Dinsey, aspirin is a great and effective nsaid painkiller and anti-inflammatory. But, take too much and you're nothing more than a hairy sack of decaying meat.
A certain balanced level of CO₂ is necessary for life on the planet. However, when excess CO₂ builds up in the atmosphere because we are producing more than nature can handle and cleanse, we get a buildup of the greenhouse effect, in which heat from the sun pierces the upper atmosphere to strike the Earth and the portion that is reflected from the Earth's surface can't re-pierce the built-up CO₂ layer and remains in our atmosphere, warming the planet.
We know this to be true and scientists have demonstrated it experimentally thousands of times. In addition, we have the geological record, in particular samples of air bubbles in cored drilled in the Antarctic that let us test the air going back between 300,000 and 600,000 years. There have been previous build-ups in CO₂ which have coincided with warm periods in the Earth's past.
However, natural rises and falls of CO₂ levels happen over geological timespans - taking many thousands, even millions of years, to significantly affect our climate. There are only two causes of sudden significant changes happening in timespans of mere centuries, decades, years, and even shorter.
One is catastrophic natural disasters, which fall into two sub-categories; 1) meteorite or comet collisions with the Earth's surface, or 2) massive super-volcano eruptions resulting in widespread production of flow basalt. We have seen neither of these sufficient to cause the dramatic rises in CO₂ in the atmosphere of the kind we are now seeing in all of recorded history.
The only other mechanism that can change the levels of CO₂ in the atmosphere as quickly and dramatically as we have been experiencing over the past few decades, and which is growing larger year after year, is the introduction of excess CO₂ into the atmosphere by the human use of fossil fuels.
It never amazes me how little study of the actual mechanisms of climatology the climate-change deniers bother to do - making them credulously susceptible to the nonsense that people like Senator Inhofe and the pseudo-scientific representatives of the polluting industries and those zealots of the unregulated laissez-faire free-market who fear that the truth on global climate change might lead to more regulations and set back their efforts to replace democracy with a market-based corporatocracy.
It seems with every issue where science and either conservative politics or religion are at odds, the opponents of science gather all of the 'evidence' for their opinions from ideological sources with obvious agendas, never from actually learning the science they are deriding in their ignorance.
Study the science, not the pundits of either side.
As Robert A. Heinlein wrote through the voice of his character, Lazarus Long:
"What are the facts? Again and again and again--what are the facts? Shun wishful thinking, ignore divine revelation, forget that 'the stars foretell,' avoid opinion, care not what the neighbors think, never mind the unguessable 'verdict of history,'--what are the facts, and to how many decimal places? You pilot always into an unknown future; facts are your only clue. Get the facts!"
