By J. Bruce Neill, Ph.D. and Leah Biery, Sanibel Sea School
Mired in the morass of the Gulf oil blowout is the Gulf Loop Current. Over the course of the ongoing disaster in our backyard, you’ve probably heard reports that oil could enter the Loop Current and make its way to the Florida Keys, where it could impact fragile mangrove, seagrass, and coral reef ecosystems.
After hearing that something “could” or “might” happen, it is easy to assume that it probably won’t, but on Tuesday, May 19th, officials at the National Oceanic and Atmospheric Administration announced that surface oil has entered the Loop Current and will likely arrive in the Florida Keys within 10 days. Some oceanographers predict that traces of oil could reach Key West as early as Sunday, May 23rd.
The Gulf of Mexico basically has a single entrance and a single exit. Most saltwater enters the Gulf of Mexico from the Caribbean Sea through a narrow passage between the Yucatan Peninsula and Cuba – called the Yucatan Channel, or the Straits of Yucatan. The water that flows through this passage is called the Yucatan Current.
Much of the Yucatan Current roughly follows the shoreline of the Yucatan Peninsula north and west and continues to the western Gulf. The eastern part of the Yucatan Current flows along the northern edge of Cuba; it is called the Florida Current.
A third, central portion of the Yucatan Current flows northward, then to the east, eventually turning south towards the Florida Keys. This is the now famous Gulf Loop Current.
The Loop Current and the Florida Current combine and flow between the southern tip of Florida and Cuba as the Gulf Stream. It is joined and pushed along by an Atlantic current (the Antilles Current) to flow northward along the eastern seaboard of North America, eventually flowing to Europe.
By now, you’ve probably realized that ocean currents are very complex. Oceans are better thought of as a series of fairly discrete rivers flowing in their own directions stacked on one-another between the surface and the ocean floor. To make things more complicated, not only do currents flow differently at different depths, they vary horizontally over space as well. So we have a series of adjacent rivers flowing in separate directions, stacked on even more rivers flowing in their own directions.
The Loop Current is a surface current, typically 100 – 200 miles offshore at the latitude of Lee County, although prevailing weather patterns can cause it to meander significantly. However, it is rarely less than 100 miles from our shores, so it is likely to bypass Lee County and deposit oil in the Tortugas, the Marquesas and the Keys. You may be thinking, whew, we lucked out – but not so fast.
BP is releasing oil from a pipe 5000 feet below the surface of the ocean. It is not simply rising to the surface where we can scoop it up. Remember all those stacked currents? In all likelihood, a significant amount of oil is being transported below the surface on deeper currents in other directions. It is likely that oil carried by deeper currents will end up in Lee County over the coming weeks or months.
So what do we do? We wait, and we plan for the worst and hope for the best. Most importantly, we learn from this horrific event and act to avoid similar disasters in the future.
In the meantime, find and practice ways to conserve energy. Investigate solar hot water heaters, drive your car less, and turn your thermostat up a degree or two. Go out and enjoy our pristine beaches.
Simple answers would be nice, but unfortunately there are none. Let’s push our leaders to support ways to reduce our reliance on fossil fuels.
Perhaps this is our chance to take the lead, and let our leaders follow.
A helpful video of Gulf currents… http://www.youtube.com/watch?v=pE-1G_476nA&feature=player_embedded#!