Mr President, I ask a further supplementary question. I refer the minister to findings of the UN Environment Program that pledges made under the Copenhagen Accord would at best provide 60 per cent of what is required to meet a two-degree stabilisation target. Why has the government modelled its carbon tax on scenarios that rely on far stronger global action when even the voluntary, non-binding pledges made under the Copenhagen Accord do not come close to meeting Labor's modelled scenarios?