Scientific American: An additional 150 people join the ranks of humanity every minute, a pace that could lead our numbers to reach 9 billion by 2050. Changing that peak population number alone could save at least 1.4 billion metric tons of carbon from entering the atmosphere each year by 2050, according to a new analysis–the equivalent of cutting more than 10 percent of fossil fuel burning per year. “Demography will matter to greenhouse gas emissions over the next 40 years,” said earth systems scientist …