hurricane-curry guadeloupe

Global Climate Change and Hurricanes:
the Science, the Controversy & the Risk
Judith A. Curry
Deadliest Hurricanes to Hit Central
America and the Caribbean
Storm
Deaths
Locations Affected
Great Hurricane of 1780
>22,000
Barbados, Martinique
Hurricane Mitch (1998)
11,000 – 18,000
Honduras, Nicaragua
Hurricane Fifi (1974)
8,000 – 10,000
Belize, Guatemala, Honduras
Hurricane Flora (1963)
7,186 – 8,000
Tobago, Hispaniola, Cuba
1930 Dominican Republic Hurricane
2,000 – 8,000
Hispaniola, Cuba
Pointe-a-Pitre Bay Hurricane (1776)
>6,000
Martinique, Guadeloupe
San Ciriaco Hurricane (1899)
3,433
Puerto Rico
1932 Cuba Hurricane
3,033
Cuba, Bahamas
1934 Yucatan Hurricane
1,000 – 3,000
Belize, Guatemala,
El Salvador, Honduras
1931 Belize Hurricane
2,500
Belize, Guatemala
Hurricane Stan (2005)
1,620
Guatemala, El Salvador,
Nicaragua, Honduras, Costa
Rica
Atlantic Landfalling Storms Striking
Hurricane Strength Distribution for Landfalling Storms in Central America and the Carribean
Central
America and the Caribbean
35
30
Number of Systems
25
20
15
10
5
0
1951-1955 1956-1960 1961-1965 1966-1970 1971-1975 1976-1980 1981-1985 1986-1990 1991-1995 1996-2000 2001-2005
Year
Tropical Storms/Depressions
Cat 1&2
Cat 3, 4, 5
Are more hurricanes a harbinger of
the Caribbean’s future?
To assess the Caribbean’s risk from landfalling
hurricanes in the coming decades, we must understand:
 Impact of global warming on hurricane activity
 Natural variability in the Atlantic Ocean
 Nature of local risks
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
WMO
4th Assessment Report
Summary for Policy Makers
UNEP
“Warming of the climate system is unequivocal, as is now
evident from observations of increases in global average
air and ocean temperatures, widespread melting of snow
and ice, and rising global average sea level.”
“Most of the observed increase in globally averaged
temperatures since the mid-20th century is very likely
[>90%] due to the observed increase in anthropogenic
greenhouse gas concentrations.”
UNEP
Warmest 12 years:
1998,2005,2003,2002,2004,2006,
2001,1997,1995,1999,1990,2000
Global surface temperature has increased 0.74oC since 1906
Meehl et al, 2004
Increased global temperatures since 1970 is
attributed to greenhouse warming
WMO
IPCC AR4: Hurricanes
Detection of Change
UNEP
 There is observational evidence for an increase of intense
tropical cyclone activity in the North Atlantic since about
1970, correlated with increases of tropical sea surface
temperatures
 There are suggestions of increased intense tropical
cyclone activity in other regions where concerns over data
quality are greater
 Multi-decadal variability and the quality of the tropical
cyclone records prior to 1970 complicate the detection of
long-term trends in tropical cyclone activity
UNEP
North Atlantic Tropical Cyclones and SST
11 year running mean
surface
aircraft
recon
satellite
Increased tropical cyclone activity since 1970,
correlated with increasing sea surface temperatures
Global View of Tropical Cyclones
N. Indian Ocean
6%
W. Pacific Ocean
40%
S. Indian Ocean
19%
E. Pacific Ocean
17%
N. Atlantic Ocean
11%
SW Pacific Ocean
8%
Each year there are about 85-90 tropical cyclones globally
Global tropical cyclone intensity
Webster, Holland, Curry, Chang (2005) Science
# of cat 4+5 hurricanes has doubled globally since 1970
Data quality questioned in the Indian Ocean, Pacific Ocean
Wall Street Journal
February 2, 2006
Cold Front
Debate Shatters Civility of Weather Science
Hurricanes Worsened by Global Warming?
Spats are so tempestuous,
sides are barely talking
Charge of “brain fossilization”
Tropical cyclone
genesis/intensification factors

Sea water temperature > 26.5oC.
Major hurricanes >28.5oC

Small vertical shear (minimal variation of
wind with height)

Moist mid-troposphere & convective instability

Pre-existing weather disturbance

Not too close to the equator
These factors change both with
natural climate variability (e.g., El
Nino) and global warming
Global trends in the tropics since 1970
Sea surface temperature
0.5oC (1oF) increase
Wind shear
no trend
Hoyos et al. 2006
WMO
IPCC AR4: Hurricanes
Projections of Future Change
UNEP
 It is likely [>66%] that future tropical cyclones will
become more intense, with larger peak wind speeds
and more heavy precipitation associated with
ongoing increases of tropical SSTs
 The apparent increase in the proportion of very
intense storms since 1970 in some regions is much
larger than simulated by current models for that
period
UNEP
TC intensity - SST link
Hurricane intensity change scaled for a 0.5oC SST increase:
Webster et al. obs:
+6.0%
Climate models:
Knutsen/Tuleya (2004): +2.0%
Oouchi et al. (2006):
+2.1%
Potential intensity theory:
Emanuel
+2.7%
Holland
+5.3%
3-legged stool analogy: Observations, theory, and climate
models agree that hurricane intensity should increase; they
disagree on the magnitude of the increase. The stool stands.
Intensity Distribution of North Atlantic
Tropical Cyclones
50%
45%
40%
TS
Cat1
35%
30%
Cat2
Cat3
25%
20%
Cat4
Cat5
15%
10%
5%
0%
1970-1982
1983-1994
1995-2006
Since 1995, there has been a shift in the intensity
distribution towards more major hurricanes
What does the future hold for hurricane
activity in the North Atlantic?
Combined impacts of greenhouse warming and natural variability
The uncertain
climate
future
Climate
Model
Projections
WMO
UNEP
Jkljl
Jlkjlj
Lhjljk
Scenario simulations indicate 1.8-4.0oC temperature increase by 2100
Climate model projections of
future hurricane activity
For a 2.5oC temperature increase:
• up to 30% increase in number of N. Atlantic tropical cyclones
(no increase or slight decrease in global numbers)
• 10% increase in tropical cyclone intensity
• 30% increase in the number
of major hurricanes
Relationship between # of Atlantic storms
and sea-surface temperature
Obs:
1oF increase in SST --> +5 storms/year
Model: 1oF increase in SST --> +1 storm /year
North Atlantic Ocean
11 year centered running mean
Atlantic Multidecadal Oscillation (AMO)
Number of Storms
14
12
10
8
6
4
2
0
1850
1870
1890
1910
Named Storms
1930
1950
Hurricanes
1970
1990
2010
Cat. 4&5
Since 1995, there has been 40-50% greater activity
than the previous peak period ca. 1950
Projections for the average number
of NATL tropical cyclones for 2025
(0.5oC warming)
# of Tropical Cyclones:
• Avg for last 50 yrs: 10
• Avg last decade:
14
• Avg ca. 2025:
15-20
category 4+5
3-4
The combination of greenhouse
warming and natural variability
will produce unprecedented
tropical cyclone activity in the
coming decades
What does the increase in North Atlantic
hurricane activity mean for the Caribbean?
Landfalling tropical cyclones striking
the Caribbean and Central America
18
16
14
12
10
8
6
4
2
0
1900
1920
1940
1960
1980
2000
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m
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Ja
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Hurricane Landfall Location
1970-2006
20%
15%
10%
5%
0%
SST Changes:
Gulf of Mexico and
Caribbean
Warmest
decade
Summary: Projection for next two decades
 The number of North Atlantic tropical cyclones
most likely will increase in coming decades and
intensity is expected to continue to increase
 The number of Caribbean landfalls will most likely
continue to increase
UNEP