| Global Warming is a term denoting a | | | | water and have weakened over warmer |
| gradual warming of the Earths average | | | | water. There may be a small "boost" to |
| temperature. The term has become | | | | a hurricanes strength as it moves over |
| synonymous to the Earths warming | | | | the Gulf Stream, if upper air wind |
| exclusively due to man-made effects, | | | | profiles do not change much. Some of |
| especially carbon dioxide. Carbon | | | | the computer generated hurricane models |
| dioxide concentrations have increased | | | | have this bias built in and will rapidly |
| from 300 parts per million to 384 parts | | | | strengthen a tropical cyclone if |
| per million since 1900, with the most | | | | predicted to go over a warm pool of |
| accelerated increase during the past 40 | | | | water. |
| years. Some scientists have drawn the | | | | The recent upturn in tropical cyclone |
| conclusion that the increase in the | | | | activity was predicted long before |
| Earths average temperature (about 1°F | | | | Global Warming became a household name. |
| since 1975) is essentially solely based | | | | The tropical |
| on man-made activities such as the | | | | Atlantic has been known to vary in |
| burning of fossil fuels, biomass | | | | cycles, and this recent upturn was |
| burning, and deforestation. | | | | expected. If you were to compare the |
| Causes of Global Warming | | | | period from 1900 to about 1950, with the |
| The Earths atmosphere is made up of | | | | 1950s until now, you would find an |
| different gases. Nitrogen makes up 78% | | | | actual decrease in the average number of |
| of the total composition, Oxygen 21%, | | | | hurricanes and their intensity. It also |
| Argon 1% and traces gases .1%. Carbon | | | | is noted that the upswing in hurricane |
| dioxide makes up most of the volume of | | | | numbers over the past ten years or more |
| the rare gases. Water vapor varies from | | | | has been only in the North Atlantic |
| almost 0% over the deserts to 4% over | | | | basin. Other hurricane formation |
| the oceans. Water vapor, carbon | | | | regions have not shown this same trend. |
| dioxide, methane, ozone, and nitrous | | | | The Effects of Global Warming on |
| oxide are the gases of interest since | | | | Hurricanes: Summary |
| these are the greenhouse gases. | | | | There has been a noted increase in the |
| Greenhouse gases can reradiate heat or | | | | number of hurricanes in the Atlantic |
| trap heat absorbed by the Earth from the | | | | Ocean, Caribbean Sea, and Gulf of Mexico |
| sun. Water vapor is by far the largest | | | | since the mid-1990s. The long term |
| mechanism for heat retention out of the | | | | average is that ten tropical storms will |
| greenhouse gases. | | | | form per year,of which about six will |
| In the past, the Earths orbital | | | | become hurricanes. Since the mid-1990s |
| eccentricity, variance of the tilt and | | | | the average has been fifteen tropical |
| wobble have led to periods of warmer | | | | storms, of which eight have become |
| weather. Even though the solar energy | | | | hurricanes. There has also been an |
| from the sun is considered a constant, a | | | | upward trend in the concentration of the |
| slight change could cause temperature | | | | greenhouse gas carbon dioxidedue to mans |
| fluctuations. Recently, Mars has also | | | | activities over the past 100 years. |
| shown a decrease in ice coverage without | | | | During this time, hurricanes have gone |
| greenhouse gas changes. The cause for | | | | through cycles where they have been more |
| the reduction in aerial coverage is | | | | numerous, such as the cycle that we are |
| unknown. | | | | in now. Some scientists have drawn a |
| In summary, there are three mechanisms | | | | one to one correlation between the |
| which would cause global warming, or in | | | | Earths temperature increase and the |
| other words allow for a warming of the | | | | number of hurricanes and their |
| Earths average temperature. These are: | | | | intensity. As we have noted, the number |
| (1) solar energy variance, (2) gradual | | | | one factor in tropical cyclone intensity |
| changes in the Earths orbit, tilt, and | | | | is related to the atmospheric wind shear |
| wobble, and (3) greenhouse gas changes. | | | | profile. There is even some research |
| It is difficult to calculate what | | | | that suggests that higher temperatures |
| percentage of the recent warming could | | | | couldactually increase the wind shear |
| be attributed to human activities. We | | | | profile resulting in a decrease in |
| can eliminate changes in the Earths | | | | hurricane activity. The upward cycle in |
| orbit, tilt, and wobble causing a | | | | hurricane numbers is expected to |
| temperature increase since these are | | | | continue for several more years. If |
| long term effects. | | | | this trend were to continue for a |
| What are the Effects of Global Warming | | | | considerably longer period, only then |
| on Hurricanes? | | | | could one draw a conclusion that warmer |
| There is a common misconception that | | | | temperatures have played some part to |
| since the global temperature has | | | | cause an increase in tropical cyclone |
| increased, hurricanes also must increase | | | | formation. |
| in number and intensity. The primary | | | | Rich Johnson - Expert Hurricane |
| factor in the ability of a hurricane to | | | | Forecasts | Travel Resources |
| strengthen or weaken is the wind shear | | | | Rich is a Certified Broadcast |
| profile of the atmosphere - not water | | | | Meteorologist with 25 years of weather |
| temperature. It always has been warm | | | | forecasting and television experience. |
| enough in the tropics to produce | | | | His expertise is in tropical meteorology |
| hurricanes. This temperature equates to | | | | forecasting hurricanes. His website |
| a sea surface temperature of about | | | | TropicalWeather.net is dedicated to |
| 80°F. If you study the behavior of | | | | helping travelers cope with tropical |
| hurricanes you can find cases where | | | | weather. |
| hurricanes have strengthened over cooler | | | | |