Fact #1: A small concentration of CO2 is a big deal.
How can so little CO2 have a significant effect?
...It’s like your mouth. Your taste buds are designed to detect particular tastes, and most things you put in your mouth don’t have those tastes.
Everyone would agree, for example, that water does not taste spicy. Only a few compounds produce that “heat” sensation in the taste buds. The one that does it for hot peppers is called capsaicin.
Most people can easily detect one drop of capsaicin in a glass of water. If you put enough capsaicin in a glass of water to match the concentration of CO2 in the atmosphere (one molecule of capsaicin for every 2600 molecules of water), it tastes like you’re drinking a liquefied jalapeño pepper straight up.
If you hear or read somewhere that the amount of carbon dioxide in the atmosphere is so small that it must be unimportant, your source is either too naive to know better or trying to deceive you.
Fact #2: The fraction of CO2 molecules in the atmosphere that were produced by man is different from the fraction of CO2 molecules in the atmosphere that are there because of man.
...For every two man-produced molecules of CO2 that have been taken up by plants or absorbed in the ocean, there’s one molecule of natural CO2 that would have been taken up or absorbed, except that its place was filled by a man-produced molecule of CO2.
So it’s been effectively squeezed out into the atmosphere.
If you hear or read somewhere that the amount of man-produced CO2 in the atmosphere is only a small fraction of the total CO2 in the atmosphere and that therefore man is having a small effect, your source is either too naive to know better or trying to deceive you.
Fact #3: Carbon dioxide is good for plants, in the sense that it makes them grow more rapidly.
A common skeptic argument is that CO2 is good for plants. From these simple numbers, we see that plants as a whole are certainly benefiting from climate change, in the sense that they are extracting more carbon from the atmosphere and turning it into plant material than before.
If you hear or read somewhere that man’s addition of CO2 to the atmosphere has been generally harmful to plant productivity, your source is either too naive to know better or trying to deceive you.
More details on the CO2-plant connection
As long as the climate effects are small, they don’t matter much, but to the extent that climate changes faster than plants can move around to keep up with it, climate change will be bad for native plants.
Worse, in the tropics, the climate may change into something with no existing analogue on Earth and thus no pre-adapted species ready to move in.
Is there any source out there that has all three of these facts correct?
I know of one: the IPCC. (Anyone who says the IPCC isn’t reliable should be asked, “Compared to what?”)