ABP to introduce 'Carbon Budgets'

Does it really make sense to introduce 'Carbon Budgets' as a constraint on the mandates for Asset Managers? First of all, the calculation of carbon usage for all investment options is expensive and it is also more than likely to be imprecise or liable to be gamed. And why not a Carbon budget for fixed income investments (even more complicated and expensive, how much Carbon usage to you allocate to a bond?), and before we forget, I hope there will be Carbon budget for 'Private' Equity and Hedge Funds? And last not least, don't forget the HFT firms. And what about Bank lending?
Nevermind that there is a simple solution at hand (Tax Carbon if you are hell-bent on limiting its use). Why not act according to the principle, what is good for the Consultants MUST be good for the Consumer (here in the shape of hapless end investors in Mutual and Pension Funds, Private Banks and Insurance Companies).
And while we are on the subject of Climate Hysteria, has any political or business 'leder' ever received a democratic mandate for imposing ever-more 'green' taxes, costs and regulations on the citizen/consumer/investor anywhere in the world?