The Parliament joins Edinburgh Castle and the Forth Bridge in marking Earth Hour, which will be held on March 28. A number of iconic landmarks around the globe, including the Eiffel Tower and the Christ the Redeemer statue in Rio de Janeiro, are also taking part.Over 500 cities are taking part in the event, which is being organised by conservation charity WWF. Dr Richard Dixon, director of WWF Scotland, said: “It is great news the Parliament has given its backing to Earth Hour.”

Historic Scotland officials are looking at covering Edinburgh Castle rock with massive sections of mesh to try to stabilise the wall. The city council is already looking at preventing buses and taxis from parking below the castle rock for at least 18 months while tests are carried out. A ban on coaches entering the esplanade is being explored to help protect the castle rock and improve safety for visitors.

A spokesman for Historic Scotland, the agency responsible for the care and maintenance of the castle, said a decision on whether to keep any mesh in place in the “long term” would not take place until initial works had been completed. The spokesman added: “The precautionary measures are designed to identify and secure areas of rock which might be at risk of coming loose.

“It is the latest stage in an on-going monitoring, care and maintenance programme which aims to conserve the castle rock in the best possible condition and minimise the number of rock falls which are the inevitable result of the natural erosion which has been taking place for millions of years.”

David Storrar, regional architect for Historic Scotland, added: “The castle rock is a national treasure and we carry out regular specialist maintenance work to protect it and maintain rock stability.

“Our consultant engineers recently identified eight areas on the north-west face where it would be prudent to carry out precautionary stabilisation work.

“This will involve drilling into the rock and inserting stainless steel pins to keep it firmly in place.”