Understanding the Science of Climate Change

Talking Points – Impacts to the Gulf Coast

Natural Resource Report NPS/NRPC/NRR—2010/210

National Park Service

U.S. Department of the Interior

Natural Resource Program Center
ON THE COVER

Great Egret in front of cypress trees, Everglades National Park; NPS photo.
Understanding the Science of Climate Change

Talking Points – Impacts to the Gulf Coast

Natural Resource Report NPS/NRPC/NRR—2010/210

Rachel Loehman

Rocky Mountain Research Station

Fire Sciences Laboratory

5775 West US Hwy 10

Missoula, MT 59808-9361

Greer Anderson

National Oceanic and Atmospheric Association

National Marine Fisheries Service

1829 South Oregon Street

Yreka, CA 96097

With special thanks to the US Forest Service’s Rocky Mountain Research Station and contributions from (in alphabetical order): 

Mike Aymond, Rebecca Beavers, Virginia Burkett, Maria Caffrey, Alice Clarke, Mark Ford, Robert Ford, Louise Hose, Caroline 

Jezierski, Nina Kelson, Fritz Klasner, and Leigh Welling. Layout and design: Sara Melena, Angie Richman, Caitlin Shenk, and 

Katherine Stehli.

June 2010

U.S. Department of the Interior

National Park Service

Natural Resource Program Center

Fort Collins, Colorado
The Natural Resource Publication series addresses natural resource topics of interest and applicability to a broad 

readership in the National Park Service and to others in the management of natural resources, including the scientific 

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Views, statements, findings, conclusions, recommendations and data in this report are solely those of the author(s) 

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National Park Service.

This report is available from the Natural Resource Publications Management website:

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Please cite this publication as:

Loehman, R., and G. Anderson. 2010. Understanding the science of climate change: Talking points - impacts to the 

Gulf Coast. Natural Resource Report NPS/NRPC/NRR—2010/210. National Park Service, Fort Collins, Colorado.

NPS 999/100222, June 2010
Contents 

Introduction ............................................................................................................................................................1

Climate Change Impacts to the Gulf Coast.............................................................................................................. 2

Summary.........................................................................................................................................................................................2

List of Parks and Refuges .............................................................................................................................................................3

Sectors:

 Temperature............................................................................................................................................................................4

 The Water Cycle .....................................................................................................................................................................5

 Vegetation................................................................................................................................................................................7

 Wildlife ....................................................................................................................................................................................8

 Disturbance............................................................................................................................................................................ 11

 Visitor Experience................................................................................................................................................................ 14

No Regrets Actions .................................................................................................................................................15

Global Climate Change...........................................................................................................................................18

Sectors:

 Temperature and greenhouse gases................................................................................................................................... 18

 Water, Snow, and Ice.............................................................................................................................................................21

 Vegetation and Wildlife .......................................................................................................................................................23

 Disturbance...........................................................................................................................................................................26

References ........................................................................................................................................................... 27
National Park Service 1

Purpose

Climate change presents significant risks to our nation’s natural 

and cultural resources. Although climate change was once believed to be a future problem, there is now unequivocal scientific evidence that our planet’s climate system is warming (IPCC 

2007a). While many people understand that human emissions 

of greenhouse gases have contributed to recent observed climate changes, fewer are aware of the specific impacts these 

changes will bring. This document is part of a series of bioregional summaries that provide key scientific findings about 

climate change and impacts to protected areas. The information 

is intended to provide a basic understanding of the science of 

climate change, known and expected impacts to resources and 

visitor experience, and actions that can be taken to mitigate and 

adapt to change. The statements may be used to communicate 

with managers, frame interpretive programs, and answer general questions to the public and the media. They also provide 

helpful information to consider in developing sustainability 

strategies and long-term management plans. 

Audience

The Talking Points documents are primarily intended to provide 

park and refuge area managers and staff with accessible, up-todate information about climate change and climate change impacts to the resources they protect. 

Organizational Structure

Following the Introduction are three major sections of the document: a Regional Section that provides information on changes 

to the Gulf Coast, a section outlining No Regrets Actions that 

can be taken now to mitigate and adapt to climate changes, and 

a general section on Global Climate Change. The Regional Section is organized around six types of changes or impacts, while 

the Global Section is arranged around four topics.

Regional Section

•	 Temperature 

•	 The Water Cycle (including snow, ice, lake levels, sea levels 

and sea level rise, and ocean acidification)

•	 Vegetation (plant cover, species range shifts, and phenology)

•	 Wildlife (aquatic, marine, and terrestrial animals, range shifts, 

invasive species, migration, and phenology)

•	 Disturbance (including range shifts, plant cover, plant pests 

and pathogens, fire, flooding, and erosion)

•	 Visitor Experience

Global Section

•	 Temperature and Greenhouse Gases

•	 Water, Snow, and Ice

•	 Vegetation and Wildlife

•	 Disturbance

Information contained in this document is derived from the 

published results of a range of scientific research including 

historical data, empirical (observed) evidence, and model projections (which may use observed or theoretical relationships). 

While all of the statements are informed by science, not all statements carry the same level of confidence or scientific certainty. 

Identifying uncertainty is an important part of science but can 

be a major source of confusion for decision makers and the 

public. In the strictest sense, all scientific results carry some 

level of uncertainty because the scientific method can only 

“prove” a hypothesis to be false. However, in a practical world, 

society routinely elects to make choices and select options for 

actions that carry an array of uncertain outcomes. 

The statements in this document have been organized to help 

managers and their staffs differentiate among current levels 

of uncertainty in climate change science. In doing so, the 

document aims to be consistent with the language and approach 

taken in the Fourth Assessment on Climate Change reports by 

the Intergovernmental Panel on Climate Change. However, this 

document discriminates among only three different levels of 

uncertainty and does not attempt to ascribe a specific probability to any particular level. These are qualitative rather than 

quantitative categories, ranked from greatest to least certainty, 

and are based on the following: 

•	 “What scientists know” are statements based on measurable 

data and historical records. These are statements for which 

scientists generally have high confidence and agreement 

because they are based on actual measurements and observations. Events under this category have already happened or 

are very likely to happen in the future.

•	 “What scientists think is likely” represents statements beyond 

simple facts; these are derived from some level of reasoning 

or critical thinking. They result from projected trends, well 

tested climate or ecosystem models, or empirically observed 

relationships (statistical comparisons using existing data). 

•	 “What scientists think is possible” are statements that use a 

higher degree of inference or deduction than the previous 

categories. These are based on research about processes that 

are less well understood, often involving dynamic interactions among climate and complex ecosystems. However, 

in some cases, these statements represent potential future 

conditions of greatest concern, because they may carry the 

greatest risk to protected area resources. 

I. Introduction 
2 Climate Change Talking Points NPS/FWS—2010

II. Climate Change Impacts to the Gulf Coast

The Gulf Coast bioregion 

that is discussed in this section is shown in the map to 

the right. A list of parks and 

refuges for which this analysis is most useful is included 

on the next page. To help the 

reader navigate this section, 

each category is designated 

by color-coded tabs on the 

outside edge of the document.

Summary

Predicted climate changes in the Gulf Coast bioregion include increased air and sea surface temperatures, altered fire regimes 

and rainfall patterns, increased frequency of extreme weather events, rising sea levels, increased hurricane intensity, and potential destruction of coastal wetlands and the species that reside within them. Prolonged drought conditions, storm surges, 

and rising sea levels may reduce availability of freshwater resources, alter river and wetland hydrology, increase erosion, and 

induce changes in the distribution of coastal plant and animals species. For example, intense hurricane activity may decrease 

survival of endangered Florida manatees, and sea level rise may allow mangrove habitats to expand at the expense of upland 

habitat areas. Coastal development, dredging, reservoir construction, diversion of surface water, and groundwater pumping 

may exacerbate the effects of climate changes on biotic communities.

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
National Park Service 3

U.S. National Park Service Units

•	 Big Cypress NPR

•	 Big Thicket NPR

•	 De Soto NME

•	 Dry Tortugas NP

•	 Everglades NP

•	 Gulf Islands NS

•	Jean Lafitte NHP&NPR

•	 New Orleans Jazz NHP

•	 Padre Island NS

•	 Palo Alto Battlefield NHP

U.S. Fish & Wildlife Service Units

•	 Anahuac NWR

•	 Aransas NWR

•	 Bayou Sauvage NWR

•	 Bayou Teche NWR

•	 Big Boggy NWR

•	 Big Branch Marsh NWR

•	 Bogue Chitto NWR

•	 Bon Secour NWR

•	 Brazoria NWR

•	 Breton NWR

•	 Caloosahatchee NWR

•	 Cameron Prairie NWR

•	 Cedar Keys NWR

•	 Chassahowitzka NWR

•	 Crystal River NWR

•	 Delta NWR

•	 Egmont Key NWR

•	 Florida Panther NWR

•	 Grand Bay NWR

•	 Great White Heron NWR

•	Island Bay NWR

•	J.N. “Ding” Darling NWR

•	 Key West NWR

•	 Lacassine NWR

•	 Laguna Atascosa NWR

•	 Lake Wales NWR

•	 Lower Refuge Grande Valley NWR

•	 Lower Suwannee NWR

•	 Mandalay NWR

•	 Matlacha Pass NWR

•	 McFaddin NWR

•	 Mississippi Sandhill Crane NWR

•	 Moody NWR

•	 National Key Deer Refuge

•	 Passage Key NWR

•	 Pine Island NWR

•	 Pinellas NWR

•	 Sabine NWR

•	 San Bernard NWR

•	 Santa Ana NWR

•	 Shell Keys NWR

•	 St. Marks NWR 

•	 St. Vincent NWR

•	Ten Thousand Islands NWR

•	Texas Point NWR

•	Trinity River NWR

NHP National Historical Park

NME National Memorial

NP National Park

NPR National Preserve 

NS National Seashore

NWR National Wildlife Refuge

List of Parks and Refuges

Acronym Unit Type

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
4 Climate Change Talking Points NPS/FWS—2010

The Gulf Coast is prone to hurricanes as thunderstorm complexes approaching from 

the east develop into low pressure systems that can quickly intensify. Hurricane Katrina approaches the Gulf Coast (Top); NASA photo. Katrina flooded Bayou Sauvage 

NWR with saltwater (Bottom). Most of the saltwater was pumped out through the 

levee system that protects the refuge. USFWS photo.

A. TEMPERATURE

What scientists know....

•	 Southeastern temperature trends have 

varied over the past 100 years, with a 

warm period during the 1920s-1940s followed by a cooling trend through the 

1960s. Since the 1970s, temperatures have 

been increasing, with much of the warming occurring in winter months (Burkett et 

al. 2001, Ning et al. 2003).

•	 Regional temperature changes are several 

times larger than the global average, there 

has been a decrease in the daily temperature range, and daily minimum temperatures are increasing at twice the rate of 

maximum temperatures. Minimum temperatures have increased by 0.83oC since 

1950 (Ning et al. 2003).

•	 Recent studies show that the mean temperature of the oceans between depths of 

0 and 300 meters increased by 0.31oC between 1948 and 1998 and that this warming signal is observable to depths of 3000 

meters (Levitus et al. 2000).

•	 Tropical oceans have warmed about 0.6oC 

over the instrumental record, including 

about 0.5oC since 1970. Tropical cyclones, 

which form only over warm oceans from 

which they gain energy, (mainly from 

the latent heat of condensation) have increased in intensity since the 1970s (Anthes et al. 2006).

•	 In confined coastal bays and estuaries, especially along the southern coast, water 

temperature will be directly influenced by 

changes in air temperature. Consequently, 

the temperatures of these shallow waters 

are expected to closely track the projections for changes in regional air temperatures, and will be especially vulnerable to 

increasing warming (Twilley et al. 2001).

What scientists think is likely....

•	 Some models predict a twofold increase 

in the number of days that fall above the 

present-day high-temperature thresholds, 

resulting in increased mean seasonal temperatures and shifts in daily temperatures 

(Hayhoe et al. 2007).

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
National Park Service 5

South Carolina, Tennessee, Alabama, and 

parts of Louisiana, with mixed changes 

across most of the remaining area. The 

percentage of the Southeast landscape 

experiencing severe wetness (periods in 

which the PDSI averages more than +3) increased approximately 10% between 1910 

and 1997 (Burkett et al. 2001).

•	 Much of the increase in precipitation observed in the region over the past 100 years 

was associated with intense rainfall events 

(rainfall amounts greater than 5 cm per 

day). Moderate rainfall events, generally 

beneficial to agriculture and water supply, 

contributed to only a small percentage of 

the increased precipitation (Burkett et al. 

2001).

•	 There is evidence for an enhanced hydrologic cycle in the Gulf Coast region, 

including a decreased daily temperature 

range, more atmospheric water vapor, increased precipitation, more intense precipitation events, and stronger extratropical storms (Ning et al. 2003).

•	 Aquatic ecosystems are especially vulnerable to extreme climatic changes such as 

drought because these disturbances alter 

the flow regime, water chemistry and, ultimately, the biotic community. During 

extreme drought streams typically form a 

series of disconnected pools and surface 

flow ceases, a response that can potentially 

reset the aquatic community (Griswold et 

al. 2008).

•	 Accumulation of nutrients and toxic waste, 

coupled with increased temperature and 

lowered dissolved oxygen, stress aquatic 

species. Survival after drought depends on 

specific life-history traits including resistance to desiccation and the ability to colonize habitats rapidly through drift, aerial 

migration and ⁄or oviposition (Griswold 

et al. 2008). 

What scientists think is likely....

•	 A recent study predicted a net increase 

during the late 21st century in the number 

of days in which severe thunderstorm environmental conditions occur. The largest 

increases in storm activity are during the 

summer season, in proximity to the Gulf 

The Davis Bayou salt marsh at 

Gulf Islands National Park; NPS 

photo.

•	 Increasing seasonal and annual average 

temperatures will increase the July heat index, decrease winter cold spells, and cause 

a northward shift in the frost line (Twilley 

et al. 2001).

What scientists think is possible....

•	 Average air temperatures in Florida will 

continue to increase in the coming decades, with average low temperatures in 

winter increasing by 1.7-5.6oC and average 

high temperatures in summer increasing 

by 1.7-3.9oC by 2100 (Harwell et al. 2001).

•	 The heat index (measure of human comfort based on temperature and humidity) is projected to rise by as much as 4 to 

8oC across the entire southeastern U.S. by 

2100. (Twilley et al. 2001). 

•	 An ensemble of regionally downscaled 

general circulation models indicate that 

the average annual temperature in the 

Gulf Coast region is likely to increase by 

1-2°C by 2050. Extreme high temperatures 

(above 37.8°C [100°F]) are also expected 

to increase in the region (Keim et al. 2008).

B. THE WATER CYCLE

What scientists know....

•	 Annual rainfall trends show very strong 

increases of 20-30% or more over the past 

100 years across Mississippi, Arkansas, 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
6 Climate Change Talking Points NPS/FWS—2010

of Mexico and Atlantic coastal regions 

(Trapp et al. 2007). 

•	 Climate changes are predicted to increase 

water supply stress in Florida by the year 

2020 by as much as 34%, depending on 

precipitation patterns projected by climate models. Population increase will 

likely amplify climate-induced water supply stress across the region (Sun et al. 

2008).

•	 Large river system (e.g., Mississippi) discharges are expected to increase. Water 

flows will be determined by rainfall trends 

in watersheds far upstream of the Gulf 

Coast, as well as by massive human-engineered flood control structures. Smaller, 

local river systems are expected to experience decreased discharge due to increased 

evaporation and droughts (Twilley et al. 

2001).

What scientists think is possible....

•	 Regional climate projections for the Gulf 

Coast for the late 20th century include 

increases in both extreme precipitation 

events and in the frequency of dry days, 

suggesting that climate change could result in simultaneous enhancement of both 

wet and dry conditions (Diffenbaugh et 

al. 2005).

•	 More frequent or longer lasting droughts 

and reduced freshwater inflows may increase the incidence of extreme salt concentrations in coastal ecosystems, resulting in a decline of valuable habitats such as 

the mangroves, baldcypress, water tupelo, 

and seagrasses in Florida Bay and South 

Texas lagoons (Krauss et al. 2000; Twilley 

et al. 2001).

•	 Estuaries in the southeast/Gulf of Mexico region tend to have lower freshwater 

turnover times (higher flushing rates) than 

other U.S. estuaries, and climate change 

may increase these flushing rates. Alternatively, introduced chaotic and episodic 

climate changes (e.g. droughts and floods) 

may result in loss of wetlands and decreased flushing rates, as open water habitat increases and estuaries deepen. A lower 

flushing rate could lead to more harmful 

algal blooms (because of a longer residence time) or higher salinities (because 

of increased seawater mixing). It is not 

known whether these factors will compensate for each other so that equilibrium 

is maintained (Ning et al. 2003).

•	 Permanent reductions of freshwater flows 

in rivers from both human activities and 

climate change may substantially reduce 

biological productivity in Mobile Bay, 

Apalachicola Bay, Tampa Bay, and the lagoons of Texas (Twilley et al. 2001).

•	 The oxygen-poor (hypoxic) waters in the 

Gulf of Mexico off of Louisiana now extend across as many as 20,480 square kilometers, depending on the amount of 

nitrate-laden fresh water discharged by 

the Mississippi River. A 20% increase in 

discharge, as predicted by some climate 

models, could increase the risk of hypoxia 

and expand the oxygen-poor “dead zone” 

(Twilley et al. 2001). 

C. VEGETATION

What scientists know....

•	 In wild plants and animals, climate-induced extinctions, distributional and phenological changes, and species range shifts 

are being documented at a growing rate 

(Parmesan 2006). 

•	 Changes in climate significantly affect vegetation phenology, morphology, distribution, growth, and reproduction. Most 

observed changes are linked with temperThe J.N. “Ding” Darling National 

Wildlife Refuge is one of the 

largest mangrove ecosystems in 

the United States; USFWS photo.

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
National Park Service 7

tidal flooding has resulted in decreased 

species richness in coastal forest stands 

(Desantis et al. 2007).

•	 Mangrove systems and other tidal wetlands are threatened by climate change 

effects, especially sea level rise. Other 

climate change components that threaten these ecosystems include high water 

events, storminess, temperature and precipitation, and ocean circulation patterns. 

Loss of mangroves will result in reduced 

coastal water quality, reduced biodiversity, 

loss of fish and crustacean nursery habitat, 

and loss of ecosystem services for human 

populations (Gilman et al. 2008).

•	 Experimental long-term exposure to elevated atmospheric CO2 caused an increase in above ground shoot biomass of 

a Florida scrub-oak ecosystem, in particular of Myrtle oak, the dominant species. Growth stimulation was sustained 

throughout the experiment, although 

there was significant variability between 

years resulting from variations in total annual rainfall. The absolute stimulation of 

above ground biomass generally declined 

over time, reflecting increasing environmental limitations to long-term growth 

response (Seiler et al. 2008).

What scientists think is likely....

•	 Land-use change models for Waccasassa 

Bay State Preserve Park in Florida predict 

a 17.5% reduction in coastal forest due 

to conversion to salt marsh. The models estimate that 50% of the forests that 

were present in the Preserve in 1973 will 

disappear between 2108 and 2228, and 

all forests will be gone by 2273–2393. In 

addition, faunal and floral migration into 

upland areas on private land adjacent to 

the Preserve is likely to be impeded by 

development in the region (Castaneda and 

Putz 2007).

•	 Although salt marshes may be able to survive rates of sea level rise as high as 50 centimeters, an estimate that is lower than the 

expected rise in sea level for much of the 

coastal U.S. over the next 100 years, local 

subsidence or hydrologic changes could 

increase the rate of relative sea level at 

individual marshes, potentially exceeding 

Mangrove maze; USFWS photo.

ature change either directly or indirectly 

(i.e. altered moisture availability) (Root et 

al. 2003).

•	 Harmful algal blooms (red tides) have 

become more extensive in recent years. 

Warmer coastal waters, especially in combination with nutrient pollution, can also 

increase the intensity, duration, and extent 

of blooms of harmful algae and cyanobacteria. Red tides, considered a natural 

phenomenon and not dependent on pollution, are already a chronic problem in 

many areas and thrive in warmer waters 

(Harvell et al. 1999). 

•	 Sea level rise and drought interactions 

have accelerated forest decline on the Gulf 

Coast of Florida, including dramatically 

increased mortality and increased water 

stress in Southern red cedar and cabbage 

palm. In addition, increased frequency of 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
8 Climate Change Talking Points NPS/FWS—2010

the ability of some salt marshes to adapt 

(Boesch et al. 2000). 

•	 In general, coastal wetlands will survive if 

the increase in sediment surface elevation 

equals the rate of relative sea level rise, 

or if they are able to migrate inland or to 

areas of higher elevation; however, if soil 

accumulation does not keep pace with sea 

level rise, or if bluffs, coastal development, 

or shoreline protective structures (dikes, 

sea walls, jetties) block wetland migration, 

wetlands may be excessively inundated, 

reduced in area, and replaced by open water (Scavia et al. 2002, Gilman et al. 2008).

What scientists think is possible....

•	 Warmer winter temperatures projected for 

the southeastern U.S. may make northward expansion of the range of mangroves 

possible (Boesch et al. 2000).

•	 Heavy storm surges that completely saturate the vadose (unsaturated) zone at 30 

parts per thousand (ppt) for 1 day could 

lead to a regime shift in which mangroves 

dominate areas previously dominated 

by hardwood hammocks. Lighter storm 

surges that saturated the vadose zone at 

less than 7 ppt, the tolerance level of hardwood hammocks, did not cause vegetation shifts in model simulations. Rate of 

mangrove domination is determined by 

the residence time of high salinity in the 

vadose zone, dependent on the thickness 

of the vadose zone and precipitation (Teh 

et al. 2008).

•	 Elevated atmospheric CO2 concentrations may mitigate some of the effects of 

droughts on Florida scrub-oak ecosystems 

through increased photosynthetic capacity under dry-air conditions (Li et al. 2007).

•	 Modeled effects of sea level rise on a forest-open water transition zone in Terrebone Basin, Louisiana predict dramatic 

loss of marsh and increasing interface between open water and relatively resistant 

forest. Results suggest that coastal stability 

structures may be initially effective in facilitating marsh reestablishment, but that 

additional management efforts are necessary to sustain marshlands (Shirley and 

Battaglia 2008).

D. WILDLIFE

What scientists know....

•	 Many tropical species are moving into the 

United States as climates warm in southern 

regions. For example, Florida has five new 

species of tropical dragonfly, and many 

tropical butterflies that are normally confined to Mexico are starting to breed as 

far north as Austin, Texas. Although such 

species migrations may increase overall 

species diversity, there are also potentially 

negative implications including competition with native species and introduction 

of new diseases (NRC 2008).

•	 Hurricanes can affect breeding activity of 

colonially nesting wading birds through 

destruction of nesting habitat by wind 

and storm surges, intrusion of saltwater 

into freshwater wetlands, and reduced resource availability (e.g. freshwater invertebrates) in foraging habitats (Leberg et 

al. 2007). 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience

A healthy coral reef environment (Top); Bleached coral reef 

(Bottom); NASA photos. 
National Park Service 9

•	 In regions of the low-lying southeastern 

U.S. coast that are undergoing subsidence, 

a projected relative sea level rise of 0.6 to 

1.2 meters over the next 100 years will reconfigure shorelines and fragment barrier 

islands. Animal species that depend on 

coastal marshes and mangroves, including fish species, migratory waterfowl, and 

wading birds will be adversely affected 

(NRC 2008).

•	 Loss of late-succession dune plants, projected to occur with sea level rise and 

resulting changes in coastal habitat, will 

result in loss of dependent animal species 

such as the endangered Kemp’s ridley sea 

turtle and the endangered Choctawatchee 

beach mouse (Feagin et al. 2005).

•	 Reefs off the Florida Keys are to varying 

degrees already in degraded condition due 

to the effects of overfishing, land-based 

pollution by nutrients and sediments, and 

coastal development (Pandolfi et al. 2005).

•	 Episodes of coral reef bleaching and mortality are due primarily to climate-induced 

ocean warming. By far the most significant 

cause of coral bleaching in the past 25 

years has been sea surface temperatures 

that exceed the normal summer maxima 

by 1 or 2oC for at least 4 weeks. The 

most severe events typically accompany 

coupled ocean–atmosphere phenomena, 

such as the El Niño-Southern Oscillation 

(ENSO), which result in sustained regional 

elevations of ocean temperature (Baker et 

al. 2008, Wilkinson and Souter 2008). 

•	 Rising atmospheric CO2 concentrations 

will result in slower growth of corals that 

are trying to recover from bleaching and 

other disturbances. Such interactions of 

multiple disturbance agents will continue 

to challenge the survival of coral reefs 

(Wilkinson and Souter 2008). 

•	 Bleaching episodes have resulted in catastrophic loss of coral cover in some locations and have changed coral community 

structure in many others, with a potentially critical influence on the maintenance of 

biodiversity in the marine tropics. Bleaching also sets the stage for other declines in 

reef health such as increased coral diseases, the breakdown of reef framework by 

bioeroders, and the loss of critical habitat 

for associated reef fishes and other biota 

(Baker et al. 2008).

•	 Staghorn and elkhorn corals, important 

cold-sensitive reef building species historically restricted to warm waters in Biscayne 

Bay, are expanding their ranges northward 

along the Florida peninsula and into the 

northern Gulf of Mexico, coincident with 

increasing ocean temperatures (Precht 

and Aronson 2004). These corals were recently listed as Threatened on the Federal 

list of endangered and threatened species.

•	 Adult survival for the endangered Florida 

manatee is high (~97%) in years with no 

or low intensity storms in the northern 

Gulf of Mexico, and decreases (~81-93%) 

in years with intense hurricane activity. 

Decreased survival may be due to direct 

mortality, indirect mortality, and/or emigration from the region as a consequence 

of storms (Langtimm and Beck 2003). 

•	 Storm surges significantly decrease reproductive output in sea turtles by lowering 

the number of nests that hatch and the 

number of hatchlings that emerge, with 

species-specific variations in severity: 

leatherback turtles, early nesters, are least 

affected by storms because most offspring 

hatch before the arrival of the tropical 

cyclone season; loggerhead turtles, intermediate nesters, suffer losses of some 

nests; and green turtles, with a late nesting 

season that overlaps the tropical cyclone 

season, are most severely affected (Pike 

and Stiner 2007).

Florida panther at Everglades 

National Park (Top); NPS photo. 

West Indian Manatee (Bottom); 

USFWS photo. 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
10 Climate Change Talking Points NPS/FWS—2010

•	 There is particular concern for individual 

animal species that are already stressed 

and have greatly reduced ranges, such as 

manatees, Cape Sable sparrow and Florida 

panther. Additional stress resulting from 

higher temperatures could put those populations at increased risk for extirpation or 

extinction (Harris and Cropper 1992). 

•	 The construction of sea-wall defenses 

and other protective measures for coastal 

habitats against rising sea levels could potentially negatively impact coastal marine 

species; for example, in Florida between 

1974 and 1996 approximately 4% of manatee deaths were caused by crushing or 

drowning in flood gates and canal locks 

(Reynolds and Powell 2002).

•	 Simulated landscape-level changes (increasing water levels or decreasing habitat 

availability) were associated with dramatic population declines and increases in 

extinction risk for the endangered Cape 

Sable seaside sparrow of the South Florida 

Everglades. The sparrows are dependent 

on the plant community structure of the 

Everglades’ marl and mixed-marl prairies 

and the timing of seasonal floods within 

these prairies, which may be altered due to 

a combination of shrub and tree invasions, 

sea level rise, and hydrologic changes (Elderd and Nott 2008).

•	 A comparison of median capture dates for 

15 bird species between the Gulf Coast 

of Louisiana and stations approximately 

2,500 km to the north suggests that Nearctic-Neotropical migratory birds may be 

able to adjust their rate of migration to 

match annual variations in ambient temperatures or associated factors such as 

leaf emergence and resource availability 

(Marra et al. 2005).

•	 In GIS-based simulations, potential habitat for the endangered Lower Keys marsh 

rabbit decreased across its geographic distribution with modeled sea level rise of 0.3 

to 0.9 meters. Simulated upslope migration of vegetation, protection of natural 

areas, and abandonment of developed 

areas slightly offset habitat loss resulting 

from sea level rise (LaFever et al. 2007).

What scientists think is likely....

•	 Higher air temperatures may result in 

a shift in sex ratio of sea turtles, with 

more female offspring produced at higher 

temperatures (Booth 2006, Hawkes et al. 

2007). Populations of turtles in southern 

parts of the United States are currently 

highly female biased and are likely to become ultra-biased with as little as 1oC of 

warming, and experience extreme levels of 

mortality if warming exceeds 3oC. For example, at modeled temperature increases 

of 7.5oC, loggerhead turtles show 100% 

female hatchling production and lethally 

high incubation (Hawkes et al. 2007).

•	 A single catastrophic hurricane, series of 

smaller hurricanes, or increased hurricane 

activity associated with climatic change 

could increase the probability of extinction for Florida manatees (Langtimm and 

Beck 2003).

•	 Important Florida gamefish species vulnerable to sea level rise include bonefish, flounder, gag grouper, gray snapper, 

permit, pompano, redfish, snook, spotted 

seatrout, and tarpon. Rising sea levels will 

negatively impact habitat areas for these 

fishes, and reduce habitat for important 

prey species such as shrimp, crabs, and 

smaller fish (Click and Clough 2006).

What scientists think is possible....

•	 Specific changes in mammal populations 

and movements may be hard to predict 

due to the complexity of interactions with 

their environment and the rapid pace of 

change that is expected. However, U.S. 

national parks could lose on average 8.3% 

and up to 20% of current mammalian species diversity. The greatest loss of species 

is expected to occur in the most southerly 

national parks where ecosystem types will 

become more limited (Burns et al. 2003).

•	 Warming temperatures may drive complex shifts in ocean circulation, nutrient 

supplies, plankton production, and other 

factors that shape marine ecosystems, in 

ways that are difficult to predict (Frumhoff 

et al. 2007).

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience

A reddish egret (Top), dowitchers (Center), and a nesting 

Kemp’s Ridley sea turtle (Bottom) at Padre Island National 

Seashore; NPS photos. 
National Park Service 11

E. DISTURBANCE

What scientists know....

•	 In Louisiana alone more than one third of 

the deltaic plain that existed in the beginning of the 20th century has been lost to 

a combination of sea level rise and local 

subsidence. In the Gulf of Mexico and the 

South Atlantic, the ecological processes 

that lead to accretion of wetlands and continued productivity have not been able to 

keep pace with the physical processes that 

lead to relative rising sea level (Burkett et 

al. 2005).

•	 Most of the U.S. Gulf of Mexico coastline 

has experienced rates of relative sea level 

increase that are significantly greater than 

those observed on the U.S. Pacific coast or 

farther north on the Atlantic Coast (Scavia 

et al. 2002).

•	 Rates of relative sea level rise along the 

Gulf Coast are higher than global average 

rates due to local subsidence (sinking). 

Relative sea level rise rates range from 0.20 

cm per year along some parts of the Texas 

coast to around 1 cm per year in the Mississippi River delta plain. The average rate 

of regional sea level rise began to increase 

significantly around 1930 (Twilley et al. 

2001).

•	 A Coastal Vulnerability Index, developed 

by the USGS, identifies areas that are likely 

to be most affected by future sea level rise. 

Much of the Gulf Coast region along the 

Louisiana-Texas coast has been assessed 

as highly vulnerable. The highest-vulnerability areas are typically lower-lying beach 

and marsh areas with less than a meter of 

tidal range ; their susceptibility is primarily a function of geomorphology, coastal 

slope and rate of relative sea level rise 

(Thieler and Hammar-Klose 2000). 

•	 Coastal vulnerability assessments for Dry 

Tortugas National Park, Gulf Islands National Seashore and Padre Island National 

Seashore show significant areas of shoreline classified as having high vulnerability 

to sea level rise (Pendleton et al. 2004a, 

Pendleton et al. 2004c, Pendleton et al. 

2005).

•	 Storms, hurricanes, and typhoons produce high winds which in turn generate 

large waves and currents. The storms may 

also produce storm surges that temporarily raise water levels far above normal. 

These surges are a primary cause of beach 

erosion in the U.S., and usually move nearshore and beach sand seaward where it 

may be stored in offshore bars or lost from 

the active system when deposited in very 

deep water (Boesch et al. 2000). 

•	 Hurricanes, typhoons, and their related 

impacts affect societies directly through 

acute damage on human settlements, often with major loss of life, and indirectly 

through their impact on coastal ecosystems such as coral reefs, seagrass beds, and 

mangroves that support local societies and 

economies (Adger et al. 2005). 

•	 Hurricanes are a significant factor in reducing short-term carbon storage in U.S. 

forests. Single storms can convert the 

equivalent of 10% of the total annual carbon sequestrated by U.S. forests into dead 

and downed biomass, and because forests 

require at least 15 years to recover from 

severe storms, a large amount of forest 

carbon is indirectly lost through reduced 

carbon sequestration capacity (McNulty 

2002).

•	 The La Niña phase of the El Niño Southern Oscillation climatic cycle is associated 

with decreased dry-season rainfall, lowered surface water levels, increased lightning strikes, more fires, and large areas 

burned in Everglades National Park. In 

contrast, the El Niño phase is associated 

with increased dry-season rainfall, raised 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience

Subsidence along the Texas 

coast decreases the land area 

available for certain water birds 

to nest; USFWS photo.
12 Climate Change Talking Points NPS/FWS—2010

surface water levels, decreased lightning 

strikes, fewer fires, and smaller areas 

burned (Ebi et al. 2007).

•	 The spread of invasive species has been 

on the rise over the past 50 years due to 

a number of factors including climatic 

conditions. For example, the Chinese tallow tree has been invading coastal prairies 

from the Carolinas to south Texas, where 

periods of decreased flooding have allowed for its wide-spread establishment. 

The northward spread of tallow is limited 

only by low winter temperatures (Twilley 

et al. 2001, Burkett et al. 2005).

•	 Field studies at salt marshes along the 

coasts of Georgia and Louisiana show that 

drought-induced stress and grazing snails 

act synergistically to cause plant death and 

conversion of marshes to exposed mudflats. More frequent droughts, resulting 

from increasing climatic extremes, may increase system susceptibility to intense and 

prolonged vegetation loss and large-scale 

collapse (Silliman et al. 2005).

•	 Estimates of Hurricane Katrina’s effect on 

Gulf Coast forests indicate mortality and 

severe structural damage to 320 million 

large-diameter trees, and a total biomass 

loss of 105 Tg C, an amount equivalent to 

50 to 140% of the net annual U.S. carbon 

sink in forest trees (Chambers et al. 2007). 

What scientists think is likely....

•	 Even if greenhouse gas emissions are stabilized, the rate of sea level rise will likely 

continue to increase beyond 2100 because 

of the time it takes for oceans and ice 

sheets to approach equilibrium conditions 

with the atmosphere (Scavia et al. 2002).

•	 Relative sea level is likely to rise between 

0.3 to 1.8 meters by the end of the 21st 

century, depending upon model assumption and geographic location. The highest 

rate of relative sea level rise will very likely 

be in the central and western parts of the 

Gulf Coast (Louisiana and East Texas) 

where subsidence rates are highest (Keim 

et al. 2008).

•	 Rising relative sea level will increase vulnerability to storm surges and flooding. 

Depending on the trajectory and scale of 

individual storms, facilities at 9 meters 

above sea level or below could be subject 

to direct storm surge impacts (Keim et al. 

2008).

•	 A rise in sea level or changes in storms or 

storm surges may result in the increased 

erosion of shores and associated habitat, 

altered tidal ranges in rivers and bays, increased salinity of estuaries and freshwater 

aquifers, changes in patterns of chemical and microbiological contamination in 

coastal areas, and a change in sediment 

and nutrient transport (Boesch et al. 2000).

Coastal vulnerability in the U.S. 

is most pronounced along the 

gulf and Atlantic coasts; USGS 

image. 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
National Park Service 13

•	 Secondary impacts associated with sea 

level rise include inundation of waste disposal sites and landfills and the subsequent 

release of toxins and pollutants; and increased siltation of subtidal habitats due 

to shoreline erosion (Boesch et al. 2000).

•	 Future projections of tropical cyclone 

activity consistently indicate that greenhouse warming will cause the intensity 

(mean maximum wind speed) of tropical 

cyclones to increase by 2-11% by 2100. It 

is likely that the frequency of tropical cyclones will either decrease or remain unchanged, with high variability at the scale 

of individual basins (Knutson et al. 2010).

What scientists think is possible....

•	 Decreased runoff coupled with increasing 

sea-levels could lead to increased salt-water intrusion in some areas, affecting vegetation, fish, and water resources (Twilley 

et al. 2001, IPCC 2007a).

•	 A drier climate along the Gulf Coast, combined with such activities as dredging, reservoir construction, surface water diversions, and groundwater pumping, could 

accelerate local subsidence and sinkhole 

formation in areas underlain by limestone 

(Twilley et al. 2001).

•	 Sea level rise may increase beach erosion along shorelines, constraining coastal 

plants to narrow stretches of beach and 

resulting in a breakdown of the successional process. Late-succession species 

are important for dune building, sediment 

binding, and reduction of erosion (Feagin 

et al. 2005). 

•	 Model projections indicate that the invasive Chinese tallow tree has the potential 

to spread 500 kilometers northward beyond its current distribution in coastal 

areas of eastern Texas, Louisiana, Mississippi, Alabama, and Florida, as the result 

of increased minimum temperatures and 

decreased aridity in the eastern and western U.S. (Pattison and Mack 2008).

•	 Sea level rise on Key Deer National Wildlife Refuge may allow mangrove habitats 

to expand at the expense of upland and 

transitional habitats. A sea level rise of 

about 0.2 meters may result in the loss of 

most of the upland and transitional habitat in the central portion of Sugarloaf Key, 

and as sea level rise approaches 0.5 meters 

about 95% of Sugarloaf will become mangrove forest and mudflat, leaving only a 

small amount of remnant upland habitat 

in the southeast portion of the Key (Ross 

et al. 2008).

•	 Model simulations results suggest that 

heavy storm surges that completely saturate saline-intolerant areas in southern 

Florida could result in vegetation regime 

shifts from hardwood hammocks to saline-tolerant mangroves (Teh et al. 2008).

•	 A 38 cm rise in average sea level is projected to result in the loss of 50% (9,294 

ha) of critical saltmarsh, 84% (67,438 ha) 

of tidal flats, 14% (70, 680 ha) of dry land, 

30% (405 ha) of ocean beaches, and 60% 

(2,380 ha) of estuariane beaches at nine 

areas along Florida’s coast, including Pensacola Bay, Apalachicola Bay, Tampa Bay, 

Charlotte Harbor, Ten Thousand Islands, 

Florida Bay, Biscayne Bay, St. Lucie Estuary and Indian River Lagoon (Click and 

Clough 2006).

•	 Forest fire seasonal severity rating is projected to increase from 10 to 30% in the 

Southeast by 2060. In addition, model 

projections simulate a large increase in 

fire activity and biomass loss, sufficient to 

convert the southernmost closed-canopy 

forests to savannas (Backlund et al. 2008). 

Goat’s-foot morning glory 

grows on a dune field in Padre 

island National Seashore; NPS 

photos.

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience
14 Climate Change Talking Points NPS/FWS—2010

•	 More intense hurricane activity may result 

in increased damages to structures and 

property along the Gulf Coast (Peterson 

et al. 2008).

•	 Economic and social vulnerability to hurricane damage is increasing rapidly, predominantly because of the rise in population and property values near coastlines 

(Anthes et al. 2006).

•	 Sea level rise poses threats to cultural 

and historic resources and infrastructure 

(Pendleton et al. 2004b). For example, 

Fort Massachusetts of the Gulf Islands 

National Seashore may be lost to the rising 

waters of the Mississippi Sound and Gulf 

of Mexico if it is not protected (Caffrey 

and Beavers 2008).

•	 Effects of projected climate changes on 

human health include increased incidence 

of heat stress and heat stroke, respiratory 

distress from pollutants released during 

wildfires, cardio-respiratory morbidity 

and mortality associated with ground-level ozone, and injury and death from floods, 

storms, fires, and droughts (Epstein 2001, 

Confalonieri et al. 2007). 

•	 Increases in maximum temperatures, precipitation, and sea surface temperature 

are linked with increased transmission of 

dengue fever, a mosquito-borne disease, 

on the Texas-Mexico border (Brunkard 

et al. 2008).

•	 Increasing intensity of severe storms and 

floods may pose threats to historic structures, roads and trails, archeological sites, 

administrative facilities, and other park 

resources and infrastructure. 

•	 Increased summer temperatures will likely 

lead to increased utility expenditures in 

parks in the summer and, potentially, decreases in the winter.

•	 Potentially poorer visibility due to smoke 

from increased wildland fire activity will 

likely cause a negative impact on visitor 

experiences.

F. VISITOR EXPERIENCE

•	 The locations of climatically ideal tourism 

conditions are likely to shift toward higher 

latitudes under projected climate change, 

and as a consequence spatial and temporal redistribution of tourism activities 

may occur. The effects of these changes 

will depend greatly on the flexibility demonstrated by institutions and tourists as 

they react to climate change (Amelung et 

al. 2007).

•	 Changes to the terrestrial and aquatic species compositions in parks and refuges are 

likely to occur as ranges shift, contract, or 

expand (Burns et al. 2003).

•	 Parks and refuges may not be able to meet 

their mandate of protecting current species within their boundaries, or in the case 

of some refuges, the species for whose 

habitat protection they were designed. 

While wildlife may be able to move northward or to higher elevations to escape 

some effects of climate change, federal 

boundaries are static (Burns et al. 2003). 

Temperature Water Cycle Vegetation Wildlife Disturbance Visitor Experience

A campsite among the palm 

trees at Dry Tortugas National 

Park; NPS photo.
National Park Service 15

III. No Regrets Actions: How Individuals, Parks, Refuges, and 

Their Partners Can Do Their Part

Individuals, businesses, and agencies release carbon dioxide (CO2), the principal greenhouse gas, through burning of fossil 

fuels for electricity, heating, transportation, food production, and other day-to-day activities. Increasing levels of atmospheric 

CO2 have measurably increased global average temperatures, and are projected to cause further changes in global climate, with 

severe implications for vegetation, wildlife, oceans, water resources, and human populations. Emissions reduction – limiting 

production of CO2 and other greenhouse gases - is an important step in addressing climate change. It is the responsibility of 

agencies and individuals to find ways to reduce greenhouse gas emissions and to educate about the causes and consequences 

of climate change, and ways in which we can reduce our impacts on natural resources. There are many simple actions that each 

of us can take to reduce our daily carbon emissions, some of which will even save money.

Agencies Can...

Improve sustainability and 

energy efficiency

•	 Use energy efficient products, such as 

ENERGY STAR® approved office equipment and light bulbs.

•	 Initiate an energy efficiency program to 

monitor energy use in buildings. Provide 

guidelines for reducing energy consumption.

•	 Convert to renewable energy sources 

such as solar or wind generated power.

•	 Specify “green” designs for construction 

of new or remodeled buildings.

•	 Include discussions of climate change in 

the park Environmental Management 

System. 

•	 Conduct an emmisions inventory and set 

goals for CO2 reduction.

•	 Provide alternative transportation options such as employee bicycles and shuttles for within-unit commuting. 

•	 Provide hybrid electric or propane-fueled 

vehicles for official use, and impose fuel 

standards for park vehicles. Reduce the 

number and/or size of park vehicles and 

boats to maximize efficiency.

•	 Provide a shuttle service or another form 

of alternate transportation for visitor and 

employee travel to and within the unit. 

•	 Provide incentives for use of alternative 

transportation methods.

•	 Use teleconferences and webinars or other 

forms of modern technology in place of 

travel to conferences and meetings.

Implement Management Actions

•	 Engage and enlist collaborator support 

(e.g., tribes, nearby agencies, private landholders) in climate change discussions, responses, and mitigation. 

•	 Develop strategies and identify priorities 

for managing uncertainty surrounding climate change effects in parks and refuges. 

•	 Build a strong partnership-based foundation for future conservation efforts.

•	 Identify strategic priorities for climate 

change efforts when working with partners.

•	 Incorporate anticipated climate change 

impacts, such as decreases in lake levels, 

rising sea levels, or changes in vegetation 

and wildlife, into management plans.

•	 Encourage research and scientific study in 

park units and refuges.

An interpretive brochure about 

climate change impacts to National Parks was created in 2006 

and was distributed widely. This 

brochure was updated in 2008.
16 Climate Change Talking Points NPS/FWS—2010

•	 Design long-term monitoring projects and 

management activities that do not rely 

solely on fossil fuel-based transportation 

and infrastructure.

•	 Incorporate products and services that address climate change in the development 

of all interpretive and management plans. 

•	 Take inventory of the facilities/boundaries/species within your park or refuge 

that may benefit from or be vulnerable to 

climate change mitigation or adaptation 

activities.

•	 Limit development on or adjacent to 

beaches. This dynamic habitat will be 

needed by many species and serves as a 

critical buffer with adjacent rising waters.

•	 Participate in gateway community sustainability efforts.

•	 Recognize the value of ecosystem services 

that an area can provide, and manage the 

area to sustain these services. Conservation is more cost-effective than restoration 

and helps maintain ecosystem integrity.

•	 Provide recycling options for solid waste 

and trash generated within the park.

Restore damaged landscapes

•	 Restoration efforts are important as a 

means for enhancing species’ ability to 

cope with stresses and adapt to climatic 

and environmental changes. Through restoration of natural areas, we can lessen climate change impacts on species and their 

habitats. These efforts will help preserve 

biodiversity, natural resources, and recreational opportunities.

•	 Strategically focus restoration efforts, both 

in terms of the types of restoration undertaken and their national, regional, and 

local scale and focus, to help maximize 

resilience.

•	 Restore human altered sediment supplies 

to increase resilience of sandy coasts (e.g. 

barrier island ability to survive storm impacts, overwash, etc.).

•	 Restore and conserve connectivity within 

habitats, protect and enhance instream 

flows for fish, and maintain and develop 

access corridors to climate change refugia. 

•	 Restore natural hydrologic functions of 

coastal wetlands to help protect coastal 

areas against hurricanes and flooding.

Educate staff and the public

•	 Post climate change information in easily accessible locations such as on bulletin 

boards and websites.

•	 Provide training for park and refuge employees and partners on effects of climate 

change on resources, and on dissemination of climate change knowledge to the 

public.

•	 Support the development of region, park, 

or refuge-specific interpretive products on 

the impacts of climate change. 

•	 Incorporate climate change research and 

information in interpretive and education 

outreach programming.

•	 Distribute up-to-date interpretive products (e.g., the National Park Service-wide 

Climate Change in National Parks brochure).

•	 Develop climate change presentations for 

local civic organizations, user and partner 

conferences, national meetings, etc.

•	 Incorporate climate change questions and 

answers into Junior Ranger programs.

Park Service employees install 

solar panels at San Francisco 

Maritime National Historical 

Park (Top); At the National Mall, 

Park Service employees use 

clean-energy transportation to 

lead tours; NPS photos. 
National Park Service 17

The Climate Friendly Parks 

Program is a joint partnership 

between the U.S. Environmental Protection Agency and the 

National Park Service. Climate 

Friendly Parks from around the 

country are leading the way in 

the effort to protect our parks’ 

natural and cultural resources 

and ensure their preservation 

for future generations; NPS image. 

•	 Help visitors make the connection between reducing greenhouse gas emissions 

and resource stewardship.

•	 Encourage visitors to use public or nonmotorized transportation to and around 

parks.

•	 Encourage visitors to reduce their carbon 

footprint in their daily lives and as part of 

their tourism experience.

Individuals can...

•	 In the park or refuge park their car and 

walk or bike. Use shuttles where available. 

Recycle and use refillable water bottles. 

Stay on marked trails to help further ecosystem restoration efforts.

•	 At home, walk, carpool, bike or use public transportation if possible. A full bus 

equates to 40 fewer cars on the road. 

When driving, use a fuel-efficient vehicle.

•	 Do not let cars idle - letting a car idle for 

just 20 seconds burns more gasoline than 

turning it off and on again.

•	 Replace incandescent bulbs in the five 

most frequently used light fixtures in the 

home with bulbs that have the ENERGY 

STAR® rating. If every household in the 

U.S. takes this one simple action we will 

prevent greenhouse gas emissions equivalent to the emissions from nearly 10 million cars, in addition to saving money on 

energy costs.

Reduce, Reuse, Recycle, Refuse

•	 Use products made from recycled paper, 

plastics and aluminum - these use 55-95% 

less energy than products made from 

scratch. 

•	 Purchase a travel coffee mug and a reusable water bottle to reduce use of disposable products (Starbucks uses more than 1 

billion paper cups a year). 

•	 Carry reusable bags instead of using paper 

or plastic bags. 

•	 Recycle drink containers, paper, newspapers, electronics, and other materials. Bring recyclables home for proper 

disposal when recycle bins are not available. Rather than taking old furniture and 

clothes to the dump, consider “recycling” 

them at a thrift store. 

•	 Keep an energy efficient home. Purchase 

ENERGY STAR® appliances, properly 

insulate windows, doors and attics, and 

lower the thermostat in the winter and 

raise it in the summer (even 1-2 degrees 

makes a big difference). Switch to green 

power generated from renewable energy 

sources such as wind, solar, or geothermal.

•	 Buy local goods and services that minimize 

emissions associated with transportation.

•	 Encourage others to participate in the actions listed above.

For more information on how you can reduce carbon emissions and engage in climatefriendly activities, check out these websites:

EPA- What you can do: http://www.epa.gov/

climatechange/wycd/index.html

NPS- Do Your Part! Program: http://www.

nps.gov/climatefriendlyparks/doyourpart.

html

US Forest Service Climate Change Program: 

http://www.fs.fed.us/climatechange/

United States Global Change Research Program: http://www.globalchange.gov/

U.S. Fish and Wildlife Service Climate change: 

http://www.fws.gov/home/climatechange/

“Humankind has not 

woven the web of life. 

We are but one thread 

within it. Whatever we 

do to the web, we do 

to ourselves. All things 

are bound together. 

All things connect.”

 —Chief Seattle
18 Climate Change Talking Points NPS/FWS—2010

IV. Global Climate Change

The IPCC is a scientific intergovernmental, international body established by the World Meteorological Organization (WMO) 

and by the United Nations Environment Programme (UNEP). The information the IPCC provides in its reports is based on 

scientific evidence and reflects existing consensus viewpoints within the scientific community. The comprehensiveness of the 

scientific content is achieved through contributions from experts in all regions of the world and all relevant disciplines including, where appropriately documented, industry literature and traditional practices, and a two stage review process by experts 

and governments.

Definition of climate change: The IPCC defines climate change as a change in the state of the climate that can be identified (e.g. 

using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, 

typically decades or longer. All statements in this section are synthesized from the IPCC report unless otherwise noted.

A. Temperature and 

Greenhouse Gases

What scientists know...

•	 Warming of the Earth’s climate system is 

unequivocal, as evidenced from increased 

air and ocean temperatures, widespread 

melting of snow and ice, and rising global 

average sea level (Figure 1).

•	 In the last 100 years, global average surface 

temperature has risen about 0.74°C over 

the previous 100-year period, and the rate 

of warming has doubled from the previous 

century. Eleven of the 12 warmest years in 

the instrumental record of global surface 

temperature since 1850 have occurred 

since 1995 (Figure 1).

•	 Although most regions over the globe have 

experienced warming, there are regional 

variations: land regions have warmed faster than oceans and high northern latitudes 

have warmed faster than the tropics. Average Arctic temperatures have increased 

at almost twice the global rate in the past 

100 years, primarily because loss of snow 

and ice results in a positive feedback via 

increased absorption of sunlight by ocean 

waters (Figure 2).

•	 Over the past 50 years widespread changes 

in extreme temperatures have been observed, including a decrease in cold days 

and nights and an increase in the frequency of hot days, hot nights, and heat waves.

•	 Winter temperatures are increasing more 

rapidly than summer temperatures, particularly in the northern hemisphere, and 

Figure 1. Observed changes in (a) global average surface temperature; (b) 

global average sea level from tide gauge (blue) and satellite (red) data and (c) 

Northern Hemisphere snow cover for March-April. All differences are relative 

to corresponding averages for the period 1961-1990. Smoothed curves represent decadal averaged values while circles show yearly values. The shaded 

areas are the uncertainty intervals estimated from a comprehensive analysis of 

known uncertainties (a and b) and from the time series (c) (IPCC 2007a).
National Park Service 19

there has been an increase in the length 

of the frost-free period in mid- and highlatitude regions of both hemispheres.

•	 Climate change is caused by alterations in 

the energy balance within the atmosphere 

and at the Earth’s surface. Factors that 

affect Earth’s energy balance are the atmospheric concentrations of greenhouse 

gases and aerosols, land surface properties, 

and solar radiation. 

•	 Global atmospheric concentrations of 

greenhouse gases have increased significantly since 1750 as the result of human 

activities. The principal greenhouse gases 

are carbon dioxide (CO2), primarily from 

fossil fuel use and land-use change; methane (CH4) and nitrous oxide (N2O), primarily from agriculture; and halocarbons 

(a group of gases containing fluorine, chlorine or bromine), principally engineered 

chemicals that do not occur naturally.

•	 Direct measurements of gases trapped in 

ice cores demonstrate that current CO2 

and CH4 concentrations far exceed the 

natural range over the last 650,000 years 

and have increased markedly (35% and 

148% respectively), since the beginning of 

the industrial era in 1750.

•	 Both past and future anthropogenic CO2 

emissions will continue to contribute to 

warming and sea level rise for more than 

a millennium, due to the time scales required for the removal of the gas from the 

atmosphere. 

Figure 2. Comparison of observed continental- and globalscale changes in surface temperature with results simulated 

by climate models using either 

natural or both natural and anthropogenic forcings. Decadal 

averages of observations are 

shown for the period 1906-2005 

(black line) plotted against the 

centre of the decade and relative to the corresponding average for the period 1901-1950. 

Lines are dashed where spatial 

coverage is less than 50%. Blue 

shaded bands show the 5 to 

95% range for 19 simulations 

from five climate models using 

only the natural forcings due 

to solar activity and volcanoes. 

Red shaded bands show the 5 

to 95% range for 58 simulations 

from 14 climate models using 

both natural and anthropogenic 

forcings (IPCC 2007a).
20 Climate Change Talking Points NPS/FWS—2010

•	 Warming temperatures reduce oceanic uptake of atmospheric CO2, increasing the 

fraction of anthropogenic emissions remaining in the atmosphere. This positive 

carbon cycle feedback results in increasingly greater accumulation of atmospheric 

CO2 and subsequently greater warming 

trends than would otherwise be present in 

the absence of a feedback relationship.

•	 There is very high confidence that the 

global average net effect of human activities since 1750 has been one of warming.

•	 Scientific evidence shows that major and 

widespread climate changes have occurred with startling speed. For example, 

roughly half the north Atlantic warming 

during the last 20,000 years was achieved 

in only a decade, and it was accompanied 

by significant climatic changes across most 

of the globe (NRC 2008).

What scientists think is likely...

•	 Anthropogenic warming over the last 

three decades has likely had a discernible 

influence at the global scale on observed 

changes in many physical and biological 

systems. 

•	 Average temperatures in the Northern 

Hemisphere during the second half of the 

20th century were very likely higher than 

during any other 50-year period in the last 

500 years and likely the highest in at least 

the past 1300 years. 

•	 Most of the warming that has occurred 

since the mid-20th century is very likely 

due to increases in anthropogenic greenhouse gas concentrations. Furthermore, 

it is extremely likely that global changes 

observed in the past 50 years can only be 

explained with external (anthropogenic) 

forcings (influences) (Figure 2). 

•	 There is much evidence and scientific consensus that greenhouse gas emissions will 

continue to grow under current climate 

change mitigation policies and development practices. For the next two decades 

a warming of about 0.2oC per decade is 

projected for a range of emissions scenarios; afterwards, temperature projections 

increasingly depend on specific emissions 

scenarios (Table 1). 

•	 It is very likely that continued greenhouse 

gas emissions at or above the current rate 

will cause further warming and result in 

changes in the global climate system that 

will be larger than those observed during 

the 20th century.

•	 It is very likely that hot extremes, heat 

waves and heavy precipitation events will 

become more frequent. As with current 

trends, warming is expected to be greatest 

over land and at most high northern latitudes, and least over the Southern Ocean 

(near Antarctica) and the northern North 

Atlantic Ocean.

What scientists think is possible...

•	 Global temperatures are projected to increase in the future, and the magnitude of 

temperature change depends on specific 

emissions scenarios, and ranges from a 

1.1oC to 6.4oC increase by 2100 (Table 1). 

Table 1. Projected global average surface warming at the 

end of the 21st century, adapted 

from (IPCC 2007b).

Notes: a) Temperatures are 

assessed best estimates and 

likely uncertainty ranges 

from a hierarchy of models of 

varying complexity as well as 

observational constraints. b) 

Temperature changes are expressed as the difference from 

the period 1980-1999. To express the change relative to the 

period 1850-1899 add 0.5°C. c) 

Year 2000 constant composition 

is derived from AtmosphereOcean General Circulation Models (AOGCMs) only. 

Temperature Change (°C at 2090 – 2099 relative to 

1980 – 1999)a,b

Emissions Scenario Best Estimate Likely Range

Constant Year 2000 

Concentrationsa 0.6 0.3 – 0.9

B1 Scenario 1.8 1.1 – 2.9

B2 Scenario 2.4 1.4 – 3.8

A1B Scenario 2.8 1.7 – 4.4

A2 Scenario 3.4 2.0 – 5.4

A1F1 Scenario 4.0 2.4 – 6.4
National Park Service 21

Figure 3. Sea ice concentrations 

(the amount of ice in a given 

area) simulated by the GFDL 

CM2.1 global coupled climate 

model averaged over August, 

September and October (the 

months when Arctic sea ice concentrations generally are at a 

minimum). Three years (1885, 

1985 & 2085) are shown to illustrate the model-simulated 

trend. A dramatic reduction of 

summertime sea ice is projected, 

with the rate of decrease being 

greatest during the 21st century 

portion. The colors range from 

dark blue (ice free) to white 

(100% sea ice covered); Image 

courtesy of NOAA GFDL.

•	 Anthropogenic warming could lead to 

changes in the global system that are 

abrupt and irreversible, depending on the 

rate and magnitude of climate change.

•	 Roughly 20-30% of species around the 

globe could become extinct if global average temperatures increase by 2 to 3oC over 

pre-industrial levels.

B. Water, Snow, and Ice

What scientists know...

•	 Many natural systems are already being affected by increased temperatures, particularly those related to snow, ice, and frozen 

ground. Examples are decreases in snow 

and ice extent, especially of mountain glaciers; enlargement and increased numbers 

of glacial lakes; decreased permafrost extent; increasing ground instability in permafrost regions and rock avalanches in 

mountain regions; and thinner sea ice and 

shorter freezing seasons of lake and river 

ice (Figure 3).

•	 Annual average Arctic sea ice extent has 

shrunk by 2.7% per decade since 1978, and 

the summer ice extent has decreased by 

7.4% per decade. Sea ice extent during the 

2007 melt season plummeted to the lowest 

levels since satellite measurements began 

in 1979, and at the end of the melt season 

September 2007 sea ice was 39% below 

the long-term (1979-2000) average (NSIDC 

2008)(Figure 4).

•	 Global average sea level rose at an average 

rate of 1.8 mm per year from 1961 to 2003 

and at an average rate of 3.1 mm per year 

from 1993 to 2003. Increases in sea level 

since 1993 are the result of the following 

contributions: thermal expansion, 57%; 

melting glaciers and ice caps, 28%, melting 

polar ice sheets, 15%. 

•	 The CO2 content of the oceans increased 

by 118 ± 19 Gt (1 Gt = 109 tons) between 

A.D. 1750 (the end of the pre-industrial 

period) and 1994 as the result of uptake 

of anthropogenic CO2 emissions from the 

atmosphere, and continues to increase 

by about 2 Gt each year (Sabine et al. 

2004; Hoegh-Guldberg et al. 2007). This 

Figure 4. Arctic sea ice in September 2007 (blue line) is far below the previous low 

record year of 2005 (dashed line), and was 39% below where we would expect to be 

in an average year (solid gray line). Average September sea ice extent from 1979 to 

2000 was 7.04 million square kilometers. The climatological minimum from 1979 to 

2000 was 6.74 million square kilometers (NSIDC 2008).
22 Climate Change Talking Points NPS/FWS—2010

increase in oceanic CO2 has resulted in 

a 30% increase in acidity (a decrease in 

surface ocean pH by an average of 0.1 

units), with observed and potential severe 

negative consequences for marine organisms and coral reef formations (Orr et al. 

2005: McNeil and Matear 2007; Riebesell 

et al. 2009).

•	 Oceans are noisier due to ocean acidification reducing the ability of seawater 

to absorb low frequency sounds (noise 

from ship traffic and military activities). 

Low-frequency sound absorption has decreased over 10% in both the Pacific and 

Atlantic over the past 200 years. An assumed additional pH drop of 0.3 (due 

to anthropogenic CO2 emissions) accompanied with warming will lead to sound 

absorption below 1 kHz being reduced by 

almost half of current values (Hester et. al. 

2008).

•	 Even if greenhouse gas concentrations are 

stabilized at current levels thermal expansion of ocean waters (and resulting sea 

level rise) will continue for many centuries, 

due to the time required to transport heat 

into the deep ocean.

•	 Observations since 1961 show that the 

average global ocean temperature has increased to depths of at least 3000 meters, 

and that the ocean has been taking up 

over 80% of the heat added to the climate 

system.

•	 Hydrologic effects of climate change include increased runoff and earlier spring 

peak discharge in many glacier- and snowfed rivers, and warming of lakes and rivers. 

•	 Runoff is projected to increase by 10 to 

40% by mid-century at higher latitudes 

and in some wet tropical areas, and to decrease by 10 to 30% over some dry regions 

at mid-latitudes and dry tropics. Areas in 

which runoff is projected to decline face a 

reduction in the value of the services provided by water resources. 

•	 Precipitation increased significantly from 

1900 to 2005 in eastern parts of North 

and South America, northern Europe, and 

northern and central Asia. Conversely, 

precipitation declined in the Sahel, the 

Mediterranean, southern Africa, and parts 

of southern Asia (Figure 5).

What scientists think is likely....

•	 Widespread mass losses from glaciers and 

reductions in snow cover are projected 

to accelerate throughout the 21st century, 

reducing water availability and changing 

seasonality of flow patterns.

•	 Model projections include contraction of 

snow cover area, widespread increases 

in depth to frost in permafrost areas, and 

Arctic and Antarctic sea ice shrinkage.

•	 The incidence of extreme high sea level 

has likely increased at a broad range of 

sites worldwide since 1975. 

•	 Based on current model simulations it is 

very likely that the meridional overturning 

circulation (MOC) of the Atlantic Ocean 

will slow down during the 21st century; 

nevertheless regional temperatures are 

predicted to increase. Large-scale and 

persistent changes in the MOC may result 

in changes in marine ecosystem producFigure 5. Relative changes in 

precipitation (in percent) for 

the period 2090-2099, relative 

to 1980-1999. Values are multimodel averages based on the 

SRES A1B scenario for December 

to February (left) and June to 

August (right). White areas are 

where less than 66% of the 

models agree in the sign of the 

change and stippled areas are 

where more than 90% of the 

models agree in the sign of the 

change (IPCC 2007a).

December to February June to August
National Park Service 23

tivity, fisheries, ocean CO2 uptake, and 

terrestrial vegetation.

•	 Globally the area affected by drought has 

likely increased since the 1970s and the 

frequency of extreme precipitation events 

has increased over most areas.

•	 Future tropical cyclones (typhoons and 

hurricanes) are likely to become more 

intense, with larger peak wind speeds and 

increased heavy precipitation. Extra-tropical storm tracks are projected to move 

poleward, with consequent shifts in wind, 

precipitation, and temperature patterns.

•	 Increases in the amount of precipitation 

are very likely in high latitudes and decreases are likely in most subtropical land 

regions, continuing observed patterns 

(Figure 5).

•	 Increases in the frequency of heavy precipitation events in the coming century are 

very likely, resulting in potential damage 

to crops and property, soil erosion, surface and groundwater contamination, and 

increased risk of human death and injury.

What scientists think is possible...

•	 Arctic late-summer sea ice may disappear 

almost entirely by the end of the 21st century (Figure 3).

•	 Current global model studies project that 

the Antarctic ice sheet will remain too cold 

for widespread surface melting and gain 

mass due to increased snowfall. However, 

net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet 

mass balance.

•	 Model-based projections of global average sea level rise at the end of the 21st 

century range from 0.18 to 0.59 meters, 

depending on specific emissions scenarios 

(Table 2). These projections may actually 

underestimate future sea level rise because 

they do not include potential feedbacks or 

full effects of changes in ice sheet flow. 

•	 Partial loss of ice sheets and/or the thermal 

expansion of seawater over very long time 

scales could result in meters of sea level 

rise, major changes in coastlines and inundation of low-lying areas, with greatest 

effects in river deltas and low-lying islands.

C. Vegetation and Wildlife

What scientists know...

•	 Temperature increases have affected Arctic and Antarctic ecosystems and predator 

species at high levels of the food web.

•	 Changes in water temperature, salinity, 

oxygen levels, circulation, and ice cover 

in marine and freshwater ecosystems have 

resulted in shifts in ranges and changes 

in algal, plankton, and fish abundance in 

high-latitude oceans; increases in algal and 

zooplankton abundance in high-latitude 

and high-altitude lakes; and range shifts 

and earlier fish migrations in rivers. 

•	 High-latitude (cooler) ocean waters are 

currently acidified enough to start dissolving pteropods; open water marine snails 

Table 2. Projected global average sea level rise at the end of 

the 21st century, adapted from 

IPCC 2007b.

Notes: a) Temperatures are assessed best estimates and likely 

uncertainty ranges from a hierarchy of models of varying complexity as well as observational 

constraints.

Emissions Scenario

Sea level rise 

(m at 2090 – 2099 relative to 1980 – 1999)

Model-based range (excluding future rapid 

dynamical changes in ice flow)

Constant Year 2000 

Concentrationsa 0.3 – 0.9

B1 Scenario 1.1 – 2.9

B2 Scenario 1.4 – 3.8

A1B Scenario 1.7 – 4.4

A2 Scenario 2.0 – 5.4

A1F1 Scenario 2.4 – 6.4
24 Climate Change Talking Points NPS/FWS—2010

which are one of the primary food sources 

of young salmon and mackerel (Fabry et al. 

2008, Feely et al. 2008). In lower latitude 

(warmer) waters, by the end of this century Humboldt squid’s metabolic rate will 

be reduced by 31% and activity levels by 

45% due to reduced pH, leading to squid 

retreating at night to shallower waters to 

feed and replenish oxygen levels (Rosa 

and Seibel 2008). 

•	 A meta-analysis of climate change effects 

on range boundaries in Northern Hemisphere species of birds, butterflies, and 

alpine herbs shows an average shift of 6.1 

kilometers per decade northward (or 6.1 

meters per decade upward), and a mean 

shift toward earlier onset of spring events 

(frog breeding, bird nesting, first flowering, 

tree budburst, and arrival of migrant butterflies and birds) of 2.3 days per decade 

(Parmesan and Yohe 2003).

•	 Poleward range shifts of individual species 

and expansions of warm-adapted communities have been documented on all continents and in most of the major oceans of 

the world (Parmesan 2006).

•	 Satellite observations since 1980 indicate 

a trend in many regions toward earlier 

greening of vegetation in the spring linked 

to longer thermal growing seasons resulting from recent warming.

•	 Over the past 50 years humans have 

changed ecosystems more rapidly and extensively than in any previous period of 

human history, primarily as the result of 

growing demands for food, fresh water, 

timber, fiber, and fuel. This has resulted in 

a substantial and largely irreversible loss of 

Earth’s biodiversity 

•	 Although the relationships have not been 

quantified, it is known that loss of intact ecosystems results in a reduction in 

ecosystem services (clean water, carbon 

sequestration, waste decomposition, crop 

pollination, etc.).

What scientists think is likely...

•	 The resilience of many ecosystems is likely 

to be exceeded this century by an unprecedented combination of climate change, 

associated disturbance (flooding, drought, 

wildfire, insects, ocean acidification) and 

other global change drivers (land use 

change, pollution, habitat fragmentation, 

invasive species, resource over-exploitation) (Figure 6). 

•	 Exceedance of ecosystem resilience may 

be characterized by threshold-type responses such as extinctions, disruption of 

ecological interactions, and major changes 

in ecosystem structure and disturbance 

regimes.

•	 Net carbon uptake by terrestrial ecosystems is likely to peak before mid-century 

and then weaken or reverse, amplifying 

climate changes. By 2100 the terrestrial 

biosphere is likely to become a carbon 

source.

•	 Increases in global average temperature 

above 1.5 to 2.5°C and concurrent atmospheric CO2 concentrations are projected 

to result in major changes in ecosystem 

structure and function, species’ ecological interactions, and species’ geographical 

ranges. Negative consequences are projected for species biodiversity and ecosystem goods and services.

•	 Model projections for increased atmospheric CO2 concentration and global 

temperatures significantly exceed values 

for at least the past 420,000 years, the 

period during which more extant marine 

organisms evolved. Under expected 21st

century conditions it is likely that global 

warming and ocean acidification will compromise carbonate accretion, resulting in 

less diverse reef communities and failure 

of some existing carbonate reef structures. 

Climate changes will likely exacerbate local stresses from declining water quality and overexploitation of key species 

(Hoegh-Guldberg et al. 2007).

•	 Ecosystems likely to be significantly impacted by changing climatic conditions 

include:

i. Terrestrial – tundra, boreal forest, and 

mountain regions (sensitivity to warming); Mediterranean-type ecosystems 

and tropical rainforests (decreased 

rainfall)
National Park Service 25

Figure 6. Examples of impacts associated with projected global average surface warming. Upper panel: Illustrative examples of global 

impacts projected for climate changes (and sea level and atmospheric CO2 where relevant) associated with different amounts of increase 

in global average surface temperature in the 21st century. The black lines link impacts; broken-line arrows indicate impacts continuing with 

increasing temperature. Entries are placed so that the left-hand side of text indicates the approximate level of warming that is associated 

with the onset of a given impact. Quantitative entries for water scarcity and flooding represent the additional impacts of climate change 

relative to the conditions projected across the range of SRES scenarios A1FI, A2, B1 and B2. Adaptation to climate change is not included 

in these estimations. Confidence levels for all statements are high. Lower panel: Dots and bars indicate the best estimate and likely ranges 

of warming assessed for the six SRES marker scenarios for 2090-2099 relative to 1980-1999 (IPCC 2007a).
26 Climate Change Talking Points NPS/FWS—2010

ii. Coastal – mangroves and salt marshes 

(multiple stresses) 

iii. Marine – coral reefs (multiple stresses); 

sea-ice biomes (sensitivity to warming)

What scientists think is possible...

•	 Approximately 20% to 30% of plant and 

animal species assessed to date are at increased risk of extinction with increases in 

global average temperature in excess of 1.5 

to 2.5°C.

•	 Endemic species may be more vulnerable 

to climate changes, and therefore at higher 

risk for extinction, because they may have 

evolved in locations where paleo-climatic 

conditions have been stable.

•	 Although there is great uncertainty about 

how forests will respond to changing 

climate and increasing levels of atmospheric CO2, the factors that are most 

typically predicted to influence forests 

are increased fire, increased drought, and 

greater vulnerability to insects and disease 

(Brown 2008).

•	 If atmospheric CO2 levels reach 450 ppm 

(projected to occur by 2030–2040 at the 

current emissions rates), reefs may experience rapid and terminal decline worldwide from multiple climate change-related 

direct and indirect effects including mass 

bleaching, ocean acidification, damage to 

shallow reef communities,reduction of 

biodiversity, and extinctions. (Veron et al. 

2009). At atmospheric CO2 levels of 560 

ppmv, calcification of tropical corals is expected to decline by 30%, and loss of coral 

structure in areas of high erosion may 

outpace coral growth. With unabated CO2 

emissions, 70% of the presently known 

reef locations (including cold-water corals) will be in corrosive waters by the end 

of this century (Riebesell, et al. 2009).

D. Disturbance

What scientists know...

•	 Climate change currently contributes to 

the global burden of disease and premature death through exposure to extreme 

events and changes in water and air quality, food quality and quantity, ecosystems, 

agriculture, and economy (Parry et al. 

2007).

•	 The most vulnerable industries, settlements, and societies are generally those 

in coastal and river flood plains, those 

whose economies are closely linked with 

climate-sensitive resources, and those in 

areas prone to extreme weather events. 

•	 By 2080-2090 millions more people than 

today are projected to experience flooding 

due to sea level rise, especially those in the 

low-lying megadeltas of Asia and Africa 

and on small islands.

•	 Climate change affects the function and 

operation of existing water infrastructure 

and water management practices, aggravating the impacts of population growth, 

changing economic activity, land-use 

change, and urbanization.

What scientists think is likely...

•	 Up to 20% of the world’s population will 

live in areas where river flood potential 

could increase by 2080-2090, with major 

consequences for human health, physical 

infrastructure, water quality, and resource 

availability.

•	 The health status of millions of people is 

projected to be affected by climate change, 

through increases in malnutrition; increased deaths, disease, and injury due to 

extreme weather events; increased burden 

of diarrheal diseases; increased cardiorespiratory disease due to higher concentrations of ground-level ozone in urban 

areas; and altered spatial distribution of 

vector-borne diseases.

•	 Risk of hunger is projected to increase at 

lower latitudes, especially in seasonally 

dry and tropical regions.

What scientists think is possible...

•	 Although many diseases are projected to 

increase in scope and incidence as the 

result of climate changes, lack of appropriate longitudinal data on climate changerelated health impacts precludes definitive 

assessment.
National Park Service 27

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