Taxpayers will foot the bill for big polluters under an opposition plan that will rely primarily on the government paying for measures to offset carbon emissions.

The coalition party room has been briefed this morning on an alternative to the government's emissions trading scheme.

Sources have told smh.com.au that it relies heavily in reducing carbon by sequestering it in soil, and also includes tree planting.

It proposes that the government will spend about $1 billion a year buying carbon offsets to keep pollution levels down and meet the aim of reducing emissions by 5 per cent by 2020.