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Newsletter
April
2001
Global
Climate Change and Regional Wetlands:
Impacts And Response
By Gillian Davies and Patrick Garner
In the last 100 years global climate change has proven to
be the most insidious of organic revolutions -- on the one
hand, almost invisible in its slow turnings, and on the
other, sweeping in its worldwide implications. The majority
of the world’s scientists no longer debate its reality.
Based on current science, how may these changes affect the
New England region? And particularly, how may our vast waterways
and wetlands be altered?
Quoting Daniel Webster in his opening remarks at the 2001
AMWS Annual Meeting, President William Kuriger said, “There
is nothing as powerful as the truth, and often, nothing
as strange.” Bill also instructed the membership to,
“Always seek the truth”. Yet the truth, particularly
when it reveals itself in incremental steps, is often easily
ignored.
As scientists we do seek the truth. But driven by economic
concerns, international corporations and other commercial
stakeholders commonly resist environmental pressures to
revise manufacturing processes and forms of energy consumption.
These interests in turn exert tremendous pressure on political
decision-making in this country. Regardless, the scientific
community has reached a consensus that differs markedly
from the voices of the politicians governing our country.
REGIONAL
CLIMATIC CHANGES & IMPACTS TO WETLANDS
Graham Giese with the Woods Hole Oceanographic Institution
notes that in Massachusetts, 65 acres of upland are lost
yearly to rising sea levels, and that these adverse impacts
will continue in the future, perhaps at an increased rate
(1997, Giese). The EPA warns that many regional cold-water
rivers and streams could be significantly affected by climate
change. A recent report states, “Warmer air temperatures
will lead to warmer stream temperatures eventually making
habitat unsuitable for some cold-water fish species whose
thermal tolerance is exceeded” (1995, EPA). Paul Epstein,
Associate Director of the Harvard Medical School, writes,
“Hotter summers increase photosynthesis and metabolism
of algae, and also favor the more toxic forms—cyanobacteria
and dinoflagellates… the affects can cascade through
ecosystems and lead to increased diseases of shore birds,
sea mammals, fish and humans” (1997, Epstein).
How will global climate change affect wetlands? David Wolfe,
a professor at Cornell University, notes the following concerns
for this region’s wetlands: loss of habitat; increased
toxic contamination; increases in invasive and exotic plants;
increased eutrophication; accelerated atmospheric deposition;
and increased septic runoff into waterways. He also notes
that climate change will “… amplify many current
stresses…” (1997, Wolfe).
As wetland scientists, we note that rising temperatures
may particularly affect marginal and transitional wetland
systems, decreasing their extent and modifying their vegetative
types and diversity. Projections for increased volume of
storm precipitation, seasonal shifts of storm events and
increased peak events may lead to flashier rivers in the
spring. Warmer summer months may decrease river baseflow
in many inland areas. Shifting precipitation patterns may
dramatically alter the subtle dynamic between perennial
and intermittent streams, leading to fewer and fewer perennial
stream flows. Flooding events may become far more frequent
due to continuing urbanization in combination with increased
extreme precipitation, which in turn may create conditions
highly conducive to higher erosive impacts throughout our
river systems.
Quoting the most recent international assessment of wetland
impacts to our region, “Altered precipitation and
temperature regimes will affect the seasonal pattern and
variability of water levels of wetlands, thereby affecting
their functioning--including flood protection, carbon storage,
water cleansing, and waterfowl/wildlife habitat” (1998,
IPCC). The report goes on to note, “The responses
of affected wetlands are expected to vary; they might include
migration of the wetland area along river edges or the slope
of a receding lake and/or altered species composition. More
serious effects would include altered physical characteristics;
degradation to a simpler, less diverse form; or complete
destruction. There also could be a loss of desired attributes,
such as their ability to provide suitable habitat for particular
species; their ability to act as a feeding or breeding area
in support of an adjacent open-water commercial or recreational
fishery; or their ability to buffer occasional flooding
(Mitsch and Gosselink, 1986; IPCC 1996, WG II, Chapter 6).
Vernal pools are likely to be particularly vulnerable to
changes in precipitation and evaporation. Unlike perennial
water features, their water supply is created annually,
with no “borrowing” from water stored during
a wetter year. Life cycles of vernal pool species tend to
be adapted closely to the particular microclimate of a given
locale. If a vernal pool holds water for a shorter amount
of time, species may not have enough time to complete the
aquatic phase of their lifecycle. If vernal pools hold water
for longer periods of time, predatory insect populations
tend to increase, thus decreasing or eliminating the branchiopods
that they typically feed on. Changes in water temperature
can effect longevity of the pool, as well as the timing
of hatches (1997, Graham).
HIGHER SURFACE TEMPERATURES PROJECTED
According to the Intergovernmental Panel on Climate Change’s
Draft Third Assessment Report (issued 2/19/2001), our globally
averaged surface temperatures have increased by about 0.6
degrees Celsius during the 20th century, and are projected
to increase 1.4 to 5.8 degrees Celsius by 2100 relative
to 1990. Average global sea levels are modeled to rise 0.09
to 0.88 meters by 2100 (0.3 to 2.9 feet). Prior estimates
(released three years ago) for climate change projected
a less dramatic increase in temperature and sea level rise.
Climate change modeling capabilities have increased significantly,
resulting in revised estimates. New evidence supports the
idea that most observed climate warming over the last 50
years has been caused by humans.
The National Assessment Synthesis Team (2000, US Global
Change Research Program), has issued a report titled “Climate
Change Impacts on the United States: The Potential Consequences
of Climate Variability and Change”. It notes that
in the northeast region of the United States, coastal areas
have already warmed by up to 4 degrees F during the 20th
century. During this period, precipitation in this region
has increased by more than 20% in most areas, although some
locations have experienced precipitation decreases. These
reports are also corroborated by recent hydrological studies
from Cornell University and others (1993, Wilkes). In addition,
precipitation extremes have increased, while drought now
occurs in fewer places in New England. During the last 50
years, the time period between first and last dates of snow
cover has decreased by 7 days.
The same report goes on to state that in the Northeast,
temperatures are projected to rise 4 degrees to 9 degrees
F by 2100. Temperatures would increase the most in coastal
areas, and winter minimum temperatures would increase more
than maximum temperatures. Projections of precipitation
changes range from small regional decreases to as much as
25% increases. Increases in spring flooding are likely,
due to increased rapid snowmelt events and heavy rains falling
on frozen ground. Hurricane intensity and frequency may
change (due to warmer air carrying more water vapor).
Further, research indicates that activity of soil microorganisms
will increase with increased temperatures. Climate change
is likely to increase water temperatures as well, which
will intensify the pressures already placed on water-based
ecosystems by urban and agricultural runoff and other forms
of water pollution. Coastal salinity could be affected by
changes in precipitation and runoff. Saline wedges are expected
to be driven further up into our larger streams. Many areas
of coastal wetlands are caught between rising sea levels
and developed inland areas, which effectively prevent inland
migration of wetlands as a response to sea level rise. Less
severe winters may allow greater survival of vector-borne
diseases and their hosts (such as deer, mice and Lyme-disease
transmitting ticks).
ACTIONS,
REACTIONS & POLITICS
Although many governments in the world are willing to take
steps towards reducing the emission of greenhouse gases,
our current federal administration appears increasingly
disinterested in substantively addressing the emerging realities
about the impacts of climate change.
At this time, the Massachusetts state government is not
addressing these issues. What actions can we take on a local
or state level? Should the state be planning for impacts
from climate change? Is it unrealistic to begin to plan
for environmental impacts that may not be completely understood
for years to come? Should we modify our resource management
strategies? If so, how, and in what ways?
Rather than relying on politicians to take care of this
“global” problem for us, we believe that we
can and should begin to address these anticipated climate
changes on the local, state and regional level. In the words
of an old saying, “If the people will lead, the leaders
will follow.”
As representatives of the wetland community, what questions
do we need to be asking ourselves? What is going to happen
to the New England landscape and New England wetlands as
climate change proceeds? How should we adjust wetlands regulation
and management to account for the effects of climate change
in our region of the world? What is the particular role
of wetlands in climate change mitigation? What happens to
marginal wetlands such as vernal pools, and the species
that depend on them, as temperature, precipitation and evaporation
increase? With increased soil microorganism activity, how
will wetland soils change? What will these effects be on
wetland vegetation, and on animals dependant on wetlands?
In what ways do we shift our resource protection focus,
given what we know about climate change? How do we protect
ecosystems that are in an unusually rapid state of flux?
Are we protecting resources in a way that maximizes long-term
survival of the resource? Are some of our current policies
irrelevant in light of projected changes? What can be done
at the regional, state and local level, without waiting
for the federal government to take a leadership role?
AMWS, as an organization of professional scientists, can
play a key leadership role at the state and regional level.
We can start by educating ourselves and by actively bringing
this topic into the public policy debate. We can join with
the many regional universities and non-profit scientific
organizations that are currently studying these impacts.
For an issue that is going to have such a widespread impact
on all of our lives, and as importantly, on the lives of
our children and grandchildren, climate change impacts confront
a disturbing silence in the arena of public policy. We can
change that.
____________________________________________________________
Climate
change websites:
Intergovernmental Panel on Climate Change: www.ipcc.ch
EPA Global Warming Site: www.epa.gov/globalwarming
Union of Concerned Scientists www.ucsusa.org
SURVAS www.survas.mdx.ac.uk
National Assessment Synthesis Team www.gcrio.org/NationalAssessment
[Note: the above sites are a selected listing from 100’s
of private and government sites available worldwide. Each
of these sites has many additional links.]
Selected
References
Graham, Tim B. Climate Change and Ephemeral Pool Ecosystems:
Potholes and Vernal Pools as Potential Indicator Systems.
USGS.
IPCC. 1998. The Regional Impacts of Climate Change—An
Assessment of Vulnerability
IPCC Working Group I. 2001. (Draft) Intergovernmental Panel
on Climate Change Working Group I Third Assessment Report.
IPCC Working Group II. 2001. (Draft) Intergovernmental Panel
on Climate Change Working Group II Third Assessment Report.
Summary for Policymakers: Climate Change 2001: Impacts,
Adaptation, and Vulnerability.
New England Regional Climate Change Impacts Workshop. September
1997. Institute for the Study of Earth, Oceans, and Space.
University of New Hampshire. Speaker papers by: Paul R.
Epstein; Graham S. Giese; Barry D. Keim; and Daniel Wolfe.
Report of the Natural Resources Sector and report entitled,
“Seasons of Change: Global Warming and New England’s
White Mountains.”
Wilks and Cember. 1993. Atlas of Precipitation Extremes
for the Northeastern United States and Southeastern Canada.
Cornell University.
ADDENDUM:
SELECTED SECTIONS FROM “THE REGIONAL IMPACTS OF CLIMATE
CHANGE—AN ASSESSMENT OF VULNERABILITY (1998, IPCC)
“Seasonal
patterns in the hydrology of mid- and high-latitude regions
could be altered substantially, with runoff and streamflows
generally increasing in winter and declining in summer…
“Higher
air temperatures could strongly influence the processes
of evapotranspiration, precipitation as rain or snow, snow
and ice accumulation, and melt-which, in turn, could affect
soil moisture and groundwater conditions and the amount
and timing of runoff in the mid- and high-latitude regions
of North America. Higher winter temperatures in snow-covered
regions of North America could shorten the duration of the
snow-cover season…Warmer winters could lead to less
winter precipitation as snowfall and more as rainfall, although
increases in winter precipitation also could lead to greater
snowfall and snow accumulation, particularly at the higher
latitudes. Warmer winter and spring temperatures could lead
to earlier and more rapid snowmelt and earlier ice break-up,
as well as more rain-on-snow events that produce severe
flooding, such as occurred in 1996-97 (Yarnal et al., 1997)…
“…
climate change will have its greatest effect through alterations
in hydrological regimes-in terms of the nature and variability
of the hydroperiod (the seasonal pattern of water level)
and the number and severity of extreme events (Gorham, 1991;
Poiani and Johnson, 1993). However, other variables related
to changing climate may drive a site-specific response.
Such variables include increased temperature and altered
evapotranspiration, altered amounts and patterns of suspended
sediment loadings, fire, oxidation of organic sediments,
and the physical effects of wave energy (Mitsch and Gosselink,
1986; IPCC 1996, WG II, Chapter 6)…
“Altering
climate and acid depositions can cause declining levels
of dissolved organic carbon (DOC) in wetlands-thus increasing
the water volumes, sediment areas, and associated organisms
exposed to harmful ultraviolet-B (UV-B) irradiation. Potential
effects include changes in aquatic communities and photoinhibition
of phytoplankton (Schindler et al., 1996; Yan et al., 1996)…
“In
many regions, projected increases in hydrological variability
would result in greater impacts on water resources than
changes in mean hydrological conditions (IPCC 1996, WG II).
Increases in the frequency or magnitude of extreme rainfall
events would likely have their greatest impacts on water
resources in the winter and spring, when the ground is frozen
or soil moisture levels are high; severe flooding may be
more likely. More severe or frequent floods could result
in increased erosion of the land surface, as well as stream
channels and banks; higher sediment loads and increased
sedimentation of rivers and reservoirs; and increased loadings
of nutrients and contaminants from agricultural and urban
areas (IPCC 1996, WG II, Section 10.5.5). Longer dry spells
would likely have their greatest impact in the summer, when
streamflows generally are low. Increases in the severity
of summer droughts could result in reduced water quality
(e.g., lower dissolved oxygen concentrations, reduced dilution
of effluents) and impaired biological habitat (e.g., drying
of streams, expansion of zones with low dissolved oxygen
concentrations, water temperatures exceeding thermal tolerances)
(IPCC 1996, WG II, Sections 10.5.3 and 10.5.4)…
“Projected
increases in hydrological variability (e.g., more frequent
or larger floods) could lead to increased expenditures for
flood management and disaster assistance (IPCC 1996, WG
II, Section 14.4.3). Flood-control structures might require
modifications to accommodate larger probable maximum-flow
events. Alternatives to structural flood-control measures
can be instituted to reduce risk at a lower cost to society,
but these strategies require significant political will.
Even with the high frequency of extreme events that have
occurred recently (and their attendant costs), changes to
less-costly and more effective nonstructural methods of
risk reduction are slow in gaining acceptance… More
severe summer droughts also could increase agricultural
irrigation demands (IPCC 1996, WG II, Section 14.3.1)
“In
general, water-quality problems (particularly low dissolved
oxygen levels and high contaminant concentrations) associated
with human impacts on water resources (e.g., wastewater
effluents) will be exacerbated more by reductions in annual
runoff than by other changes in hydrological regimes (IPCC
1996, WG II, Section 14.2.4)…”
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