Over the last ten years, the Atlantic Basin has experienced tropical storm and hurricane activity like no other period. Since 1995, there have been 139 named storms, 78 hurricanes, and 38 major hurricanes. In 2004, there were 16 named storms, 7 hurricanes, and 6 major hurricanes. So far in 2005, there have been nine tropical storms, two hurricanes and two major hurricanes.
Since records have been taken in 1851, no other season has gotten off to the start that the 2005 Atlantic Hurricane Season has. Not even the prolific years of 1933, 1969, and 1995. 2005 became the earliest season to reach its sixth named storm. The previous mark was set in 1936 when the sixth tropical storm formed on August 5th of that year. Forecasters indicate that we are only getting started this season, and that we could expect between 18 and 21 named storms by season's end.
Only 1933 has had 20 storms or more. That season, there were 21 storms, 10 hurricanes, and 5 major hurricanes. The 1995 season ran a close second with 19 named storms, 11 hurricanes, and 5 major hurricanes. Next is 1969 with 18 named storms, 12 hurricanes, and 5 major hurricanes. Recent seasons that have had the most major hurricanes were 1996 and 2004 with six. There is no doubt that we are in the midst of a very active cycle for Atlantic Hurricanes.
The question is though, whether or not this increased activity is just a cyclical trend, or a sign that phenomena such as global warming are beginning to have an impact on weather and climate throughout the planet. Recently, a very prominent hurricane researcher from MIT, Dr. Kerry Emanuel, produced a study for the online version of the journal, Nature that suggests that hurricanes are lasting longer and getting stronger because of global warming.
Emanuel, who has written many papers on the subject of hurricane intensity, and provided assistance to a paper written by Hurricaneville's Greg Machos in 2003 on Category Five Intensity, used actual data from past storms instead of using powerful computer models to make the correlation. Specifically, his analysis indicates that hurricanes and typhoons in the Atlantic and Pacific since the mid 1970s have increased in strength and life span by 50 percent. According to CNN.com, Emanuel stated, "Theories and computer simulations indicate that global warming should generate an increase in storm intensity, in part because warmer temperatures would heat up the surface of the oceans."
Previous studies have analyzed possible relationships between global warming and tropical storm and hurricane frequency. However, nothing has been done as far as storm duration and intensity. Now, based on the sheer numbers over the last ten years, one could make an argument that there is definitely a correlation between global warming and tropical activity. However, Emanuel's study takes it one step further, and even goes back farther.
Critics such as hurricane researcher, Chris Landsea of NOAA, are not convinced with Emanuel's findings. Landsea, who has worked in the past on Dr. William Gray's team at Colorado State on seasonal tropical storm forecasts, contends that the increased activity is just another cycle that tropical cyclones in the Atlantic go through in relation to rainfall in the Sahel region of Africa as well as other factors. Others feel that there can't be a clear relationship between the two because data of earlier storms is being researched and re-evaluated all the time.
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There are some in the hurricane research community, who dispute the findings. Especially since Emanuel left out important data on intense storms of the 1950s and 1960s. Emanuel left out critical data such as wind speed since there were inconsistencies with that specific piece of information for storms of that period. In addition to that, some point out that researchers are using new tools and concepts to help them find out about early storms as far back as when records began in 1851.
Recently, Emanuel squared off with one of his critics, Chris Landsea, who had given an interview for this site back in November, 2000, on the CNN news program, Lou Dobbs Tonight. Landsea acknowledged that the database that NOAA and NHC has, still needs some work done on it so that researchers such as Emanuel can be able to get better data, and not encounter problems such as he did with data from the 1950s and 60s. According to the transcript from the debate on Lou Dobbs Tonight, Landsea stated, "I’m not convinced yet that we are seeing a global warming signal in the hurricane activity. We still need to reassess all the hurricanes themselves, and try to get our database cleaned up, because it’s a very messy database that Professor Emanuel has had to work with. And we’re trying to address that with some climate work.”
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At the risk of disagreement with experts in the weather and hurricane community, it is possible that despite the gaps in some of the data, Emanuel's findings may be right, or at least on to something. Let's take into account just the Category Five Hurricanes that have developed since 1975 in the Atlantic Basin. We have had David (1979), Allen (1980), Gilbert (1988), Andrew (1992), Mitch (1998), Isabel (2003), and Ivan (2004). Of those storms, Gilbert, Allen, Andrew, Mitch, and Ivan are among the most powerful storms ever recorded in the Atlantic.
In addition to that, we have seen many very intense storms that came close to Category Five strength such as Gloria (1985), Hugo (1989), Georges (1998), Floyd (1999), Lenny (1999), Dennis (2005), and Emily (2005). Now, of course, we have to keep in mind that record taking today is much more accurate than it was in 1950 or 1851 for that matter. There are more tools hurricane researchers and forecasters can use to collect the data such as satellite, radar, and hurricane hunter aircraft reconnaissance. On top of that, there is the Gulfstream aircraft, which analyzes upper level dynamics around a hurricane or tropical storm. Most of these tools didn't come into use until the 1960s.
There is also intense media coverage of these storms with live video reports from the impact areas. Back in the 1800s you didn't know a storm was coming necessarily. That's why hurricanes in those days were so deadly. There are issues with the storm data provided by the NHC. In constructing the storm database this site is using now, there were some problems encountered with the way the data was entered, and also the fact that pressure data was not recorded for many of the storms until the 1950s and 1960s with more consistent pressure data kept starting in the 1970s and 1980s.
The reason for that again was the new technologies such as satellite imagery, which could now interpret a storm's intensity from an image of the tempest well out in the Atlantic from space. Prior to that, and the hurricane hunters, the best fix for pressure data was when the storm made landfall. Another issue is the fact that the NHC only lists landfall areas for hurricanes that came ashore in the United States. For example, Hurricane Mitch, which struck in Central America, is only listed in the database file as a hurricane, but where it made landfall and at what intensity is not listed.
Similarly, storms such as Gilbert, Joan (1988), Luis (1995), Lenny (1999), Keith (2000), Iris (2001), and Fabian (2003) are treated the same way. So, for Dr. Emanuel to do his analysis, he had to do a lot of painstaking work. You could still figure out what the storms did by studying each of the plots since they would have the wind speed, and in some cases pressure besides the coordinates. By the way, the coordinates are entered in the data in several different ways, most commonly as a six or seven digit string of numbers.
Now, it is true that some of the data from the earlier storms is not known, and data from the 1950s and 60s were disregarded, and that may skew the results of the findings. However, can we really truly say that increased hurricane activity is cyclical based on only 155 years of data when the planet has been around for billions of years? True that it is the only data we have to go on, but there is anecdotal evidence of other storms that did occur all the way back from the time of Columbus, and beyond.
Take for instance the situation with Hurricane Lenny. Back in November of 1999, it accomplished two things: It was the most powerful hurricane in the month of November, and it was the first ever storm on record to hit the islands from the West. However, can we really truly say that this is the only time this has ever happened? While quite rare, it may have happened other times, and perhaps more often than we think prior to record keeping in 1851.
The fact is that the data that is at the NHC, while still very good, is also still a small sample in the grand scheme of things. To get a good idea of climate you need to have over 30 years worth of data. The NHC has over five times that so basically we're looking at just five climate cycles of tropical storm and hurricane activity on record. So, how do we establish that there are cycles of increased or decreased hurricane activity based on just five cycles of 30 years?
Better yet, much of the studies and predictions that are done today are based on tropical activity since 1950, which is an even smaller sample to work with. Now, in all fairness, while the idea of cycles of increased hurricane activity may not have enough climate cycles to firmly indicate such patterns, but the same is also true for global warming. However, the important thing to note is that never before has the planet dealt with so many man made technologies from industrial to scientific.
China and India have become economic powers, and have grown tremendously in recent years. As a result, they have been more dependent on sources of energy such as oil, coal, and other fossil burning fuels. And, they produce increasing amounts of carbon dioxide. This adds to the global warming problem, and perhaps, it is beginning to accelerate the process, which many thought wouldn't affect hurricanes and tropical storms until the middle of the 21st century.
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