To What Extent Has Global Warming Affected The Strenght And Frequency Of Hurricanes In The United States' Atlantic Coast From 1851 To 2006
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To what extent has Global Warming affected the strength and frequency of hurricanes that hit the United States Atlantic coast between 1851 and 2006 An introduction to Global Warming and Hurricanes In order to understand the effect of Global Warming in the strength and frequency of tropical cyclones, in this case hurricanes, it is important to understand what is global warming, how it forms and how hurricanes can relate to it. In recent years there has been a growing hype in the media coverage and the general public‟s views of Global Warming. Global Warming is loosely defined as the increase of mean temperatures in the sum total of the Earth‟s system from a certain period in time 1. For the 20th century Global Warming, scientists usually refer to the increase in temperatures since the early 1900s to the current time (or the past 100 years). The causes of the warming are not clear; however the United Nations Intergovernmental Panel in Climate Change, also known as the UN IPCC, suggests that it has been cause by increased radiative forcing of the troposphere by the introduction of a „foreign‟ agent, which in this case is Carbon Dioxide gas (CO2) 2. It is very important to note that Carbon Dioxide (CO2) is not a foreign agent in the surface troposphere but it is a naturally occurring trace gas in it with a concentration of 387 parts per million per volume in the atmosphere. According to the UN IPCC over the last 100 years the Earth has warmed 0.54°C above average 3. This warming measurement however has a +/- 0.18°C margin of error which is a considerably large 33% margin of error 4. This is the official margin of error however there is evidence suggesting that a larger margin of error may be present; Stephen Schneider, lead IPCC 2007 (FAR) author said: “To capture the public‟s imagination, we have to offer up some scary scenarios, make simplified dramatic statements and little mention of any doubts one might have; each of us has to decide the right balance between being effective and being honest” 5. Hurricanes are systems of extreme low pressure that develop from August to October in the Atlantic Ocean 6. They are not fully understood; until now there is insufficient empirical and conclusive evidence to say how they are formed 7. Hurricanes tend to develop over warm, deep oceans in autumn where the temperatures exceed 26°C. They develop between latitudes 5° and 20° North or South as they cannot „spin‟ closer to the equator because there would be a lack of Coriolis force. Once the Hurricanes are formed they move westbound in unpredictable and irregular routes. The hurricane‟s power and strength declines very fast when its heat source is removed; this happens by moving into colder © 2008 Gabriel Mauricio Gutiérrez Salas
waters, land or otherwise 8. Hurricanes would, in general, be stronger when the ocean temperature is hotter and thus an intense Global Warming would, in theory, increase the force of the hurricane. This however is only one factor, in many, that affects the forces of the hurricane 9. Hurricane strength and frequency in the United States Atlantic Coast from 1851 to 2006 Table 1 shows the total number of hurricanes to strike the Atlantic United States Coast divided by decade. The categories are based on the Saffir-Simpson Hurricane Scale 10 shown below:
© 2008 Gabriel Mauricio Gutiérrez Salas
Table 1. DECADE 1851-1860 1861-1870 1871-1880 1881-1890 1891-1900 1901-1910 1911-1920 1921-1930 1931-1940 1941-1950 1951-1960 1961-1970 1971-1980 1981-1990 1991-2000 2001-2006
1 7 8 7 8 8 10 10 5 4 8 8 3 6 9 3 6
2 5 6 6 9 5 4 4 3 7 6 1 5 2 2 6 2
CATEGORY 3 5 1 7 4 5 4 4 3 6 9 6 4 4 3 4 6
1851-2006
110
73
75
11
4 1 0 0 1 3 0 3 2 1 1 3 1 0 1 0 1 18
5 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0
TOTAL 1,2,3,4,5 18 15 20 22 21 18 21 13 19 24 18 14 12 15 14 15
CATEGORIES 4&5 1 0 0 1 3 0 3 2 2 1 3 2 0 1 1 1
3
279
21
(Source contains raw data)
The average number of hurricanes that hit the United States per decade is 17.9 hurricanes; this means that every year 1.79 hurricanes (2 for practical purposes) are expected to hit the United States Atlantic coast. The decade with the highest hurricane frequency (the decade with the most hurricanes hits) has been by far 1941 to 1950. The United States‟ Atlantic coast received 24 hurricanes during this decade and ten of them were Major Hurricanes. Major Hurricanes are hurricanes that reach surface wind speeds of 111 miles per hour (50 m/s or 96 knots); they are correspondent to categories 3, 4 and 5 of the Saffir-Simpson Hurricane Scale 12. Out of the ten major hurricanes in that decade nine were Category 3, one was Category 4 and there were no Category 5 hurricanes. The decade with the lowest hurricane frequency was 1971 to 1980. The United States‟ Atlantic coast only received twelve hurricanes; this is significantly lower than the 17.9 average. Only four out of the twelve hurricanes were major hurricanes and none of them were Category 4 or 5. The average number of major hurricanes per decade is 6.2 so the decade‟s major hurricane frequency is also below average. © 2008 Gabriel Mauricio Gutiérrez Salas
Category 5 hurricanes are extremely infrequent, even in decades with high activity hurricane seasons they remain unusual 13. The hurricane season is defined as the time period between June 1st and November 30th when hurricanes usually occur. The earliest hurricane to landfall in the United States was Alma in June 9 th, 1966 and the latest was FL (Tampa) on November 30th, 1925 14. From 1851 to the present there have only been three Category 5 hurricanes that hit the United States: Hurricane FL (Keys) in 1935, Hurricane Camille in 1969 and Hurricane Andrew in 1992. It is important to note that hurricanes where not given names prior to 1950 and so hurricanes from 1851 to 1949 would be named after the area where they landfall. Hurricane FL (Keys) in 1935 has been the strongest hurricane to ever hit the United States with a minimum pressure of 892 millibars and 26.35 inches. The second strongest hurricane has been Hurricane Camille in 1969 with a minimum pressure of 909 millibars and 26.84 inches. Hurricane Andrew in 1992 has been the most recent Category 5 Hurricane and it has been the third strongest; he follows FL (Keys) and Camille with a minimum pressure of 922 millibars and 27.23 inches. The damage caused by these hurricanes was catastrophic as they had intense rainfall and surges of over 18 feet which shattered the urban areas in their paths. Figure 1 shows the strike path of major hurricanes from 1931-1940; Hurricane FL (Keys) is highlighted. Fig. 115
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 2 shows the strike path of major hurricanes from 1961-1970; Hurricane Camille is highlighted. Fig. 216
Figure 3 shows the strike path of major hurricanes from 1991-2000; Hurricane Andrew is highlighted. Fig. 317
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 4 shows the total number of hurricanes that hit the United States‟ Atlantic coast from 1851 to 2006 divided by their Saffir-Simpson Hurricane Scale category. Fig. 4
Total Number of Hurricanes from 1851-2006 divided by category 5
Category
4
3
2
1
0
20
40
60
80
100
120
Number of Hurricanes
As a general trend there are less hurricanes as the Saffir-Simpson category increases; this however doesn‟t apply to Categories 2 and 3 which have seventythree and seventy-five hurricanes respectively. This is probably because the number of hurricanes in those categories is similar, however it is more likely that a Category 3 Hurricane hits the United States because it has more energy and thus it can travel further thus more of them actually make landfall in the Atlantic coast. Figure 4 also shows that there have been 96 major hurricanes making landfall, compared to a total of 279 hurricanes. This means that 34.41% of hurricanes that made landfall in the United States‟ Atlantic coast are considered Major Hurricanes.
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 5 shows the total number of Hurricanes divided by decade and Figure 6 shows the total number of Major Hurricanes divided by decade: Fig. 5
Total Number of Hurricanes by Decade
Total Number of Hurricanes
30 25 20 15 10 Hurricanes 5 0
Decade
Fig. 6
Number of Major Hurricanes divided by Decade
Number of Major Huricanes
12 10 8 6 Major Hurricanes
4 2 0
Decades
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 5 shows a rather irregular distribution of hurricanes per decade as apparently there is no defined cycle. The average number of hurricanes is around 18 per decade and the highest peak is reached in the 1941-1950 decade. From 1951-1980 the number of hurricanes decreased and now we are in a slight growing trend which is below the average (15 hurricanes). Figure 6 shows a similar pattern with the highest number of Major Hurricanes occurring, again, in the 1941-1950 decade, and then sharply going down until 1990. From 1991 to the present there is a slight rise in the number of Major Hurricanes however it still is considerably below the average and the rate of growth is below the maximum (from 1871-1880). Temperature changes in the United States from 1881 to 2006 Figure 7 shows the average temperature changes in the Continental United States divided by decades from 1881 to 2006. As shown by Figure 7, American Temperatures on average have increased since 1881. This increase has been of 0.54°C above the average (shown as 0 in Figure 7) has been an increase of 0.63°C since 1881 when the temperatures were lower than average 18. It is important to note that temperatures prior to 1881 are proxy-based 19 and thus are not included.
Temperature change in °C (+/- 0.18)
Fig. 7
Average Temperature Change Per Decade in the United States (NOAA)
0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
Average Global Temperature Change Per Decade
© 2008 Gabriel Mauricio Gutiérrez Salas
Decades
Because Figure 7 shows the averages per decade it seems that since 1961 the Earth has been experiencing warming that increases, and gets faster, every year. This however is not the case. Figure 8 shows the yearly temperature changes for the same period of time and as it becomes obvious temperature is irregular and changing rapidly every year. Fig. 8
United States Temperature Changes from 1881 to 2006 (NOAA Data)
0.7 0.65 0.6 0.55 0.5 0.45 Change in Temperature °C (+/- 0.18)
0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0
-0.05 -0.1
-0.15 -0.2 -0.25 -0.3 -0.35 -0.4 2006
2001
1996
1991
1986
1981
1976
1971
1966
1961
1956
1951
1946
1941
1936
1931
1926
1921
1916
1911
1906
1901
1896
1891
1886
1881
-0.45
Years
Temperature Change
As shown by Figure 8 the maximum recorded temperature in the United States happened in 1998. The temperature in 1998 was 0.6045° above average . This has © 2008 Gabriel Mauricio Gutiérrez Salas
been the maximum temperature in the last 120 years; however it has not been the maximum historic temperature. The closest maximum temperature is in a time known as the Medieval Optimum or Medieval Warm Period. This happened close to 1000 AD 20. Temperatures before the 1880s are reconstructed by Paleoclimatologists using proxy data such as tree rings or arctic ice core samples. When using Ice Core data scientists compare the level of current CO2 with the trapped air bubbles‟ CO2 concentration and thus give an estimate of the temperature of the earth when the air bubbles were trapped inside the ice. There are mayor flaws with using ice cores as proxies. According to them the current atmospheric CO2 levels are about 25% higher than in the pre industrial period 21. However this does not accurately represent the current atmospheric conditions. Ice cores cannot be used to store air bubbles because they are not a perfectly closed system 22. “More than 20 physicochemical processes deteriorate the CO2 and general air quality inside the polar ice” and thus compromise the data 23. This does not allow proxy data to be trusted and thus is ignored in this investigation. The current warming trend can be explained by several other factors other than CO2. There is nowhere in the current scientific literature that states that increased concentrations of Carbon Dioxide gas (CO2) increases the temperature 24. One other factor that can explain the increased temperatures is solar activity; this has been suggested by Dr. Sami Solanksy of the Max Planck Institute for Solar System Research in Germany 25. “The Sun has been at its strongest over the past 60 years and may now be affecting global temperatures 26”. At this time correlations between cosmic ray flux (caused by increased solar activity) and global warming are suggestive but the research is inconclusive. As shown by Figure 8 the warming trend started near 1906 and this cannot be explained by CO2 emissions as the CO2 emissions at the time were small and irrelevant as they could not have made a massive effect in the atmospheric system. The cooling from 1941-1960 cannot be explained by CO2 emissions as during the postwar economic boom they increased yet the temperature decreased.
© 2008 Gabriel Mauricio Gutiérrez Salas
Temperature changes in the United States from 1881 to 2006 compared to hurricane and major hurricane frequency Figure 9 shows the average temperature changes (shown in blue) compared to the hurricane frequency (shown in red) per decade between 1881 and 2006: Fig. 9
Hurricane Frequency compared to Change in Temperature between 1881 and 2006 (Per Decade) Number of Hurricanes Temperature Change 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
25
Temperature Change (°C)
Total Number of Hurricanes
30
20 15 10 5
2001-2006
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1941-1950
1931-1940
1921-1930
1911-1920
1901-1910
1891-1900
1881-1890
0
Decades
As shown by the graph there is no correlation between hurricane frequency and temperature change. From 1881 to 1900 the temperatures were below average so because of lower ocean temperatures the energy available to the hurricanes would be reduced and thus the number of hurricanes expected would be quite low. This however did not happen as in both decades hurricane levels were significantly above average. From 1901 to 1910 the temperature experienced a sharp decrease and, as expected, the hurricane number decreased, however the decade still experienced an average number of hurricanes even though it was the coldest decade on record. From 1911 to 1920 the temperatures still remained very much below average but the hurricane frequency incremented to above average levels once more. © 2008 Gabriel Mauricio Gutiérrez Salas
From 1921 to 1930 the temperatures experienced a rapid increase (one of the fastest increases in the recorded history). The hurricane frequency was expected to increase, however it shows a rapid decrease to its second lowest level from 1881 to 2006 which was very significantly below average. From 1931 to 1940 the temperatures increased to average levels and the hurricane frequency also increased to average levels. This makes this decade the „mean‟ decade for hurricanes and temperatures as for a combination of factors both temperatures and hurricane frequency were average. On the 1941 to 1950 decade the temperatures stabilized and yet this was the decade with the most hurricanes in recorded history with 24 hurricanes hitting the United States‟ Atlantic coast at average temperatures. Starting in 1971 the temperatures started to increase rapidly to record highs (in recent history, recorded with instruments and not proxy-reconstructed); however the hurricane levels for the three decades between 1971 and 2006 have been below average with 15, 14 and 15 hurricanes respectively making landfall with the United States‟ Atlantic Coast. If a clear correlation between hurricane frequency and global temperatures actually existed it would be clearly shown on the graph and the frequency would go down and/or up with the temperature. The Pearson product-moment correlation coefficient of the two samples is -0.439. This shows that the correlation is really small, if existent, and it‟s within the expected coincidence and random rate. It is also important to note that the correlation shown by the Pearson product-moment correlation coefficient is a negative correlation which means that the hurricanes actually decrease when temperatures are increased. Theoretically the temperatures would drive the hurricane frequency however in reality the data does not show this trend and the Pearson product-moment correlation coefficient. In addition to the graphs that represent the „trend‟ visually, statistical methods also show that there is no correlation between hurricane frequency and change in temperature.
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 10 shows the average temperature changes (shown in blue) compared to the major hurricane frequency (shown in red) per decade between 1881 and 2006:
Major Hurricane Frequency compared to Change in Temperature between 1881 and 2006 Number of Hurricanes
Temperature Change 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
10 8 6 4
2001-2006
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1921-1930
1911-1920
1901-1910
1891-1900
1881-1890
0
1941-1950
2
1931-1940
Total Number of Major Hurricanes
12
Decades
As shown by the graph there is no clear correlation between major hurricane frequency and temperature change. From 1881 to 1890 the temperatures were below average so because of lower ocean temperatures the energy available to the hurricanes would be reduced and thus the number of major hurricanes expected would be quite low. During this decade the number of major hurricanes (5) was below the 6.2 average. From 1891 to 1900 the temperature remained stable, however the major hurricane number increased dramatically to 8 major hurricanes which is above average. From 1901 to 1910 the temperatures reached the lowest level on record and the major hurricanes decreased by 50% compared to the 1891-1900 decade to below average levels. From 1911-1920 the temperature experienced a slight increase however the major hurricane number increased to above average levels. From 1921-1930 the © 2008 Gabriel Mauricio Gutiérrez Salas
Temperature Change (°C)
Fig. 10
temperatures continued to experience a slow increase but the major hurricane levels decreased to below average levels. From 1931 to 1950 the temperatures started to stabilize and showed a tendency to decrease however during doth decades the major hurricane levels were increasing rapidly to above average levels and in the 1941-1950 decade the record was set. During this decade the total number of major hurricanes reached a record high of 10 hurricanes which is 3.8 major hurricanes more than average, this is a significant increase and it happened when temperatures were average. From 1951 to 1970 the temperatures remained stable at average levels however the number of major hurricanes decreased sharply from record highs to just below average. From 1971 to 2000 the temperature increased rapidly to record highs reached in 1998 (0.6° above average) however major hurricane frequency remained stable experiencing a slight increase in the 1991-2000 decade but still remaining below average levels. From 2001 to 2006 the number of major hurricanes is slightly above average (+0.8) however the temperature even though it decreased from 1998 by about 0.1°C it still remained 0.5° above average. The strongest hurricane to hit the United States‟ Atlantic Coast was the Labor Day Hurricane (FL KEYS) in 1935 (It was a category 5 Hurricane). This is surprising because the temperature in 1935 was not only much lower than today but it actually was -0.0495°C below average levels. This is surprising because theoretically a year with a below average temperature would have a below average hurricane number, major hurricane number and obviously it should not have the strongest hurricane in recorded history. This same pattern repeats again. The second strongest hurricane to hit the United States‟ Atlantic Coast was Category 5 Hurricane Camille in 1969. Blaming Camille‟s strength to Global Warming is not only irresponsible but it would also be scientifically and historically inaccurately. The temperatures when Camille hit in 1969 were average. Al Gore stated in his movie An Inconvenient Truth “For a long time, the scientists have been telling us global warming increases the temperature of the top layer in the ocean, and that causes the average hurricane to become a lot stronger. So, the fact that the ocean temperatures did go up because of global warming, because of man-made global warming, starting around in the late seventies and then we had a string of unusually strong hurricanes outside the boundaries of this multi-decadal cycle that is a real factor; there are scientists who point that out, and they're right, but we're exceeding those boundaries now.” 27
© 2008 Gabriel Mauricio Gutiérrez Salas
According to the temperature data and hurricane data this is simply an irresponsible statement, an exaggeration and a lie. Out of the ten strongest hurricanes to hit the United States‟ Atlantic Coast only 2 happened after 1970. Those hurricanes were Katrina in 2005 (Third Strongest) and Andrew in 1992 (Fourth Strongest). 40% of the strongest hurricanes happened BEFORE 1945 and one of them happened before 1900. This means that Global Warming allegedly caused by increase human-made greenhouse gas emissions could not have explained 80% of the top-ten strongest hurricanes because CO2 levels started to be released in „large‟ amounts to the atmosphere after the post war economic boom when the temperatures actually decreased. After 1970 when the temperatures experienced a large increase the amount of hurricanes still remains at average levels and well below the record mid-19th century decades. 1998 has been the hottest year on record however it has also been one of the calmest years in recorded history when referring to hurricane strength and frequency. In 1998 only 3 hurricanes hit the United States‟ Atlantic Coast. They were Danny, Bonnie and Earl; categories 1, 2 and 1 respectively. Two of them barely made it to the Saffir Simpson Hurricane Scale as they were borderline tropical depressions and storms. Conclusions In conclusion Global Warming has had, if any, a minimal and irrelevant effect in the strength and frequency of hurricanes that hit the United States‟ Atlantic coast between 1851 and 2006. The data clearly shows that there is no correlation whatsoever between hurricane frequency and change in temperature. This is confirmed by the use of statistics. The data is suggestive but inconclusive in respect to the relationship between major hurricane frequency and changes in temperatures. It also shows that the general hurricane strength is unrelated to temperature as 80% of the top ten strongest hurricanes in recorded history have happened in years with average or below average temperatures. Only 2 of them (and they were not the top two) Katrina and Andrew happened with above average temperatures and they honestly failed to deliver. The effects of Katrina where enormous but not because Katrina was a strong hurricane (It was category 3 at landfall) but because New Orleans is a city basically built inside a bowl under sea level protected by inferior dykes and levees that could not withstand the water pressure and ended up „pooling‟ the water inside the city. The data shows no evidence that temperatures play an important, if any, role in hurricane strength and frequency. In order for the temperature to have an effect the rise (or fall) of temperatures would have to be dramatically. Some scientists like © 2008 Gabriel Mauricio Gutiérrez Salas
Roy W. Spencer suggested that a plus or minus 2.5°C change would be needed to have any noticeable effects in hurricane frequency and strength.
© 2008 Gabriel Mauricio Gutiérrez Salas
waters, land or otherwise 8. Hurricanes would, in general, be stronger when the ocean temperature is hotter and thus an intense Global Warming would, in theory, increase the force of the hurricane. This however is only one factor, in many, that affects the forces of the hurricane 9. Hurricane strength and frequency in the United States Atlantic Coast from 1851 to 2006 Table 1 shows the total number of hurricanes to strike the Atlantic United States Coast divided by decade. The categories are based on the Saffir-Simpson Hurricane Scale 10 shown below:
© 2008 Gabriel Mauricio Gutiérrez Salas
Table 1. DECADE 1851-1860 1861-1870 1871-1880 1881-1890 1891-1900 1901-1910 1911-1920 1921-1930 1931-1940 1941-1950 1951-1960 1961-1970 1971-1980 1981-1990 1991-2000 2001-2006
1 7 8 7 8 8 10 10 5 4 8 8 3 6 9 3 6
2 5 6 6 9 5 4 4 3 7 6 1 5 2 2 6 2
CATEGORY 3 5 1 7 4 5 4 4 3 6 9 6 4 4 3 4 6
1851-2006
110
73
75
11
4 1 0 0 1 3 0 3 2 1 1 3 1 0 1 0 1 18
5 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0
TOTAL 1,2,3,4,5 18 15 20 22 21 18 21 13 19 24 18 14 12 15 14 15
CATEGORIES 4&5 1 0 0 1 3 0 3 2 2 1 3 2 0 1 1 1
3
279
21
(Source contains raw data)
The average number of hurricanes that hit the United States per decade is 17.9 hurricanes; this means that every year 1.79 hurricanes (2 for practical purposes) are expected to hit the United States Atlantic coast. The decade with the highest hurricane frequency (the decade with the most hurricanes hits) has been by far 1941 to 1950. The United States‟ Atlantic coast received 24 hurricanes during this decade and ten of them were Major Hurricanes. Major Hurricanes are hurricanes that reach surface wind speeds of 111 miles per hour (50 m/s or 96 knots); they are correspondent to categories 3, 4 and 5 of the Saffir-Simpson Hurricane Scale 12. Out of the ten major hurricanes in that decade nine were Category 3, one was Category 4 and there were no Category 5 hurricanes. The decade with the lowest hurricane frequency was 1971 to 1980. The United States‟ Atlantic coast only received twelve hurricanes; this is significantly lower than the 17.9 average. Only four out of the twelve hurricanes were major hurricanes and none of them were Category 4 or 5. The average number of major hurricanes per decade is 6.2 so the decade‟s major hurricane frequency is also below average. © 2008 Gabriel Mauricio Gutiérrez Salas
Category 5 hurricanes are extremely infrequent, even in decades with high activity hurricane seasons they remain unusual 13. The hurricane season is defined as the time period between June 1st and November 30th when hurricanes usually occur. The earliest hurricane to landfall in the United States was Alma in June 9 th, 1966 and the latest was FL (Tampa) on November 30th, 1925 14. From 1851 to the present there have only been three Category 5 hurricanes that hit the United States: Hurricane FL (Keys) in 1935, Hurricane Camille in 1969 and Hurricane Andrew in 1992. It is important to note that hurricanes where not given names prior to 1950 and so hurricanes from 1851 to 1949 would be named after the area where they landfall. Hurricane FL (Keys) in 1935 has been the strongest hurricane to ever hit the United States with a minimum pressure of 892 millibars and 26.35 inches. The second strongest hurricane has been Hurricane Camille in 1969 with a minimum pressure of 909 millibars and 26.84 inches. Hurricane Andrew in 1992 has been the most recent Category 5 Hurricane and it has been the third strongest; he follows FL (Keys) and Camille with a minimum pressure of 922 millibars and 27.23 inches. The damage caused by these hurricanes was catastrophic as they had intense rainfall and surges of over 18 feet which shattered the urban areas in their paths. Figure 1 shows the strike path of major hurricanes from 1931-1940; Hurricane FL (Keys) is highlighted. Fig. 115
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 2 shows the strike path of major hurricanes from 1961-1970; Hurricane Camille is highlighted. Fig. 216
Figure 3 shows the strike path of major hurricanes from 1991-2000; Hurricane Andrew is highlighted. Fig. 317
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 4 shows the total number of hurricanes that hit the United States‟ Atlantic coast from 1851 to 2006 divided by their Saffir-Simpson Hurricane Scale category. Fig. 4
Total Number of Hurricanes from 1851-2006 divided by category 5
Category
4
3
2
1
0
20
40
60
80
100
120
Number of Hurricanes
As a general trend there are less hurricanes as the Saffir-Simpson category increases; this however doesn‟t apply to Categories 2 and 3 which have seventythree and seventy-five hurricanes respectively. This is probably because the number of hurricanes in those categories is similar, however it is more likely that a Category 3 Hurricane hits the United States because it has more energy and thus it can travel further thus more of them actually make landfall in the Atlantic coast. Figure 4 also shows that there have been 96 major hurricanes making landfall, compared to a total of 279 hurricanes. This means that 34.41% of hurricanes that made landfall in the United States‟ Atlantic coast are considered Major Hurricanes.
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 5 shows the total number of Hurricanes divided by decade and Figure 6 shows the total number of Major Hurricanes divided by decade: Fig. 5
Total Number of Hurricanes by Decade
Total Number of Hurricanes
30 25 20 15 10 Hurricanes 5 0
Decade
Fig. 6
Number of Major Hurricanes divided by Decade
Number of Major Huricanes
12 10 8 6 Major Hurricanes
4 2 0
Decades
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 5 shows a rather irregular distribution of hurricanes per decade as apparently there is no defined cycle. The average number of hurricanes is around 18 per decade and the highest peak is reached in the 1941-1950 decade. From 1951-1980 the number of hurricanes decreased and now we are in a slight growing trend which is below the average (15 hurricanes). Figure 6 shows a similar pattern with the highest number of Major Hurricanes occurring, again, in the 1941-1950 decade, and then sharply going down until 1990. From 1991 to the present there is a slight rise in the number of Major Hurricanes however it still is considerably below the average and the rate of growth is below the maximum (from 1871-1880). Temperature changes in the United States from 1881 to 2006 Figure 7 shows the average temperature changes in the Continental United States divided by decades from 1881 to 2006. As shown by Figure 7, American Temperatures on average have increased since 1881. This increase has been of 0.54°C above the average (shown as 0 in Figure 7) has been an increase of 0.63°C since 1881 when the temperatures were lower than average 18. It is important to note that temperatures prior to 1881 are proxy-based 19 and thus are not included.
Temperature change in °C (+/- 0.18)
Fig. 7
Average Temperature Change Per Decade in the United States (NOAA)
0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
Average Global Temperature Change Per Decade
© 2008 Gabriel Mauricio Gutiérrez Salas
Decades
Because Figure 7 shows the averages per decade it seems that since 1961 the Earth has been experiencing warming that increases, and gets faster, every year. This however is not the case. Figure 8 shows the yearly temperature changes for the same period of time and as it becomes obvious temperature is irregular and changing rapidly every year. Fig. 8
United States Temperature Changes from 1881 to 2006 (NOAA Data)
0.7 0.65 0.6 0.55 0.5 0.45 Change in Temperature °C (+/- 0.18)
0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0
-0.05 -0.1
-0.15 -0.2 -0.25 -0.3 -0.35 -0.4 2006
2001
1996
1991
1986
1981
1976
1971
1966
1961
1956
1951
1946
1941
1936
1931
1926
1921
1916
1911
1906
1901
1896
1891
1886
1881
-0.45
Years
Temperature Change
As shown by Figure 8 the maximum recorded temperature in the United States happened in 1998. The temperature in 1998 was 0.6045° above average . This has © 2008 Gabriel Mauricio Gutiérrez Salas
been the maximum temperature in the last 120 years; however it has not been the maximum historic temperature. The closest maximum temperature is in a time known as the Medieval Optimum or Medieval Warm Period. This happened close to 1000 AD 20. Temperatures before the 1880s are reconstructed by Paleoclimatologists using proxy data such as tree rings or arctic ice core samples. When using Ice Core data scientists compare the level of current CO2 with the trapped air bubbles‟ CO2 concentration and thus give an estimate of the temperature of the earth when the air bubbles were trapped inside the ice. There are mayor flaws with using ice cores as proxies. According to them the current atmospheric CO2 levels are about 25% higher than in the pre industrial period 21. However this does not accurately represent the current atmospheric conditions. Ice cores cannot be used to store air bubbles because they are not a perfectly closed system 22. “More than 20 physicochemical processes deteriorate the CO2 and general air quality inside the polar ice” and thus compromise the data 23. This does not allow proxy data to be trusted and thus is ignored in this investigation. The current warming trend can be explained by several other factors other than CO2. There is nowhere in the current scientific literature that states that increased concentrations of Carbon Dioxide gas (CO2) increases the temperature 24. One other factor that can explain the increased temperatures is solar activity; this has been suggested by Dr. Sami Solanksy of the Max Planck Institute for Solar System Research in Germany 25. “The Sun has been at its strongest over the past 60 years and may now be affecting global temperatures 26”. At this time correlations between cosmic ray flux (caused by increased solar activity) and global warming are suggestive but the research is inconclusive. As shown by Figure 8 the warming trend started near 1906 and this cannot be explained by CO2 emissions as the CO2 emissions at the time were small and irrelevant as they could not have made a massive effect in the atmospheric system. The cooling from 1941-1960 cannot be explained by CO2 emissions as during the postwar economic boom they increased yet the temperature decreased.
© 2008 Gabriel Mauricio Gutiérrez Salas
Temperature changes in the United States from 1881 to 2006 compared to hurricane and major hurricane frequency Figure 9 shows the average temperature changes (shown in blue) compared to the hurricane frequency (shown in red) per decade between 1881 and 2006: Fig. 9
Hurricane Frequency compared to Change in Temperature between 1881 and 2006 (Per Decade) Number of Hurricanes Temperature Change 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
25
Temperature Change (°C)
Total Number of Hurricanes
30
20 15 10 5
2001-2006
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1941-1950
1931-1940
1921-1930
1911-1920
1901-1910
1891-1900
1881-1890
0
Decades
As shown by the graph there is no correlation between hurricane frequency and temperature change. From 1881 to 1900 the temperatures were below average so because of lower ocean temperatures the energy available to the hurricanes would be reduced and thus the number of hurricanes expected would be quite low. This however did not happen as in both decades hurricane levels were significantly above average. From 1901 to 1910 the temperature experienced a sharp decrease and, as expected, the hurricane number decreased, however the decade still experienced an average number of hurricanes even though it was the coldest decade on record. From 1911 to 1920 the temperatures still remained very much below average but the hurricane frequency incremented to above average levels once more. © 2008 Gabriel Mauricio Gutiérrez Salas
From 1921 to 1930 the temperatures experienced a rapid increase (one of the fastest increases in the recorded history). The hurricane frequency was expected to increase, however it shows a rapid decrease to its second lowest level from 1881 to 2006 which was very significantly below average. From 1931 to 1940 the temperatures increased to average levels and the hurricane frequency also increased to average levels. This makes this decade the „mean‟ decade for hurricanes and temperatures as for a combination of factors both temperatures and hurricane frequency were average. On the 1941 to 1950 decade the temperatures stabilized and yet this was the decade with the most hurricanes in recorded history with 24 hurricanes hitting the United States‟ Atlantic coast at average temperatures. Starting in 1971 the temperatures started to increase rapidly to record highs (in recent history, recorded with instruments and not proxy-reconstructed); however the hurricane levels for the three decades between 1971 and 2006 have been below average with 15, 14 and 15 hurricanes respectively making landfall with the United States‟ Atlantic Coast. If a clear correlation between hurricane frequency and global temperatures actually existed it would be clearly shown on the graph and the frequency would go down and/or up with the temperature. The Pearson product-moment correlation coefficient of the two samples is -0.439. This shows that the correlation is really small, if existent, and it‟s within the expected coincidence and random rate. It is also important to note that the correlation shown by the Pearson product-moment correlation coefficient is a negative correlation which means that the hurricanes actually decrease when temperatures are increased. Theoretically the temperatures would drive the hurricane frequency however in reality the data does not show this trend and the Pearson product-moment correlation coefficient. In addition to the graphs that represent the „trend‟ visually, statistical methods also show that there is no correlation between hurricane frequency and change in temperature.
© 2008 Gabriel Mauricio Gutiérrez Salas
Figure 10 shows the average temperature changes (shown in blue) compared to the major hurricane frequency (shown in red) per decade between 1881 and 2006:
Major Hurricane Frequency compared to Change in Temperature between 1881 and 2006 Number of Hurricanes
Temperature Change 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35
10 8 6 4
2001-2006
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1921-1930
1911-1920
1901-1910
1891-1900
1881-1890
0
1941-1950
2
1931-1940
Total Number of Major Hurricanes
12
Decades
As shown by the graph there is no clear correlation between major hurricane frequency and temperature change. From 1881 to 1890 the temperatures were below average so because of lower ocean temperatures the energy available to the hurricanes would be reduced and thus the number of major hurricanes expected would be quite low. During this decade the number of major hurricanes (5) was below the 6.2 average. From 1891 to 1900 the temperature remained stable, however the major hurricane number increased dramatically to 8 major hurricanes which is above average. From 1901 to 1910 the temperatures reached the lowest level on record and the major hurricanes decreased by 50% compared to the 1891-1900 decade to below average levels. From 1911-1920 the temperature experienced a slight increase however the major hurricane number increased to above average levels. From 1921-1930 the © 2008 Gabriel Mauricio Gutiérrez Salas
Temperature Change (°C)
Fig. 10
temperatures continued to experience a slow increase but the major hurricane levels decreased to below average levels. From 1931 to 1950 the temperatures started to stabilize and showed a tendency to decrease however during doth decades the major hurricane levels were increasing rapidly to above average levels and in the 1941-1950 decade the record was set. During this decade the total number of major hurricanes reached a record high of 10 hurricanes which is 3.8 major hurricanes more than average, this is a significant increase and it happened when temperatures were average. From 1951 to 1970 the temperatures remained stable at average levels however the number of major hurricanes decreased sharply from record highs to just below average. From 1971 to 2000 the temperature increased rapidly to record highs reached in 1998 (0.6° above average) however major hurricane frequency remained stable experiencing a slight increase in the 1991-2000 decade but still remaining below average levels. From 2001 to 2006 the number of major hurricanes is slightly above average (+0.8) however the temperature even though it decreased from 1998 by about 0.1°C it still remained 0.5° above average. The strongest hurricane to hit the United States‟ Atlantic Coast was the Labor Day Hurricane (FL KEYS) in 1935 (It was a category 5 Hurricane). This is surprising because the temperature in 1935 was not only much lower than today but it actually was -0.0495°C below average levels. This is surprising because theoretically a year with a below average temperature would have a below average hurricane number, major hurricane number and obviously it should not have the strongest hurricane in recorded history. This same pattern repeats again. The second strongest hurricane to hit the United States‟ Atlantic Coast was Category 5 Hurricane Camille in 1969. Blaming Camille‟s strength to Global Warming is not only irresponsible but it would also be scientifically and historically inaccurately. The temperatures when Camille hit in 1969 were average. Al Gore stated in his movie An Inconvenient Truth “For a long time, the scientists have been telling us global warming increases the temperature of the top layer in the ocean, and that causes the average hurricane to become a lot stronger. So, the fact that the ocean temperatures did go up because of global warming, because of man-made global warming, starting around in the late seventies and then we had a string of unusually strong hurricanes outside the boundaries of this multi-decadal cycle that is a real factor; there are scientists who point that out, and they're right, but we're exceeding those boundaries now.” 27
© 2008 Gabriel Mauricio Gutiérrez Salas
According to the temperature data and hurricane data this is simply an irresponsible statement, an exaggeration and a lie. Out of the ten strongest hurricanes to hit the United States‟ Atlantic Coast only 2 happened after 1970. Those hurricanes were Katrina in 2005 (Third Strongest) and Andrew in 1992 (Fourth Strongest). 40% of the strongest hurricanes happened BEFORE 1945 and one of them happened before 1900. This means that Global Warming allegedly caused by increase human-made greenhouse gas emissions could not have explained 80% of the top-ten strongest hurricanes because CO2 levels started to be released in „large‟ amounts to the atmosphere after the post war economic boom when the temperatures actually decreased. After 1970 when the temperatures experienced a large increase the amount of hurricanes still remains at average levels and well below the record mid-19th century decades. 1998 has been the hottest year on record however it has also been one of the calmest years in recorded history when referring to hurricane strength and frequency. In 1998 only 3 hurricanes hit the United States‟ Atlantic Coast. They were Danny, Bonnie and Earl; categories 1, 2 and 1 respectively. Two of them barely made it to the Saffir Simpson Hurricane Scale as they were borderline tropical depressions and storms. Conclusions In conclusion Global Warming has had, if any, a minimal and irrelevant effect in the strength and frequency of hurricanes that hit the United States‟ Atlantic coast between 1851 and 2006. The data clearly shows that there is no correlation whatsoever between hurricane frequency and change in temperature. This is confirmed by the use of statistics. The data is suggestive but inconclusive in respect to the relationship between major hurricane frequency and changes in temperatures. It also shows that the general hurricane strength is unrelated to temperature as 80% of the top ten strongest hurricanes in recorded history have happened in years with average or below average temperatures. Only 2 of them (and they were not the top two) Katrina and Andrew happened with above average temperatures and they honestly failed to deliver. The effects of Katrina where enormous but not because Katrina was a strong hurricane (It was category 3 at landfall) but because New Orleans is a city basically built inside a bowl under sea level protected by inferior dykes and levees that could not withstand the water pressure and ended up „pooling‟ the water inside the city. The data shows no evidence that temperatures play an important, if any, role in hurricane strength and frequency. In order for the temperature to have an effect the rise (or fall) of temperatures would have to be dramatically. Some scientists like © 2008 Gabriel Mauricio Gutiérrez Salas
Roy W. Spencer suggested that a plus or minus 2.5°C change would be needed to have any noticeable effects in hurricane frequency and strength.
© 2008 Gabriel Mauricio Gutiérrez Salas
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