There is a rather large consensus that world temperatures were higher 1000 years ago than they are today. Two thousand years ago, it was also warmer than it is today. It is also commonly accepted that between the 14th and the 19th century, temperatures were lower than they are today; during that period Earth experienced a cold spell. Some even have called that period a mini-ice-age, although that seems like a major exaggeration. When the 19th century began, temperatures began to rise and that trend has generally continued. So here is the big question: what temperature is normal? Were the higher temperatures a thousand years ago normal? There were no carbon dioxide emissions affecting the globe at that time, but things were warmer than they are today.
This is not an unimportant question. Right now, despite the discrediting of the computer models that predicted global warming due to human activity, we still keep hearing about how climate change presents a major problem which requires strong action. But does it? Are we witnessing a gradual rise in temperatures due to human activity, or is this just the bounce back following the so called mini-ice-age? Is the use of cars and other manifestations of civilization causing warming or are we just witnessing the normal variations in long term climate? And why should we look at warming compared to the days just prior to the Industrial Revolution when the Earth was still in the grip of the mini-ice-age? Were those days of cold actually normal, or were they abnormally cold?
The truth is that we have no real answer to most of these questions. There are theories that increased carbon dioxide in the atmosphere should cause warming through a greenhouse effect. We also have, however, historical data that shows high levels of carbon dioxide during ice ages and low levels during warming periods of the past. None of this evidence is conclusive proof one way or the other, however. All we know for sure is that the models created to predict the effects of additional carbon dioxide on climate are wrong. They cannot even recreate what happened in the last century. There are simply too many variables, with the result that the computer models are overwhelmed.
Maybe the best way to put this is to give an example. Suppose some day in the distant future humans land in their space ship on a distant uninhabited planet. They land during the winter season of the area, a season that lasts for ten Earth years. After ten years on the planet, spring arrives on this planet and temperatures warm. The humans, however, conclude that this new planet is experiencing global warming because they have never before been though the cycle of the seasons on their new home. They don't understand what is normal and what is abnormal. This may very well be where we are today except the cycle is much longer. We just do not understand why the planet was much warmer 1000 and 2000 years ago or why it cooled so much 500 years ago. All we know is that it is warmer on Earth today than it was 200 years ago. We do not know why, no matter how many times you hear about a supposed consensus of scientists (that actually does not exist).
This is not an unimportant question. Right now, despite the discrediting of the computer models that predicted global warming due to human activity, we still keep hearing about how climate change presents a major problem which requires strong action. But does it? Are we witnessing a gradual rise in temperatures due to human activity, or is this just the bounce back following the so called mini-ice-age? Is the use of cars and other manifestations of civilization causing warming or are we just witnessing the normal variations in long term climate? And why should we look at warming compared to the days just prior to the Industrial Revolution when the Earth was still in the grip of the mini-ice-age? Were those days of cold actually normal, or were they abnormally cold?
The truth is that we have no real answer to most of these questions. There are theories that increased carbon dioxide in the atmosphere should cause warming through a greenhouse effect. We also have, however, historical data that shows high levels of carbon dioxide during ice ages and low levels during warming periods of the past. None of this evidence is conclusive proof one way or the other, however. All we know for sure is that the models created to predict the effects of additional carbon dioxide on climate are wrong. They cannot even recreate what happened in the last century. There are simply too many variables, with the result that the computer models are overwhelmed.
Maybe the best way to put this is to give an example. Suppose some day in the distant future humans land in their space ship on a distant uninhabited planet. They land during the winter season of the area, a season that lasts for ten Earth years. After ten years on the planet, spring arrives on this planet and temperatures warm. The humans, however, conclude that this new planet is experiencing global warming because they have never before been though the cycle of the seasons on their new home. They don't understand what is normal and what is abnormal. This may very well be where we are today except the cycle is much longer. We just do not understand why the planet was much warmer 1000 and 2000 years ago or why it cooled so much 500 years ago. All we know is that it is warmer on Earth today than it was 200 years ago. We do not know why, no matter how many times you hear about a supposed consensus of scientists (that actually does not exist).
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