(Image: Ingólfur Bjargmundsson)

This stunning image of the aurora borealis illuminating the weird underground world of a vast cave in Iceland is vying for an award.

Photographer lay in wait in the frozen 1360-metre-long lava cave to capture this image of the aurora borealis at its peak through one of the cave’s natural skylights.

The snow pedestals on which Bjargmundsson’s silhouetted subjects are standing accumulate under the skylights in places where the roof has caved in.

This stunning photo is a contender in the Astronomy Photographer of the Year award at the Royal Observatory Greenwich in London. The winners will be announced on 18 September, and then there will be a .

Cars are pricey enough, but they take another toll. Smog from road transport drains $0.8 trillion yearly from a group of 34 wealthy nations.

A from the estimates that air pollution costs OECD countries $1.7 trillion a year in healthcare and premature deaths. Road transport accounts for half of this.

Estimating the costs of environmental problems is a good way to get governments to take action, says of Columbia University in New York. “That’s the language they speak,” he says. “When it’s done right it can really make an impact.”

The most harmful emissions come from diesel engines, so the OECD wants governments to remove incentives to buy them. The organisation also suggests expanding urban bicycle sharing and electric car programmes, and introducing more charges for the use of roads.

Air pollution also costs $1.4 trillion in China and $0.5 trillion in India. Both have seen deaths due to smog rising faster than the global average.

Many nations are trying to cut smog, for instance, by making cars more efficient, but any gains have been overwhelmed by the rising number of cars in fast-expanding cities in China and India.