Maritime traffic on the world's oceans has increased four-fold over the past 20 years, likely causing more water, air and noise pollution on the open seas, according to a new study quantifying global ship traffic. The research used satellite data to estimate the number of vessels on the ocean every year between 1992 and 2012. The number of ships traversing the oceans grew by 60 percent between 1992 and 2002. Shipping traffic grew even faster during the second decade of the study, peaking at rate of increase of 10 percent per year in 2011....