Global Warming 1

Quite literally, the hottest topic of this century and will be for many more centuries to come. 'Global warming' is a huge buzz word, along with 'greenhouse gases' and 'ozone layer'. Yes, I can hear some of you moaning, "Oh god, more alarmist crap".

Everyone is talking about global warming, but how many of you actually know enough about the subject to form an opinion. How many have taken the trouble to read about it and I don't mean the alarmist articles in the papers. Here I present some history, some facts, some scenarios and finishing up with my opinions on day 3. I hope you all join in and present your own opinions, be they one liners or full stories, all is allowed.

Ice Age - You cannot fully get a feel for global warming without first understanding a little about where we are in the history of the earth's climatology. We are currently in the middle of a series of ice ages that have been going on for the last 2.5 million years. We are just about reaching the peak temperature and will be starting our descent into the next ice age in a few thousand years.

So today, I am going to bring you up to speed on ice age theory.

Study methods - Scientists have known about an Ice age for probably 200 years or more, but it was in the late 19th century that scientists started to recognize evidence of multiple ice ages. This evidence was in the form of rock deposits, strange boulders hundreds of miles out of place, carried by ancient glaciers. 'U' shaped valleys with polished rock faces, lakes formed by natural dams. Examining the layers of exposed cliff faces also provided visible evidence of multiple ice ages.

As technology advanced, methods were invented to measure the age of these samples, such as radio carbon dating, which measures the radioactive state of the carbon-14 isotope found in organic material buried thousands of years ago.

Swedish scientists discovered a method of isolating and analyzing ancient pollens, to predict the fauna of past ages. This analysis gave an indication of climatic temperatures at specific times by the type of fauna growing at that time.

By the mid 20th century there was strong evidence of ice age cycles. Evidence of cyclic changes in sea levels were discovered. We are not talking about the few inches that the 'global warming' brigade are whittering about, we are talking about in excess of 100 meter drops in sea level, due to water being taken out of the system and stored in glacial ice.

In 1947, a nuclear chemist, Harold Urey, discovered a method to measure oxygen isotopes, trapped in fossil seashells. The ratio of O18/O16 isotopes gave an indication of temperature. This was refuted years later, but the ratio still reflected the ice age cycles.

In the 1960's, fossil reefs, that had been raised by geological events and were dated by measuring the decay of uranium and other isotopes. Because uranium decays much slower than carbon, the method could look back deeper into geological history than carbon, and with more accuracy.

Ice drilling and finally, oceanic drilling operations by oil companies, produced cores that enabled a million years of detailed climate study.

Cycles and causes - Evidence of ice age cycles was mounting and so the race was on to try and find a solid explanation of cause. If this could be accomplished then further ancient effects could be explained and dated accurately and more importantly, future events could be predicted.

As early as the mid 1800's, James Croll figured out that the sun, moon and planets had a significant effect on the motion of the earth. The axis of rotation of the earth was constantly changing, even the shape of the earth's orbit was cyclically changing. He suggested at the time, that the varying distances from the earth to the sun and the angle to the sun would obviously have an effect on the climate, but the scientists of the day just didn't buy the idea. They figured that the astrological effects would be negligible and not likely to cause anything so significant as an ice age.

A Serbian engineer Milutin Milankovitch, liked Croll's ideas and continued the work in the 1920's and 30's. As well as improving the astro calculations, he also figured out that if the angle of the earth and distance from the sun was such that the winter snowfall between latitudes 55N and 65N did not completely melt away, then there would be a buildup of snow over hundreds of years. The heat energy reflected away by the white sheets of snow would exasperate the effect and the cooling would accelerate. Thus the small astral change had a magnified feedback as more cooling meant more ice, more reflection and more cooling.

Milankovitch came up with figures of 19,000 years, 23,000 years and 41,000 years as various astrological cycle times. This closely matched the earth's wobble with various ice age evidence in silts and fossil date cycles of 21,000 years. The science world was still not buying the idea, also the numbers did not fit the dates calculated for the four previous ice ages from the evidence collected by many geologists of the day and so the idea was not only rejected, but ridiculed.

The use of the new carbon dating technology in the 60's, confirmed the 21,000 year cycle in many locations, but there was also conflicting evidence from other locations.

Finally in 1973, Nick Shackleton nailed it, with his analysis of the best oceanic core to date, from the Indian ocean. The core covered a time period of over a million years. He was able to show timed cycles of 20,000, 40,000 and 100,000 years. His team even managed to split the 20,000 year cycle into 19,000 and 23,000 year cycles, which provided confirmation that not only was Milutin Milankovitch right on the mark, but also James Croll, from the mid 19th century was also correct. Also, a slight variation in the earth's orbit was discovered and this accounted for the 100,000 cycle documented from Shackleton's core analysis.

Finally the astrological events that effected the earth's rotation were accepted as 'pacemakers' for the ice ages, but the question remained - how?

As time moved on, more and better cores were extracted from the ice sheets and the ocean beds, stretching back hundreds of millennia. It was discovered that the 100,000 cycle was only a recent anomaly and that the stronger cycle was the 41,000 year cycle of Milankovitch.

The biggest discovery from the ice cores was the measurement of carbon dioxide levels which had risen and fallen with the cycles, the carbon dioxide in the ice being much higher during the cold spells. The same was discovered for the other gas, methane. I will talk more on 'greenhouse effect and gases' tomorrow.

The introduction of these gases provided explanations for the shape of the ice age cooling graphs. From a temperature peak, the graphs showed a gradual cooling. The temperature bottoms out and then rapidly rises up to the maximum, and the cycle repeats.

Explanation - as the astral cycle separates the earth from the sun, the ice sheets on the mountain tops fail to completely melt during the summer and ice starts to build. Glaciers start to form and spread. The solar reflection of the white ice sheets causes further cooling and the ice sheets start to grow.

As temperatures gradually drop, the methane and carbon dioxide gasses are dissolved into the oceans, thus reducing the greenhouse effect and promoting the cooling.

When the earth cycle gets closer to the sun, the temperatures start to rise, the gasses come out of solution. The greenhouse effect accelerates the rise in temperature and the glaciers melt more rapidly. The earth cycle moves away from the sun, a temperature balance is reached and then the whole cycle repeats.

The last ice age - the figures quoted are to the last ice age finishing some 15,000 years ago and we are roughly approaching the peak temperature. The gradual fall into the next ice age will happen in a few thousand years.

But what we talk about as the last ice age is simply one cycle that has been repeating for the last 2,500,000 years, called the neogene period. It would be more accurate to call it the last cold event in the current ice age period. This is the fifth ice age period to hit the earth, but for hundreds of millions of years in between, the earth has been ice age free.

Previous ice ages - assuming that the astro events that pull on the earth, causing the deviations that trigger the ice events, are always constant, then why have there been hundreds of millions of years without ice ages?

Scientific evidence shows that vegetation was lush and carbon dioxide levels were even higher than they are today. Despite the continuing cooling astral cycles, the warming greenhouse effect of the carbon dioxide prevented the first stage of an ice age by preventing glacier formation.

The early doubters of the astrological proposals of Croll and later Milankovitch, stated that the astrological effects were minimal and could not possibly effect the earth to produce an ice age. This is in fact true. The astrological effect is merely a poke that triggers a chain reaction of feedback effects; a small build up of ice on the mountains, heat radiation reflection, carbon dioxide and methane absorption by the cooling oceans, reduced greenhouse effect, more glaciers and the climate spirals into an ice age.

But, if the feedback parameters change, then the cycle is broken and the ice age does not happen.

This is the background completed. Hope this was not too heavy, I am trying to keep it simple. To be continued tomorrow.

Dave