Introduction to Sectoral Working Group Reports

What Sectoral Assessments Should be Pursued?

Several proposals for sectoral breakdowns were discussed by the AGCI group. To test the potential viability of using a breakdown of issues into consequence sectors, working groups were organized to consider the types of issues that would arise based on a division into ten possible sectors:

• Agriculture
• Coastal Zone
• Extreme events
• Forests
• Freshwater Ecosystems and Wetlands
• Grasslands and Arid Lands
• Parks and Public Lands
• Public Health
• Urban Areas
• Water Resources

Other areas raised for possible inclusion as sectors included the service sector (insurance, banking, etc.), the extractive sector (mining, oil, etc.), tribal lands, energy, and environmental security.

Based on discussions subsequent to the reports from these working groups, a second way of covering the topics was proposed. This scheme focused sectors around a set of topics driven by major needs of individuals and society. Each category was to be very broadly conceived. These topics were:

1) food availability (farming, ranching, fresh water, marine, fishing, aquaculture, erosion, land quality, CO₂ enhancement)

2) water availability (quality, quantity, agricultural, municipal and industrial use, habitat effects, allocation, management, runoff)

3) human health (public health, disease vectors, heat stress, natural hazards, air and water quality)

4) forest products availability (forests, timber and pulp production, fire management, shifts in tree species, wildlife, recreation)

5) ecosystem goods and services (grasslands, arid lands, freshwater aquatic systems, wetlands, migrating species, marine life, wildlife, coastal ecosystems, public lands, parks, reservations, protected areas, conservation, tourism, montane regions, endangered species, biodiversity, water purification, permafrost)

6) urban societal infrastructure or cities and communities or human habitat (urban environments, rural settlements, flow of goods, links to natural hazards, insurance, real estate, equity, indigenous people, systems and institutions, housing )

One scheme focused sectors around a set of topics driven by major needs of individuals and society.

7) energy availability (energy supplies, demand, systems, natural resource extraction and mining, oil, coal, natural gas, renewable energy sources, transportation , heating, commercial and residential needs, international implications, coastal issues, utility deregulation, green marketing)

with the possible addition of:

8) national and international economies (jobs, broad economic issues, economic growth mechanisms, flows of goods and services, financial mechanisms and instruments)

9) natural hazards and extreme events (floods, hurricanes, fire, connections to El Niño and other climate phenomena)

Other alternative organizational schemes were also proposed, including one based on:

(1) water availability

(2) food availability

(3) energy availability

(4) ecosystems and endangered species

(5) quality of life (human health, coasts, migration, storms, transport)

Note: Since the AGCI workshop, the National Assessment Synthesis Team has decided to focus most of its attention on five sectors: Agriculture, Water, Coastal Zone, Health, and Forests. Each of these sectors is to be very broadly interpreted, so that, for example, forests covers everything from biodiversity to recreation to lumbering to rural communities. Because of these broad interpretations, these five topics encompass virtually all of the many sectors discussed by the group in Aspen.

Brief reports from the AGCI sectoral working groups follow.

Since the AGCI workshop, the National Assessment Synthesis Team has decided to focus most of its attention on five sectors: Agriculture, Water, Coastal Zone, Health, and Forests.

Agriculture

This sector would deal with the important areas of food and fiber production. When assessing the impacts of climate change on U. S. agriculture, it is important to bear in mind their close connections to international markets and other trends that are controlled far from the region being farmed. Some of the global and national drivers of regional agricultural systems include supply, demand and pricing, changes in comparative advantage, government programs, multinational agro-business, and international food distribution.

Current Stresses Include:

• climate variability
• pests/diseases (including invasive exotic species)
• air pollution
• water supply (declining aquifer levels, droughts, floods, etc.)
• soil quality (erosion, salinity, toxicity, etc.)
• urban-rural land competition
• changing farm structure
• fiscal risk (e. g., capital depreciation)

Additional Stresses Brought About by Climate Change Include:

• frequency and magnitude of extremes versus means
• shifts in the magnitude and timing of critical climate resources ( e. g., soil moisture, growing season lengths)
• pests and pathogens, especially shifting zones and timing
• elevated carbon dioxide effects
• changes in nitrogen deposition
• soil erosion, particularly following downpours
• mapping out agricultural potential
• comparative advantage changes

Potential Coping Mechanisms Include:

• information dissemination, defining roles of private sector, agricultural cooperative extension, etc.
• directing technological innovation
• soil/nutrient/water conservation programs
• applying new technologies (e. g., bio. tech., breeding, precision agriculture, integrated pest management)
• altering pest management systems
• shifting crop species and cropping zones
• more flexibility in government programs
• market mechanisms
• increasing carbon sequestration
  • When assessing the impacts of climate change on U. S. agriculture, it is important to bear in mind their close connections to international markets and other trends that are controlled far from the region being farmed.

Potential Surprises Include:

• new diseases and pests emerging, especially resistant strains
• multiplicative effects of human management and environmental change may be great; the whole may be greater than the sum of its parts
• anticipated rise in productivity may fail to materialize
• world market changes (e. g., what will happen in Africa or China and how will this affect the U. S.'s comparative advantage)
• positive potential surprises such as biotechnology breakthroughs
• additional unforeseen surprises
  • Multiplicative effects of human management and environmental change may be great; the whole may be greater than the sum of its parts.

Coastal Zone

This sector includes all ecological and physical impacts from climate change in the coastal zone out to 200 miles. It encompasses fish and fisheries (including those that migrate through this zone), marine mammals, turtles, corals, mangroves, coastal forests, aquaculture, wetlands, and tidal influences. An increasing portion of the human population inhabits the coastal zone. This sector is important in providing:

• water filtration and cleansing
• habitat for fish, birds and mammals, including about 70 percent of marine fishery species which spend part of their lives in this zone
• breeding ground for land mammals and anadromous fish that reproduce in bays and estuaries
• food source for humans
• coastal protection: mangroves and corals protect barrier islands and coast line from storm damage
• economic base: fisheries, recreation, tourism, transportation, mineral extraction , oil and gas extraction

Current Stresses Include:

• pollution, both point and non-point source
• subsidence (e. g., 2.5 inches (6.4 cm) per year in New Orleans)
• human population growth
• coastal erosion
• storm surges
• increasing ultraviolet radiation (UV) due to ozone depletion
• overfishing
• upstream development (water diversions impact timing, quantity and quality of water reaching coast as well as sedimentation changes)
• nutrient loading and other pollution from agriculture
• contaminants
• oil spills, other hydrocarbons, spills from big transportation systems
• climate variability (at interannual and decadal time scales)
  • In the case of the interaction of climate variability and overfishing, the root stock of particular fish species can be at stake.

There is pronounced decadal as well as seasonal and interannual climate variability which is far in excess of expected climate change. Variability in water temperature, salinity, circulation patterns, currents, and sea level rise all have dramatic impacts on these coastal ecosystems. Mobile species and immobile ones show differential responses to climate variability (e. g., for migratory birds, short term variability can have large impacts). Natural variability also has substantial impacts on ecosystem structure. Other stresses, such as overfishing, interact with natural variability to create larger impacts than either would alone. In the case of the interaction of climate variability and overfishing, the root stock of particular fish species can be at stake.

Additional Stresses brought about by Climate Change Include:

These impacts can be characterized as being primarily from changes in temperature, precipitation, sea ice loss, and sea level rise. Impacts in these four categories are outlined below. In reality, however, there are numerous interactions of these elements with each other and with existing stresses.

Temperature:

• changes in migration timing, routes and food availability along the path way (e. g., the 2° C average increase in temperature of the Columbia River has caused salmon to return a month earlier, and shad, coho and other species to return a week earlier than normal)
• changes in fish distribution, with a generally northward shift (reaching the lethal limit for some species without migration opportunities)
• reduction in winter mortality for some species
• changes in algal composition (effects on dinoflagellates, cyanobacteria, red tides, and range and intensity of toxic algal blooms)
• potential spread of the organism that causes cholera
• pathogen increases
• temperature responses of invasive exotics: could enhance harmful species ; perturbed environments are more invasible and temperature change is a perturbation; rapidly reproducing species are less economically valuable
• changes in reproductive cycles (birds' breeding cycles are strongly affected by temperature)
• stratification changes effect mixing and this effects species
• surprise thresholds beyond which changes can occur in ecosystem structure
  • Additional stresses brought about by climate change include changes in fish distribution, with a generally northward shift (reaching the lethal limit for some species without migration opportunities).

Precipitation:

• changes in amount and timing of river flows, which also affects population migration and reproduction
• storms can overload sewage treatment capability, especially in urban environments (there are thresholds in the human system; waste processing has a limit; more extreme events will dramatically change the composition of runoff as system capacities are exceeded and nutrient loading and pollution will increase)
• fish egg oxygenation and nest destruction affected by flows
• salinity change affect reproduction
• runoff changes effect feeding of estuaries and breeding cycles
• timing of winter and spring precipitation are most critical; amounts fall as rain versus snow are key to storage and availability issues; effects of extreme events; and the combined effects of temperature, precipitation and timing changes
• effects of precipitation on the seasonal hydrological cycle
• ability of wetlands to migrate and at what rate (a combined effect of temperature, precipitation and sea level rise)
• salt water intrusion (in estuarine systems the extent of salt water intrusion is a function of net stream flow)

Sea Ice Loss:

• loss of sea ice impacts marine mammals greatly, as well as algae under ice and the animals that graze on the algae (important component of the food chain)
• changes in seasonal snow cover impacts life cycle of ducks and geese
• sea ice loss leads to coastal erosion
• sea ice loss increases the destructive impacts of storm surges
• shipping season could increase
• fishing season could expand

Sea Level Rise:

• migration of wetlands curtailed by efforts to protect the built environment (if wetlands can't migrate inland, they will be lost)
• wetlands loss impacts all coastal plants and animals (loss of seal pupping and turtle beaches, loss of marsh habitat)
• storm frequency and intensity change combined with sea level rise will have negative effects
• salt water incursions into aquifers and breeding areas
• salinity changes will affect species mix
• increased stresses on port towns and cities, and oil extraction industry

Major Overall Impacts:

• fisheries and other economic impacts may be small nationally but large locally
• subsistence economies will experience major changes
• sea level rise will have large impacts on coastal communities
  • Impacts to fisheries and other economic sectors may be small nationally but large locally.

Potential Coping Mechanisms Include:

• Improve resource and coastal management, and ecosystem research and monitoring ;
• Control invasive species more effectively;
• Implement fishery management that recognizes shifting species ranges and abundances;
• Conduct research on management systems and on aquatic ecosystems;
• Increase control of non-native fishes and other non-native aquatic and marine species;
• In coastal areas, integrate the management of fisheries with other uses of coastal zones;
• Develop long-term monitoring systems to distinguish between natural environmental variability, effects of human disturbances, and climate change;
• Monitor health problems (e. g., red tides, cholera) that could be sensitive to climate change and harm fish stocks and/or consumers.
• Consider sea level rise projections when capital infrastructure needs to be renewed.
• Consider changes storm surges and variability in building coastal protection devices such as sea walls and barriers.
• Control future development in sensitive habitats.
• Place value on sediment load somewhat equal to flood protection when planning levees for flood control and commercial purposes.
• Use better assessment tools including information services such as Geographic Information Systems (GIS) and remote sensing to determine and protect sensitive areas, for planning purposes and decision making purposes.
• Improve water management, including controlling point and non-point sources of pollution.
• Build consideration of downstream water quality and quantity issues into Federal Energy Regulatory Commission (FERC) licensing procedures.
• In future development, consider impacts of coastal erosion, storm surges, sea ice, etc.
• Reduce existing stresses e. g., overfishing, overdevelopment of coastal areas, damage to coral reefs from human activities, pollution, destruction of habitat, etc.
• If predictions of increased use of pesticides under climate change come to pass, the coastal problems will be exacerbated.
• Develop methods for valuing ecosystem services.
• Reduce damage to coral reefs from human activities.
• Implement international treaty on ozone protection to protect coral reefs from bleaching from UV-B exposure.
• Improve forecasting of extreme weather events.
  • Reduce existing stresses, e. g., overfishing, overdevelopment of coastal areas, damage to coral reefs from human activities, pollution, and destruction of habitat.

Extreme Events and Climate Variability

Due to the nature of the subject matter, this working group report follows a format somewhat different from the other sectors.

Climate variability and extreme events already have a wide variety of impacts on society. Extreme events are defined by this working group as those that exceed society's elasticity. Experience with natural disaster reduction can teach important lessons for coping with climate change. Building societal resilience with regard to climate variability and extreme events will go a long way toward addressing the climate change challenge.

The group suggested that existing tools are not fully utilized and are inadequate to meet future challenges. In particular, new information technologies are not fully exploited and the current understanding of links between climate change, climate variability and extreme events is inadequate.

Factors that are Changing How Impacts are Experienced Include:

• population growth
• urbanization
• economic growth
• technological advance
• ecosystem management

Coping mechanisms in place are of varying effectiveness and are generally tuned to the current climate.

There is currently great public interest in this area, in part as a result of the ongoing national focus on extreme events and in part as a result of the national dialogue being facilitated by the Federal Emergency Management Administration (FEMA) through its National Mitigation Strategy and its 2000-page assessment of natural hazards.

Current understanding of links between climate change, climate variability and extreme events is inadequate.

Forests

The forest sector working group defined two sub-sectors: unmanaged and managed forests. Within managed forests, there are two additional categories, commercial and urban.

Current Stresses Include:

• pests
• drought
• air pollution
• harvest practices
• demographics
• fire
• invasive species

Additional Stresses brought about by Climate Change Include:

Potential Coping Mechanisms Include:

For Managed Systems:

• planted species replacement
• genetic variants of species
• changing planting regimes - density, timing, rotation
• biomass production (7-10 years)
• precision forestry
• reforestation/afforestation projects
• fertilization

For Non-Managed Systems:

• wildlife corridors, zoning, land purchasing for species preservation
• fire management
• facilitate appropriate species through seeding and preparation
• pollution control
• invasive species control
• introduction of wildlife species
• managed access
• maintain biodiversity

Tundra

Climate impacts on arctic and alpine tundra were also discussed briefly by this working group. Existing stresses include the effects of warming, toxic contaminants, nitrogen deposition, and human pressures like tourism and hunting. Additional impacts from climate change would act to increase the stress that is already on the system. Coping strategies would need to be national in scope; little can be done locally. Mitigating species habitat constraints with land set asides was one example suggested. The group also discussed the example of making greater use of already heavily used lands and leaving the least used ones alone.

Additional impacts from climate change would act to increase the stress that is already on the system.

Freshwater Ecosystems/Wetlands

This sector would deal with the important areas of all types of plant and animal species in fresh water systems, including both natural systems and those managed to supply human needs. This sector would include wetlands, migrating species, fisheries, hatcheries, etc.

Key issues of concern involve potential feedback effects, tolerances, quantifying needs, economic and social implications, legal implications, and adaptations. A central question is: How do critical ecosystem functions relate to goods and services valued by humans?

Current Stresses Include:

• societal consumption
• societal wastes
• physical manipulation
• exotic invasions

Additional Stresses brought about by Climate Change Include:

• water balance changes
• physical and temperature changes
• biological changes
• ultraviolet radiation changes
• upstream watershed processes

Potential Coping Mechanisms Include:

• Relieve current stresses since they are already highly influencing aquatic system integrity.
• Natural systems have little buffers; more active management is needed.
• Set priorities for water resources management.
  • How do critical ecosystem functions relate to goods and services valued by humans?

Grasslands and Arid Lands

Grasslands and arid lands are of many types and generally must be treated with regional resolution. Their regional systems include the North, Central and South Great Plains, the Southwest, Central California, Central Florida, Palouse, and the Great Basin.

Arid Lands include the Mojave, Sanoran, Chihuahua, Great Basin, Colorado Plateau, and Chaparel. When thinking about arid lands, it is also important to remember that most land ownership is public, but most water use is private.

Tundra regions of North America are in Alaska and Canada.

Current Stresses Include:

• population shifts (absolute and ethnic composition)
• economic restructuring (NAFTA, etc.)
• technological change
• values (cultural, environmental, etc.)
• consumption changes
• environmental changes
• institutional changes

Additional Stresses Brought About by Climate Change Include Changes in the Following Critical Variables:

• seasonal distribution of precipitation (onset, intensity, duration)
• amount of precipitation
• temperature
  • growing season length
  • frost-free days
  • last frost day
  • minimum and maximum temperatures
  • extreme events (frequency and magnitude)
• drought index
• soil moisture
• El Niño Southern Oscillation (ENSO) characteristics
• biotic thresholds

Multiple stresses already drive changes in the availability and distribution of water, land and energy. Climate change will add additional drivers and affect existing ones as these drivers interact with climate change variables.

With regard to arid lands, it is important to remember that most land ownership is public, but most water use is private.

In evaluating climate change impacts, it will be important to consider the context of other key questions affecting grasslands and arid lands. These include:

• How will climate change interact with critical drivers to change grasslands and arid lands?
• What is the future of government subsidies?
• How will water rights be resolved?
• If the characteristics of ENSO change, how will different systems change?

Key information needs for undertaking an assessment of the consequences of climate change on grasslands and arid lands include:

• synthesis of historical trends
• new studies of contemporary sectors (e. g. , pests/disease)
• analog studies of historic climate periods under contemporary sectoral conditions
• analog studies with scenarios of critical economic/social/technological trends
• a suite of GCM simulations including:
  • fully coupled transient runs
  • with GHG forcing and sulfates
  • which are regionally downscaled
  • and topographically realistic
  • with monsoonal patterns captured
  • and ENSOs resolved

    How will climate change interact with critical drivers to change grasslands and arid lands?

Parks and Public Lands

This sector would include national parks, forests, monuments, sanctuaries, preserves, military bases, and all state and federal lands. This sector is important because public lands:

• include a significant portion of the nation's land representing a wide range of landscapes and ecosystems
• contain important natural resources vital to the economy through grazing, mining, agriculture, recreation, and tourism
• protect unique ecosystems and flora and fauna
• serve as a major source of freshwater
• provide unique experiences to the public

Current Stresses Include:

• increased development, recreation, economic uses
• fragmentation of habitat (especially surrounding land)
• air and water pollution
• vulnerabilities to exotic invasive species and pests
• altered disturbance and hydrologic regimes
• climate variability

Additional Stresses brought about by Climate Change Include:

• increased climate variability
• accelerated sea level rise and glacier melting
• increased competition for water and land
• accelerated spread of exotic species, pests and diseases
• accelerated habitat loss and loss of biodiversity
• changes to fundamental ecosystem processes

Potential Coping Mechanisms Include:

• developing tools and policies for managing frequency and intensity of disturbances (e. g., controlling grazing and erosion, limiting access, restoring natural cycles such as fires and floods, creating buffer zones and wildlife migration corridors)
• expanding efforts to curtail or mitigate exotic species and diseases
• emphasizing ecosystem approaches, enhance corridors and linkages among lands
• developing adaptive management strategies
• expanding biological inventories, monitoring and research
• expanding public education efforts
  • Public lands contain important natural resources vital to the economy through grazing, mining, agriculture, recreation, and tourism.

Public Health

This sector would include all issues relating to human health, ranging from the health of individuals to general issues of societal health. It would also include issues such as changes in land use that may present trade-offs for public health. Some current examples of this include:

Current and Foreseen Stresses Include:

population growth

• urban density
• expansion to new environments
• poverty
• health care and immunization
• sewage and waste disposal

social and behavioral changes

• changing hygiene (e. g., hand and food washing)
• "religious" behaviors/customs
• poverty (urban and rural)
• water use (wells, water treatment)

dispersal (of diseases and vectors)

• human travel (business, pleasure, migration)
• shipping and commerce (air, sea, land)

infrastructure

• inadequate monitoring and surveillance

severe weather

• heavy rain (toxins, water-borne disease)
• drought (dust-borne agents, water storage)
  • Changes in land use may present trade-offs for public health.

Additional Stresses brought about by Climate Change:

In addition, there are a number of diseases that are likely to be affected by climate change and variability, including:

Water-borne diseases

• Cholera
• Cryptosporidiosis

Vector-borne diseases (vectors include rodents, ticks, mosquitoes)

• Viruses

  St. Louis encephalitus

  Dengue

  Hantavirus

• Bacteria

  Bubonic plague and other plagues

  Lyme disease

• Protozoa

  Malaria

Several key questions were identified relating to climate variability and public health. Vector-borne disease provides an example of the range of issues. At the basic physiological level, there is a positive impact of temperature on development rates of pathogens in their vectors while there is a negative impact on vector survival. Thus, there is an optimal temperature for a given vector/pathogen pair. It is important to know if future temperatures are likely to be lower than, equal to, or higher than those current-day optima (and, perhaps, how rapidly higher temperature optima could be selected).

It is important to know how climate change may impact the habitats of vectors and vertebrate hosts of these agents of human disease.

At a much larger scale, it is important to know how climate change may impact the habitats of vectors (especially larval habitats) and vertebrate hosts of these agents of human disease. When birds are the normal vertebrate hosts (as with several mosquito-transmitted encephalitis viruses), changes over very large or widely separated areas (as with migratory birds) and habitat types may need to be considered. Preliminary examination of animal case reports for several vector-borne diseases suggests the potential for case reduction would be considerable.

Potential Coping Mechanisms Include:

monitoring, surveillance and communication

• local/regional collection
• national coordination

improved access to services

• local infrastructure
• national support

resiliency: building a public health infrastructure

• local
• national (post-disaster)

education and training

• local
• national (support, advanced training)

research

• impacts of climate variation
• basic ecology and epidemiology
• data set collection, including cost-benefit analyses

pollutant reduction

• allergies, asthma
• greenhouse gas reduction

The working group also offered suggestions on bringing together stakeholders from the local, state, regional and national levels through a variety of professional health associations.

In the category of potential surprises it was mentioned that although it seems counter intuitive, warming could actually increase winter-related deaths due to cold, as complacency can occur when overall weather is warmer. For example, in Tallahassee, Florida, more people die from cold during winters that are warmer than usual.

Although it seems counter intuitive, warming could actually increase winter-related deaths due to cold, as complacency can occur when overall weather is warmer.

Urban Areas

This sector would focus on where the people are. Eighty percent of the people in the U. S. live in urbanized areas on roughly 20 percent of the U. S. land area. The urban sector exists in a context dominated by external connections and complexity. An analysis of climate change effects will be characterized by important second and third order impacts.

Eighty percent of the people in the U. S. live in urbanized areas on roughly 20 percent of the U. S. land area.

This working group discussed the vulnerabilities of urbanized areas to climate change, including built infrastructure, institutional infrastructure, social infrastructure, human services (comfort, convenience, mobility, land housing, energy, water, waste disposal, health, security, and recreation), and key linkages such as communication and transportation. Issues of concern include quality of life, the fluxes and flows of dynamic systems, the time frames of decision making, and interdependence.

Current Stresses Include:

• population, demographics, real estate development, congestion
• aging physical infrastructure
• deteriorating environmental quality, health problems
• social stresses: security, diversity, equity, social net, shrinking public sector budgets
• economic stresses: economic restructuring, poverty

Additional Stresses brought about by Climate Change Include:

First order vulnerabilities to climate change and variability

• sea level rise, storm surges, coastal erosion
• extreme events: floods, hurricanes, tornadoes, fire, etc.
• other climate-related variabilities: heat waves, droughts, blizzards
• disease vectors and epidemics
• water availability/cost and quality

Second order vulnerabilities

• reductions in air quality
• health impacts: heat stress, air pollution, water-borne diseases
• greater effect of overall impacts of certain segments of the population: the poor, elderly, young, and those in risk prone areas and situations
• infrastructure costs of changes in temperature and precipitation regimes: e. g., changes in energy requirements, or costs of coping with sea level rise

Third order vulnerabilities

• impacts of shifts in regional comparative advantage
• impacts on consumers and local businesses of climate change abatement policies
• political and social tensions

Potential Coping Mechanisms Include:

• information and education
• making institutions more adaptive
  • longer design horizons
  • win-win potentials
  • improvements in resiliency
• engineering/physical infrastructure investments
• regulatory initiatives
  • land use control
  • building standards
  • water conservation

Special attention should be paid to coastal areas in regard to all of the above.

The working group expressed concern about the capacity of existing government structures to handle the new stresses outlined above. For example, the capacity may not exist to handle interjurisdictional issues that may arise. They believe that if urban areas begin by developing systems for dealing with climate variability, they will thus be improving their resilience to climate change as well, e. g., building codes designed to withstand extreme events will also help deal with climate change impacts.

Vulnerabilities of urbanized areas to climate change include built infrastructure, institutional infrastructure, social infrastructure, human services, communication, and transportation.

Water Resources

This sector would include issues of water supply (surface and ground water, precipitation, runoff, and water system management), aquatic ecosystems (natural and altered rivers, lakes, and wetlands), hydrologic extremes (floods and droughts), and coastal resources. Both water quality and quantity aspects would be considered, as the two are intertwined in most water resource issues. See Figure 2.16 for average consumptive use and renewable water supply by region.

The current situation in water management is reflected in the following:

• considerable information exists and is available, but is underutilized
• local and regional problems include aging infrastructure, costly investments, average demands exceeding former yields, inefficient use, increasing conflicts among competing uses, institutional rigidity in dealing with new perspectives and values with regard to ecosystem management and watershed perspectives
• problems are being addressed across the U. S.; about 300 watershed studies are underway with a more multi-objective view
• legislation has been drafted in response to recommendations following the Mississippi floods; for example, a drafted law would allow the Army Corps of Engineers to buy and restore wetlands rather than rebuilding levees after a flood
• legal and institutional changes are slow regarding water rights, appropriation, market pricing of water, legal constraints on water allocation, federal, state and local assignment of responsibility
• a disconnect exists between federal water policies and local land use management decisions that affect flood plains and water use
• nationally, water withdrawals in the U. S. have dropped since 1980, even in the face of rising population

Current Stresses Include:

• failure and aging of water infrastructure
• increasing water-based recreational use and conflicts with established uses
• increasing demands for instream flows (e. g., to protect endangered species or restore aquatic ecosystems)
• interannual variability
• effects of floods and droughts
• increasing population and economic growth
• rapid urban growth, especially in coastal areas
• increasing competition between water uses
• declines in aquatic species due to degraded water quality and loss of habitat (including diminished flows)
• reduction in extent of wetlands
• seawater intrusion into coastal aquifers
• physical modifications of estuarine systems
• excessive nutrient inputs and other pollutants to estuaries
  • Problems include aging infrastructure, costly investments, demands exceeding yields, inefficient use, increasing conflicts among competing uses, and institutional rigidity.

Additional Stresses brought about by Climate Change Include:

• changes in amount, frequency, and intensity of precipitation affecting magnitude and timing of runoff
• changes in magnitude and frequency of floods and droughts
• intensification of the water cycle, including increased evaporation, precipitation and streamflows
• increases in amounts of water needed for irrigation, industrial process cooling and domestic uses
• increased evaporative losses from water supply systems
• lowered surface water and soil water storage amounts
• changes in mean flows, flow variability and water temperature in aquatic habitats
• changes in extent and timing of ice cover on rivers and lakes
• sea level rise and associated impacts
• changing river discharges
• shrinkage of mountain glaciers
• reduction in areal extent of continuous and discontinuous permafrost
• decreased proportion of precipitation falling as snow, leading to reductions in spring runoff and increases in winter runoff, reducing the effective storage capacity of snow pack as a natural reservoir
• erosion of shorelines and associated habitat caused by rising sea level (in the past, estuaries and coastal wetlands could migrate inland, but human infrastructure has diminished this possibility in many places)
• increased salinity in estuaries and freshwater aquifers
• altered tidal ranges in rivers and bays
• changes in sediment and nutrient transport
• increased coastal flooding

Potential Coping Mechanisms Include:

• developing water management strategies that are robust to a wide range of possible climatic conditions
• continuing attempts to model future climate
• developing river basin simulation models that are able to predict flow conditions from the first principles of climate, topography, land use, and engineering
• developing robust observational systems to provide current data on temperature, precipitation, stream flow, and ground water conditions to managers on a real time basis
• permanent evacuation of some flood prone areas
• enhanced flood warning and evacuation planning
• flood proofing of structures
• creation of additional natural storage through restoration or creation of wetlands
• better maintenance of levees

The working group suggested that more attention be paid to boundary problems both between states and between the U. S. and Canada. In addition, they felt that more attention should be paid to where water is being overdrafted and diminishing ground water supplies, and in places where ecosystem impacts are large, such as the Everglades.

A decreased proportion of precipitation falling as snow would lead to reductions in spring runoff and increases in winter runoff, reducing the effective storage capacity of snow pack as a natural reservoir.

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