The sea ice at the North Pole could vanish completely within the next few years, polar explorer Pen Hadow told guests at the Green Guardian Awards gala dinner at Epsom Downs Racecourse.

Starting with just a few ice free days in summer, scientists predict the length of time the sea will be exposed to the warming effect of the sun each year will increase to weeks then months.

No-one knows how thick the remaining ice is, so next year Pen is leading a 140 day expedition across the ice pack to measure this.

His success in being the first man to make a solo crossing between Canada and the North Geographic Pole was partly based on his understanding that, with ever increasing stretches of water, the only way to get there was to go direct, swimming across the open leads dragging an inflatable sled.

Congratulating all the finalists on what they have been doing to protect the environment, he said changing behaviours here helped protect ice in the northern ocean - a vital heat shield against global warming.

He was speaking to a rapt audience of 240 people including environmental activists, MPs and business and council leaders at the awards ceremony on Friday night.

They were there to celebrate the achievements of those people and organisations in south west London leading the way towards sustainability.

The Queen’s Stand had been transformed into an autumnal forest with trees hung with environmental messages and lit by low energy LED lights - part of a package of measures to reduce the event’s carbon footprint.

This year, there were over 50 finalists from seven boroughs, all of whom had been winners in their category at a borough level.

Introducing the awards, Sean Duggan, group editor for the South London Guardian series and the project’s founder, said: “The primary aim of this event is to say an unforgettable thank you to them for everything they have been doing.

“But, as they say, there are no free lunches – or in this case dinners, and the other aim of this evening is to ensure that they leave tonight inspired and encouraged to go on to do even more – and to share their enthusiasm and experience with as many people as they can.”

He described the Green Guardian project, launched three years ago, as an “outstanding example of co-operation” and paid tribute to the council partners, Kingston, Sutton, Merton, Wandsworth, Richmond and Hounslow, sponsor businesses and HSBC, which sponsored the drinks and provided £500 prizes for both the primary and secondary schools.

The winners received a range of superb prizes, from a holiday in tipi in Wales to one in a five star hotel in London, a birdcam for the Young Environmentalist and an electric bike for the Green Champion.