Should we really be afraid of Global Warming? Or is this the true grim reality.
Quote (Nigel Cawthorne 2005)
Before the current preoccupation with global warming, scientists were predicting the coming of a new ice age. Given that ice ages - that is eras when thick sheets of ice extended from the poles over vast tracts of land occurred regularly during the history of the Earth, this idea did not seem too far=fetched. The last ice age ended around 12 000 years ago.
Until the 1970's, scientists believed that over the last million years, there have only been four ice ages and the warm, or interglacial, periods between them had lasted between 100 000 and 300 00 years, meaning that there was a long time to go to the next one. Then a geologist named Dr Cesare Emilinai from the University of Miami looking a core samples extracted from the bottom of the Atlantic and pacific oceans, and the Caribbean sea. Using a method called isotope analysis; he discovered that there had actually been seven ice ages, and that the interglacial periods had lasted for no more than 10 000 years. All of this, Dr Emilinai realized meant that a new ice age was now about 200 years overdue.
There are a number of theories about how ices ages begin and they may even be caused in a number of different ways. The general scientific consensus, however, is that the long-term cycle is caused by a slight variation in the output of the sun, eccentricity in the earth’s orbit a long term wobble in the earth’s axis. At the moment the earth is moving towards minimum tilt, the position in which ice ages are most likely to occur.
Increased snowfall at the poles thicken the ice sheet there and the weight of the ice forces it to flow outwards and the process is set in motion, the ice sheets literally feed themselves reflection more light and heat out the atmosphere back into space with their dazzling white surfaces. As the ice sheets spread, they cool the earth, allowing them to spread, which cools the earth.
The spreading ice sheets give a greater area for the snow to fall on and, in the centre they grow thousands of feet high. This gives them, a slightly domed top. As the wind blows over it, the pressure and temperature fall until they reach the dew point, the point where the air can hold no more water vapor. It is deposited in form of hoarfrost, like the ice-flakes that appear around the cooling element in a fridge building the centre even higher, increasing the weight of the ice and forcing the ice sheet to spread further.
During the last ice age, some 30% of the earth’s surface was covered with snow. Skipping the description of the Ice age, if you want to know it, go to Wikipedia or something.
Although Homo Sapiens did exist during the last ice age, they numbered only a few million, not the approximately six billion today. There is no evidence that agriculture had begun, but, in suck conditions, it would have been rendered impossible. With the drop in sea level, the continental shelves would have been exposed leaving only deep water fish, virtually useless as a food source for starving humans. The pickings for the hunter-gatherers would be equally as slim, leading to a steep reduction in Human population. Despite global warming, there is currently a dispute among scientists about where the temperature in the Antarctica is falling or rising. While there is plenty of evidence that the polar ice sheets are breaking up around the edges, some are reporting that the ice sheets are actually getting thicker.
Ironically, global warming itself could help bring on a new ice age. Currently, warmth is moved around the planet by huge currents of warm water flowing out from the equator. One of these is the Gulf Stream, which flows up through the North Atlantic, warming the eastern seaboard of the United States, the grand banks off Newfoundland and northeast Europe. As it moves northwards it cools and the heavy saline water sinks to the bottom of the ocean to make its return journey.
However, it is feared the increased melting of Greenland’s ice sheet due to global warming will inject so much fresh water into the system that it will dilute the salt water of the Gulf Stream. With less salt in the water it will no longer sink at northern latitudes – effectively shutting of the North Atlantics conveyor belt.
There are signs this is happening. The Greenland ice sheet is currently dumping 50 cubic kilometers of ice and snow into the sea each year, and this pace is accelerating as melt water lubricates the base of the glacier speeding its progress.
Other important sources of fresh water in northern latitudes are the Ob, the Enesai and the Elena Rivers in northern Russia, which between them discharge fresh water equivalent to the outflow of three Mississippi’s. Global warming is expected to increase rainfall in their Siberian catchment area. As a result of this predicted increase in rainfall these rivers are expected to deliver at least 50% more fresh water into the sinking zone.
If the Atlantic conveyor shuts down, Britain would have the climate of Iceland, and the whole of northern Europe would disappear under ice and snow. The geological record shows the Gulf Stream did indeed shut down for 1000 years during the last ice age. And this is not a problem for just Europe. Other large scale currents could be switched off too.
There is also a theory that higher global temperatures will cause more evaporation from the seas, increasing snow at the poles, and triggering the spreading of the ice sheets. And billowy white clouds of water vapor high in the atmosphere block out our sun and reflect heat and light back into space.
In some models of climate change a catastrophic fall in temperature go underway, it would be unstoppable and the ice sheets would continue to spread until all earths water was locked up in them.
Once the Earth had turned into a frozen ball, life here would become impossible. This happened before when the Earth was formed 4.6 billion years ago, heat was generated as the pieces were compacted by gravity. Over time, as this activity slowed down, the earth cooled.
Back then, the Sun’s radiation was much weaker. Ice sheets were able to form at the poles and were pushed towards the Equator, until the earth was encased in a shell of ice a kilometer thick. The white ball reflected solar radiation back into space and the temperature dropped to -50 degrees C.
It seems that the earth escaped from this frozen hell through the action of volcanoes. As well as bringing heat from inside the Earth to the surface, they pumped CO2 and other greenhouse gases into the atmosphere, which trapped the Sun’s rays. Apparently, the earth lapsed back into its frozen state at least five times until life exploded on the planet at the beginning of the Cambrian period, some 540 million years ago, shortly after the output of the sun reached something approaching today’s level.
Even within historical time there have been dramatic dips in temperature. A “little” ice age occurred during the 1500’s and 1850, when solar activity was low. The main westerly storm belts shifted some 300 miles to the south and northern latitudes came under cool continental conditions. This snuffed out of the Viking colony in Greenland, whose 500 year existence was ended by encroaching glaciers. The Thames froze over; becoming a skating rink for his court by 1690, eight years of crop failure brought serious famine to Britain, killing as many people in Scotland as the plague was killing on the Continent. Sea Ice reached the Faroe Islands, some 200 miles north of mainland Britain. Following the edge of the pack ice, several kayaks carrying Eskimos turned up in Scotland. Glaciers advanced in Norway, and in Switzerland several villages were lost under ice. Frost Fairs on the frozen ice of the Thames in London continued as late as 1814 when the earth emerged from the mini ice age.
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