Global Warming Effects Around the World

Mississippi Delta, LA, USA

Top Impact

Oceans (Sea level)

Other Impacts

People (Costs)

Ecosystems (Salt water)

Aerial view of wetlands in Louisiana's Mississippi River Delta, which are now threatened by sea level rise

Sea-level rise associated with climate change—combined with local sinking of the ground—are destroying the wetlands of Louisiana's Mississippi Delta. Deprived of sediment from a river no longer allowed to flood naturally, the wetlands erode and sink, reducing the area's protection against storm surge and destroying habitat for plants and animals. 1

Key Facts

Coastal wetlands in the Mississippi Delta are disappearing. Many factors contribute to the stress placed on wetlands, including the massive oil spill in the Gulf of Mexico in the summer of 2010. But natural forces are at work as well—local sinking of the ground and accelerating rates of sea-level rise,2,4 which scientists expect to further accelerate due to climate change.2,14,15

  • Over the past century, Louisiana has lost 1,900 square miles (4,920 square kilometers) of coastal wetlands—more than one-third of its coastal plain.2,5
  • Because coastal wetlands help protect the coastline from storm surge, Louisiana's capacity to absorb the surge from hurricanes such as Katrina in 2005 has been weakened.2,6
  • Increases in extreme weather in the Gulf Coast region—home to the U.S. oil and gas industry—are expected to disrupt the nation's energy production and supply.2

Details

Sea-level rise from global climate change further threatens wetlands in Louisiana's Mississippi Delta, with implications for the region's ecosystem and economy.

Besides global sea-level rise, several factors influence regional sea-level rise, including local sinking (subsidence) or rising (uplift) of the land, and circulation of the atmosphere and the ocean.2,3

Over the past century, Louisiana has experienced high rates of local relative sea-level rise,2 stemming mostly from the sinking of local land.4 Human alterations such as levees can limit flooding, but they also reduce the natural flow of sediments that build the delta. The extraction of fluids and sediment during oil and gas drilling can disrupt the region's underlying geologic formations. Both of these effects can make the ground sink. The net effect has been the loss of 1,900 square miles (4,920 square kilometers) of coastal wetlands in the state—more than one-third of its coastal plain.2,5

Because coastal wetlands help protect the coastline from storm surge, Louisiana's capacity to absorb the surge of hurricanes such as Katrina that devastated the region in 2005, has been weakened.2,6 Along with increasing sea surface temperatures, sea-level rise can destroy or degrade natural resources such as mangroves.7

In 2005, Hurricanes Katrina and Rita took more than 1,800 lives and eliminated 217 square miles (562 square kilometers) of low-lying coastal marshes and barrier islands in southern Louisiana.2,8,9 The human tragedy of these two disasters touched people around the country. Their economic impact was also felt nationwide.

The gulf coastal plains are home to one-third of the nation's oil and gas refining and processing capacity. During the hurricane, oil and gas production from the gulf halted, oil and gas pipelines closed, and nearly 20 percent of the nation's refinery capacity was knocked out.2,10

The energy industry lost an estimated $15 billion directly—not counting the costs of repairs and resuming production.2,11 When facilities such as the Yscloskey gas processing plant on the Louisiana coast were shut down for six months, the owners lost revenues, workers lost wages, and consumers paid higher prices.2,11

What the Future Holds

In 2007 the Intergovernmental Panel on Climate Change projected a global sea-level rise of at most two feet (0.59 meters) by the end of this century, if we do nothing to reduce our heat-trapping emissions.12,13 If, on the other hand, we make significant efforts to reduce emissions,12 the IPCC expected that sea-level rise between now and the end of the century could be limited to 1.25 feet (0.38 meters).13

Recent evidence of increasing rates of global sea-level rise suggests that these projections may be too low, and that we can expect increases of between three and four feet (0.91 to 1.22 meters) this century.2,14,15 But even with a two-foot (0.59 meters) rise in sea level in this century, a large portion of remaining U.S. coastal wetlands are likely to disappear.2,16 In the Mississippi Delta, where the land is sinking rapidly, heavy sediment loads cannot rebuild soil fast enough to overcome losses from sea-level rise.16,17

Accelerated sea-level rise risks fragmenting barrier islands and endangering homes, other buildings, and infrastructure.2 In the Mississippi Delta, scientists expect observed and projected increases in extreme weather to exert a dramatic impact on U.S. energy production and supply.2Sea-level rise, high winds, and storm surge threaten several thousand offshore drilling platforms, dozens of refineries, and thousands of miles of pipelines.2

Sea-level rise is also expected to disrupt transportation, through more frequent and severe flooding of highways, railroads, and airports.2 The State of Louisiana has already spent tens of millions of dollars to remove storm-related debris and repair submerged roads.2,18 Now, in response to rising risks of storm surge and flooding—related in part to climate change—the state is elevating Highway 1 above the 500-year flood level.18 Highway 1 is the only road that connects Port Fourchon, which supports 75 percent of deepwater oil and gas production in the Gulf of Mexico, with the rest of the nation.2,18

Scientists also expect sea-level rise to alter coastal ecosystems, displacing them farther inland if no barriers remain. The combination of loss of wetlands and the likely increase in salinity of those that remain could cause major ecological disruptions, such as a decline of wetland-dependent coastal fish and shellfish populations.2,19

Credits

Endnotes

  1. Photograph courtesy of ThinkStock. Aerial view of swamp in Louisiana. Accessed 30 Nov 2010 at http://www.thinkstockphotos.com/ search/ #86504567
  2. U.S. Global Change Research Program. 2009. Global climate change impacts in the United States. Edited by T.R. Karl, J.M. Melillo, and T.C. Peterson. Cambridge University Press.
  3. Mitrovica, J.X., N. Gomez, and P.U. Clark, 2009: The sea-level fingerprint of West Antarctic collapse. Science 323(5915):753.
  4. Janetos, A., L. Hansen, D. Inouye, B.P. Kelly, L. Meyerson, B. Peterson, and R. Shaw. 2008. Biodiversity. In: The effects of climate change on agriculture, land resources, water resources, and biodiversity in the United States. Edited by P. Backlund, A. Janetos, D. Schimel, J. Hatfield, K. Boote, P. Fay, L. Hahn, C. Izaurralde, B.A. Kimball, T. Mader, J. Morgan, D. Ort, W. Polley, A. Thomson, D. Wolfe, M.G. Ryan, S.R. Archer, R. Birdsey, C. Dahm, L. Heath, J. Hicke, D. Hollinger, T. Huxman, G. Okin, R. Oren, J. Randerson, W. Schlesinger, D. Lettenmaier, D. Major, L. Poff, S. Running, L. Hansen, D. Inouye, B.P. Kelly, L. Meyerson, B. Peterson, and R. Shaw. Synthesis and assessment product 4.3. Washington, DC: U.S. Department of Agriculture, pp. 151-181.
  5. Burkett, V.R., D.A. Wilcox, R. Stottlemeyer, W. Barrow, D. Fagre, J. Baron, J. Price, J.L. Nielsen, C.D. Allen, D.L. Peterson, G. Ruggerone, and T. Doyle. 2005. Nonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications. Ecological Complexity 2(4):357-394.
  6. Day, J.W., Jr., D.F. Boesch, E.J. Clairain, G.P. Kemp, S.B. Laska, W.J. Mitsch, K. Orth, H. Mashriqui, D.J. Reed, L. Shabman, C.A. Simenstad, B.J. Streever, R.R. Twilley, C.C. Watson, J.T. Wells, and D.F. Whigham. 2007. Restoration of the Mississippi Delta: Lessons from hurricanes Katrina and Rita. Science 315(5819):1679-1684.
  7. Mimura, N., L. Nurse, R.F. McLean, J. Agard, L. Briguglio, P. Lefale, R. Payet, and G. Sem. 2007. Small islands. In: Climate change 2007: Impacts, adaptation, and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 687-716.
  8. Nicholls, R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. Ragoonaden, and C.D. Woodroffe. 2007. Coastal systems and low-lying areas. In: Climate change 2007: Impacts, adaptation, and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 315-356.
  9. Barras, J.A. 2006. Land area change in coastal Louisiana after the 2005 hurricanes: A series of three maps. Open-file report 2006-1274. Washington, DC: U.S. Geological Survey. Online at http://pubs.usgs.gov/ of/ 2006/ 1274. Accessed April 12, 2010.
  10. Holtz-Easkin, D. 2005. Macroeconomic and budgetary effects of Hurricanes Katrina and Rita. Statement before the Committee on the Budget, U.S. House of Representatives. Washington, DC: Congressional Budget Office. Online at http://www.cbo.gov/ doc.cfm? index=6684. Accessed April 12, 2010.
  11. Bull, S.R., D.E. Bilello, J. Ekmann, M.J. Sale, and D.K. Schmalzer. 2007. Effects of climate change on energy production and distribution in the United States. In: Effects of Climate Change on Energy Production and Use in the United States. Edited by T.J. Wilbanks, V. Bhatt, D.E. Bilello, S.R. Bull, J. Ekmann, W.C. Horak, Y.J. Huang, M.D. Levine, M.J. Sale, D.K. Schmalzer, and M.J. Scott. Synthesis and assessment product 4.5. Washington, DC: U.S. Climate Change Science Program, pp. 45-80.
  12. The emissions scenarios referred to here are the high-emissions path known as A1FI and the low-emissions path known as B1 from the Intergovernmental Panel on Climate Change.
  13. Solomon, S., D. Qin, M. Manning, R.B. Alley, T. Berntsen, N.L. Bindoff, Z. Chen, A. Chidthaisong, J.M. Gregory, G.C. Hegerl, M. Heimann, B. Hewitson, B.J. Hoskins, F. Joos, J. Jouzel, V. Kattsov, U. Lohmann, T. Matsuno, M. Molina, N. Nicholls, J. Overpeck, G. Raga, V. Ramaswamy, J. Ren, M. Rusticucci, R. Somerville, T.F. Stocker, P. Whetton, R.A. Wood, and D. Wratt. 2007. Technical summary. In: Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H. L. Miller. Cambridge University Press, pp. 20-91.
  14. Rahmstorf, S., A. Cazenave, J.A. Church, J.E. Hansen, R.F. Keeling, D.E. Parker, and R.C.J. Somerville. 2007: Recent climate observations compared to projections. Science 316(5825):709.
  15. Pfeffer, W.T., J.T. Harper, and S. O'Neel. 2008. Kinematic constraints on glacier contributions to 21st-century sea-level rise. Science 321:1340-1343.
  16. Field, C.B., L.D. Mortsch,, M. Brklacich, D.L. Forbes, P. Kovacs, J.A. Patz, S.W. Running, and M.J. Scott. 2007. North America. In: Climate change 2007: Impacts, adaptation, and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 617-652.
  17. Rybczyk, J.M., and D.R.Cahoon. 2002. Estimating the potential for submergence for two wetlands in the Mississippi River Delta. Estuaries 25:985-998.
  18. Kafalenos, R.S., K.J. Leonard, D.M. Beagan, V.R. Burkett, B.D. Keim, A. Meyers, D.T. Hunt, R.C. Hyman, M.K. Maynard, B. Fritsche, R.H. Henk, E.J. Seymour, L.E. Olson, J.R. Potter, and M.J. Savonis. 2008. What are the implications of climate change and variability for Gulf coast transportation? In: Impacts of climate change and variability on transportation systems and infrastructure: Gulf Coast study, phase I. Edited by M.J. Savonis, V.R. Burkett, and J.R. Potter. Synthesis and assessment product 4.7. Washington, DC: U.S. Department of Transportation, pp. 4-1 to 4F-27.
  19. Zimmerman, R.J., T.J. Minello, and L.P. Rozas. 2002. Salt marsh linkages to productivity of penaeid shrimps and blue crabs in the northern Gulf of Mexico. In: Concepts and controversies in tidal marsh ecology. Edited by M.P. Weinstein and D.A. Kreeger. Kluwer, pp. 293-314.
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