Much criticism of globalization revolves around the economic growth it brings. According to one argument, growth consumes more nonrenewable natural resources and increases environmental damage—despoliation through toxic runoffs into rivers and oceans, air pollution from factory and vehicle emissions, and deforestation that can affect weather and climate. In addition, globalization opponents contend that by buying from more distant locations, the added transportation increases the carbon footprint, which refers to the total set of greenhouse gases emitted. They point further to the more than 1000 container ships plying the seas, each of which pollutes as much as 50 million cars do because of reliance on heavy oil as a fuel.