Quick, what's the most common material on earth?
In terms of atoms, it's oxygen, followed by sillicon, then nickel and iron. In terms of material, sillicon dioxide. Better known as sand.
Sand is industrially useful. It can readily be turned into glass by heating it, and by heating it more in the presence of carbon, one can purify the silicon for use in microchips.
Does this mean that every time you buy a computer, you've contributed to global warming?
In a word, yes.
However, this is reversible. Every time you buy a computer, plant a tree. The tree will suck its own weight of carbon out of the atmosphere.
And if we ever run low on carbon in the atmosphere for some reason?
Dig a huge amount of coal, take it to the Saraha desert in north Africa, and make a gazillion computers. Run them with coal power and yeah that problem is solved.