Climate change and the world’s coasts

Coastal regions may face massive increases in damages from storm surge flooding over the course of the 21st century.

According to a new study published in the Proceedings of the National Academy of Sciences, global average storm surge damages could increase from about 10-40 billion USD per year today to up to 100,000 billion USD per year by the end of century, if no adaptation action is taken. The study lead by the Berlin-based think-tank Global Climate Forum (GCF) presents, for the first time, comprehensive global simulation results on future storm surge damages to buildings and infrastructure. Drastic increases in these damages are expected, on one hand, due to rising sea-levels and, on the other hand, due to population and economic growth. Asia and Africa may be particularly hard hit because of their rapidly growing coastal mega-cities, such as Shanghai, Manila or Lagos.

“If we ignore this problem, the consequences will be dramatic,” explained Jochen Hinkel from GCF and the study’s lead author. In 2100, up to 600 million people (around 5 percent of the global population) could be affected by coastal flooding if no adaptation measures are put in place. “Countries need to take action and invest in coastal protection measures, such as building or raising dikes, amongst other options,” urged Hinkel. With such protection measures, the projected damages could be reduced to below 80 billion USD per year during the 21st century. The researchers found that investments level of 10 to 70 billion USD per year could achieve such a reduction.

Prompt action is needed most in Asia and Africa, where today large parts of the population are

already affected by storm surge flooding. Yet even Germany must invest in coastal protection. It is not only dikes that are needed however. Alternative and more flexible coastal protection measures that better fit the natural environmental should also be developed. Examples of such alternatives to dikes are the reintroduction of mangrove forests, the rehabilitation of coastal dunes or artificial oyster banks.

Meeting the challenge of adapting to rising sea-levels will not be easy. “Poor countries and heavily impacted small-island states are not able to make the necessary investments alone. They need international support,” explained Hinkel. Adding to the challenge, international finance mechanisms have thus far proved sluggish in mobilising funds for adapting to climate change, as the debate on adaptation funding at the recent climate conference in Warsaw once again confirmed.

“If we do not reduce greenhouse gases swiftly and substantially, some regions will have to seriously consider relocating significant numbers of people in the longer run,” explained Hinkel. Yet regardless of how much sea-level rise climate change brings, careful long-term regional and urban planning can ensure that development in high-risk flood zones is avoided. This long-term perspective is however a challenge to bring about, as coastal development tends to be dominated by short-term interests of, for example, real-estate and tourism companies, which prefer to build directly at the waterfront. More

 

Our Perpetual Ocean

This is an animation of ocean surface currents from June 2005 to December 2007 from NASA satellites. Watch how bigger currents like the Gulf Stream in the Atlantic Ocean and the Kuroshio in the Pacific carry warm waters across thousands of miles at speeds greater than four miles per hour (six kilometers per hour); how coastal currents like the Agulhas in the Southern Hemisphere move equatorial waters toward Earth's poles; and how thousands of other ocean currents are confined to particular regions and form slow-moving, circular pools called eddies. Credit: NASA/SVS
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The swirling flows of tens of thousands of ocean currents were captured in this scientific visualization created by NASA's Goddard Space Flight Center in Greenbelt, Md.

"There is also a 20-minute long tour, which shows these global surface currents in more detail," says Horace Mitchell, the lead of the visualization studio. "We also released a three-minute version on our NASA Visualization Explorer iPad app."

Both the 20-minute and 3-minute versions are available in high definition here: http://svs.gsfc.nasa.gov/goto?3827

The visualization covers the period June 2005 to December 2007 and is based on a synthesis of a numerical model with observational data, created by a NASA project called Estimating the Circulation and Climate of the Ocean, or ECCO for short. ECCO is a joint project between the Massachusetts Institute of Technology and NASA's Jet Propulsion Laboratory in Pasadena, Calif. ECCO uses advanced mathematical tools to combine observations with the MIT numerical ocean model to obtain realistic descriptions of how ocean circulation evolves over time.

These model-data syntheses are among the largest computations of their kind ever undertaken. They are made possible by high-end computing resources provided by NASA's Ames Research Center in Moffett Field, Calif.

ECCO model-data syntheses are being used to quantify the ocean's role in the global carbon cycle, to understand the recent evolution of the polar oceans, to monitor time-evolving heat, water, and chemical exchanges within and between different components of the Earth system, and for many other science applications.

In the particular model-data synthesis used for this visualization, only the larger, ocean basin-wide scales have been adjusted to fit observations. Smaller-scale ocean currents are free to evolve on their own according to the computer model's equations. Due to the limited resolution of this particular model, only the larger eddies are represented, and tend to look more 'perfect' than they are in real life. Despite these model limitations, the visualization offers a realistic study in both the order and the chaos of the circulating waters that populate Earth's ocean.

Data used by the ECCO project include: sea surface height from NASA's Topex/Poseidon, Jason-1, and Ocean Surface Topography Mission/Jason-2 satellite altimeters; gravity from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment mission; surface wind stress from NASA's QuikScat mission; sea surface temperature from the NASA/Japan Aerospace Exploration Agency Advanced Microwave Scanning Radiometer-EOS; sea ice concentration and velocity data from passive microwave radiometers; and temperature and salinity profiles from shipborne casts, moorings and the international Argo ocean observation system. More