해수면 상승에 대한 대응이 시급하고 중요한 이유

[류혁근]

KISTI 미리안 『글로벌동향브리핑』

2014-02-10

해수면 상승에 대한 대응이 시급하고 중요한 이유

http://mirian.kisti.re.kr/futuremonitor/view.jsp?cn=GTB2014020113&service_code=03

새롭게 보고된 연구 결과는 21세기 동안 해안지역에서 폭풍 해일 홍수로 인한 피해가 엄청난 규모로 증가할 것이라고 예측하였다.

과학저널 Proceedings of the National Academy of Sciences를 통해 발표된 연구 결과에 따르면 적응 대책이 없이는 전세계 평균 폭풍 해일 피해 규모는 현재 연간 100에서 400억 달러에서 21세기 말에는 1,000,000억 달러까지 증가할 수 있을 것으로 예상된다.

본 연구는 베를린을 거점으로 한 세계기후포럼(Global Climate Forum, GCF)과 영국 사우샘프턴 대학교에 의해 수행되었으며, 미래에 발생하게 될 홍수가 연안의 범람원의 건물과 기반시설에 미칠 영향에 대한 종합적인 시뮬레이션 결과를 제시하였다. 이러한 홍수의 피해 규모는 해수면 상승과 연안지역의 인구 및 경제 성장으로 인하여 급격하게 증가할 것으로 예상된다. 상하이, 마닐라, 나이지리아 라고스와 같이 빠르게 성장하고 있는 연안 도시들로 인해 아시아와 아프리카는 특별히 큰 피해를 입을 것으로 예상된다.

GCF 소속이며 본 연구의 주저자인 Jochen Hinkel은 이러한 문제들은 간과한다면, 그에 따른 결과는 처참할 것이라고 주장하였다. 적응 대책이 마련되지 않는다면 2100년에는 전세계 인구의 5퍼센트에 달하는 6억의 인구가 연안 홍수 현상으로 인한 영향을 받게 될 것이다.

연구진은 각 국가들은 다른 어떤 대책보다도 둑을 세우거나 이미 있는 둑의 높이를 올리는 것과 같이 연안지역을 보호하는 대책들을 시행하고 투자할 필요가 있다고 주장하였다. 이러한 보호 대책들을 통해 21세기 동안 예상된 피해 규모는 연간 800억 달러 이하로 감소될 것이다. 연구진은 연간 100억에서 700억 달러 규모의 투자를 통해 이러한 감축을 이룰 수 있음을 발견하였다. 오늘날 연안 인구의 상당수가 이미 폭풍 해일 홍수로 인한 피해를 겪고 있는 아시아와 아프리카에서는 즉각적인 대책이 촉구된다.

그러나 최근 영국 서남부에서 발생한 연안 홍수 현상에서 나타난 바와 같이 유럽에 대한 투자 또한 필요하다. 본 연구의 공저자인 사우샘프턴 대학교의 Robert Nicholls 교수는 만약 해수면 상승이라는 문제를 간과한다면, 해안 홍수로 인한 피해는 계속해서 증가할 것이며, 현재에는 만족할만한 수준의 방어 대책도 시간이 지남에 따라 이 피해를 막을 수 없게 될 것이라고 설명하였다. 따라서 보다 높은 수준의 방지 대책을 계획하고 홍수에 견딜 수 있는 건물을 세우고 연안지역의 토지 이용을 전략적으로 계획하는 등의 방법을 통해 이러한 문제에 적응해 나가야 한다.

계속해서 상승하고 있는 해수면에 대한 적응이라는 문제에 직면하는 것은 쉽지 않다. 가난한 국가들과 이 문제에 크게 영향을 받는 작은 섬으로 이루어진 지역들은 자체적으로 필요한 재원을 확보하기 어려우며 국제적인 지원을 필요로 한다. 적응 과제와 더불어, 국제 재정 메커니즘은 기후 변화에 적응하는 데에 대한 재원을 모으는 데에 부진함이 확인되었다.

연구진은 만약 온실가스 배출의 상당량을 당장 감축할 수 없다면, 일부 지역들은 상당히 많은 수의 인구를 대피시키는 것을 심각하게 고려해야 한다. 그러나 기후 변화로 인해 해수면이 얼마나 상승하는가 와는 상관 없이 홍수로 인한 위험율이 높은 지역이 적절하게 개발되기 위해서는 신중한 장기적, 전략적 계획이 필요하다. 그러나 미래에 대한 충분한 대책 없이 해안가에 바로 건물을 짓는 것을 선호하는 부동산이나 관광 기업들과 같이 장기적인 이득만을 우선시하는 연안 개발 경향은 장기적인 관점에서 해결해야 할 과제가 되고 있다.

http://www.sciencedaily.com/releases/2014/02/140204131549.htm

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Climate change threatens to cause trillions in damage to world's coastal regions if they do not adapt to sea-level rise

Date: February 4, 2014

Source: University of Southampton

Aerial views during an Army search and rescue mission show damage from Hurricane Sandy to the New Jersey coast, Oct. 30, 2012. Credit: US Air Force photo by Master Sgt. Mark C. Olsen

Summary:

New research predicts that coastal regions may face massive increases in damages from storm surge flooding over the course of the 21st century. Global average storm surge damages could increase from about $10-$40 billion per year today to up to $100,000 billion per year by the end of century, if no adaptation action is taken.

According to the study published in the Proceedings of the National Academy of Sciences, global average storm surge damages could increase from about $10-$40 billion per year today to up to $100,000 billion per year by the end of century, if no adaptation action is taken.

The study, led by the Berlin-based think-tank Global Climate Forum (GCF) and involving the University of Southampton, presents, for the first time, comprehensive global simulation results on future flood damages to buildings and infrastructure in coastal flood plains. Drastic increases in these damages are expected due to both rising sea levels and population and economic growth in the coastal zone. Asia and Africa may be particularly hard hit because of their rapidly growing coastal mega-cities, such as Shanghai, Manila and Lagos.

"If we ignore this problem, the consequences will be dramatic," explains Jochen Hinkel from GCF and the study's lead author. In 2100, up to 600 million people (around 5 per cent 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," urges Hinkel. With such protection measures, the projected damages could be reduced to below $80 billion per year during the 21st century. The researchers found that an investment level of $10 to $70 billion per year could achieve such a reduction. Prompt action is needed most in Asia and Africa where, today, large parts of the coastal population are already affected by storm surge flooding.

However, investment must also occur in Europe as shown by the recent coastal floods in South West England. Professor Robert Nicholls from the University of Southampton, who is a co-author of the paper, says: "If we ignore sea-level rise, flood damages will progressively rise and presently good defences will be degraded and ultimately overwhelmed. Hence we must start to adapt now, be that planning higher defences, flood proofing buildings and strategically planning coastal land use."

Meeting the challenge of adapting to rising sea levels will not be easy, explains Hinkel: "Poor countries and heavily impacted small-island states are not able to make the necessary investments alone, they need international support." 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," adds Hinkel. Yet regardless of how much sea-level rise climate change brings, the researchers say careful long-term strategic planning can ensure that development in high-risk flood zones is appropriately designed or avoided. Professor Nicholls says: "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 with little thought about the future."

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Story Source:

The above story is based on materials provided by University of Southampton. Note: Materials may be edited for content and length.

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Journal Reference:

1. J. Hinkel, D. Lincke, A. T. Vafeidis, M. Perrette, R. J. Nicholls, R. S. J. Tol, B. Marzeion, X. Fettweis, C. Ionescu, A. Levermann. Coastal flood damage and adaptation costs under 21st century sea-level rise. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1222469111

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University of Southampton. "Climate change threatens to cause trillions in damage to world's coastal regions if they do not adapt to sea-level rise." ScienceDaily. ScienceDaily, 4 February 2014. <www.sciencedaily.com/releases/2014/02/140204131549.htm>.

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Date: February 23, 2012

Source: Princeton University

'Storm of the century' may become

'storm of the decade'

Summary:

Researchers report that projected increases in sea level and storm intensity brought on by climate change would make devastating storm surges -- the deadly and destructive mass of water pushed inland by large storms -- more frequent in low-lying coastal areas. Regions such as the New York City metropolitan area that currently experience a disastrous flood every century could instead become submerged every one or two decades.

Simulations by researchers from Princeton University and the Massachusetts Institute of Technology revealed that projected increases in sea level and storm intensity brought on by climate change could make devastating storm surges more frequent. Using the New York City area as a model, the researchers found that floods experienced every century could instead occur every one or two decades. The worst simulated flood (left) was a 15.5-foot storm surge at Manhattan's Battery (black star) that stemmed from a high-intensity storm (black line) moving northeast and very close to the city. A weaker but larger northwest-bound storm (right) that was further from the city would result in floodwater nearly 15 feet deep as its strongest winds pushed water toward the Battery. The colored contours represent the maximum surge height, from 0 (blue) to 5 (violet) meters.

Credit: Image by Ning Lin

As the Earth's climate changes, the worst inundations from hurricanes and tropical storms could become far more common in low-lying coastal areas, a new study suggests. Researchers from Princeton University and the Massachusetts Institute of Technology found that regions such as the New York City metropolitan area that currently experience a disastrous flood every century could instead become submerged every one or two decades.

The researchers report in the journal Nature Climate Change that projected increases in sea level and storm intensity brought on by climate change would make devastating storm surges -- the deadly and destructive mass of water pushed inland by large storms -- more frequent. Using various global climate models, the team developed a simulation tool that can predict the severity of future flooding an area can expect.

The researchers used New York City as a test case and found that with fiercer storms and a 3-foot rise in sea level due to climate change, "100-year floods" -- a depth of roughly 5.7 feet above tide level that occurs roughly once a century -- could more likely occur every three to 20 years. What today are New York City's "500-year floods" -- or waters that reach more than 9 feet deep -- could, with climate change, occur every 25 to 240 years, the researchers wrote.

The research is not only the first to examine the future intensity of storm surges, but also to offer a tool for estimating an area's vulnerability, said co-author Michael Oppenheimer, the Albert G. Milbank Professor of Geosciences and International Affairs at Princeton.

"Coastal managers in cities like New York make daily decisions about costly infrastructure that would be affected by such storms. They need a reliable indicator of the risk," he said.

"Our modeling approach is designed as a key step in this direction," Oppenheimer said. "As the world warms, risks will increase across a variety of fronts, and the threat to coastal infrastructure in the face of an already-rising sea level and potentially stronger hurricanes could be one of the most costly unless we are able to anticipate and reduce vulnerability."

Lead author Ning Lin, a postdoctoral fellow at MIT, said that knowing the frequency of storm surges may help urban and coastal planners design seawalls and other protective structures. Lin, who received her Ph.D. from Princeton in 2010, began the project at Princeton then continued it at MIT; the current report is based on her work at MIT.

"When you design your buildings or dams or structures on the coast, you have to know how high your seawall has to be," said Lin, noting that Manhattan's seawalls now stand a mere 5 feet high. "You have to decide whether to build a seawall to prevent being flooded every 20 years."

Lin and Oppenheimer worked with study co-authors Kerry Emanuel, an MIT atmospheric science professor, and Erik Vanmarcke, a Princeton professor of civil and environmental engineering. Lin, Vanmarcke and Emanuel also co-wrote a 2010 report on the project published in the Journal of Geophysical Research that was based on Lin's work at Princeton.

Carol Friedland, an assistant professor of construction management and industrial engineering at Louisiana State University, sees the latest results as a useful tool to inform coastal design -- particularly, she notes, as most buildings are designed with a 60- to 120-year "usable lifespan."

"The physical damage and economic loss that result from storm surge can be devastating to individuals, businesses, infrastructure and communities," Friedland said. "For current coastal community planning and design projects, it is essential that the effects of climate change be included in storm-surge predictions."

The researchers ran a total of 45,000 storm simulations for the New York City region under two scenarios: current climate conditions from 1981 to 2000 based on observed data and four global climate models; and projected climate conditions for the years 2081 to 2100 based on the four climate models, as well as future carbon dioxide output as predicted by the Intergovernmental Panel on Climate Change (IPCC). Oppenheimer is a longtime participant in the IPCC.

Storms in the simulations occurred within a 125-mile (200-kilometer) radius of the Battery, at the southern tip of Manhattan, and generated a maximum wind speed of at least 50 miles per hour. Hurricanes are classified as having a maximum wind speed of at least 74 miles per hour.

Once the researchers simulated storms in the region, they then simulated the resulting storm surges using three different methods, including one used by the National Hurricane Center (NHC). In the days or hours before a hurricane hits land, the NHC uses a storm-surge model to predict the risk and extent of flooding from the impending storm. Such models, however, have not been used to eval‎uate multiple simulated storms under a scenario of climate change.

Again, the group compared results from multiple methods: one from the NHC that simulates storm surges quickly, though coarsely; another method that generates more accurate storm surges, though more slowly; and a method in between, developed by Lin and her colleagues, that estimates relatively accurate surge floods, relatively quickly.

The researchers found that the frequency of massive storm surges would go up in proportion to an increase in more violent storms and a rise in sea level, the researchers reported. They noted that climate models predict that the sea level around New York City could rise by 1.5 to nearly 5 feet by the end of the 21st century.

Flooding was amplified by the storm's wind direction and proximity to the city. The worst simulated flood, a 15.5-foot storm surge at Manhattan's Battery, stemmed from a high-intensity storm moving northeast and very close to the city. On the other hand, a weaker but larger northwest-bound storm that was further from the city resulted in floodwater nearly 15 feet deep as its strongest winds pushed water toward the Battery.

Floods of this magnitude outstrip the most devastating storm surges in the city's recorded history, Lin said. The worst accompanied the 1821 Norfolk and Long Island hurricane, which packed winds of 135 miles per hour and is one of only four hurricanes known to have made landfall in New York City since pre-Columbian times.

"The highest [surge flood] was 3.2 meters [10.4 feet], and this happened in 1821," Lin said. "That's the highest water level observed in New York City's history, which is like a present 500-year event."

The study was published online Feb. 14 by the journal Nature Climate Change, and was supported by the U.S. National Oceanic and Atmospheric Administration, and the Princeton Environmental Institute through a fellowship from the Program in Science, Technology and Environmental Policy based in Princeton's Woodrow Wilson School of Public and International Affairs.

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Story Source:

The above story is based on materials provided by Princeton University. The original article was written by Morgan Kelly (Jennifer Chu of MIT contributed to this story). Note: Materials may be edited for content and length.

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Journal Reference:

1.Ning Lin, Kerry Emanuel, Michael Oppenheimer, Erik Vanmarcke. Physically based assessment of hurricane surge threat under climate change. Nature Climate Change, 2012; DOI: 10.1038/nclimate1389

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Cite This Page:

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Princeton University. "'Storm of the century' may become 'storm of the decade'." ScienceDaily. ScienceDaily, 23 February 2012. <www.sciencedaily.com/releases/2012/02/120223133216.htm>.