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Department of Commerce
U.S. Department of Commerce
4-2002
Climate Change Impacts on U.S. Coastal and
Marine Ecosystems
Donald Scavia
National Ocean Service, don.scavia@noaa.gov
John C. Field
University of Washington
Donald F. Boesch
University of Maryland Center for Environmental Science
Robert W. Buddemeier
University of Kansas
Virginia Burke$
U.S. Geological Survey
See next page for additional authors
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Scavia, Donald; Field, John C.; Boesch, Donald F.; Buddemeier, Robert W.; Burke?, Virginia; Cayan, Daniel R.; Fogarty, Michael;
Harwell, Mark A.; Howarth, Robert W.; Mason, Curt; Reed, Denise J.; Royer, >omas C.; Sallenger, Asbury H.; and Titus, James G.,
"Climate Change Impacts on U.S. Coastal and Marine Ecosystems" (2002). Publications, Agencies and Sta% of the U.S. Department of
Commerce. 563.
h?p://digitalcommons.unl.edu/usdeptcommercepub/563
Authors
Donald Scavia, John C. Field, Donald F. Boesch, Robert W. Buddemeier, Virginia Burke?, Daniel R. Cayan,
Michael Fogarty, Mark A. Harwell, Robert W. Howarth, Curt Mason, Denise J. Reed, >omas C. Royer,
Asbury H. Sallenger, and James G. Titus
>is article is available at DigitalCommons@University of Nebraska - Lincoln: h?p://digitalcommons.unl.edu/usdeptcommercepub/
563
Estuaries Vol.
25,
No.2,
p.
149-164 April2002
Climate Change Impacts
on
U.S. Coastal and Marine Ecosystems
DONALD
SCAVIA\
JOHN
C.
FIELD2,
DONALD
F.
BOESCH
3
,
ROBERT
W.
BUDDEMEIER
4
,
VIRGINIA
BURKETT
5
,
DANIEL
R.
CAYA,'\I6,
MICHAEL
FOGARTY
7
,
MARK
A.
HARWELL
8
,
ROBERT
W.
HOWARTH
9
,
CURT
MAsON
IO
,
DENISE]'
REEDll,
THOMAS
c.
ROYER
12
,
AsBURY
H.
SALLENGER
I3
, AND
JAMES
G.
TITUS
14
1 National Ocean Service, National Oceanic
and
Atmospheric Administration, 1305 East
West
Highway, Silver Spring, Maryland
20910
2College
of
Ocean
and
Fisheries
Science,
1492
NE Boat
Street,
University
of
Washington, Seattle,
Washington 98195
3University
of
Maryland Center for Environmental
Science,
P.
O.
Box 775, Cambridge,
Maryland 21401
4Kansas Geological Survey, University
of
Kansas,
1930
Constant Avenue, Lawrence,
Kansas
66047
5National Wetlands Research
Center,
U.S.
Geological Survey, 700 Cajundome Boulevard, Lafayette,
Louisiana 70506
6S
c
ripps Institute
of
Oceanography, University
of
California, San
Diego,
9500 Gilman Drive,
La
Jolla, California 92093-0224
7 National Marine Fisheries Service, National Oceanic
and
Atmospheric Administration,
166
Water
Street,
Woods
Hole,
Massachusetts 02543
8 Rosenstiel School
of
Marine
and
Atmospheric
Science,
University
of
Miami,
4600
Rickenbacker
Causeway, Miami, Florida
33149
9Ecology
and
Evolutionary
Biology,
Cornell University, Ithica, New
York
14853
1ORR2
Box 156AB, Charles Town,
West
Virginia 25414
11
Department
of
Geology
and
Geophysics,
University
of
New Orleans,
2000
Lakeshore Drive,
New Orleans, Louisiana 70148
12
Center for Coastal Physical Oceanography, Department
of
Ocean, Earth
and
Atmospheric
Sciences,
Old Dominion University, 768
West
52nd
Street,
Norfolk, Virginia
23529
13Centerfor Coastal
Geology,
U.S.
Geological Survey,
600
4th
Street,
South,
St.
Petersburg,
Florida 33701
l40ffice
of
Economy
and
the Environment, Global Programs Division (6205]), Environmental
Protection Agency, Washington,
DC
20460
ABSTRACT:
Increases
in
concentrations
of
greenhouse
gases
projected
for
the
21st
century
are
expected
to
lead
to
increased
mean
global
air
and
ocean
temperatures.
The
National
Assessment
of
Potential
Consequences
of
Climate
Variability
and
Change
(NAST
2001)
was
based
on
a
series
of
regional
and
sector
assessments.
This
paper
is a
summary
of
the
coastal
and
marine
resources
sector
review
of
potential
impacts
on
shorelines,
estuaries,
coastal
wetlands,
coral
reefs,
and
ocean
margin
ecosystems.
The
assessment
considered
the
impacts
of
several
key
drivers
of
climate
change:
sea
level
change;
alterations
in
precipitation
patterns
and
subsequent
delivery
of
freshwater,
nutrients,
and
sediment;
increased
ocean
temperature;
alterations
in
circulation
patterns;
changes
in
frequency
and
intensity
of
coastal
storms;
and
increased
levels
of
atmospheric
CO
•.
Increasing
rates
of
sea-level
rise
and
intensity
and
frequency
of
coastal
storms
and
hurricanes
over
the
next
decades
will
increase
threats
to
shorelines,
wetlands,
and
coastal
development.
Estuarine
productivity
will
change
in
response
to
alteration
in
the
timing
and
amount
of
freshwater,
nutrients,
and
sediment
delivery.
Higher
water
temperatures
and
changes
in
freshwater
delivery
will
alter
estuarine
stratification,
residence
time,
and
eutrophication.
Increased
ocean
temperatures
are
expected
to
increase
coral
bleaching
and
higher
CO.
levels
may
reduce
coral
calcification,
making
it
more
difficult
for
corals
to
recover
from
other
disturbances,
and
inhibiting
poleward
shifts.
Ocean
warming
is
expected
to
cause
poleward
shifts
in
the
ranges
of
many
other
organisms,
including
commercial
species,
and
these
shifts
may
have
secondary
effects
on
their
predators
and
prey.
Although
these
potential
impacts
of
climate
change
and
variability
will
vary
from
system
to
system,
it
is
important
to
recognize
that
they
will
be
superimposed
*
Corresponding
author;
e-mail: Don.Scavia@noaa.gov.
© 2002 Estuarine Research Federation
149
This document is a U.S. government work and
is not subject to copyright in the United States.
150
D.
Scavia et
al.
upon,
and
in
many
cases intensify,
other
ecosystem
stresses
(pollution, harvesting,
habitat
destruction,
invasive species,
land
and
resource
use,
extreme
natural
events), which
may
lead
to
more
significant
consequences.
Introduction
The
158,000
km
of
coastline
and
8.8
million
km
2
of
ocean
within
its
territorial
sea
provide
the
U.S.
with a
wide
range
of
essential
goods
and
services
through
fisheries, biological diversity, oil, gas,
min-
eral
deposits,
and
commercial
and
recreational
op-
portunities.
In
addition
to
economic
benefits
de-
rived
from
extracting
goods,
these
ecosystems
pro-
vide critical services,
such
as
nutrient
cycling,
flood
control,
waste
treatment,
species
refuge,
genetic
re-
sources,
and
recreational
and
cultural
activities.
While
these
services typically lie
outside
traditional
markets,
Costanza
et
al. (1997)
estimated
that
coastal
and
marine
environments
constitute
over
half
of
the
value
of
global
ecological services.
Over
half
of
the
U.S.
population
lives
on
the
17%
of
land
considered
coastal
(Culliton
1998).
Within
the
next
25 years,
the
coastal
population
is
likely
to
increase
by
approximately
25%,
or
by
18
million
people,
with
most
of
the
growth
occurring
in
the
already
crowded
states
of
California,
Florida,
Texas,
and
Washington
(Boesch
et
al.
2000).
Pop-
ulation
growth
increases
demand
for
coastal
and
marine
resources,
which
increases
both
the
stress
on
those
resources
and
their
vulnerability
to
cli-
mate
change
and
variability.
Climate
change
will
interact
with
these
existing
and
increased
stresses,
potentially
accentuating
their
negative
impacts.
In
1997,
the
U.S.
Global
Change
Research
Pro-
gram
(USGCRP)
initiated
an
assessment
of
the
sig-
nificance
of
climate
change
for
the
U.S.
This
Na-
tional
Assessment
of
Potential
Consequences
of
Climate
Variability
and
Change
(NAST 2001)
drew
on
inputs
from
academia,
government,
the
public
and
private
sectors,
and
interested
citizens,
and
was
based
on
a series
of
regional
and
sector
assess-
ments.
This
paper
is a
summary
of
the
coastal
and
marine
resources
sector
review
of
potential
impacts
on
shorelines,
estuaries, coastal
wetlands,
coral
reefs,
and
ocean
margin
ecosystems.
Forces
of
Climate
Change
Climate
change
scenarios
selected
for
the
Na-
tional
Assessment
are
based
on
general
circulation
model
(GCM)
simulations
conducted
by
the
Unit-
ed
Kingdom's
Hadley
Centre
for
Climate
Predic-
tion
(HadCM2)
and
the
Canadian
Climate
Centre
(CGCM1),
hereinafter
referred
to
as
the
Hadley
and
Canadian
models,
respectively (NAST
2001).
The
simulations
incorporate
similar,
mid-range
as-
sumptions
about
future
greenhouse
gas
emissions
during
the
next
100 years,
but
differ
in
how
they
represent
the
effects
of
some
important
processes.
On
average
over
the
U.S.,
the
Hadley
model
pro-
jects
a
much
wetter
climate
than
does
the
Cana-
dian
model,
while
the
Canadian
model
projects
a
greater
increase
in
temperature
than
does
the
Hadley
model.
Output
from
these
models
should
be
viewed as two
plausible
climate
futures.
The
cur-
rent
spatial
resolution
of
GCMs is
not
sufficient
to
simulate
changes
in
the
geographical
distribution
of
storms.
SEA-LEVEL
CHANGE
During
the
last 100 years, globally
averaged
sea
level
has
risen
approximately
10-20
cm,
or
about
1
to
2
mm
yr-l (IPCC 1996).
Local
rates
ofrelative
sea-level rise vary
from
about
2
mm
yr-l
in
New
England,
Florida,
and
parts
of
the
Gulf
Coast,
to
3-5
mm
yr-l
in
the
mid-Atlantic,
5-10
mm
yr-l
in
parts
of
Texas
and
Louisiana,
and
anywhere
from
-10
to
+2
mm
yr-l
along
the
Pacific
Coast
(Nich-
olls
and
Leatherman
1996; Zervas
2001).
These
variations
are
caused
by
regional
differences
in
groundwater
and
oil withdrawal,
compaction
of
muddy
soils,
subsidence,
isostatic
rebound,
and
tectonic
uplift.
Over
the
next
100 years,
global
warming
is
expected
to
accelerate
the
rate
of
sea-
level rise by
expanding
ocean
water
and
melting
alpine
glaciers (IPCC
2001).
The
full
range
of
model
projections
from
the
most
recent
Intergov-
ernmental
Panel
on
Climate
Change
assessment
(IPCC 2001)
spans
from
9
to
88
cm
rise
in
global
sea
level by 2100.
Model
averages
range
more
nar-
rowly
from
31
to
49
cm.
These
projections
are
broadly
consistent
with
previous
studies
(IPCC
1996;
Titus
and
Narayanan
1996; Wigley 1999)
and
the
Canadian
and
Hadley
models
(Boesch
et
al.
2000; NAST 2001).
Even
if
greenhouse
gas emis-
sions
are
stabilized,
the
rate
of
sea-level rise will
likely
continue
to
increase
beyond
2100
because
of
the
time
it
takes
for
oceans
and
ice
sheets
to
ap-
proach
equilibrium
conditions
with
the
atmo-
sphere.
Regional
differences
in
land
movement
and
impacts
of
climate
change
on
atmospheric
pressure
and
alongshore
winds
will
continue
to
produce
differences
in
local
sea
level relative
to
the
land.
Uncertainty
about
local
future
sea
levels is
about
50%
greater
than
for
the
global
average
(IPCC
2001).
COASTAL
STORMS
The
number
of
hurricanes
in
a given
year
can
vary by a
factor
of
three
or
more
in
consecutive
years.
Although
trends
in
hurricanes
and
tropical
cyclones
cannot
be
attributed
to
current
climate
Coastal and Marine Climate Change Impacts 151
2025-2034
2090-2099
Canadian
New England
Mid-Atlantic
S Atlantlc-E
Gutfl=======r-
Mississippi R
WGuif
PacificNW
Hadley
-100 -75
-50
-25 0 25 50
Percent Change in Runoff
californiaIL....,.._....--==~=::==~W
-75
-50
-25 0 25
50
75 100 125 150
Percent Change in Runoff
Fig. 1.
Projected
changes
in
average
annual
runoff
for
basins
draining
to
coastal
regions
from
the
Canadian
and
Hadley
Centre
General
Circulation Models
(Data
from
Wolock
and
McCabe 1999).
change,
there
is a
strong
inter-decadal
mode
in
North
Atlantic
hurricane
variability
showing
great-
er
activity
along
the
East
Coast
and
peninsular
flor-
ida
between
1941
and
1965
and
the
1990s
(Land-
sea
et
al.
1996),
and
this
condition
of
higher
activ-
ity
may
last
for
decades
(Bengtsson
2001;
Golden-
berg
et
al. 2001).
Timmermann
et
al. (1999)
suggest
that
future
sea
surface
temperatures
in
the
tropical
Pacific
are
likely
to
resemble
present-day
EI
Nino
conditions
and,
because
fewer
hurricanes
occur
in
the
Atlantic
during
EI
Nino
years (Pielke
and
Landsea
1999),
Atlantic
hurricane
frequency
could
decrease
in
the
future.
During
recent
severe
EI
Nino
events
(1982-1983,
1997-1998),
eastern
Pacific
winter
storms
tracked
farther
south
than
in
previous
years
causing
extensive wave
and
storm
damage,
coastal
erosion,
and
flooding
in
Califor-
nia
(Griggs
and
Brown
1998).
While
it
may
be
difficult
to
identify
climate
change
effects
on
hurricane
frequency,
hurricane
wind
strength
could
increase
as a
result
of
elevated
sea
surface
temperatures.
Knutson
et
al. (1998)
and
Knutson
and
Tuleya
(1999)
showed
increases
in
hurricane
wind
strength
of
5-10%
are
possible
with a 2.2°C
warmer
sea
surface.
For
a
moderate
hurricane,
such
an
increase
in
wind
strength
could
translate
into
as
much
as a 25%
increase
in
the
destructive
power
of
its winds. Wave
height
and
storm
surge
would
increase
similarly,
magnifying
coastal
impacts.
Other
research
suggests
that
trop-
ical cyclones
could
become
more
intense
(Kerr
1999). Regardless
of
potential
changes
in
frequen-
cy
and
intensity, coastal
storms
and
resulting
storm
surges
will
be
riding
on
a
higher
sea
level, increas-
ing
the
vulnerability
of
shorelines.
FRESHWATER
INFLOW
The
hydrologic
cycle
controls
the
strength,
tim-
ing,
and
volume
of
delivery
of
freshwater
and
its
chemical
and
sediment
load
to
coastal ecosystems.
That
cycle is likely
to
change
under
a
changing
climate.
In
contrast
to
the
general
agreement
among
GCMs
for
direction,
if
not
the
pace,
of
tem-
perature
change,
regional
projections
of
precipi-
tation
vary
considerable
(NAST
2001).
Simple
wa-
ter-balance
models
developed
by
Wolock
and
McCabe
(1999)
based
on
the
precipitation
and
temperature
projections
of
the
Canadian
and
Had-
ley
models
provide
some
basis
to
forecast
river
run-
off
(Fig.
1).
The
Hadley
model
predicts
a
34%
in-
crease
in
total
runoff
along
U.S.
Atlantic
and
Gulf
coasts by
the
last
decade
of
the
century,
while
the
drier
and
hotter
Canadian
model
projections
show
a
decrease
of
32%.
While
these
differences
illus-
trate
the
uncertainty
regarding
future
rainfall
and
runoff
patterns,
both
models
predict
that
there
will
be
an
increase
in
extreme
rainfall events,
which
can
increase
significantly
the
chemical
and
sedi-
ment
load
delivered
to
the
coast.
This
increased
flashiness,
which
already
has
begun
during
the
20th
century,
is likely
to
become
more
common,
as
could
droughts
and
floods
(Karl
et
al. 1995).
OCEAN
TEMPERATURE
AND
ICE
EXTENT
Based
on
analysis
of
five
million
ocean
temper-
ature
profiles,
mean
temperature
of
the
upper
300
m
of
the
oceans
has
increased
by 0.31°C
over
the
past
45
yr
(Levitus
et
al. 2000)
with
the
warming
signal
observable
to
depths
of
3,000
m.
Evidence
suggests
that
the
signal was
primarily
due
to
cli-
mate
change
with
anthropogenic
causes, as
op-
posed
to
climate
variability (Levitus
et
al.
2001).
These
results
are
in
strong
agreement
with
projec-
tions
of
many
general
circulation
models.
Barnett
et
al. (2001)
calculated,
with
confidence
exceeding
95%,
that
human-produced
greenhouse
gases
are
responsible
for
the
horizontal
and
temporal
char-
acter
of
the
observed
increase
in
ocean
tempera-
ture.
The
aerial
extent
of
arctic
ice
has
declined
by as
much
as 7%
per
decade
over
the
last 20 years
(Johannessen
et
al. 1999)
and
thinned
by as
much
as 15%
per
decade
(Rothrock
et
al. 1999).
While