It does not. Earlier he says it is a trace gas and it is. It is negligible as a green house gas. When you try to be reasonable with the other side they capitalize on it and distort your position.
Keep the message simple. Carbon dioxide does not significantly contribute to Global Warming. It contributes to plant growth.
Contributes is greatly understating CO2's star role in the carbon cycle. Carbon is the key atom of all organic life. The source of all this carbon is the atmospheric trace gas CO2.
Leftists at some point will switch their focus from CO2's effects on climate, nearly nothing, to its role as the critical choke point of all life on Earth, nearly everything. Leftist envy is driven by this existence of competitive life forms which consume THEIR limited resources. By attacking life at its choke point, they believe it will reduce the source of their mental anguish, and they will finally achieve happiness.
The carbon they want to eliminate is you.