• Invitation
• Abstract Directory
• GOM Agenda
• FISC Agenda
•     POSTERS:
• MON
• TUE
• WED

2: Climate Variability and Change

Dr. Virginia Burkett, U.S. Geological Survey, Many, Louisiana

During the past 100 years the average temperature of the Earth’s atmosphere has risen by 0.74º C, with the greatest increase in warming occurring in the northern hemisphere, during winter months, and at high latitudes. The rate of atmospheric and ocean surface warming over the past 50 years increased significantly over that of the past 100 years. Atmospheric warming alters water availability by increasing evapotranspiration rates. Warming also increases the moisture-holding capacity of the atmosphere and intensifies the hydrologic cycle. Annual precipitation has increased slightly, but significantly, in coastal Mississippi and Alabama since 1905. Although precipitation has generally increased across most of the reminder of North America, it is occurring in the form of more heavy downpours with the number of days between rainfall events increasing for most of the Northern Hemisphere and droughts becoming more common in some regions. As ocean volume increases due to thermal expansion and a decline in land ice, low-lying coastal wetlands may be inundated and fresh-water wetlands that fringe the coastline may tend to become more saline. The warming of the ocean surface, coupled with the increase in the moisture holding capacity of the atmosphere, portends an increase in the intensity of tropical cyclones globally. The relationships between warming and increased tropical storm intensity during recent decades are particularly strong in the main development region for hurricanes in the North Atlantic Ocean. Whether or not hurricanes increase in frequency or intensity, however, flooding is likely to increase along the low-lying Gulf of Mexico shoreline as sea level continues to rise.

The projected changes in climate for the 21st century by the Intergovernmental Panel on Climate Change predict a suite of environmental consequences that could place many coastal, wetland, and aquatic systems at risk in the central Gulf Coast region. Model results, climatic trends during the past century, and climate theory all suggest that extrapolation of the 20th century temperature record would likely underestimate the range of change that could occur in the next few decades along Mississippi/Alabama coastline. While there is still considerable uncertainty about the rates of change that can be expected, there is a strong consensus regarding the direction of change for most of the climate variables that affect water levels, salinity and disturbance regimes (storms, fires, drought), and habitats in the central Gulf Coast region. The large and growing pressures of human development, however, are responsible for most of the current stresses on Gulf Coast natural resources which include: water quality and sediment pollution, drainage and filling of wetlands, human settlements along barrier island shorelines, dredging of natural rivers and engineered waterways, and flood-control levees that have decreased the amount of sediment delivered to the Gulf coastal zone. These and other human development activities could amplify the effects of climate change on coastal ecosystems. Examples from South Florida will illustrate how interactions of human development activities and climate change influence coastal ecosystems.

Contact Information: Virginia Burkett, U.S. Geological Survey, 540 North Courthouse St., Many, LA 71449; phone 318 256 5628; email: Virginia_burkett@usgs.gov

Richard Z. Poore1, Kristine DeLong1, Kathy Tedesco1, Lisa Osterman1, Julie Richey2, and Terrence Quinn3

1 U.S. Geological Survey, Florida Integrated Science Center, St. Petersburg, Florida
2 University of South Florida, St. Petersburg, Florida
3 University of Texas, Austin, Texas

Human activities and natural processes are currently influencing climate variability. Better information on past natural climate variability and its impact on ecosystems are needed to help discriminate between natural variability and human-related changes and to improve forecasts of future change and its societal impact. Better understanding of variability in the Gulf of Mexico is important because the Gulf of Mexico is a significant source of moisture for a large area of North America.

Researchers at the USGS, the University of Texas, Austin, and the University of South Florida are collaborating to establish a network of marine records of climate variability in the northern Gulf of Mexico for the last few thousand years. The marine records are based on analyses of microfossil assemblages and variations in the isotopic and trace-element content of microfossil shells in AMS 14C-dated sediment cores from the continental slope and shelf. Previous studies have established relations between shell chemistry and seawater characteristics such as temperature and salinity; however, these relations have not been defined for the Gulf of Mexico. Thus, part of the collaborative effort involves a sediment-trap experiment to provide a direct calibration of variations in microfossil assemblages and shell chemistry to seawater characteristics in the northern Gulf of Mexico. The northern Gulf of Mexico marine climate records resolve multi-decadal and centennial-scale variability, and these records are being integrated with coastal terrestrial climate records to develop a history of climate variability along the northern Gulf Coast.

Contact Information: Richard Poore, U.S. Geological Survey, 600 4th Street South, St. Petersburg, FL 33701; phone:727 803 8747; email: rpoore@usgs.gov

The USGS Role in Mangrove Ecosystem Research at Global Scales

T.J. Smith III1, D. Cahoon2, R. Day3, D. DeAngelis1, A. Demopoulos1, T. Doyle3, C. Giri4, K. Hart1, K. Krauss3, D. Krohn1, C. Langtimm1, C. McIvor1, K. McKee3, B. Middleton3, B. Stith1, E. Swain1

1 U.S. Geological Survey, Florida Integrated Science Center, St. Petersburg, Florida
2 U.S. Geological Survey, Patuxent Wildlife Research Center, Beltsville, Maryland
3 U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana
4 Contracted with the USGS Earth Resources Observation and Science Center, Souix Falls, South Dakota

Mangroves dominate the quiescent coastlines of the world’s tropical and sub-tropical regions. These forested ecosystems provide valuable goods and services to human societies, including forest products, serving as habitat for commercial and recreational fisheries, stabilization of shorelines, and interception and sequestering of nutrients and pollutants from upland runoff. Additionally, mangroves are home to numerous critically endangered species worldwide including: the Proboscis Monkey (Malaysia), American Crocodile (Florida and the Caribbean), Scarlet Ibis (Trinidad), and the Bengal Tiger (Bangladesh) to name a few. Mangrove forests are under threat from both natural and anthropogenic forces. Natural forces include sea-level rise and increasing frequency of tropical cyclones. Human impacts include coastal development (e.g., for ports), conversion into ponds for aquaculture and pollution (e.g., oil spills). USGS scientists are studying mangrove ecosystems around the world including in the United States, Mexico, the Virgin Islands, Belize, Honduras, Panama, Federated States of Micronesia, Palau, Australia, New Zealand, Papua New Guinea and Malaysia. The research focuses on a variety of topics and covers scales from an individual organism to the landscape. A major theme of USGS research in mangroves is their response to disturbance and global climate change, and consequent effects on the diverse and important animal life that depends on mangrove forests. The approaches taken by USGS scientists are varied and include intensive field surveys, the use of permanent plots / sampling sites to record long-term change, geochemical techniques to interpret foodweb relationships, field and laboratory experiments, and modeling studies of hydrology and vegetation dynamics. The USGS will continue to conduct studies of mangrove ecosystems to provide resource managers around the world with information upon which sound decisions can be made.

Contact Information: Thomas_J_Smith, U.S. Geological Survey, 600 4th Street South, St. Petersburg, FL 33701; phone:727 803 8747; email: tom_j_smith@usgs.gov