This is how Environmental Affairs Minister Edna Molewa sees things.

"We are in big trouble. This [climate change] is a crisis. This world will run out of food . this world will run out of natural resources and all other resources that we have," she said.

Molewa was speaking at the launch of a pilot project by her department to test four fully electric cars as part of the government's commitment to reducing carbon emissions by 34% by 2020 and by 42% by 2025.

The department will test the Nissan Leaf to see how best it might fit into the transport system.

Greenhouse-gas emissions are seen as the biggest cause of rising global temperatures, with cars being the third-largest contributor to the emissions.

The authorities want to have as many as half the cars on the roads electricity powered in 10 years' time - but this is probably too stiff a challenge.

For energy-efficient vehicles to be taken up in the market, there would have to be a high level of government buy-in.

Mike Whitfield, managing director of Nissan SA - who was present at the launch - said the introduction of cars like the Leaf relied heavily on private-public partnership.

"It [the car] does well in developing markets where there is good government involvement."

In Sweden, drivers of electric cars do not pay for parking, and in Stockholm they do not pay congestion charges or toll fees.

Leo Kok, spokesman for Toyota SA, said: "In California, there are dedicated lanes for energy-efficient (or high-occupancy) vehicles, and in Japan there are decent tax breaks."

The Department of Environmental Affairs' initiative is a step in the right direction, but it is expected to take up to 50 years for energy-efficient cars to break into the market.

"For the next 50 years, 99.9% of the cars on our road will still be petrol driven," said Energy Minister Dipuo Peters.

The government is considering tax breaks for companies that use energy-efficient practices but Peters could not say whether such breaks would be extended to motorists who opted to go green.

A fully charged Leaf - charged either for six hours at home or for 30 minutes by a quick-charge system at a petrol station, shopping centre or public parking area - can travel up to 660km.

With its 80kW of power it has better acceleration than a V6 petrol engine, claimed Whitfield.