They way I see it :
1) CO2 is an insulating gas, provable in a junior school science project
2) We have released measurable amounts of CO2 by burning fossil fuels, the quantity of which you can calculate in a high school maths lesson.
3) We know the size of the atmosphere
4) Therefore we know as a percentage, how much more CO2 we should have
AND
5) We can measure the CO2 increase very accurately - and it IS on the increase at a rate greater than at any time in earths history.
Currently we are fairly sure a chunk was absorbed by the sea, as the sea is becoming more acidic and the amount we expect to find - that we KNOW we released, isn't there. The sea is saturating though (again you can demonstrate this easily in a school lab), so we should expect to see CO2 levels rising more quickly ongoing.
By far the majority of science papers out there conclude the same thing, the deniers cling to tiny bits of obscure contrary evidence and bang on and on about it, ignoring the bulk of the evidence altogether. Its like the moon landings being a hoax, they cling to scraps of "evidence" and totally miss the bigger picture (like that the Russians were watching very very closely).
Of course, there will always exceptions and queries, but in science, it is the wealth of data which is used, not odd exceptions.
I have never met a "denier" with a really credible argument, just a bunch of people with a good reason to find a way of avoiding the truth.
Chosen Charity:
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