At present we're in a 'gold rush' phase, and the rewards from mining result with a large amount of resources being spent on it.
Mining rewards will diminish over time so it will no longer be feasible to mine as much as in the 'gold rush' phase. So the carbon footprint will not be growing all the time.
In fact, there's a race to make the current hardware to become more power efficient. If you live in a sunny place, you could probably pick up 240 Watt solar panels for around $300, a connect a Raspberry pi @ 3.5 watts, then a 10 GH/s Erupter blade @ 75 watts.
Mining rewards will diminish over time so it will no longer be feasible to mine as much as in the 'gold rush' phase. So the carbon footprint will not be growing all the time.
In fact, there's a race to make the current hardware to become more power efficient. If you live in a sunny place, you could probably pick up 240 Watt solar panels for around $300, a connect a Raspberry pi @ 3.5 watts, then a 10 GH/s Erupter blade @ 75 watts.