Many scientists believe that Mankind's greatest disaster - the destruction of the earth - will be inevitable if we don't change our mode of running our planet. But if we take some decisive action in this aspect, the prospect that we long for will appear before us. In other words, our future is in our own hand's to a great extent; our future is in fact the product of the joint decisions we make today. Needless to say, our present action will make certain prospect more likely to come true compared with some other prospects.