,000 year cycle has been a feature of climate for about a million years. For two million years before that the cycle was the same except that it was 40,000 years long and temperatures were warmer. The whole three million years, in turn, is part of an ice age phase of the earth in which temperatures have generally been falling. There have also been hot house phases.

There are ominous signs that the Earth's weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production - with serious political implications for just about every nation on Earth. The drop in food output could begin quite soon, perhaps only 10 years from now. The regions destined to feel its impact are the great wheat-producing lands of Canada and the U.S.S.R. in the North, along with a number of marginally self-sufficient tropical areas - parts of India, Pakistan, Bangladesh, Indochina and Indonesia - where the growing season is dependent upon the rains brought by the monsoon.

The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it. In England, farmers have seen their growing season decline by about two weeks since 1950, with a resultant overall loss in grain production estimated at up to 100,000 tons annually. During the same time, the average temperature around the equator has risen by a fraction of a degree - a fraction that in some areas can mean drought and desolation. Last April, in the most devastating outbreak of tornadoes ever recorded, 148 twisters killed more than 300 people and caused half a billion dollars' worth of damage in 13 U.S. states.

To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world's weather. The central fact is that after three quarters of a century of extraordinarily mild conditions, the earth's climate seems to be cooling down. Meteorologists disagree about the cause and extent of the cooling trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. "A major climatic change would force economic and social adjustments on a worldwide scale," warns a recent report by the National Academy of Sciences, "because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century."

Paris- A sudden plunge of global temperatures at the dawn of human civilisation may have been caused by a comet impact, a British researcher argues.

Known as 'the Younger Dryas', it has been also called the Big Freeze and the Last Blast of the Ice Age - but for researchers trying to understand the Earth's ancient climate, it's one of the big mysteries of the field.

Around 12,900 years ago, Earth was on a steadily warming trend after almost 100,000 years of harsh glaciation, during which ice sheets placed a swathe of the northern hemisphere under a dead hand, extending their thrall as far as south as New England and Wales.

Oxford University is involved in a research project to unearth 30,000 year old climate records, before they are lost forever. The rings of preserved kauri trees, hidden in New Zealand's peat bogs, hold the secret to climate fluctuations spanning back to the end of the last Ice Age.

The team, led by Exeter University, has been awarded a grant from the Natural Environment Research Council to carry out carbon dating and other analyses of the kauri tree rings. The trees store an immense amount of information about rapid and extreme climate change in the past. For instance, wide ring widths are associated with cool dry summer conditions. The scientists believe their findings will help us understand what future climate change may bring.

Tree rings are now known to be an excellent resource for extracting very precise and detailed data on atmospheric carbon from a particular time period. Therefore this study could help plug a large gap in our knowledge of climate change by extending historical weather records that only date back to the mid-nineteenth century.

The ocean current that gives western Europe its relatively balmy climate is stuttering, raising fears that it might fail entirely and plunge the continent into a mini ice age.

The dramatic finding comes from a study of ocean circulation in the North Atlantic, which found a 30% reduction in the warm currents that carry water north from the Gulf Stream.

The slow-down, which has long been predicted as a possible consequence of global warming, will give renewed urgency to intergovernmental talks in Montreal, Canada, this week on a successor to the Kyoto Protocol.

Harry Bryden at the Southampton Oceanography Centre in the UK, whose group carried out the analysis, says he is not yet sure if the change is temporary or signals a long-term trend. "We don't want to say the circulation will shut down," he told New Scientist. "But we are nervous about our findings. They have come as quite a surprise.

Ireland suffered its coldest winter in almost five decades as the country shivered in the big freeze, it was revealed.

Met Eireann said temperatures were around two degrees lower than average during the season, making it the coldest winter recorded since 1963.

Arctic conditions experienced at the end of last year continued through January and February, with widespread spells of frost, sleet and snow.

Temperatures plummeted to below minus 10C in some places, with minus 16.3C recorded at Mount Juliet, Co Kilkenny, on January 7.

A leading scientist has revealed that Europe could be just five years away from the start of a new Ice Age.

While climate change campaigners say global warming is the planet's biggest danger, renowned physicist Vladimir Paar says most of central Europe will soon be covered in ice.

The freeze will be so complete that people will be able to walk from England to Ireland or across the North Sea from Scotland to northern Europe.

Professor Paar, from Croatia's Zagreb University, has spent decades analysing previous ice ages in Europe and what caused them.

"Most of Europe will be under ice, including Germany, Poland, France, Austria, Slovakia and a part of Slovenia," said the professor in an interview with the Index.hr.

"Previous ice ages lasted about 70,000 years. That's a fact and the new ice age can't be avoided.

A new ice age is due now, but you won't hear it from the green groups, who like to play on Western guilt about consumerism to make us believe in global warming.

The Earth's climate is changing in a dramatic way, with immense danger for mankind and the natural systems that sustain it. This was the frightening message broadcast to us by environmentalists in the recent past. Here are some of their prophecies.

The facts have emerged, in recent years and months, from research into past ice ages. They imply that the threat of a new ice age must now stand alongside nuclear war as a likely source of wholesale death and misery for mankind.
(Nigel Calder, former editor of New Scientist, in International Wildlife, July 1975)

The cooling has already killed thousands of people in poor nations... If it continues, and no strong measures are taken to deal with it, the cooling will cause world famine, world chaos, and probably world war, and this could all come about by the year 2000. (Lowe Ponte, The Cooling, 1976)

Manatees, sea turtles and fish in the Sunshine State are dying in record numbers because of the unusually long cold snap.

With temperature in central Florida dipping down again this week, conservationists are bracing for more animal and plant deaths due to unusually long winter cold snaps that have resulted in record wildlife losses.

Manatees have been among the hardest hit, with over 200 killed in January alone, and carcasses continuing to wash ashore. The highest number of manatee deaths for a single calendar year in Florida waters is 429, so local officials are closely monitoring these endangered marine mammals.

"Manatees can experience what is known as cold stress syndrome when they are exposed to water below 68 degrees Fahrenheit (20 degree Celsius) for long periods," Florida's Fish and Wildlife Research Institute spokesperson Carli Segelson told Discovery News. "This can result in death, or weaken manatees, leaving them more vulnerable to other health issues later."

If human activities could change climate, why not change it on purpose, to suit us better? From 1945 into the 1970s, much effort went into studies of weather modification. American entrepreneurs tried cloud-seeding to enhance local rainfall, Russian scientists offered fabulous schemes of planetary engineering, and military agencies secretly explored "climatological warfare." The hopes and fears promoted basic research on climate change by raising large sums of government money and a few provocative ideas. In the mid 1970s the visionary projects were abandoned. Research turned instead to controversial "geoengineering" schemes for interventions that might restrain global warming if it started to become unbearable.

"Intervention in atmospheric and climatic matters . . . will unfold on a scale difficult to imagine at present. . . . this will merge each nation's affairs with those of every other, more thoroughly than the threat of a nuclear or any other war would have done." - John von Neumann¹