Time: In the course of a long weekend in 1991, the Philippines’ Mount Pinatubo volcano injected enough sulfur dioxide into the stratosphere to temporarily reduce the sunlight reaching the earth’s surface by about 10%. As a result, global temperatures dropped by an average of 0.5 degrees C over the next 18 months. Turns out the lesson nature taught us that weekend has not been wasted; it may help us combat global warming. The late climate scientist Stephen Schneider used to compare the modern world’s…