Already hundreds of thousands die each year of starvation and should climate change accelerate man will not have time to adjust to the new climate fast enough to provide enough food to support the existing population. Also should global warming (regardless of whether man causes it or not) cause a rapid rise in ocean levels (due to melting of land based ice) millions if not billions of people that now live near current sea level will be displaced. Results could be catastrophic for all life on earth reducing the population by billions in a relatively short period of time.