Counting emissions within national boundaries, in other words, is like counting calories but only during breakfast and lunch. If going clean in the US makes other places dirtier, then you’ve got to add that to the ledger. The carbon sums are sure to be lower than they would be otherwise, but the reductions might not be as robust as thought, especially if producers desperate to cash in on the renewable jackpot do things as cheaply and quickly as possible, which for now means fossil fuels. On the other side, environmental remediation is costly in every way. Want to clean up those tailings ponds, bury the waste deep underground, keep the water table from being poisoned? You’re going to need motors and you’re probably going to burn oil.