The Likely Consequences of The Likely Consequences of Climate Change for the United States: Climate Change for the United States:

Results of the US National AssessmentResults of the US National Assessment

Michael C. MacCrackenMichael C. MacCracken

Senior Scientist for Climate Programs atSenior Scientist for Climate Programs at

The Climate Institute, Washington DC; andThe Climate Institute, Washington DC; and

President,President,

International Association of International Association of

Meteorology and Atmospheric SciencesMeteorology and Atmospheric Sciences

Brief Biographical SketchBrief Biographical Sketch Student, Princeton University, mechanical engineering, 1960-64Student, Princeton University, mechanical engineering, 1960-64 Ph.D. student in applied science, University of California Davis Ph.D. student in applied science, University of California Davis

(climate model analysis of ice age hypotheses), 1964-68(climate model analysis of ice age hypotheses), 1964-68 Research scientist, Lawrence Livermore National Laboratory Research scientist, Lawrence Livermore National Laboratory

(modeling of perturbations to climate and air quality; leader of (modeling of perturbations to climate and air quality; leader of Atmospheric and Geophysical Sciences Division), 1968-93Atmospheric and Geophysical Sciences Division), 1968-93

Executive Director , Office of the interagency U.S. Global Executive Director , Office of the interagency U.S. Global Change Research Program (USGCRP), 1993-97Change Research Program (USGCRP), 1993-97

Executive Director, National Assessment Coordination Office of Executive Director, National Assessment Coordination Office of the USGCRP, 1997-2001the USGCRP, 1997-2001

Senior Scientist, Office of the USGCRP, 2001-02 (retired, 2002)Senior Scientist, Office of the USGCRP, 2001-02 (retired, 2002) Member, Integration team, Arctic Impact Climate Assessment, Member, Integration team, Arctic Impact Climate Assessment,

2002-042002-04 Senior Scientist for Climate Programs, Climate Institute, 2003-Senior Scientist for Climate Programs, Climate Institute, 2003- President, International Association of Meteorology and President, International Association of Meteorology and

Atmospheric Sciences, 2003-07 (also serving on executive Atmospheric Sciences, 2003-07 (also serving on executive committees of IUGG and SCOR and planning team for workshop committees of IUGG and SCOR and planning team for workshop on effects of impacts of asteroids and comets).on effects of impacts of asteroids and comets).

The “Climate Change” issue is The “Climate Change” issue is traditionally subdivided into traditionally subdivided into

three componentsthree components1. 1. The Science:The Science: How has the climate changed and how is How has the climate changed and how is

it expected to change in the future?it expected to change in the future?2. 2. The Impacts:The Impacts: What are the likely environmental and What are the likely environmental and

societal consequences of changes in climate and to societal consequences of changes in climate and to what extent can we adapt?what extent can we adapt?

3. 3. The Choices:The Choices: What are the options available for What are the options available for mitigating the changes?mitigating the changes?

The political processThe political process--involving leaders from both the --involving leaders from both the public private sectors--then faces the challenging task public private sectors--then faces the challenging task of evaluating and reconciling the available information of evaluating and reconciling the available information and deciding on the path to take. and deciding on the path to take.

Outline of talkOutline of talk

Very brief overview of scientific understanding Very brief overview of scientific understanding about global warming (area 1)about global warming (area 1)

Structure and format of the U.S. National Structure and format of the U.S. National Assessment (area 2)Assessment (area 2)

The types of impacts that the US can be The types of impacts that the US can be expected to experience (area 2)expected to experience (area 2)

Concluding remarksConcluding remarks

********************************************************************************************** Questions (areas 1, 2, 3 if desired)Questions (areas 1, 2, 3 if desired)

A hundred years of climate research A hundred years of climate research can be summarized in 5 key findingscan be summarized in 5 key findings 1. The atmospheric concentrations of CO1. The atmospheric concentrations of CO22, CH, CH44, N, N22O and other gases O and other gases

are increasing as a result of human activities, primarily because of are increasing as a result of human activities, primarily because of use of fossil fuels (coal, oil, and natural gas) and deforestationuse of fossil fuels (coal, oil, and natural gas) and deforestation

2. Higher concentrations of radiatively active gases like CO2. Higher concentrations of radiatively active gases like CO22, CH, CH44, ,

and Nand N22O tend to enhance the natural greenhouse effect and warm the O tend to enhance the natural greenhouse effect and warm the

planetplanet 3. Human-induced changes in atmospheric composition have very 3. Human-induced changes in atmospheric composition have very

likely contributed to global warming of about 0.6ºC (or more) since likely contributed to global warming of about 0.6ºC (or more) since 19001900

4. Plausible scenarios of future energy-related emissions are 4. Plausible scenarios of future energy-related emissions are projected to cause global warming of 1.4 to 5.8ºC and sea-level rise projected to cause global warming of 1.4 to 5.8ºC and sea-level rise of about 10 to 90 cm by the end of the 21of about 10 to 90 cm by the end of the 21stst century century

5. Moderating the rate of global warming will require significant 5. Moderating the rate of global warming will require significant reductions in emissions and take many decadesreductions in emissions and take many decades

Source: Mann et al., 2003

Several reconstructions of Northern Hemisphere average Several reconstructions of Northern Hemisphere average temperature indicate that the centuries prior to the temperature indicate that the centuries prior to the

Industrial Revolution were relatively cool Industrial Revolution were relatively cool

The increase in COThe increase in CO22 emissions is projected to emissions is projected to

cause a significant further increase in surface cause a significant further increase in surface temperature around the world (1.4 to 5.8ºC)temperature around the world (1.4 to 5.8ºC)

IPCC temperature increases

Source: IPCC TAR, 2001Source: IPCC TAR, 2001

Projected Temperature Change

Projected

CO2 Concentration

The projected The projected increase in global increase in global

average temperature average temperature could result in global could result in global temperatures being temperatures being

higher than they higher than they have been in tens of have been in tens of

millions of yearsmillions of years

Prather diagram

Source: IPCC TAR, 2001 and M. PratherSource: IPCC TAR, 2001 and M. Prather

““Global warming” is shorthand for a wide array Global warming” is shorthand for a wide array of potential changes in the climateof potential changes in the climate

Warming is very likely to be greater in high than low latitudes, with the Warming is very likely to be greater in high than low latitudes, with the sea ice melting back and land glaciers and ice sheets meltingsea ice melting back and land glaciers and ice sheets melting

Warming is very likely to be greater over land than over the oceansWarming is very likely to be greater over land than over the oceans Warming is very likely to be greater in winter than in summer in many Warming is very likely to be greater in winter than in summer in many

locations, but not all; however, the summertime heat index will make locations, but not all; however, the summertime heat index will make summertime changes feel worse, with more intense heat wavessummertime changes feel worse, with more intense heat waves

Total evaporation is very likely to increase, leading to more rapid drying Total evaporation is very likely to increase, leading to more rapid drying of soils and earlier onset of drought of soils and earlier onset of drought

Total global precipitation is very likely to increase, and to occur Total global precipitation is very likely to increase, and to occur especially in relatively intense events (especially tropical cyclones) that especially in relatively intense events (especially tropical cyclones) that could increase flood likelihood in some regions. could increase flood likelihood in some regions.

The highest percentage increase in precipitation is likely to occur in The highest percentage increase in precipitation is likely to occur in mid- to high-latitudes; reductions in rainfall could occur in the subtropics mid- to high-latitudes; reductions in rainfall could occur in the subtropics

The potential for unexpected changes will be increased because the The potential for unexpected changes will be increased because the balancing influences now acting may be disrupted and because various balancing influences now acting may be disrupted and because various thresholds could be exceededthresholds could be exceeded

Health ImpactsHealth ImpactsWeather-related mortality/heat stressInfectious diseasesAir quality-induced respiratory effects

Agriculture ImpactsAgriculture ImpactsCrop yields and commodity pricesIrrigation demandsPests and weed

Water Resource ImpactsWater Resource ImpactsChanges in water supply and timingWater qualityIncreased competition for water

Coastal Area ImpactsCoastal Area Impacts Erosion of beachesInundation of coastal wetlandsCosts to defend coastal communities

Forest ImpactsForest ImpactsChange in forest compositionShift geographic range of forestsForest health and productivity

Ecosystem ImpactsEcosystem ImpactsShifts in ecological zonesLoss of habitat and speciesCoral reefs threatened

As a result, climate change could lead to a range As a result, climate change could lead to a range of important impactsof important impacts

Climate Changes

Sea Level Rise

Temperature

Precipitation

Adapted from EPAAdapted from EPA

The IPCC has provided a summary of how climate change is The IPCC has provided a summary of how climate change is likely to affect peoples and environments around the worldlikely to affect peoples and environments around the world

While the IPCC Impacts Assessment is a First Step, While the IPCC Impacts Assessment is a First Step, Much More Refined Studies Are NeededMuch More Refined Studies Are Needed

Changes in climate are most readily studies and estimated by Changes in climate are most readily studies and estimated by starting at the global level and working to finer scales (top-starting at the global level and working to finer scales (top-down)down)

The consequences of climate change are most appropriately The consequences of climate change are most appropriately studied by starting from the local environment and aggregating studied by starting from the local environment and aggregating to larger scales (bottom-up)to larger scales (bottom-up)

The key challenge is in building a strong interface between the The key challenge is in building a strong interface between the two type of effortstwo type of efforts

The latest versions of climate models are now providing The latest versions of climate models are now providing sufficient resolution for starting to seriously examine local and sufficient resolution for starting to seriously examine local and regional consequencesregional consequences

What is now most needed is an intensive effort to put the What is now most needed is an intensive effort to put the translate and apply these results to examine potential translate and apply these results to examine potential environmental, resource and societal consequences--and this environmental, resource and societal consequences--and this is starting to happen (Canada, UK, US, Arctic, etc.)is starting to happen (Canada, UK, US, Arctic, etc.)

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressorare needed to see this picture.

Model with300 km grid

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressorare needed to see this picture.

Model with75 km grid

QuickTime™ and aCinepak decompressorare needed to see this picture.

Model with50 km grid

The first US National Assessment took place The first US National Assessment took place from 1997 to 2001 and focused on evaluating from 1997 to 2001 and focused on evaluating potential consequences and response optionspotential consequences and response options

Regional workshops and assessmentsRegional workshops and assessments examined the most examined the most important issues in 20 regions that covered the countryimportant issues in 20 regions that covered the country

Sectoral workshops and assessmentsSectoral workshops and assessments examined the array examined the array of issues that could affect agricultural productivity, forest of issues that could affect agricultural productivity, forest health and productivity, water resources, human health, and health and productivity, water resources, human health, and coastal areas and marine resources. More recent studies are coastal areas and marine resources. More recent studies are starting to look at transportation, air quality, water quality, etc.starting to look at transportation, air quality, water quality, etc.

A A National SynthesisNational Synthesis provided an overview of the range of provided an overview of the range of issues facing the Nation as a whole, finding that the potential issues facing the Nation as a whole, finding that the potential impacts on ecosystems and water resources were likely to be impacts on ecosystems and water resources were likely to be the most importantthe most important

While much more could be done now with the very new capabilities that are being While much more could be done now with the very new capabilities that are being developed, unfortunately the US research program is presently stuck on evaluating developed, unfortunately the US research program is presently stuck on evaluating

remaining uncertainties about how much the climate change will beremaining uncertainties about how much the climate change will be

Regional workshops were held in 1997-98 Regional workshops were held in 1997-98 to identify potential impacts meriting to identify potential impacts meriting

further assessmentfurther assessment

A special workshop was also held in A special workshop was also held in 1998 to address issues relating to 1998 to address issues relating to

Native Peoples/Native HomelandsNative Peoples/Native Homelands

Workshop and assessment reports Workshop and assessment reports can be viewed under “Assessments” can be viewed under “Assessments”

at http://www.usgcrp.govat http://www.usgcrp.gov

The participating groups in the The participating groups in the US National Assessment were asked to evaluate US National Assessment were asked to evaluate the vulnerability of the environment and society the vulnerability of the environment and society

to three classes of climate outcomesto three classes of climate outcomes

Continuation of the types and range of climate conditions Continuation of the types and range of climate conditions that prevailed during the 20that prevailed during the 20thth century century

Results of simulations from leading climate models Results of simulations from leading climate models assuming continued reliance on fossil fuels for most of the assuming continued reliance on fossil fuels for most of the world’s energy needs (leading to an emissions rate of about world’s energy needs (leading to an emissions rate of about 20 GtC/yr in 2100)20 GtC/yr in 2100)

The possibility that nonlinear changes could occur, for The possibility that nonlinear changes could occur, for example if the threshold for an impact were to be exceeded example if the threshold for an impact were to be exceeded (and then examined model simulations and proxy indicators (and then examined model simulations and proxy indicators to estimate possible likelihood)to estimate possible likelihood)

Climate models were found to Climate models were found to be reasonably able to be reasonably able to

represent the large-scale represent the large-scale distribution of annual distribution of annual

average temperature (ºF) for average temperature (ºF) for the present climate of the USthe present climate of the US

Canadian Model Hadley (UK) Model

Climate models were also Climate models were also found to be reasonably found to be reasonably

able to represent the able to represent the seasonal temperature seasonal temperature

range (ºF) for the present range (ºF) for the present climate of the USclimate of the US

Canadian Model Hadley (UK) Model

Climate models were also Climate models were also able to simulate some able to simulate some

features of the monthly features of the monthly average precipitation (in./mo), average precipitation (in./mo),

but were not able to but were not able to adequately resolve the adequately resolve the

complex effects of complex effects of mountain rangesmountain ranges

Canadian Model Hadley (UK) Model

The two climate model simulations that were available The two climate model simulations that were available to be used in the US National Assessment to be used in the US National Assessment

projected a 21projected a 21stst century warming of about 5 - 10ºF century warming of about 5 - 10ºF

Find the Hadley and Canadian model estimates of change in temp

Canadian model scenario for Canadian model scenario for increase by 2100increase by 2100

Hadley model scenario for Hadley model scenario for increase by 2100increase by 2100

Plots show the projected change in annual average temperature over the 21st century

Projections of the change in precipitation were less Projections of the change in precipitation were less certain, indicating the possibility of eithercertain, indicating the possibility of either

“hotter and drier” or “warmer and moister” conditions “hotter and drier” or “warmer and moister” conditions

Canadian model scenario for Canadian model scenario for change by 2100change by 2100

Hadley model scenario for Hadley model scenario for increase by 2100increase by 2100

Plots show the projected percentage change in Plots show the projected percentage change in annual precipitation over the 21annual precipitation over the 21stst century (in %) century (in %)

Note: More recent results form a wider selection of models suggest that the apparent Note: More recent results form a wider selection of models suggest that the apparent increase in winter precipitation projected for the southwestern US may not be robustincrease in winter precipitation projected for the southwestern US may not be robust

Model projections indicated that more of the Model projections indicated that more of the precipitation will occur as part of intense rainfall eventsprecipitation will occur as part of intense rainfall events

More intense More intense events could events could increase the increase the potential for potential for flooding, but flooding, but with likelihood with likelihood of greater of greater drying and drying and lower river and lower river and lake levels lake levels between stormsbetween storms

The prospective changes in climate would be The prospective changes in climate would be roughly equivalent to imposing climatic conditions roughly equivalent to imposing climatic conditions

many hundreds of miles away many hundreds of miles away

Preliminary indications were that the Preliminary indications were that the El Niño-La Niña cycle would be likely to intensifyEl Niño-La Niña cycle would be likely to intensify

More hurricanes strike the More hurricanes strike the US under La Niña than El US under La Niña than El

Niño conditionsNiño conditions

A greater range would lead to A greater range would lead to increased interannual increased interannual variability over the USvariability over the US

Changes in precipitation were projected Changes in precipitation were projected to alter the availability of water resourcesto alter the availability of water resources

Storm intensity, track, and number would be likely to Storm intensity, track, and number would be likely to shift, although most types of changes remain uncertainshift, although most types of changes remain uncertain

Warmer conditions will lead to reduced springtime Warmer conditions will lead to reduced springtime snowpack and altered timing of river runoff (with less in snowpack and altered timing of river runoff (with less in summer)summer)

A larger fraction of the precipitation is likely to come in A larger fraction of the precipitation is likely to come in intense storms, continuing the 20intense storms, continuing the 20thth century trend century trend

Warmer conditions will lead to warmer water Warmer conditions will lead to warmer water temperatures and faster drying of soils between stormstemperatures and faster drying of soils between storms

Average river flows and lake levels will be lower, Average river flows and lake levels will be lower, especially in summer; creating greater competition for especially in summer; creating greater competition for water resources)water resources)

Whether a region was relatively wet or dry, Whether a region was relatively wet or dry, potential water-related impacts were of potential water-related impacts were of

concern across the United Statesconcern across the United States

Even with increased Even with increased wintertime wintertime

precipitation, warmer precipitation, warmer winters and a rising winters and a rising

snowline are projected snowline are projected to lead to significant to lead to significant

reductions in reductions in springtime snowpack springtime snowpack

in the western US, in the western US, greatly impacting greatly impacting

water resource water resource management in these management in these

regionsregions

The costs of extreme weather events have been The costs of extreme weather events have been increasing, probably reflecting both the increased increasing, probably reflecting both the increased

exposure of society and perhaps the slow change in the exposure of society and perhaps the slow change in the number and/or intensity of extreme eventsnumber and/or intensity of extreme events

1629447213010203040506070

1998

Annual losses, in thousand million U.S. dollars

1950 1990198019601970

Global costs of extreme weather events (inflation-adjusted)

Total economic lossesInsured lossesNumber of eventsDecadal average13

The present distribution of ecosystems is a The present distribution of ecosystems is a result of plants and wildlife adapting to result of plants and wildlife adapting to prevailing climatic and soil conditions prevailing climatic and soil conditions

Ecosystem Ecosystem Impacts by 2100Impacts by 2100

Even accounting for Even accounting for the effects of COthe effects of CO22

fertilization and fertilization and enhancement, enhancement, changes in the changes in the

climate will lead to climate will lead to regional changes in regional changes in

the predominant the predominant vegetation types and, vegetation types and,

as a result, in the as a result, in the extant wildlife. Some extant wildlife. Some

of the transition is of the transition is likely to occur likely to occur

relatively rapidly as a relatively rapidly as a result of fires and result of fires and

other disturbancesother disturbances

Overall forest productivity is expected to rise, although Overall forest productivity is expected to rise, although the predominant tree species in a location may change. the predominant tree species in a location may change.

In some areas, drier summers are likely to raise the In some areas, drier summers are likely to raise the potential for fires.potential for fires.

-100%

-50%

No change

+50%

+100-200%

>200%

Hadley Canadian

For hot, dry summertime conditions (Canadian model scenario), forest mass For hot, dry summertime conditions (Canadian model scenario), forest mass burned increases significantly, especially in the western US and the lower burned increases significantly, especially in the western US and the lower

Mississippi-central Appalachians. For warm, moist conditions (Hadley Mississippi-central Appalachians. For warm, moist conditions (Hadley scenario), increased fire likelihood occurs mainly in the western US.scenario), increased fire likelihood occurs mainly in the western US.

Simulated change in biomass burnt by wildfires between the 20Simulated change in biomass burnt by wildfires between the 20 thth and 21 and 21st st centuries (per cent)centuries (per cent)

The effects of The effects of climate climate change on change on terrestrial and terrestrial and marine marine ecosystems ecosystems and wildlife and wildlife are projected are projected to vary across to vary across the countrythe country

The US agricultural sector is likely to be able to adapt to The US agricultural sector is likely to be able to adapt to climate change. Overall productivity is likely to increase due climate change. Overall productivity is likely to increase due to the higher COto the higher CO22 level and improved water use efficiency. level and improved water use efficiency.

With increased production:With increased production:• Commodity prices would be expected to fall, benefiting consumers, but causing Commodity prices would be expected to fall, benefiting consumers, but causing economic harm in marginal farming areas;economic harm in marginal farming areas;• What happens in other world grain-growing regions will have large effect;What happens in other world grain-growing regions will have large effect;• Issues of changes in pests and plant diseases have yet to be evaluated.Issues of changes in pests and plant diseases have yet to be evaluated.

For agriculture, a key factor will be the lengthening of the frost free For agriculture, a key factor will be the lengthening of the frost free season, continuing a trend that is already underwayseason, continuing a trend that is already underway

Global sea level is projected to rise by about 9 to 88 Global sea level is projected to rise by about 9 to 88 cm during the 21cm during the 21st st century, with a mid-range value century, with a mid-range value likely (or even higher if augmented by accelerated likely (or even higher if augmented by accelerated

melting of the Greenland ice sheet )melting of the Greenland ice sheet )

U.S. Sea Level Trends 1900-2000

1900 1920 1940 1960 1980 2000Year

40

20

0

Scale (cm)

Galveston, TX

New York, NY

Baltimore, MD

Key West, FL

San Francisco, CA

Sitka, AK

Global sea level rose 10-20 cm Global sea level rose 10-20 cm during the 20during the 20thth century century

Contributions to global sea level rise are projected to Contributions to global sea level rise are projected to come mainly from thermal expansion of ocean waters come mainly from thermal expansion of ocean waters and melting of mountain glaciers. Changes in Greenland and melting of mountain glaciers. Changes in Greenland and Antarctica are projected to approximately balance.and Antarctica are projected to approximately balance.

The area of The area of Greenland Greenland

experiencing experiencing summertime melting summertime melting

appears to be appears to be increasing, with increasing, with

some edge regions some edge regions showing very rapid showing very rapid deterioration. With deterioration. With only a little more only a little more global warming, global warming, seasonal melting seasonal melting

could spread across could spread across the plateau.the plateau.

Orange is area experiencing melting Orange is area experiencing melting in 1992; red is additional area in 1992; red is additional area experiencing melting in 2002.experiencing melting in 2002.

US coastal regions will be exposed to rising sea level US coastal regions will be exposed to rising sea level and higher storm surges, especially if hurricanes become and higher storm surges, especially if hurricanes become

more intense and possibly more frequentmore intense and possibly more frequent

purple

Mid-range (50% probability) estimates of effective Mid-range (50% probability) estimates of effective sea level rise by 2100 and by 2200 (i.e., accounting sea level rise by 2100 and by 2200 (i.e., accounting

for changes in coastal elevation)for changes in coastal elevation)

Portland, ME19 43

New York, NY22 48

Seattle, WA19 42

San Francisco, CA15 36

Los Angeles13 32

Charleston, SC25 53

Grand Isle, LA55 112

Miami Beach, FL20 44

Source: U.S. EPA (1995).

Estimates are in inches.

The Gulf and East coasts are particularly The Gulf and East coasts are particularly vulnerable to projected sea level rise vulnerable to projected sea level rise

Coastal islands and wetlands are the “shock absorbers” in the event of hurricanesCoastal islands and wetlands are the “shock absorbers” in the event of hurricanes

Coral reefs are threatened by both ocean warming Coral reefs are threatened by both ocean warming and the change in ocean acidity caused by the rising and the change in ocean acidity caused by the rising

COCO22 concentration concentration

The potential consequences for human health The potential consequences for human health are of several interacting typesare of several interacting types

The nighttime minimum temperature is projected to The nighttime minimum temperature is projected to increase more than the daytime maximumincrease more than the daytime maximum

The potential impacts include higher daytime peak The potential impacts include higher daytime peak electricity demand, longer periods of high electricity electricity demand, longer periods of high electricity

demand, and reduced combustion efficienciesdemand, and reduced combustion efficiencies

(a)ColdLesscoldweatherPreviousclimateNewclimateMorehotweather

AverageIncrease in mean

Hotmorecoldweather

Morerecord hotweather(b)ColdMorerecordcoldweatherPreviousclimateNewclimateMorehotweather

AverageIncrease in variance

HotMorerecord hotweatherLesschangeforcoldweather(c)ColdPreviousclimateNewclimate

Much morehotweatherAverage

Increase in mean and varianceHotMorerecord hotweather

An increase in the An increase in the average of a distribution average of a distribution

can lead to very large can lead to very large changes in the changes in the

probability that cold and probability that cold and hot extremes may be hot extremes may be

experiencedexperienced..

Projections are for Projections are for very large increases very large increases in the number and in the number and

intensity of extreme intensity of extreme heat episodesheat episodes

The average summertime heat index is projected to The average summertime heat index is projected to increase by much more than the temperatureincrease by much more than the temperature

Peak loads are likely to become higher, increasing need for electric reservesPeak loads are likely to become higher, increasing need for electric reserves

0

20

40

60

80

100

Atl

anta

Cin

cin

nat

i

Det

roit

Los

An

gele

s

Min

nea

pol

is

Ph

ilad

elp

hia

San

Fra

nci

sco

Current UKMO GFDL

Dal

las

Ch

icag

o

Kan

sas

Cit

y

Mem

ph

is

New

Yor

k

St.

Lou

is

The probability that 4 days in June will exceed The probability that 4 days in June will exceed a city’s temperature threshold for heat stress a city’s temperature threshold for heat stress

could increase significantlycould increase significantly

Source: Probabilities of Temperature Extremes in the U.S.A, Version 1, NCDC, 1999; Kalkstein, 1989

%

0

150

300

450

600

750

050

100150200250300

0102030405060

050

100150200250300

0

4080

120

160

200

0

250

500

750

1000

1250

1500

Average Annual Excess Weather-Related Mortality for Average Annual Excess Weather-Related Mortality for 1993, 2020 and 2050 Climate1993, 2020 and 2050 Climate

GFDL Climate Change Scenario

Los Angeles

New York City

DallasAtlanta

Sources: Kalkstein and Green (1997); Chestnut et al.(1995)

Phoenix

Note: Includes both summer and winter mortality. Assumes full acclimation to changed climate. Includes population growth.

Chicago

1993

2020

2050

Strengthening public health and community Strengthening public health and community planning is likely to help moderateplanning is likely to help moderate

some types of potential consequencessome types of potential consequences

Community design and standards Community design and standards can limit mosquito habitatcan limit mosquito habitat

Air-conditioning and better Air-conditioning and better housing can limit heat stresshousing can limit heat stress

Some types of changes in climate Some types of changes in climate will affect particular regionswill affect particular regions

Coastal regions will be Coastal regions will be affected by:affected by:

Rising sea levelRising sea level Higher storm surgesHigher storm surges Increased peak Increased peak

hurricane winds and hurricane winds and rainfall ratesrainfall rates

Warmer and saltier Warmer and saltier estuarine watersestuarine waters

More stagnant More stagnant summer conditionssummer conditions

Various regions of the country Various regions of the country will be affected by:will be affected by:

Drier forest conditions that Drier forest conditions that make them more susceptible make them more susceptible to firesto fires

Increasingly difficult Increasingly difficult restoration of pre-disturbance restoration of pre-disturbance ecosystemsecosystems

Altered regions of high windsAltered regions of high winds Shifting landscapes and Shifting landscapes and

potential for biomass fuelspotential for biomass fuels

Examples of Potential Coupling of Transportation Examples of Potential Coupling of Transportation Issues with Climate Variability and ChangeIssues with Climate Variability and Change

Examples of potential location-based issuesExamples of potential location-based issues Great Lakes (changes/variations in lake ice duration and extent, lake Great Lakes (changes/variations in lake ice duration and extent, lake

levels, outflow through the St. Lawrence River, hydropower, etc.) levels, outflow through the St. Lawrence River, hydropower, etc.) Mississippi-Missouri-Ohio River system (changes/variations in Mississippi-Missouri-Ohio River system (changes/variations in

summer/fall- and winter/spring-time river flow, water supplies for cities, summer/fall- and winter/spring-time river flow, water supplies for cities, etc.etc.

Coastal waterways (changes/variations in ocean levels, rates of erosion Coastal waterways (changes/variations in ocean levels, rates of erosion and changes in barrier islands, etc.)and changes in barrier islands, etc.)

Panama Canal (changes/variations in water flow due to El Nino)Panama Canal (changes/variations in water flow due to El Nino) Arctic/Northwest and Northeast Passages (less summertime sea ice; Arctic/Northwest and Northeast Passages (less summertime sea ice;

fragile environment in case of accidents) fragile environment in case of accidents)

Examples of potential event-based issuesExamples of potential event-based issues Hurricanes (frequency, locations, and intensity may change)Hurricanes (frequency, locations, and intensity may change) Warmer temperatures (generally make combustion engines less efficient, Warmer temperatures (generally make combustion engines less efficient,

increase A/C demand, etc.)increase A/C demand, etc.) Ice storms (likely to have poleward shift to regions not used to them)Ice storms (likely to have poleward shift to regions not used to them)

Examples of key regional consequences within the USExamples of key regional consequences within the US

RegionRegion Environmental Environmental ConsequenceConsequence

Economic Economic ConsequenceConsequence

Consequence Consequence to Peopleto People

NortheastNortheast Wetland inundationWetland inundation Reduced Reduced wintertime wintertime recreationrecreation

Rising Rising summertime heat summertime heat

indexindex

SoutheastSoutheast Loss of coastal Loss of coastal ecosystems; ecosystems;

changing forestschanging forests

Increasing Increasing productivity of productivity of

hardwood forestshardwood forests

Increased coastal Increased coastal flooding; longer, flooding; longer, hotter summershotter summers

MidwestMidwest Higher lake and Higher lake and river temperatures river temperatures alter fish speciesalter fish species

Increasing Increasing agricultural agricultural productivityproductivity

Lowered lake and Lowered lake and river levels; hotter river levels; hotter

summerssummers

Great PlainsGreat Plains Warmer winters Warmer winters allow more allow more

invasive speciesinvasive species

Increasing Increasing agricultural agricultural productivityproductivity

Worsened climatic Worsened climatic extremes in extremes in

spring/summerspring/summer

WestWest Altered Altered ecosystems, and ecosystems, and

more firemore fire

Rising snowline Rising snowline intensifies water intensifies water

problemsproblems

Shift toward warm Shift toward warm season recreation; season recreation; greater fire dangergreater fire danger

NorthwestNorthwest Stress to cold/cool Stress to cold/cool water ecosystems water ecosystems

and fishand fish

Earlier winter Earlier winter runoff tightens runoff tightens water supplieswater supplies

Shift to warm Shift to warm season recreation; season recreation;

coastal erosioncoastal erosion

The Arctic is a particularly vulnerable regionThe Arctic is a particularly vulnerable region

Alaska is threatened by bothAlaska is threatened by bothcoastal erosion and permafrost meltingcoastal erosion and permafrost melting

Meltback of sea ice Meltback of sea ice endangers wildlife, impacts endangers wildlife, impacts subsistence harvests, and subsistence harvests, and allows increased coastal allows increased coastal erosionerosion

Melting of permafrost Melting of permafrost undermines structures and undermines structures and weakens forests, with trees later weakens forests, with trees later attacked by pests and made attacked by pests and made more vulnerable to firesmore vulnerable to fires

Trend in the Bering SeaTrend in the Bering Sea

As the sea ice As the sea ice melts back, melts back, there will be there will be increased increased

opportunity for opportunity for seasonal seasonal shipping shipping

through the through the Arctic Ocean, Arctic Ocean, but doing it but doing it

safely is likely safely is likely to require great to require great

care and care and preparation.preparation.

While it is important to look closely at regional While it is important to look closely at regional consequences, the closer the examination of potential consequences, the closer the examination of potential

regional and sectoral impacts in the US, the more regional and sectoral impacts in the US, the more couplings appear to worldwide impactscouplings appear to worldwide impacts

Economic and Market Couplings:Economic and Market Couplings: imported products, imported products, export markets, investments, international well-beingexport markets, investments, international well-being

Shared Resources and Environments:Shared Resources and Environments: water water resources, hydropower, fisheries, migrating species, resources, hydropower, fisheries, migrating species, ocean resources, biodiversityocean resources, biodiversity

Human Health:Human Health: disease prevalence and vectors, health disease prevalence and vectors, health of visitors, disease level of countries where visit and do of visitors, disease level of countries where visit and do businessbusiness

International Security and Well-Being:International Security and Well-Being: pressures for pressures for immigration, environmental refugees, levels of immigration, environmental refugees, levels of international conflict and requirements for peace-international conflict and requirements for peace-keeping, concern for relatives and peopleskeeping, concern for relatives and peoples

If done in the context of the multiple stresses facing If done in the context of the multiple stresses facing society, preparing for climate change can improve society, preparing for climate change can improve

resilience and reduce potential adverse impactsresilience and reduce potential adverse impacts

Addressing the Addressing the potential impacts potential impacts of climate change of climate change in the context of in the context of other stresses other stresses

can reduce can reduce overall overall

vulnerability and vulnerability and limit exposure to limit exposure to multiple stressesmultiple stresses

Copies of the US National Assessment reports are Copies of the US National Assessment reports are available from Cambridge University Press and at available from Cambridge University Press and at http://www.usgcrp.gov/usgcrp/nacc/default.htmhttp://www.usgcrp.gov/usgcrp/nacc/default.htm