Global Warming Effects Around the World

Osaka, Japan

Top Impact

Oceans (Sea level)

Other Impacts

People (Costs)

Freshwater (Extreme wet)

Coastal flooding could put people and property at risk in Osaka, Japan

Osaka, an economic center of Japan also known for its restaurants and retail shops, is vulnerable to sea-level rise stemming from global warming. Unless we curb our heat-trapping emissions, scientists and economists project that coastal flooding and storm surges are likely to put millions of people and valuable assets in Osaka and other cities at risk.1

Key Facts

Osaka has been an economic and commercial center of Japan for hundreds of years.2 As global warming causes sea levels to rise,8,9,17,18 several million people in Osaka and other Japanese cities are at risk from coastal flooding.4

  • Osaka was among the world's 10 port cities most exposed to coastal flooding and wind damage from a typhoon (tropical cyclone) in 2005.4
  • In Japan, sea-level rise of 3.3 feet (1 meter) could put another 4.1 million people at risk of flooding, and inundate more than 900 square miles of land (2,339 square kilometers) in major cities.8,16 Such a rise is well within the range of scientists' projections, if today's trends in global warming pollution continue.9,10,19,21
  • Economists project that Osaka could suffer the loss or damage of nearly U.S.$1 trillion in assets owing to coastal flooding by the 2070s—more than four times its current economic risk of U.S.$216 billion.4,22

Details

A former capital of Japan, Osaka has been an economic and commercial center for centuries.2 More than 2.5 million people live in the city, and Osaka is the country's second-most-populous prefecture, after Tokyo.2 Osaka is also known as the "kitchen of Japan," and is famous for delicious food.2,3

In 2005, Osaka was one of the world's port cities most exposed to coastal flooding and wind damage.4 More than 10 percent of the population of greater Osaka—and more than U.S.$200 billion in economic assets—are considered vulnerable to coastal flooding.4

Storm surges are one cause of coastal flooding. Like other densely populated coastal areas, Japan is particularly exposed to the environmental, economic, and social effects of typhoons.5,6 The last half of the twentieth century brought no significant trend in the number of typhoons (tropical cyclones) making landfall each year in Japan, and the number of port-related disasters actually fell owing to improved coastal protection. However, average annual costs to repair damage from typhoons in Japan reached some U.S.$240 million.5,7

In Osaka and other coastal cities, sea-level rise can increase the magnitude and danger of storm surges.5,8 Sea level has been rising globally since the end of the last ice age, but the rate has accelerated over the past two decades.9 From 1993 to 2003, for example, that rate rose to 0.12 inches (3.1 millimeters) per year—70 percent higher than the average rate for the twentieth century.10,11

Scientists attribute this recent acceleration in global sea-level rise to global warming.12 Oceans are expanding as they warm, while shrinking glaciers and the melting Greenland and Antarctic ice sheets are adding water to the oceans.10,13

Besides global sea-level rise, several other factors influence regional sea-level rise. These include sinking (subsidence) and rising (uplift) of the land, circulation of the atmosphere and the ocean, and the origin of meltwater.13,14,15

Along the East Asia coast, annual rates of sea-level rise range from 0.06 to 0.17 inches (1.5 to 4.4 millimeters). Scientists attribute this variation to regional differences in land surface movement.8,16 In some coastal areas of Asia, a one-foot (0.30-meter) rise in sea level can produce nearly 150 feet (45 meters) of land erosion.8

What the Future Holds

Over this century and beyond, scientists expect a warming world to drive further sea-level rise, putting several million more people in Japan at risk of flooding.8,13,17,18

If we do nothing to reduce our carbon emissions,19 scientists project that global sea level is likely to rise as high as nearly two feet (59 centimeters) above recent average levels by the end of this century.20 If, on the other hand, we make significant efforts to reduce heat-trapping emissions, sea-level rise between now and the end of the century could be limited to 1.25 feet (38 centimeters).20

Recent evidence of faster rates of global sea-level rise suggests that these projections may be too low.9,10 Given recent accelerated melting of glaciers and shrinking of ice sheets, scientists are now publishing studies suggesting that a rise of 2.6 feet (80 centimeters) is plausible—and that as much as 6.6 feet (2 meters) is possible (though less likely).21 Scientists expect regional variations in land movement and ocean circulation to continue, and to affect local sea-level rise.13,15

In Japan, sea-level rise of 3.3 feet (1 meter) could put as many as 4.1 million more people at risk of flooding, by inundating more than 900 square miles (2,339 square kilometers) of land in major Japanese cities.8,16

Given global sea-level rise, storm surge, local changes in land levels, and other factors, economists project that coastal flooding could put nearly U.S.$1 trillion in Osaka's assets at risk by the 2070s—more than four times the city's economic risk today of U.S.$216 billion.4,22,23 The costs of protecting cities from rising sea levels and storms are also likely to rise—as are the costs of repairing storm damage.5,8

Decisions we make today could have a profound impact on the security and culture of the people of this ancient city.

Credits

Endnotes

  1. Photograph used by permission. Amanda Ribarchik. Dotonbori Canal-Osaka, Japan. June 2010.
  2. Osaka Recreation and Tourism Bureau. About Osaka. 2010. Online at http://www.osaka-info.jp/ en/ about/. Accessed June 21, 2010.
  3. City of Osaka. 2010. Historical overview. Online at http://www.city.osaka.lg.jp/ contents/ wdu020/ english/ events_tourism/ history/ overview.html. Accessed June 21, 2010.
  4. Nicholls, R.J., S. Hanson, C. Herweijer, N. Patmore, S. Hallegatte, J. Corfee-Morlot, J. Château, and R. Muir-Wood. 2008. Ranking port cities with high exposure and vulnerability to climate extremes. Environment working paper no. 1. Paris: Organisation for Economic Co-operation and Development. Online at http://www.oecd.org/ officialdocuments/ displaydocumentpdf? cote=ENV/WKP%282007%291 &doclanguage=en. Accessed June 21, 2010.
  5. 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 Lindenm, and C.E. Hanson. Cambridge, UK: Cambridge University Press, pp. 315-356.
  6. United Nations Development Programme. 2004. Reducing disaster risk: A challenge for development. New York, NY: Disaster Reduction Unit, Bureau for Crisis Prevention and Recovery.
  7. Hay, J.E., and N. Mimura. 2006. Supporting climate change vulnerability and adaptation assessments in the Asia-Pacific region: An example of sustainability science. Sustainability Science 1. doi 10.1007/s11625-11006-10011-11628.
  8. Cruz, R.V., H. Harasawa, M. Lal, S. Wu, Y. Anokhin, B. Punsalmaa, Y. Honda, M. Jafari, C. Li, and N. Huu Ninh. 2007: Asia. 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. 469-506.
  9. 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.
  10. Bindoff, N.L., J. Willebrand, V. Artale, A, Cazenave, J. Gregory, S. Gulev, K. Hanawa, C. Le Quéré, S. Levitus, Y. Nojiri, C.K. Shum, L.D. Talley, and A. Unnikrishnan. 2007. Observations: Oceanic climate change and sea level. 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. 386-432.
  11. Douglas, B.C. 1997. Global sea rise: A redetermination. Surveys in Geophysics 18:279-292. doi:10.1023/A:1006544227856.
  12. Hegerl, G.C., F. W. Zwiers, P. Braconnot, N.P. Gillett, Y. Luo, J.A. Marengo Orsini, N. Nicholls, J.E. Penner, and P.A. Stott. 2007. Understanding and attributing climate change. 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. 664-745.
  13. 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.
  14. Mitrovica, J.X., N. Gomez, and P.U. Clark, 2009: The sea-level fingerprint of West Antarctic collapse. Science 323 (5915):753.
  15. Yin, J., M.E. Schlesinger, and R.J. Stouffer. 2009. Model projections of rapid sea-level rise on the northeast coast of the United States, Nature Geoscience doi: 10.1038/NGEO462.
  16. Mimura, N. and H. Yokoki. 2004. Sea level changes and vulnerability of the coastal region of East Asia in response to global warming. SCOPE/START Monsoon Asia Rapid Assessment report. Washington, DC.
  17. Meehl, G.A., T.F. Stocker, W.D. Collins, P. Friedlingstein, A.T. Gaye, J.M. Gregory, A. Kitoh, R. Knutti, J.M. Murphy, A. Noda, S.C.B. Raper, I.G. Watterson, A.J. Weaver, and Z.-C. Zhao. 2007. Global climate projections. 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. 747-845.
  18. Clark, P.U., A.J. Weaver, E. Brook, E.R. Cook, T.L. Delworth, and K. Steffen. 2008. Introduction: Abrupt changes in the Earth's climate system. In: Abrupt climate change. Synthesis and assessment product 3.4. Reston, VA: U.S. Geological Survey, pp. 19-59.
  19. The emissions scenarios referred to here are the high-emissions paths known as A2 and A1FI and the low-emissions path known as B1 from the Intergovernmental Panel on Climate Change.
  20. 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.
  21. 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.
  22. Richardson, Michael. 2008. Facing a rise in sea level. Japan Times. Online at http://search.japantimes.co.jp/ cgi-bin/ eo20080924a1.html. Accessed June 18, 2010.
  23. The economists used the FAC scenario described in Appendix 1 of Nicholls et al. (2008; see endnote 5). The projection includes water levels based on global sea-level rise, plus a storm enhancement factor, minus natural and human-induced local subsidence, combined with expected population and economic growth.
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