The point when the global average temperature passes the threshold of 2° above pre-industrial averages represents a severe threat to the planet. However, it’s very hard to find a reliable reference for when we will reach this point. Presently, the 2° target floats abstractly in the public mind. The Climate Clock acts a public line in the sand, saying “this is the date”. It is a measuring stick by which we can evaluate our progress. Each year, a week before Earth Day, the clock will be stopped, a group of leading climate scientists from around the world will evaluate the latest data and then, on Earth Day, the scientists will restart the Clock with a new time.