AlterNet: From Mt. Everest to the Maldives, people worldwide are turning an arcane number into a movement for a stable climate. Bill McKibben asks: Will you join them? Let’s say you occasionally despair for the future of the planet. In that case, the place you need to be this week is the website for 350.org. Every few minutes, something new arrives at our headquarters, where young people hunched over laptops do their best to keep up with the pace. News that activists in …