Ali Garrigan, currently one of six Greenpeace activists climbing exterior of The Shard, has compared the rise in temperatures in London to that of the Arctic.
Near the top thinking about the 1.4 degree rise here and the 10 degree rise in the Arctic. Scary. #IceClimb
More top news
A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.