WARM ocean ominous for coral bleaching and hurricanes
We were in the Upper Florida Keys for Father’s Day weekend — Tavernier to be specific. As soon as we got there, Rachel jumped in the water and said it was hotter than last year. At age 9 she instantly knew what the scientists have been observing for months. It’s WARM. This has very ominous implications for hurricanes this season, as well as coral bleaching. Both are driven by higher than normal temperatures.
Indeed here is the post I found from DR. Mark Eakin, coordinator for NOAA’s Coral Reef Watch:
Our satellite data show that sea surface temperature (SST) along the Florida coast and in the Keys has taken a dramatic upturn since mid-May (2010), with this year seeing first an extreme cold outbreak earlier this year and now an extremely warm spring season. (See the web site linked from below for graphics and more details.)
SST in the region increased significantly in mid-May with a dramatic increase near 2ºC over several days at some locations. Another SST hike started in early June and continues along the Florida coast, in the Keys, and also in the Bahamas. These two events pushed the SST in the region way above what we have seen in our satellite data from the past 10 years for the region. At many locations, SSTs are now more than 1ºC above the highest SSTs observed at this time of the year. At some locations, SST has already reached a level that is not usually reached until late July to early August and exceeds the thresholds for developing coral bleaching. In fact, all of our Florida reef pixels currently are at Bleaching Watch or Bleaching Warning status. Most pixels through the Greater and Lesser Antilles and around the Caribbean coast of South and Central America are at Bleaching Watch as well.
Surface wind speed has been low during the past few days in the region. It may accelerate the already significant warming, if persistent.
This summer is most likely a stressful bleaching season for the corals along the Florida coast, in the Keys, and in the Bahamas. The forecasted active hurricane season may relieve the bleaching thermal stress as the hurricanes did in 2005, but this will depend on storm tracks.
Anomalously warm conditions have existed across most the Caribbean since January and our Outlook product shows potential for strong warming this year in the Caribbean and Western Pacific.
C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
For more information including maps and historical comparisons see http://coralreefwatch.noaa.gov
Of course the relevance of the warmer water to coral bleaching and hurricanes is completely different.
In the case of corals, for the past few decades, widespread bleaching of coral reefs has been observed worldwide. As the name implies, the normal diverse coloration of hard corals turns to a bleached white. Corals get their color from a particular algae and the tiny coral polyp animals, which live together in a special symbiotic relationship.
It has now been determined that the bleaching happens in response to unusually warm temperatures, even for a very brief period of time. It seems counter-intuitive, since ocean temperatures change so much during a year.
The best way to think of it is that our bodies can also tolerate a fairly wide range of temperature. But if our core temperature get much above 105 degrees F (41 C) for long, there is a good chance us dying too. While corals have a different temperature range of tolerance than humans, it is a good metaphor. The sensitivity of corals was a surprising finding by coral reef scientists, but has been fairly well proven and accepted in the last few years.
HURRICANES are a different phenomenon of course. Essentially hurricanes serve the function of redistributing ocean heat from the equatorial region towards the higher latitudes. To be really simplistic, the difference between ocean heat levels in the tropics and the colder, North Atlantic creates the environment for the cyclonic winds of a hurricane, which then moves tremendous amounts of heat energy northward, re-balancing the temperatures.
As we are all becoming aware there are many other factors such as the wind shear patterns which are affected by those changing temperature patterns over in the Pacific Ocean — the so-called El Nino and La Nina. It is complex. But the forecasting and modeling continue to improve. Too much complexity for simple prediction. It is clear, however, that unusually warm ocean temperatures such as we are now finding in the Caribbean region are very conducive to greater hurricane activity.