What is the link between hurricanes and global warming?

"According to the National Hurricane Center, storms are no more intense or frequent worldwide than they have been since 1850. Constant 24-7 media coverage of every significant storm worldwide just makes it seem that way." (Paul Bedard)

Comments 1 to 7:

1. Will Nitschke (www.capitaloffice.com.au) at 16:09 PM on 19 December, 2007
   A well balanced article. Excellent. Thank you!
   
   "It's important to remember that hurricane activity is just one possible side-effect of global warming. While the empirical evidence linking global warming and hurricane intensity seems robust, it has no bearing on the central question of whether human CO2 emissions are causing global warming."
   
   True, but if human CO2 emissions causing global warming do not have damaging consequences, such as increased storm activity, the 'central question' is no longer central, is it?
   
   Some interesting data on hurricanes:
   
   Fewest Northern Hemisphere Hurricane Days since 1977. 3rd Lowest since 1958 (behind 1977 and 1973). See:
   http://www.coaps.fsu.edu/~maue/tropical/
   Response: If the only consequence of global warming was increased hurricane activity, then you'd have a point. However, they are the tip of the iceberg (pardon the pun). See positives and negatives of global warming for a more comprehensive list.
2. Will Nitschke (www.capitaloffice.com.au) at 22:26 PM on 22 December, 2007
   Your list of potential catastrophes makes interesting reading. But there are no citations, so I wonder how many of these items are speculations and how many have any scientific backing to them. Presumably if the global temperature dropped 2C then we could construct an equally long list of potential catastrophes. It seems that the implications of all this is that somehow, miraculously, the current average global temperature must be perfect.
3. Alan McIntire at 13:20 PM on 26 December, 2007
   http://www.physorg.com/news116687408.html
   
   "Titled "Effect of Remote Sea Surface Temperature Change on Tropical
   Cyclone Potential Intensity," their study found that long-term changes
   in potential intensity are more closely related to the regional
   pattern of warming than to local ocean temperature change. Regions
   that warm more than the tropical average are characterized by
   increased potential intensity, and vice versa. "A surprising result is
   that the current potential intensity for Atlantic hurricanes is about
   average, despite the record high temperatures of the Atlantic Ocean
   over the past decade." Soden said. "This is due to the compensating
   warmth in other ocean basins."
   
   "As we try to understand the future changes in hurricane intensity, we must look beyond changes in Atlantic Ocean temperature. If the Atlantic warms more slowly than the rest of the tropical oceans, we
   would expect a decrease in the upper limit on hurricane intensity,"
   Vecchi added. "This is an interesting piece of the puzzle."
   - A. McIntire
4. Sam Spade at 06:29 AM on 25 October, 2009
   HISTORICAL HURRICANE FREQUENCY
   
   ..........Landsea et al, 2009 (From NYT Aug12, 2009)
   The researchers studied storms that played themselves out at sea, either in a day or two or over a longer period, from 1878 to 2008. By the late 19th century, they estimated meterologists missed perhaps two of the larger storms each year, and by the 1950s they were picking up on average all but one each year.
   Yet the researchers estimate that a century ago, as many as 80 percent of short-lived storms came and went without ever being officially noticed.
   Over all, they conclude, storm counts have not changed in the last century.
   
   ..........Mann et al, 2009 (Ditto)
   ...used a mathematical model of hurricane activity and measurements of sediment to estimate how often major storms struck the Gulf and Atlantic Coasts of the United States in the last 1500 years.
   ...the researchers worked with sediment samples from Puerto Rico, the Gulf Coast and the Atlantic Coast from Florida to New England.
   
   Although current numbers are relatively high, they say, both analytical methods suggest that a period of high storm frequency, possibly even higher than today's, began in the year 900 and lasted until 1200 or so.
   
   
   ..........Lund et al, 2009 September 22, 2009
   Clemson University press release:
   
   Hurrican Frequency Is Up, But Not Their Strength...
   
   In a new study, Clemson University researchers have concluded that the number of hurricanes and tropical storms in the Atlantic Basin is increasing, but there is no evidence that their individual strengths are any greater than storms of the past or that the chances of a U.S. strike are up.
   ...studied changes in the tropical cycle record in the North Atlantic between 1851 and 2008.
   "This is a hot button issue in the argument for global warming," said Lund. "Climatologists reporting to the U.S. Senate as recently as this summer testified to the exact opposite of what we find. Many researchers have maintained that warming waters of the Atlantic are increasing the strength of these storms. We do not see evidence for this at all, however we do find that the number of storms has recently increased."
   The study represents one of the first rigorous statistical assessments of the issue with uncertainty margins calculated in...
   While the study did conclude that more storms are being documented, researchers found no evidence of recent increases in U.S. landfall strike probability of the strongest hurricanes. Lund notes that "because these types of storms are so uncommon, it will take many years of data to reliably assess this issue."
5. Sam Spade at 12:51 PM on 25 October, 2009
   FACTORS INHIBITING HURRICANES
   
   ...while water temperature is the most important factor in tropical cyclone dynamics, many other environmental factors affect these storms. These include: the deep warm water; moisture availibility; weak wind shear; a source of rotation, and no land interaction/landfall. Only when all these factors exist can a hurricane reach its maximum potential intensity for a given water temperature. In fact, few hurricanes reach their potential because some inhibiting factor exists. Furthermore, global warming could enhance some negative influences regionally; an ensemble of 18 global climate models show that wind shear and dry air will increase in the Atlantic, while in contrast the opposite occurs in the west Pacific where environmental factors favor more hurricanes. Therefore, anthropogenic warmer oceans do not necessarily correlate to increased tropical cyclone activity or stronger hurricanes globally. Climate models give mixed results on whether the average storm intensities will change, but most show evidence for some increase in intensity.
   Pat Fitzpatrick, Hurricanes and Climate...~2007
   
   One inhibiting factor is the El Nino, a body of relatively warm equatorial water in the eastern Pacific. Absent for the past few years, it is expected to bring weak to moderately warm water to the South American west coast. A characteristic of El Nino is westerly winds in the upper troposphere that act to shear the tops off Atlantic easterly waves coming off the African Coast, preventing them from growing into named storms or hurricanes...
   However, this (weak to moderate) El Nino will fall well short of the one that occurred in 2007, limiting the season's total named storms to seven.
   From William Gray's 2001 hurricane forecast
   
   Working in a strategically located lagoon off Puerto Rico, Donelly and Woodruff compiled the long record (cores, 2007) of strong hurricanes in the Atlantic region. The 5,000 year record identified two factors that appeared to heighten Atlantic activity: weak El Ninos in the tropical Pacific and strong monsoons in West Africa.
   Scientists have established that strong El Ninos can stunt hurricane activity by causing strong high-altitude winds that inhibit hurricane formation.
   Other reseaqrchers have identified that storms over western Africa generate atmospheric waves that move into the Atlantic and provide "seedlings" for hurricane development...
   Oceanus Feb 13, 2009
6. Mizimi at 05:59 AM on 2 November, 2009
   The formation of Atlantic hurricanes also appears to be strongly influenced by Saharan dust. The dust from the Sahara tracks westwards into the ocean and causes local cooling, depressing the temp. below thresholds needed for hurricanes to form.
   
   ntrs.nasa.gov/archive/nasa/casi.../20080039568_2008038939.pdf - summarises the work by Lau & Kim.
7. oracle2world at 12:53 PM on 8 March, 2010
   Glad the consensus has determined hurricane frequency should be retired to the ash heap of arguments. So how did this one slip through the consensus?
   
   ----
   Global warming is causing more frequent hurricanes in the North Atlantic and Gulf of Mexico, according to a study from the National Center for Atmospheric Research.
   
   The increased frequency of tropical cyclones ``is largely a response'' to a 1 degree Celsius rise in sea water temperatures since 1905 that was caused by greenhouse gases, the study found. Since 1995, the North Atlantic has experienced an average of 15 tropical storms a year, of which eight became strong enough to be called hurricanes. That compares with 10 tropical storms and five hurricanes per year from 1930 to 1994, the report says.
   
   ``There is an 80 percent chance that the majority of the current increases have been impacted by global warming,'' said Greg Holland, director of the research center in Boulder, Colorado, and co-author of the study. ``The bad news is that we've gone up in numbers overall, and in the proportion of major hurricanes as well.''
   
   -- http://www.climateark.org/shared/reader/welcome.aspx?linkid=81144

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