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Working Group II Definitions

Likelihood of an outcome or result
Virtually certain > 99% probability of occurrence
Extremely likely > 95%
Very likely > 90%
Likely > 66%
More likely than not > 50%
Very unlikely < 10%
Extremely unlikely < 5%.

Confidence in a statement
Very high confidence: At least a 9 out of 10 chance of being correct
High confidence: About an 8 out of 10 chance
Medium confidence: About a 5 out of 10 chance
Low confidence: About a 2 out of 10 chance
Very low confidence: Less than a 1 out of 10 chance

Confidence symbols in the text
*** Very high confidence
** High confidence
* Medium confidence

Key Assumptions

The Working Group II report discusses future impacts "for the range of unmitigated climate changes projected by the IPCC over this century judged to be relevant for people and the environment." Its different scenarios of future emissions of greenhouse gases "do not include additional climate initiatives, which means that no scenarios are included that explicitly assume implementation of the United Nations Framework Convention on Climate Change or the emissions targets of the Kyoto Protocol."

Sources: Scientists

North Carolina


Listen to South Regional Pre-release Briefing
Key passages from report released April 16 (North America Chapter)
Key passages from report released April 6 (Impacts)
Key passages from report released February 2 (Science)
Regional Resources

North America Chapter of the IPCC's WGII Technical Report:
"Climate Change 2007: Impacts, Adaptation and Vulnerability"

Issued April 16

On April 16, 2007, the Intergovernmental Panel on Climate Change (IPCC) released the North America chapter of the Working Group II technical report in Washington, D.C. This new chapter details the North American findings summarized in the global Summary for Policymakers released on April 6.

Key Passages:

Future Impacts and Vulnerabilities


"Simulations of the Edwards aquifer in Texas under average recharge project lower or ceased flows from springs, water shortages, and considerable negative environmental impacts."

"In the Ogallala aquifer region, projected natural groundwater recharge decreases more than 20% in all simulations with warming of 2.5C or greater."

Coastal regions

"Up to 21% of the remaining coastal wetlands in the U.S. mid-Atlantic region are potentially at risk of inundation between 2000 and 2100. Rates of coastal wetland loss, in Chesapeake Bay and elsewhere, will increase with accelerated sea-level rise, in part due to 'coastal squeeze' [high confidence]."

"Many salt marshes in less developed areas have some potential to keep pace with sea-level rise (to some limit) through vertical accretion. Where rapid subsidence increases rates of relative sea-level rise, however, as in the Mississippi Delta, even heavy sediment loads cannot compensate for inundation losses."

"Higher sea levels in combination with storm surges will cause widespread problems for transportation along the Gulf and Atlantic coasts."

Agriculture, forestry and fisheries

"Research since the TAR supports the conclusion that moderate climate change will likely increase yields of North American rain fed agriculture, but with smaller increases and more spatial variability than in earlier estimates [high confidence]. Most studies project likely climate-related yield increases of 5-20% over the first decades of the century, with the overall positive effects of climate persisting through much or all of the 21st century. This pattern emerges from recent assessments for corn, rice, sorghum, soybean, wheat, common forages, cotton and some fruits, including irrigated grains. Increased climate sensitivity is anticipated in the south-eastern U.S. and in the U.S. Cornbelt, but not in the Great Plains."

"In the continental U.S., cold-water species will likely disappear from all but the deeper lakes, cool-water species will be lost mainly from shallow lakes, and warm water species will thrive except in the far south, where temperatures in shallow lakes will exceed survival thresholds."

Tourism and recreation - Safe and effective

"Although coastal zones are among the most important recreation resources in North America, the vulnerability of key tourism areas to sea level rise has not been comprehensively assessed. The cost to protect Florida beaches from a 0.5m rise in sea level with sand replenishment was estimated at US$1.7-8.8 billion."

Current Sensitivities/ Vulnerabilities

Coastal regions

"Relative sea level is rising in many areas, yet coastal residents are often unaware of the trends and their impacts on coastal retreat and flooding."

"Many coastal areas in North America are potentially exposed to storm-surge flooding."

Infrastructure and extreme events

"The devastating effects of hurricanes Ivan in 2004 and Katrina, Rita, and Wilma in 2005 . illustrate the vulnerability of North American infrastructure and urban systems that were either not designed or maintained to adequate safety margins."

"North America very likely will continue to suffer serious losses of life and property simply due to growth in property values and numbers of people at risk [very high confidence]. Of the US $19 trillion value of all insured residential and commercial property in the U.S. states exposed to North Atlantic hurricanes, US $7.2 trillion (41%) is located in coastal counties. This economic value includes 79% of the property in Florida, 63% of the property in New York, and 61% of the property in Connecticut."

"Flood hazards are not limited to the coastal zone. River basins with a history of major floods (e.g., the Sacramento, the Fraser, the Red River, the upper Mississippi), illustrate the sensitivity of riverine flooding to extreme events and highlight the critical importance of infrastructure design standards, land use planning, and weather/flood forecasts."

Energy, industry and transportation

"North American industry, energy supply, and transportation networks are sensitive to weather extremes that exceed their safety margins. Costs of these impacts can be high. For example, power outages in the U.S. cost the economy US $30-130 billion annually. The hurricanes crossing Florida in the summer of 2004 resulted in direct system restoration costs of US $1.4 billion to the four Florida public utilities involved."

"The impacts of hurricanes Katrina, Rita, and Wilma in 2005 and Ivan in 2004 demonstrated that the Gulf of Mexico offshore oil and natural gas platforms and pipelines, petroleum refineries, and supporting infrastructure can be seriously harmed by major hurricanes which can produce national level impacts, and require recovery times stretching to months or longer."


"The poor and marginalized in Canada and the U.S. have historically been most at risk from weather shocks, with vulnerability directly related to income inequality. Differences in individual capacity to cope with extreme weather were evident in New Orleans during and after Hurricane Katrina, when the large majority of those requiring evacuation assistance were either poor or in groups with limited mobility - including elderly, hospitalized, and disabled citizens."

"Extensive property damage in Florida during Hurricane Andrew in 1992 led to significant revisions to the building code. If all properties in southern Florida met this updated code in 1992, then property damage from Hurricane Andrew would have been lower by nearly 45%. Florida will, however, still experience extensive damage from hurricanes through damage to the large number of older homes and businesses. Other financial barriers come from the challenge property owners face in recovering the costs of protecting themselves. Hidden adaptations tend to be undervalued, relative to obvious ones. For example, homes with storm shutters sell for more than homes without this visible adaptation, while less visible retrofits, such as tie-down straps to hold the roof in high winds, add less to the resale value of the home, relative to their cost."

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The IPCC's "Climate Change 2007: Impacts, Adaptation and Vulnerability"
Issued April 6

Working Group II of the Intergovernmental Panel on Climate Change released this part of the IPCC's Fourth Assessment Report on April 6.

"Climate Change 2007: Impacts, Adaptation and Vulnerability" summarizes current knowledge about impacts of climate change that have already been observed. It also projects future impacts, based on scenarios in which no explicit actions are taken to address global warming and activity continues on a business-as-usual path. That is, the projections assume that climate change impacts are not mitigated by actions such as cuts in greenhouse gases nor by policies that would enhance adaptability to global warming.

The report includes these statements about continent-scale and global-scale changes that relate to issues of concern in the Southern United States.

Key passages:

"Drought-affected areas will likely increase in extent. Heavy precipitation events, which are very likely to increase in frequency, will augment flood risk [high confidence]."

"Coasts are projected to be exposed to increasing risks, including coastal erosion, due to climate change and sea-level rise and the effect will be exacerbated by increasing human-induced pressures on coastal areas [very high confidence]."

"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, especially where rapid urbanisation is occurring [high confidence]."

[Following passages from the report's North America section:]

"Moderate climate change in the early decades of the century is projected to increase aggregate yields of rain-fed agriculture by 5-20%, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or depend on highly utilised water resources [high confidence]."

"Disturbances from pests, diseases, and fire are projected to have increasing impacts on forests, with an extended period of high fire risk and large increases in area burned [very high confidence]."

"Cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts. The growing number of the elderly population is most at risk [very high confidence]."

"Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution. Population growth and the rising value of infrastructure in coastal areas increase vulnerability to climate variability and future climate change, with losses projected to increase if the intensity of tropical storms increases. Current adaptation is uneven and readiness for increased exposure is low [very high confidence]."

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The IPCC's "Climate Change 2007: The Physical Science Basis"
Issued Feb. 2

The IPCC's new report includes these statements about global-scale changes that relate to issues of concern in the South, such as weather extremes, hurricanes and sea level rise. The summary issued Feb. 2 does not have region-level projections for the U.S.

Key passages:

Extreme weather
"The frequency of heavy precipitation events has increased over most land areas, consistent with warming and observed increases of atmospheric water vapour."

"Widespread changes in extreme temperatures have been observed over the last 50 years. Cold days, cold nights and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent."

"More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics. Increased drying linked with higher temperatures and decreased precipitation have contributed to changes in drought. Changes in sea surface temperatures (SST), wind patterns, and decreased snowpack and snow cover have also been linked to droughts."

"It is very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent." (In IPCC terminology, "very likely" means a probability greater than 90 percent and "likely" greater than 66 percent.)

For more report excerpts see Extreme Weather.

Hurricanes and sea level rise
"Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium, due to the timescales required for removal of this gas from the atmosphere."

"Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs (sea surface temperatures). There is less confidence in projections of a global decrease in numbers of tropical cyclones. The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period."

"Extra-tropical storm tracks are projected to move poleward, with consequent changes in wind, precipitation, and temperature patterns, continuing the broad pattern of observed trends over the last half-century."

For more IPCC excerpts see Hurricanes and Sea Level Rise.

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Regional Resources

"In U.S., Climate Change May Hit Southeast Hardest," a 2005 article by National Geographic News
(http://news.nationalgeographic.com/news/2005/08/0811_050811_climatechange.html), reported that climate experts believe the "low-slung, storm-whipped coastal areas from the Carolinas to Texas are most vulnerable" among U.S. regions.

"Heat - The Number One Non-Severe Weather Related Killer in the United States" provides detailed background information on heat waves. The article was published in 2006 in the National Oceanic and Atmospheric Administration's NOAA Magazine.

Carolinas Integrated Sciences and Assessments (CISA) and Southeast Climate Consortium (SECC) are two of the team efforts supported by the National Oceanic and Regional Integrated Sciences and Assessments (RISA) program. RISA funds "research that addresses complex climate sensitive issues of concern to decision-makers and policy planners at a regional level."
CISA (North and South Carolina): http://www.zebra-baker.com/CISA/SECC (Florida, Georgia and Alabama): http://secc.coaps.fsu.edu/

The U.S. Environmental Protection Agency produced individual information sheets in 1998, presenting the agency's then-current assessment of past and possible future impacts of climate change in each state. PDF files can be downloaded here:
http://yosemite.epa.gov/oar/globalwarming.nsf/content/ImpactsStateImpacts.html?OpenD ocument

The U.S. National Assessment of the Potential Consequences of Climate Variability and Change was published by the federal government in 2001. It included information for 19 regions and nine mega-regions of the country. Those regional reports can be downloaded here:

Climate and Farming.org, a website produced by Cornell University, the University of Vermont and other partners about climate change and Northeast agriculture, provides resources and links relevant to agriculture in other regions, too.

Examples of region-related research

New hurricane study
A new study, reported in February in the journal Geophysical Research Letters, supports the conclusion "that global warming has contributed to the emergence of stronger hurricanes in the Atlantic Ocean." A University of Wisconsin press release about the study is available here:

Other recent hurricane studies
A series of studies since 2005 has linked global warming with intensified hurricane activity. References and PDF files are available here:

Excerpt from one of the studies (Atlantic Hurricane Trends Linked to Climate Change, Mann, M.E. and Emanuel, K.A. (2006): "This article presents results indicating that anthropogenic factors are likely responsible for long-term trends in tropical Atlantic warmth and tropical cyclone activity. In addition, this analysis indicates that late twentieth century tropospheric aerosol cooling has offset a substantial fraction of anthropogenic warming in the region and has thus likely suppressed even greater potential increases in tropical cyclone activity."

A Semi-Empirical Approach to Projecting Future Sea-Level Rise
Rahmstorf, S. (2006)-
Abstract available here: http://www.sciencemag.org/cgi/content/abstract/315/5810/368

BBC News: "Current sea level rise projections could be under-estimating the impact of human-induced climate change on the world's oceans, scientists suggest. By plotting global mean surface temperatures against sea level rise, the team found that levels could rise by 59% more than current forecasts." http://news.bbc.co.uk/2/hi/science/nature/6179409.stm

State Resources

FLORIDA [top of page]

"Threats to coral include warmer water, pollution"
St. Petersburg Times, March 5, 2007

"Official: Parts of state could be under water from 'warming'"
Pensacola News Journal, February, 28, 2007
http://www.pensacolanewsjournal.com/apps/pbcs.dll/article?AID=/20070228/NEWS01/ 702280363/1006

Stephen Mulkey, PhD
Department of Botany
Director, Research and Outreach/Extension
School of Natural Resources and Environment

Gainesville, FL, USA 32611-8526
Phone ; Fax ; Cell

LOUISIANA [top of page]

Denise J. Reed, Ph.D.
Professor, Department of Earth and Environmental Science
University of New Orleans

"La. vulnerable to changing global climate"
Baton Rouge Advocate, March 16, 2007

"Warming Imperils Md. Species"
Washington Post, March 19, 2007
http://www.washingtonpost.com/wp-dyn/content/article/2007/03/18/ AR2007031801364.html?sub=AR

MARYLAND [top of page]

Margaret Palmer, Ph.D.
Professor and Director of the Chesapeake Biological Laboratory,
University of Maryland Center for Environmental Science

NORTH CAROLINA [top of page]

Len Pietrafesa, Ph.D.
Associate Dean, Office of External Affairs
Professor Ocean & Atmospheric Sciences
College of Physical & Mathematical Sciences
North Carolina State University

"N.C. coast called vulnerable"
Raleigh News & Observer, March 15,2007

OKLAHOMA [top of page]

David Karoly, Ph.D.
Williams Chair and Professor of Meteorology
School of Meteorology, National Weather Center
University of Oklahoma

Climate change and attribution of causes

TEXAS [top of page]

Robert Harriss, Ph.D.
President and CEO
Houston Advanced Research Center
Tel: (voice)
Fax: (fax)


Bruce McCarl, Ph.D.
Regents Professor
Department of Agricultural Economics

Agriculture and forestry

"Severe heat, drought predicted for life in 22nd-century Texas / Global warming report also warns of more flooding"
Houston Chronicle, Feb. 3, 2007

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