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No of course it isn't. A few million years ago, atmospheric carbon dioxide levels were EIGHT THOUSAND PPM. That's 20 times higher than current levels of around 400ppm.

Where did the coal come from? How did the carbon get in the coal? The answer is that coal is dead plants. They got ALL their carbon dioxide from the atmosphere. ALL the carbon that is in the coal used to be in the atmosphere! ALL OF IT!!!

Here is a graph:

[link to en.wikipedia.org]

The orange line is atmospheric carbon dioxide levels. Today is on the left of the graph. As you move to the right of the graph, you are moving back into the past. Look how high the levels were 500 million years ago!

Then the levels dropped rapidly until about 300 million years ago. This was due to all those plants sucking carbon dioxide out of the atmosphere and turning it into coal. The coal was all laid down during the Carboniferous Period.

[link to en.wikipedia.org]

You will never get an environmental activist to admit that carbon dioxide levels were MUCH HIGHER in the past. They like to pretend that 400ppm is the highest level it has ever been, when in fact, 400ppm is in fact pretty much the LOWEST CARBON DIOXIDE LEVELS EVER ON THE PLANET. Sure it was a tiny bit lower a couple of hundred years ago. But current levels are way lower than the planet and life has easily survived in the past.