A string of recent international studies projected into the next decades agree unhesitatingly describe a disturbing horizon thousands of cities and millions of partially or totally under water inhabitants by rising sea levels caused, in turn, by global warming and climate change in general.

This global study makes a first estimation of the exposure of the world’s great port cities to coastal flooding due to storm surge and damage from high winds.

It also investigates how climate change may impact each port city through coastal flooding by 2070, as its collapse and population growth and urbanization.

The assessment provides a much more complete than previous studies and analysis focuses on the 136 port cities around the world with more than one million inhabitants.

Most of these large port cities are in Asia (38%), and many of them (27%) environments deltas, also mainly in Asia.

The cities in areas of delta (such as the Rio de la Plata, the Orinoco and the Amazon, NDR) tend to be at greater risk of coastal flooding due to their tendency to be at a lower level and the background of significant collapse (natural and anthropogenic).

(…) The analysis shows that a large number of people are already exposed to coastal flooding in large port cities. In all cities, about 40 million people (0.6% of the world population, or nearly 1 in 10 of the total population of cities considered here) are exposed to an event of coastal flooding in 100 years.

The exhibition focuses on some of the cities: the 10 cities with the highest exposure of the population meets half the total exposure and 30 major cities, 80 percent. Of those 30 cities, 19 are in the deltas. For the conditions of 2005 the top 10 cities in terms of population most exposed are Mumbai, Guangzhou, Shanghai, Miami, Ho Chi Minh City, Calcutta, the Grand New York, Osaka-Kobe, Alexandria and New Orleans.

The area of ​​a hospital in New Orleans, USA, after Katrina.

The ten cities with the highest exposure of the population today are almost equally divided between developed and developing countries. When considering the assets, the current distribution is much more inclined to developed countries and the wealth of the cities becomes key naturally.

The total value of assets exposed in 2005 was estimated at US $ 3 billion in the US, or 5% of global GDP that year (measured in international dollars). The top 10 cities in this ranking is Miami, the Grand New York, New Orleans, Osaka-Kobe, Tokyo, Amsterdam, Rotterdam, Nagoya, Tampa-St Petersburg and Virginia Beach.

These cities contain 60% of total exposure, but for only three countries, and the wealthy: United States, Japan and the Netherlands.

For 2070, the total exposed population could grow more than threefold, to 150 million, due to the combined effects of climate change (sea level rise and increased storminess), subsidence, population growth and urbanization.

The total exposure of assets could grow even more dramatically, to US $ 35 billion by 2070, more than ten times as current levels and an increase of 9% of projected annual GDP in that period.

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More than 1,700 cities and towns across the US, including Boston, New York and Miami, will see vast populations live below the high tide line at the end of this century, according to a new study estimated the impact of climate change.

To these 1,700 people under the expected future water due to emissions of greenhouse gases already accumulated in the atmosphere, according to the analysis published in the Proceedings of the National Academy of Sciences. In 80 of these cities, the future under water come much earlier, in the next decade.

“Even if we could stop global emissions morning for a dime, Fort Lauderdale, Miami Gardens, Hoboken and New Jersey will be under sea level,” said Benjamin Strauss, Climate Central researcher and lead author of the article.

But the drastic cuts in emissions-much higher than Barack Obama and other world leaders have agreed so far – could safely put about 1,000 of those cities to avoid a rise in sea level, according to the study.

(…) Those 1,700 cities have 25% of its population living below the high tide line in 2100. A group of 79 cities and towns with a combined population of 835,000 people, remain under water already in 2023. Around half the population of Fort Lauderdale, Hoboken, and Palm Beach would be living below the high tide line in 2023.

By Suzanne Goldenberg.

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The water level of the sea could rise up to 20 meters at the end of the XXI century, if the ice of West Antarctica and Greenland suffer a similar thaw Pliocene. At that time, the Earth experienced a global increase in temperature similar to that provided today by various research groups.

These findings correspond to a study published in the journal Nature Geoscience, which involved scientists from Imperial College London and has enjoyed the participation of experts from Spanish CSIC.

He tells us that work in the Pliocene Earth experienced a global increase in temperature became 2 ° C and 3 ° C above (between 5.33 million and 2.58 million years ago years period) the similar to the current and expected later this century.

Another similarity factor is that the atmospheric CO2 concentration then was very similar to that existing today in our atmosphere.
Both factors then prompted the merger of much of the ice planet, fostering a sea level rise of up to 20 meters.

Here’s where the big news of this study is, because until then it was believed that the melting of the Antarctic ice had caused an increase of 10 meters.

To reach these conclusions, researchers analyzed samples of oriental Pliocene Antarctic marine mud. These tests were made in 2010, as part of the International Ocean Drilling Program, co-led by the CSIC, more than three kilometers deep in Antarctica itself.

Among the mud rocks that were carried by glaciers and icebergs, of which after analysis has revealed their place of origin they are found; a key to reconstruct the extent of glaciers and its evolution throughout the time data.


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