Are Hurricanes Increasing in Frequency and Intensity?

Luke Annala-Kinne, Dylan Esmonde, Emma McArdle, Rylee Sweeney

Al Gore’s documentary, “An Inconvenient Truth,” makes statements such as;

“The number of Category 4 and 5 hurricanes has most doubled in the last 30 years.”

After looking at the documentary’s website, www.climatecrisis.net, I began to research Gore’s sources.

Information regarding hurricanes was mainly from Kerry Emanuel.

Frequency vs. Time

• Using chi-squared analysis, I found that the chi-squared sum proved the null hypothesis correct- There is not a correlation between the passing of time (and warmer world temperatures) and hurricane frequency.

“Increasing destructiveness of tropical cyclones over the past 30 years”

By Kerry Emanuel Power Dissipation Index

“Although the frequency of tropical cyclones is an important scientific issue, it is not by itself an optimal measure of tropical cyclone threat. The actual monetary loss in wind storms rises roughly as the cube of the wind speed as does the PD.”

Nowhere in this paper does Emanuel relate the PDI to the Saffir-Simpson system of categorizing hurricanes.

What do the experts say?• IPCC:

– Frequency— “no clear trend” with current debate

– Intensity— “more likely than not” that future storms will increase in intensity

• NOAA:– Frequency— “variability

makes detecting any long-term trends in tropical cyclone activity difficult”

– Intensity— “Model studies and theory project a 3-5% increase in wind-speed per degree Celsius increase of tropical sea surface temperatures.”

NOAA Hurricane Modeling

Source: http://www.gfdl.gov/~tk/glob_warm_hurr.html

Hurricane Frequency + 10 Year Average

0

2

4

6

8

10

12

14

16

1850 1870 1890 1910 1930 1950 1970 1990 2010

10 Year Average (1851-2006)

3

4

5

6

7

8

9

1850 1870 1890 1910 1930 1950 1970 1990 2010

10 Year Average + 6 Order Polynomial

3

4

5

6

7

8

9

1850 1870 1890 1910 1930 1950 1970 1990 2010

Category 4 and 5 Hurricanes

0

1

2

3

4

5

1850 1870 1890 1910 1930 1950 1970 1990 2010

Year

Ca

teg

ory

4 and 5

10 Year Averaged Categories + 50 Year Trendlines

1.5

1.7

1.9

2.1

2.3

2.5

2.7

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

10 year avg Category

1860-1900 trendline

1910-1950 trendline

1960-2006 trendline

50 Year Trendline Predictions for 2050

1

1.5

2

2.5

3

3.5

4

1850 1870 1890 1910 1930 1950 1970 1990 2010 2030 2050

Year

Hur

rica

ne C

ateg

ory

10 year avgCategory1860-1900 Prediction

1910-1950 Prediction

Linear (1960-2006trendline)

Change in Wind Speed

Change In Wind Speed Over Time y = -0.1275x + 303.5

R2 = 0.7015

45

50

55

60

65

70

75

1850 1870 1890 1910 1930 1950 1970 1990 2010

Series 1Linear (Series 1)

Standard Deviatiion = 7.24

Wind Speed Change as a Function of

Temperature

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

1860 1880 1900 1920 1940 1960 1980 2000 2020

Series1

Temperature Vs. Windspeed

40

45

50

55

60

65

-0.4 -0.2 0 0.2 0.4 0.6

Series1

R=.52

Table Of Most Deadly Hurricanes

Rank Hurricane Season Fatalities

1 Great Hurricane 1780 22,000

2 Mitch 1998 11-18,000

3 Galveston 1900 8-12,000

4 Fifi 1974 8-10,000

5 Dominican Republic 1930 2-8,000

6 Flora 1963 7-8,000

7 Pointe-a-Pitre 1776 6,000+

8 Newfoundland 1775 4-4,163

9 Okeechobee” 1928 4,075+

10 San Ciriaco 1899 3,433+

Table Of Most Costly HurricanesName Year

Katrina 2005

Andrew 1992

Wilma 2005

Charley 2004

Ivan 2004

Hugo 1989

Agnes 1972

Betsy 1965

Rita 2005

Frances 2004

Name (cont) Year (cont)

Camille 1969

Diane 1955

Jeanne 2004

Frederic 1979

New England (1938) 1938

TS Allison 2001

Floyd 1999

Great Atlantic (1944) 1944

Fran 1996

Conclusions

• Compounding factors cause fuzzy data and large seasonal variation

• Extant hurricane data too unclear to make accurate predictions of future activity

• No pattern to indicate a clear increase in frequency or intensity

EXCELSIOR