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Five things about today’s ocean that would surprise Benjamin Franklin

March 26, 2015

In his lifetime, Benjamin Franklin crossed the Atlantic Ocean eight times, fueling his growing fascination with natural science by writing and conducting experiments while at sea.

It was during those maritime travels that he observed ocean currents off the east coast of North America, particularly a fast-moving body of warm surface water flowing from the Gulf of Mexico around the southern tip of what is now the Florida peninsula, and then bending off to the northeast (near Cape Hatteras in North Carolina) before continuing to Iceland and the British Isles.

Over many years, Franklin measured water temperature and performed other experiments that led him to create the first chart of the Gulf Stream—or what he called “a river in the ocean.” Franklin promoted harnessing the powerful current to speed up delivery of mail from Europe to the colonies, as well as to improve the efficiency of other commercial shipping.

Today, the Gulf Stream is one of the world's most intensely studied currents for different reasons: It warms the European subcontinent and plays an important role in the transfer of heat, salt, and carbon towards the Arctic.

Susan Lozier, Duke University’s Ronie-Richele Garcia-Johnson Professor of Ocean Sciences, is at the forefront of such research, especially the ocean’s role in climate variability and climate change. "It’s important to understand how increasing ocean temperatures and increasing ice melt will impact ocean circulation,” she said. “And, just as importantly, we need to understand how changes in ocean circulation impact ocean temperatures and ice melt.  It’s all about connections.”

Lozier, who will talk about the impact of her groundbreaking work when Duke Forward returns to San Francisco on April 21, shares five things about today’s ocean that would surprise Benjamin Franklin:

1. Ocean currents, long mapped solely for navigation, are now studied because they redistribute heat from the warm tropics to the cool polar regions. Without Earth’s fluids—the ocean and the atmosphere—the temperature difference between the Equator and poles would be 230 degrees Fahrenheit!

2. Rather than thermometers in wooden buckets used during Franklin’s time, ocean temperatures today are measured by a host of autonomous floats and gliders that take measurements from the waters’ depths then pop to the surface to relay their information to a satellite.

3. It has since been established that every ocean—not just the North Atlantic—has a “Gulf Stream” on the western side of the basin. These western boundary currents are fast by global ocean standards—yet it would still take about 16 days to get from Miami to Cape Hatteras while riding the Gulf Stream.

4. The coldest ocean temperatures are found at the surface, not at the bottom. Ocean water is cooled by its exchange with the atmosphere and once it is below the surface, there is no way for it to lose more heat.

5. Hurricanes intensify when they pass through Gulf Stream waters because those waters are so warm. Heat lost from the Gulf Stream waters supplies energy to drive strong hurricane winds.

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