Emitting carbon dioxide is not something we can opt out of. By the very fact of our existence, we are polluters of the Earth's atmosphere, breathing in oxygen and breathing out this greenhouse gas. In addition, we are (mostly) born into societies which are driven by fossil fuels.
Cobalt is an element required for production of tech products, found most abundantly in the DRC. Much of the mining there is performed in unregulated mines, where child labour is common and disease and injury are rife.