http://www.coindesk.com/carbon-footprint-bitcoin/While the figures seem somewhat scary at first (312lbs of carbon dioxide into the air per coin, equivalent of 15.9 gallons of gazoline burnt), it's most probably way less than what is required for the maintenance of fiat currencies: energy used by banks and ATM, building and fueling armored cars, printing money, powering the myriad of computers used to make the money virtual, etc.
Besides, it can be argued that fiat currencies, because of inflation, favours mass consumption, while deflatory currencies like Bitcoin favour savings. This alone definitely overcompensates for the carbon footprint of the network.
Also, since competition is fierce, miners who use cheap, renewable energy (ie. solar) will ultimately be at a great advantage.
This is very misleading.
How do you determine how much of the mining is used to "create" new bitcoins, and how much of it is used to process and secure transactions?
Personally, I'd say that the creation of the new bitcoins uses 0 energy and results in 0 lbs of carbon dioxide. It's the intensive processing and securing of a fast, global, irreversible, secure payment system that is creating the carbon dioxide and using the energy. Now, divide the total carbon dioxide by the number of satoshis moved in a day and see how much is created per transacted satoshi.
After the year 2140, when mining continues at a significant pace, and 0 new bitcoins are being created, how exactly are they going to divide by zero to get the pollution per new bitcoin?