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Originally Posted by spadlet
BUT the earth has gone through periods of warming before and ice ages. In those cases there was not the current trend of human emissions to be the cause of the changes. Life adapted and continued to live on the Earth. The issues with the current climate change are related to the speed with which the clomate is changing, as it happening so quickly that it is difficult for species to adapt. Humans will also have to adapt to different living conditions, regardless of whether the changes are directly related to humans or not. There is not adequate documantation of the causes and responces of previous large climate chages for people to predict with any certainty what will happen or exactly how and why it is happening.
There are correlations between increases in emissions and changes in climate. There are also correlations between the sales of sun hats and the sales of sun block. Sales of sun hats do not cause sales in sun block, they are connected by the fact that they are both related to changes in the weather. Correlations do not prove dependancy. Scientific theories continue to exist because they cannot be disproved. Once a theory is disproved it becomes invalid. The link between the increase emissions from humans and changes to the climate does not appear to have been scientifically disproven, hence it is a live theory. However until we can explain exactly what is happening, how it is happening and accurately predict what will happen we do not know if the theory will turn out to be in the relms of the world being flat (which was a valid theory until somebody managed to sail around it without falling off) or the relms of the existance of gravity (which increases in knowledge have all confirmed and behaviour continued to correspond to predictions).
Stories continue to be published about revisions to predictions from organisations such as the IPCC. This would illustrate that their current understanding of the subject is not sufficient to enable them to explain exactly what is happening, how it is happening or accurately predict what will happen.
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Yes you are right, the earth has gone through several warming and cooling cycles. But before the industrial revolution, only 200 years ago, the carbon count never exceeded 275 parts per million. It seemed that at that level, the climate of the earth fluctuated in a fairly narrow range allowing species to flourish over a long period of time. However, in the last 200 years that carbon concentration has risen from the "normal" pre-industrial level of 275 to about 385 today. This number is significant because above 350 scientist now believe that we will quickly reach a tipping point of climate change that will be irreversable no matter what steps we take. In fact, we may have already reached that point according to some, as evidenced by the alarming melting rate of earth's glacers and polar ice sheets.
A foremost climatologist, NASA's Jim Hansen, submitted a paper to Science magazine with several co-authors. The abstract attached to it argued -- "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm." He cites six irreversible tipping points -- amoung them massive sea level rise and huge changes in rainfall patterns, -- that we'll pass if we don't get back down to 350 soon; but instead of slowing down our carbon emissions, we are speeding up ! A few weeks ago came the news that atmospheric carbon dioxide had jumped 2.4 parts per million last year -- two decades ago, it was going up barely half that fast!
The Indian scientist and economist Rajendra Pachauri, who accepted the Nobel Prize on behalf of the Intergovernmental Panel on Climate Change last year said "If there's no action before 2012, that's too late. What we do in the next two to three years will determine our future. This is the defining moment."
The world has been talking about climate change for more than a decade and has made no progress, instead we continue to pour carbon into the atmosphere at an ever increasing rate. We are already seeing some of the consequences of our addiction. It is irrefutable that we are suffocating the planet - no one can realistically say that climate change is not the result of human activity -- there is just too much overwhelming evidence that it is. So given that the world does not have the will power to kick its carbon habit and change its life style or for emerging countries to abandon lifitng its citizens out of poverty, an agressive internation program to cut back on the world's population along with continued carbon management is the only realistic, long term solution. But it may already be too late.