Global Climate Change

This series of pages is being written in response to what I see as a global crisis.  For years now we have been assailed by TV, newspapers, and politicians with a loud and very clear message - "Planet Earth is getting warmer and man's activities are responsible!"  We are further told that "There is a global consensus among scientists that man-made carbon dioxide is the primary cause of global warming."

I am so unhappy with these statements, and by the bad science which is being demonstrated by all those "scientists" who are supposed to have contributed to the "global consensus" that I felt I had write something, to try to stop the misinformed and biased political train before it wrecks itself in the station, with all of us on board.

These pages will examine the facts.  Not just the facts which conveniently fit and support the model of runaway temperature rises, claimed to be caused by the CO2 produced by mankind, but all the other facts which point in a very different direction and which are being ignored by the global warming "disciples" simply because they do not fit the theory.  I should stress that I am not a climatologist, nor am I an oceanographer, but I know a number of people who are, and I read their work.  I also like to think I can see something if it is staring me in the face, and when we speak about global warming I feel frankly that most people have become so blinded by the "hype" that they can't see the truth.  I am a scientist, I am a reasonable astro-photographer, I have a good understanding of most things astronomical - and recently I have made an intensive study of all the current science associated with the climate changes which are clearly taking place on planet Earth.  So here, presented in the clearest way I can, are all the factors which we know are influencing our climate, to help you make your own judgement about what's happening, and to decide for yourself whether you, like me, feel we are being deceived.

Is Global Warming Happening?
Before we start it is important to establish whether the major claim of the "warmists" is correct.  Is the planet actually warming up?

Well, the answer based on all available data is "yes - but".  The "but" is that, as I will show in a moment, the Earth's climate has always been subject to cycles of warming and cooling, so we should not be too surprised to learn that the average temperature varies all the time, whatever we do in our 4x4's or with our smoky chimneys.  In fact, in the current episode, global warming began long before the "Industrial Revolution".  It actually began 18,000 years ago as the earth started warming its way out of the Pleistocene Ice Age, a time when much of North America, Europe, and Asia lay buried beneath great sheets of glacial ice.  And this is one of the most important messages I want to communicate to you, so I will repeat - Earth's climate is constantly changing and cycling from cold to warm and back again.  Our climate has been dominated by ice ages and glaciers for the past several million years and we are currently enjoying a temporary reprieve from the deep freeze.

This is because approximately every 100,000 years Earth's climate warms up temporarily.  These warmer intervals, called interglacial periods, appear to last approximately 15,000 to 20,000 years before we go back to a cold, ice age climate.  We are currently standing at year 18,000 in the current inter-glacial period, and so we have to believe that our current respite from the ice is much nearer its end than its beginning.

"Global warming" during Earth's current interglacial warm period has greatly altered our environment and the distribution and diversity of all life. For example:

  • Approximately 15,000 years ago the earth had warmed sufficiently to halt the advance of glaciers, and sea levels worldwide began to rise.

  • By 8,000 years ago the land bridge across the Bering Strait was drowned, cutting off the migration of men and animals to North America.

  • Since the end of the last Ice Age, Earth's temperature has risen approximately 16 degrees F (9 degrees C) and sea levels have risen a total of 300 feet (100 metres)!  Forests have returned where once there was only ice.

I don't intend in this article to go deeply into the ways we can measure historic and prehistoric temperatures.  I will only summarise it here by saying that by using a mixture of oxygen isotope ratios, temperature sensitive tree ring data, ice core data and numerous other sources it is possible to calculate pretty accurately what the various data looked like way into the distant past.  I am not saying the methods used are foolproof, but I, and most scientists around today are satisfied that there is sufficient scientific basis and peer review confidence that we can be pretty sure the data are good.

So how exactly has global temperature varied with time?

This is a plot of global temperature variation for the last 1,000 years.  You can see that there is a fairly definite cycle - of about 500 years - and the well documented Medieval Warm Period is easy to see, as is the "Little Ice Age" between about 1350AD and 1850AD, when again there is extensive documentation of a period of lower than average temperatures.  The point is our current "warm" interval is normal, and could have been predicted using these data.
Historical temperature and carbon dioxide data referenced from R. S. Bradley and J. A. Eddy, based on J. T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge University Press, Cambridge, 1990 and published in EarthQuest, vol 5, no 1, 1991.
If we go back even further in time things get really interesting because we can see evidence of yet more cycles - much longer this time, with a period of perhaps 4,500 years.  For the current debate about man-made global warming, the period known as the Holocene Maximum should be examined, because it was the hottest period in human history. However, this period occurred approximately 7500 to 4000 years before the present day, long before humans invented industrial pollution.  Early man was powerless to change things then, and I would submit we are powerless to change things now.
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