Carbon, of course...the basic building block of life that has been repurposed as leftist fear porn.
Don’t forget nitrogen as yet another killer element.
I wonder just how many tons of nitrogen in the form of nitrate are stripped from the air and dropped into the soil in just one frontal passage? That alone should keep the fear mongers busy for ages working on just that one “problem”.
I seem to recall something about the natural nitrogen cycle that was taught to us back in grade screwl science.