The German government adopted Wednesday a plan aimed at accelerating its efforts to cut carbon gas emissions by 2020.

Germany has pledged to cut its greenhouse gas emissions by 40 percent between 1990 and 2020, but at the current pace, Europe's top economy looks set to to fall short of that goal by as many as six or seven percentage points.

The programme adopted by the cabinet Wednesday aims at cutting carbon emissions by between 62 million and 78 million tonnes from now until 2020.

"We must close the gap. It's about keeping our promises and meeting the goals we have set ourselves," environment minister Barbara Hendricks told a news conference.

"We will treble the efforts we have made in the past five years," the minister said.

Twelve days of UN climate talks opened in Lima, Peru this week, where 195 countries are drawing the outlines of a 2015 deal to roll back climate change.

"We'll show in Lima that we can reach what we've pledged to reach," Hendricks said.

"All sectors will contribute."

Under the new proposals, the biggest contribution -- a reduction of 25-30 million tonnes -- would come from measures to boost energy efficiency, including tax incentives for the renovation of buildings' heating and hot water systems.

Economy minister Sigmar Gabriel estimated that a combination of public and private schemes could unlock as much as 40 billion euros in investments in energy efficiency measures in the coming years.

The electricity sector itself will contribute an additional reduction of 22 million tonnes of carbon gas emissions by capping the use of coal-fired power stations.

Coal remains Germany's biggest source of electricity generation, jeopardising the country's efforts to meet its climate goals.

The contribution of the electricity sector had therefore been a crunch issue between Hendricks and Gabriel.

Hendricks was calling for a reduction in capacity of the coal-fired power stations, while Gabriel was concerned about security of supply, costs and jobs in the sector.

The additional goal now agreed is equivalent to an annual reduction in carbon dioxide emissions of 4.4 million tonnes.

The opposition Green party and environmentalist groups are calling for a complete abandonment of coal and accuse the government's efforts in this area of being too timid.

Power station operators can choose how to meet their reduction commitments, either by closing down old and the most pollutant plants or spreading the reductions across a number of sites.

The transport sector will contribute a reduction of seven to 10 million tonnes by increasing road taxes for the most pollutant trucks and heavy goods vehicles. Car drivers will be entitled to courses where they can learn how to economise on fuel.