"Environmental considerations will take centre stage in this competition for the very first time, with clear and measurable objectives, and we hope that it will leave a lasting legacy," said Erik Falt, of the UN Environment Programme which backs Green Goal.

The scheme would offset 100,000 tonnes of heat-trapping carbon dioxide generated within Germany by transportation, construction and maintenance of the stadiums and the presence of 3.2 million spectators, it said.

Carbon offset projects include planting forests, which soak up carbon as they grow. Most scientists blame carbon dioxide, emitted by burning fossil fuels, as a main cause of rising temperatures that could wreak havoc with the climate.

"The pitch at the Berlin Olympiastadion and other stadia will be watered from a new rainwater harvesting system and water-free urinals in the men's toilets will feature at numerous key locations," Green Goal said in a statement.