"The reason for this is simple: before signing the Act, Britain was already signed up to the EU’s Emissions Trading System (ETS), designed to encourage EU member states to reduce their CO2 emissions on a collective basis. This is achieved via Emissions Allowances (EAs), a type of carbon credit. Member states reluctant to cut their carbon emissions too drastically can buy EAs instead. So long as the total number of EAs in circulation remains the same, it means that when one country cuts its emissions by a lot, other countries are able to reduce their emissions by less. "
So the Act will not save the planet at all - merely cost everyone in the UK a great deal of money for nothing.