...Frequently Asked Questions

1.  Is global warming giving us more severe hurricanes? Short answer – probably not.

The Colorado State University hurricane team points out that tropical storm formation and development are complicated processes.  They don’t believe that higher carbon dioxide levels and sea surface temperatures by themselves produce more or stronger storms.  For instance:

Between 1945 and 1969 (a period of slight global cooling) there were 80 severe Atlantic hurricanes and 201 severe hurricane days.  From 1970 to 1995 (a period of modest warming with an 18% rise in CO2 levels) there were only 38 severe Atlantic hurricanes and 63 severe hurricane days.

Also, it’s the difference between the temperatures of the sea surface and the upper air that causes the warm, moist updraft to get these storms started.  That difference hasn’t changed much, as air and water are warming together.

However, a Florida State University study suggests there may be some effect on the biggest storms.  The FSU team believes warmer seas could strengthen the “heat engine” that drives tropical cyclones, pulling warm air in at the bottom and spilling colder air out at the top.  The study included storms from all the world’s cyclone areas, but only the most severe ones – those that didn’t run into shearing winds, dust clouds or land masses to slow them down before reaching their peak strength.  Between 1981 and 2006, the average top speed of these storms increased nearly 11.5% (from 140 mph to 156) though sea surface temperatures rose only about 1%.  So we may not get more storms, but the worst might be worse,

2. Do we really need tropical storms and hurricanes? Short answer – yes.

These storms are part of our “normal” climate.  When they don’t come, we may have other problems.  First and most important of these is drought.  Last year, Montego Bay got only 37.1 inches of rain, well short of the long-term average.  It’s far below 2005 and 2007 – hurricane years with more than 60 inches of rain – and early 2010 rainfall, though improving, extended the “long dry” to nearly two years.

The second hazard is reef damage.  Tropical storms can have some benefits for the reefs.  Big waves and strong currents bring cool, food-rich water up from the deep ocean, add oxygen and sweep exposed areas clean of silt and algae.  They also add fresh water to keep the sea’s saltiness within the limits marine life can stand.

Less-than-normal storm cooling increases the risk of coral bleaching.  This happens when corals lose the algae that live in their cells, help to feed them, and give them colour.  “Thermal stress” – bright sun and warm water – is the main cause.  If it has no other problems, healthy coral can recover from short periods of bleaching.  However, Montego Bay’s coral is already stressed by pollution, silt, and an unbalanced food chain with too much algae and too few fish.  Scattered bleaching was reported in the Marine Park last fall.  Another year with no storms could be a serious problem.