Is it normal to not have kids by 40?

Climate change is a natural phenomena that is constantly happening. If you mean pollution, most of that is produced by ships, lorries etc transporting useless crap that people buy, like cheap clothes and technology. Certain parts of the world are increasing in population, while the "first world" population is actually reducing. Africa's population is rising rapidly but most of the pollution is being caused by the USA, China and Europe, all of whose native populations are falling.