Sea level rise could nearly wipe out some of the world's most important coastal cities by 2050, according to a new study that suggests the impact on humans will be three times as great as previously estimated.
In a paper published on Tuesday, the authors developed a more accurate calculation of land elevation based on satellite readings, the standard way to estimate the impact of a large area of sea-level rise, and found that previous data were too optimistic. New research suggests that by the middle of the century, about 150 million people will be living on land below sea level.
Southern Vietnam could disappear altogether.
The first map shows earlier projections of inundated land by 2050. But the new outlook, the second map, suggests that the lower parts of the country will be flooded at high tide.
More than 20 million people, almost a quarter of Vietnam's population, live on land that is about to be submerged.
The study, by the new jersey-based scientific group Climate Central, was published in the journal Nature Communications. It says much of ho chi minh city, Vietnam's economic hub, will disappear with it. These projections do not take into account future population growth or land loss from coastal erosion.
由新泽西州的科学组织气候中心(Climate Central)所做的这项研究，发表在《自然通讯》(Nature Communications)期刊上。它称，越南的经济中心胡志明市的大部分地区将随之消失。这些预测没有考虑未来的人口增长或海岸侵蚀造成的土地损失。
Scott a. Kulp, one of the authors of the paper and A researcher at the climate center, said that standard elevation measurements using satellites make it difficult to distinguish real ground height from the tops of trees or buildings. So he and Benjamin Strauss, the chief executive of the climate center, used artificial intelligence to determine error rates and correct them.
论文作者之一、气候中心研究员斯科特·A·库尔普(Scott a . Kulp)说，使用卫星进行的标准高程测量很难区分真实的地面高度与树木或建筑物的顶部。因此，他和气候中心的首席执行官本杰明·施特劳斯(Benjamin Strauss)使用人工智能来确定错误率并进行校正。
In Thailand, more than 10 percent of residents now live on land that could be submerged by 2050, compared with just 1 percent based on earlier technology. Bangkok, the political and commercial capital, is particularly vulnerable.
Loretta Hieber Girardet, a United Nations disaster relief officer and Bangkok resident, said climate change would put pressure on cities in several ways. Global warming is flooding more places and will force poor farmers to leave their land and look for work in cities.
联合国减灾官员、曼谷居民洛蕾塔·希伯·吉拉德特(Loretta Hieber Girardet)表示，气候变化将在多个方面给城市带来压力。全球变暖淹没了更多的地方，而且还将迫使贫穷的农民离开土地到城市寻找工作。
It's a terrible formula, she said.
Shanghai is one of Asia's most important economic engines, and flooding is threatening to erode many cities in and around its heartland.
The discovery does not mean the end of these regions. New figures show that 110 million people already live below the high tide line, which strauss attributes to seawalls and other protective measures. Strauss says cities must invest heavily in such defenses, and quickly.
But even with the investment, defensive measures can only go so far. Strauss cites the example of New Orleans, a city below sea level that suffered devastating damage in 2005 after large parts of its levees and other protective equipment failed during Hurricane Katrina. "How deep do we want to live in a bowl?" He asked.
New projections show that large parts of mumbai, one of the world's largest cities and India's financial center, are in danger of being destroyed. The city center has a long history, and its core, once a series of islands, is particularly vulnerable.
Dina Ionesco of the International Organization for Migration, an intergovernmental group that coordinates Migration and development action, said that overall, the research suggests that countries should now start preparing for more people to relocate within their own countries.
协调移民和发展行动的政府间组织国际移民组织(International Organization for Migration)的黛娜·约内斯科(Dina Ionesco)说，总的来说，研究表明，各国现在应该开始为更多居民在国内重新安置做好准备。
We've been trying to sound the alarm, Mr. Yonesko said. "We knew it was coming." She added that there is little modern precedent for migration on this scale.
The disappearance of cultural heritage will also cause losses. The Egyptian city of Alexandria, founded by Alexander the great around 330 BC, could be submerged by rising waters.
Elsewhere, migration caused by rising sea levels could trigger or exacerbate regional conflicts.
By 2050, basra, Iraq's second largest city, could be flooded. If that happens, the impact could extend far beyond Iraq's borders, said John Castellaw, a retired Marine lieutenant general who served as chief of staff of the U.S. central command during the Iraq war.
Further loss of land from rising sea levels "could contribute to social and political instability in the region, which could lead to armed conflict and increase the likelihood of terrorism," said Mr Castello, who is on the advisory board of the Center for Climate and Security, a research and lobby group in Washington.
因为海平面上升而进一步损失土地，“可能促进该地区社会和政治不稳定，从而引发武装冲突，增加恐怖主义的可能性，”卡斯特洛表示，他目前是华盛顿研究和游说团体气候与安全中心(Center for Climate and Security)的顾问委员会成员。
So this is much more than an environmental issue, he said. "This is a humanitarian and security issue, as well as a possible military issue."