4°C Global Warming Could Submerge Lands for 470 to 760 Million People

Summary: A scenario of 4 degrees Celsius global warming could submerge lands for 470 to 760 million people, according to Climate Central's Nov. 9 analysis.

London, after 4 degrees C warming (left), after 2 degrees C warming (right): Climate Central, CC BY 2.0, via climatecentral.org

An analysis posted Nov. 9, 2015, on nonprofit news organization Climate Central’s website provides searing images of flooded and submerged major cities in scenarios of post 2100 sea level rises stemming from global warming increases of 2 degrees Celsius (3.6 degrees Fahrenheit) and 4 degrees C (7.2 degrees F).

Chilling numbers spotlight the differences in long-term global sea level rises effected by the 2 degrees C difference between the two global warming models. A median sea level rise of 4.7 meters (15.4 feet), in a range of 3 to 6.3 meters (9.8 to 20.6 feet), is projected for a 2 degrees C temperature increase. Global warming by 4 degrees C yields a median rise of 8.9 meters (29.19 feet), in a range of 6.9 to 10.8 meters (22.6 to 35.4 feet). Warming of 2 degrees C could affect about 130 million people across the globe while 4 degrees C global warming could sufficiently raise sea levels to submerge homelands for 470 to 760 million people globally.

China stands as the country with the most to lose and the most to gain in the two warming scenarios. About 145 million of China’s population occupy lands implicated in the 4 degrees C global warming model. A warming limit of 2°C whittles the affected population down to 64 million.

Apart from Australia, every populated continent is represented in the top-20 at-risk countries. Greater percentages of the landed population for small nations, such as Guyana, Suriname and the Netherlands, and for small island nations, such as the Cayman Islands and the Marshall Islands, are at risk from 4 degrees C global warming. Even with 2 degrees C warming, five megacities, all sited in Asia, face the prospect of 25 percent implicated land: Shanghai and Hong Kong in China; Hanoi, Viet Nam; Mumbai, India; Osaka, Japan.

The business-as-usual approach for the 21st century, without carbon emission cuts, yields the 4 degrees C global warming scenario, which may engender locked-in sea level rises as early as within 200 years or as far off as 2,000 years. The carbon-cutting framework of the proposed international target of 2 degrees C significantly reduces the area of locked-in sea level rising.

Climate Central offers its website users an interactive Mapping Choices global platform that responds to user input of any coastal city name or postal code worldwide with a local map visualization comparing possible consequences of warming and emissions scenarios.

Conveying information with effective graphics and videos, Climate Central’s online analysis features information presented in the organization’s November 2015 report, Mapping Choices: Carbon, Climate, and Rising Seas, Our Global Legacy. The transfer of information from the report to online graphics and videos has the purpose of providing valuable information preparatory to the United Nations’ critical global climate summit, the 21st session of the Conference of the Parties (COP 21), scheduled from Nov. 30 to Dec. 12, 2015, in Le Bourget, outside of Paris.

“It is really daunting, and sad, to look at what happens if we warm the planet by 4° Celsius. So many great monuments of the world, so many great cities, would be below the sea level in that scenario,” notes Dr. Ben Strauss, vice-president of sea level and impacts at Climate Central.

screenshot of Climate Central's Mapping Choices' scenarios for Chesapeake, Norfolk and Portsmouth in Virginia: Surging Seas Mapping ChoicesClimate Central @climatecentral via Facebook Oct. 12, 2015

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

My special thanks to Dan Rizza at Climate Central for permission to include images of London: CC BY 2.0, via Climate Central @ http://www.climatecentral.org/news/global-icons-at-risk-from-sea-level-rise-pictures-19633

screenshot of Climate Central's Mapping Choices' scenarios for Chesapeake, Norfolk and Portsmouth in Virginia: Surging Seas Mapping ChoicesClimate Central @climatecentral via Facebook Oct. 12, 2015, @ https://www.facebook.com/climatecentral/posts/10156084369415024

For further information:

Climate Central @climatecentral. "Today we launched Mapping Choices, an interactive map that allows anyone to type in a coastal U.S. city and compare projected long-term consequences of different emissions and warming scenarios." Facebook. Oct. 12, 2015.
Available @ https://www.facebook.com/climatecentral/posts/10156084369415024

climatecentraldotorg. "Mapping Choices." YouTube. Nov. 8, 2015.
Available @ https://www.youtube.com/watch?v=Z1x3fJWlLu4

Mapping Choices: Carbon, Climate, and Rising Seas -- Our Global Legacy: Executive Summary. Climate Central > Research > Reports. November 2015.
Available @ http://sealevel.climatecentral.org/research/reports/mapping-choices-carbon-climate-and-rising-seas-our-global-legacy

Strauss, Benjamin. "Images Show Impact of Sea Level Rise on Global Icons." Climate Central. Nov. 8, 2015.
Available @ http://www.climatecentral.org/news/global-icons-at-risk-from-sea-level-rise-pictures-19633

Strauss, Benjamin H., Scott Kulp and Anders Levermann. "Carbon choices determine US cities committed to futures below sea level." Proceedings of the National Academy of Sciences of the United States of America, vol. 112, no. 44 (Nov. 3, 2015): 13508-13513.
Available @ http://www.pnas.org/content/112/44/13508.full

Strauss, Benjamin H., Scott Kulp and Anders Levermann. Mapping Choices: Carbon, Climate, and Rising Seas, Our Global Legacy. Climate Central Research Report. November 2015.
Available @ http://sealevel.climatecentral.org/uploads/research/Global-Mapping-Choices-Report.pdf