UN chief Ban Ki-Moon on Monday lauded a little-remembered act in Margaret Thatcher's welter of political firsts -- when she urged action on global warming. Ban "pays tribute to her contribution to addressing climate change, having been one of the first world leaders to issue a warning about its effects by calling for action at the UN General Assembly already in 1989," said the UN spokesman Martin Nesirky. Thatcher, who died Monday at the age of 87, gave a speech to the United Nations in 1989 that many environmentalists say helped bring the climate crisis into the mainstream. She later came to distance herself from her plea, however, as the cause was increasingly taken up by left wing parties. As British prime minister, Thatcher told fellow world leaders at the New York meeting that greenhouse gases had become an "insidious danger." "What we are now doing to the world, by degrading the land surfaces, by polluting the waters and by adding greenhouse gases to the air at an unprecedented rate -- all this is new in the experience of the earth," she said. "It is mankind and his activities which are changing the environment of our planet in damaging and dangerous ways," Thatcher warned, calling for a "vast international, co-operative effort" against global warming. Thatcher later changed her mind, and in her 2003 book "Statecraft" called climate change warnings "alarmist" and an excuse for "worldwide, supra-national socialism." The UN secretary general told reporters "we will miss her great leadership. She was a pioneering leader for her contribution to peace and security, particularly at the height of the Cold War. "She was also a great model as the first woman prime minister of the United Kingdom, who not only demonstrated her leadership but has given such great hope for many women for equality, gender equality in parliament," Ban added during a trip to The Hague.