Big Pic: First Map of Global Shipping Routes

Cargo Network -- Nearly 90 percent of worldwide trade is made possible because products and goods are transported over the ocean on ships. Yet for the most part, those journeys go unnoticed by the average landlubber. It was a fact that surprised Bernd Blasius, a mathematical modeler at Carl von Ossietzky University in Oldenburg, Germany, and his team. After all, international trade affects policy decisions. Not only that, but all of those ships pulling in and out of ports pick up and discharge invasive species that have cost the United States alone an estimated $120 billion per year in damaged ecosystems.

The team's new map brings those 30 trillion ton-miles (and growing) into focus, revealing that the busiest ports are in the Panama Canal, the Suez Canal, Shanghai and Singapore.

It was made using data acquired from each ships' automatic identification system, which transmits a ship's arrival and departure times to port authorities. The records are also made available by Lloyd's Register Fairplay as part of its Sea-web database. The scientists used records from 16,363 ships, which are classified into three categories: bulk dry carriers, container ships and oil tankers.

These ship categories are important to note because, according to the new map, different kinds of ships move in different patterns. "Bulk dry carriers and oil tankers tend to move in a less regular manner between ports than container ships. This is an important result regarding the spread of invasive species because bulk dry carriers and oil tankers often sail empty and therefore exchange large quantities of ballast water," the scientists write in their article, published in the Journal of the Royal Society Interface.

Image: Bernd Blasius/J. Roy. Soc Interface