[NeilBlanchard]

We know that when carbon dioxide was 1,000PPM that it was a lot warmer, and there was no permanent ice anywhere on the planet. This was about 65 million years ago.

We know that as carbon was naturally deposited in the ground and on the sea floor, from erosion and by plants, and when the level of carbon dioxide dropped to around 450PPM, Antarctica started to freeze up. Later when the levels got lower still, the Arctic started to freeze up.

We know that for the last 650,000 years, carbon dioxide has ranged between ~180PP up to ~280PPM. This is where it was for the first ~200,000 years of human existence.

Then, around 1850 we started burning coal in quantity, and a little later oil and gas. In about 1904, carbon dioxide got up to ~300PPM -- higher than it ever was for all of human existence, and higher than it ever was in the last 650,000 years.

Since then, the level of carbon dioxide has ramped up at an accelerating pace, and is now about 390PPM. Average temperatures worldwide have tracked this increase in lock step.

The Arctic ice is melting at an accelerating rate -- just the inverse of what it did when the carbon levels dropped due to natural processes. The current increase is happening at a rate that is about 10,000 times faster than it ever did from natural sources.

It took about 60 million years for the carbon to get stored in the Earth's crust, and much of that has been released back into the atmosphere in about 150 years.

We know at a very high certainty that it is the carbon coming from the fuels we humans are burning is what is causing the current temperature increase. If we compare to the last time that the level was about the same as it is now, the temperatures were higher than at any time during human existence.