UN climate chief Simon Stiell said the world “cannot afford to stumble” as climate experts gathered in the German city of Bonn on Monday for the UN’s annual June climate meetings. Opening the conference, Stiell said “climate action will need to move at a much, much faster pace” if the goal of limiting global warming to 1.5 degrees Celsius is to achieved. He added that the world is currently on course for 2.7 degrees of global heating, down from initial estimates of 5 degrees before international co-operation to tackle climate change began under the UN’s leadership. The meeting in Bonn is cruci…