A debate about the Saskatchewan government's environmental policies is swirling on the home front as Premier Brad Wall heads to Washington, D.C., to talk about energy and climate change.

The Saskatchewan Party government has already downgraded its election promise on reducing greenhouse gases by 2020, with the proposed reduction going from 32 per cent to the federal target of 20 per cent.

A proposed law aimed at controlling carbon emissions is expected to be introduced in the legislature soon, although a previous attempt died on the order paper in the spring.

That has the New Democrats saying the government has done nothing to date to fight climate change. The NDP had also accused the government of gutting a $320-million fund that would have paid for a variety of green initiatives.

Environment Minister Nancy Heppner, who's preparing to go to Copenhagen, where the world will discuss how to reduce greenhouse gas emissions, is calling on all MLAs to support the government's climate change plan.

In a speech in the legislature Tuesday, Heppner discussed her government's carbon sequestration and clean coal projects. She also mentioned the NDP more than 30 times, most of the time picking apart its record on climate change.

Both Heppner and Wall were talking up the government's plan for any penalties or carbon levies paid by Saskatchewan's high emitters to stay in the province.

"Is it going to be 100 per cent of the money that stays in the province? I don't know the answer to that, but we're heading in the right direction and I can't imagine an issue more important to our economy than this," Wall said.

Cap-and-trade system under scrutiny

However, Opposition Leader Dwain Lingenfelter says Canada and the United States are moving towards cap-and-trade systems, a different approach to what Wall and Heppner are proposing.

Under cap-and-trade proposals, companies would see their carbon emissions limited to a certain level (the cap), and then, if they exceed the cap, they'd have to buy credits from other, less-polluting companies (the trade).

Lingenfelter says a cap-and-keep system may pose problems.

"Good luck if that's what he's intending to do," he said. "I just think it's going to be very, very difficult to have a patchwork program across all the states in the United States and all the provinces."

The government says it plans to reintroduce legislation spelling out its carbon change plans this fall, meaning that unless it has the opposition's support, it won't pass until next spring.