We've all heard of ways to reduce our carbon footprint: biking to work, eating less meat, recycling.But there's another way to help the climate. A recent study from Lund University in Sweden shows that the biggest way to reduce climate change is to have fewer children."I knew this was a sensitive topic to bring up," says study co-author Kimberly Nicholas on NPR's Morning Edition. "Certainly it's not my place as a scientist to dictate choices for other people. But I do think it is my place to do the analysis and report it fairly."The study concludes that four high-impact ways to reduce CO2 gas emissions include having fewer children, living without a car, avoiding airplane travel and eating a vegetarian diet.