I know, this is not exactly new news to many of us, but it bears repeating. The more scientists study the effects of man-made global warming on Hurricanes, the more they reach the same conclusion: climate change, and in particular the warming of the oceans, is fueling an increase in the number of hurricanes and tropical storms. Here’s the latest study by two American scientists, Greg Holland of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, and Peter Webster of Georgia Institute of Technology:
The new study, published online in Philosophical Transactions of the Royal Society of London, said the increased numbers of tropical storms and hurricanes in the last 100 years is closely related to a 1.3-degree Fahrenheit rise in sea surface temperatures. […]
From 1900 to 1930, Atlantic hurricane seasons saw six storms on average, with four hurricanes and two tropical storms. From 1930 to 1940, the annual average rose to ten, including five hurricanes.
From 1995 to 2005, the average rose to 15, with eight hurricanes and seven tropical storms, the researchers said.
Changes in sea surface temperatures occurred before the periods of increased cyclones, with a rise of 0.7 degrees Fahrenheit before the 1930 period and a similar increase before the 1995 period, they said.
“These numbers are a strong indication that climate change is a major factor in the increasing number of Atlantic hurricanes,” Holland said in a statement. […]
“We are led to the confident conclusion that the recent upsurge in the tropical cyclone frequency is due in part to greenhouse warming, and this is most likely the dominant effect,” the authors wrote.
In 2004, four powerful hurricanes, Charley, Frances, Ivan and Jeanne, hit Florida. All four placed in the top ten costliest storms in U.S. history.
The record-shattering 2005 season produced 28 storms, 15 of which became hurricanes including Katrina, which caused $80 billion damage and killed 1,500 people. The 2006 season was relatively mild, with ten storms.
My recently deceased father-in-law, who worked at both NCAR and at the Hurricane Research Division of NOAA in Miami, would not have been surprised by this study’s conclusions. He had long believed that global warming would be shown to be a factor related to the increase in the number of hurricanes over time. He was a physicist by training before he became a meteorological researcher and theorist, and to him it was a matter of simple physics.
When you add energy to any system you are bound to see an increase in activity related to that system. When the oceans are heated up, and even after considering all of the other variables related to the production of tropical storms, over time you will observe an increase in the number of storms. The reason: any increase in the energy stored in the ocean’s surface water has to go somewhere. In the Atlantic, already prone to generate tropical storms and hurricanes, that is where the increased energy will eventually go. The number of storms will vary year to year, but over time the average number of storms will continue to rise so long as ocean temperatures continue to rise.
When scientists look at the evidence it is becoming increasingly clear to them that the link between hotter oceans and tropical storms is real. The hurricane seasons of 2004 and 2005 were just the beginning. Expect to see even worse in the years to come as the surface temperatures of the oceans continue to heat up due to global warming generated by man made emissions of green house gases.
Makes sense to me.
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This study indicates the intensity increases (0.5 cat.) as the amount of rain. Once the energy is taken away from the ocean surface, the frequency of hurricanes need not necessarily rise IMHO.
2. NOAA State of the Science: Atlantic Hurricanes and Climate
This link is to a [pdf] document representing the state of the science on Atlantic hurricanes and climate as developed by numerous NOAA researchers.
3. An Overview of GFDL Research on Global Warming and Hurricanes
The strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth’s climate is warmed by increasing levels of greenhouse gases in the atmosphere. Although we cannot say at present whether more or fewer hurricanes will occur in the future with global warming, the hurricanes that do occur near the end of the 21st century are expected to be stronger and have significantly more intense rainfall than under present day climate conditions. This expectation (Figure 1) is based on an anticipated enhancement of energy available to the storms due to higher tropical sea surface temperatures.
The results shown in Figure 1 are based on a simulation study carried out by Thomas R. Knutson and Robert E. Tuleya at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL). In this study hurricanes were simulated for a climate warming as projected to occur with a substantial build-up of atmospheric CO². An increase of intensity of about one-half category on the Saffir-Simpson scale was simulated for an 80 year build-up of atmospheric CO² at 1%/yr (compounded). For hurricane wind speeds, our model shows a sensitivity of about 4% per degree Celsius increase in tropical sea surface temperatures, with a larger percentage increase in near-storm rainfall.
Influence of El Niño – La Niña on Tropical Storms
"But I will not let myself be reduced to silence."