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environment

From New York to Jakarta, land in many coastal cities sinking faster than sea levels are rising

22 Comments
By Steven D’Hondt, Meng (Matt) Wei and Pei-Chin

Sea level rise has already put coastal cities on notice thanks to increasing storm surges and even sunny day flooding at high tide. These challenges will continue to grow because global projections point to a mean sea level rise of at least one foot above year-2000 levels by the end of this century.

However, many cities are facing another factor making them even more vulnerable to rising waters: land subsidence.

The three of us are scientists at the University of Rhode Island Graduate School of Oceanography working with the U.S. Geological Survey to research challenges facing waterfront cities. Our findings indicate that land is sinking faster than sea levels are rising in many coastal cities throughout the world.

By using radar images of the Earth’s surface collected from orbiting satellites, we measured subsidence rates in 99 coastal cities worldwide. These rates are highly variable within cities and from city to city, but if they continue, many metropolises will experience flooding much sooner than projected by sea level rise models.

Cities in South, Southeast and East Asia are seeing the most rapid rates of subsidence.

Indonesia, for example, is moving its capital 800 miles from Jakarta to Nusantara in large part because Jakarta is sinking at an alarming rate due to groundwater extraction.

Other regions are not immune. Our research with Tom Parsons of the U.S. Geological Survey found that most of New York Cityis sinking between 1 to 4 millimeters per year due to a combination of glacial rebound and the weight of its more than 1 million buildings. In a city where sea level is projected to rise between 8 and 30 inches by 2050, subsidence further increases its vulnerability to coastal storms.

In the U.S., most of the cities on the Atlantic coast are subsiding due to glacial rebound. Even if the rate is low at minus-1 millimeter per year, it should be accounted. Other cities in the U.S., especially in the Gulf of Mexico, including Houston and New Orleans, also face subsidence.

Governments around the world are facing the challenge of coastal areas that are subsiding, and there is a shared global challenge of mitigation against a growing flooding hazard.

While our research continues to evolve – for example, by using machine learning to improve our monitoring capability – we urge city planners, emergency managers and other decision-makers to account for subsidence in the plans they are making today to prepare for the impacts of rising sea levels in the future.

Steven D’Hondt is Professor of Oceanography, Graduate School of Oceanography, University of Rhode Island. Meng (Matt) Wei is an Associate Professor of Oceanography, University of Rhode Island and Pei-Chin Wu is a Ph.D. Candidate in Oceanography, University of Rhode Island.

The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.

© The Conversation

©2024 GPlusMedia Inc.

22 Comments
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Coastal erosion and rising seas are major problems in many locations. Cliff-side properties here today gone tomorrow.

3 ( +6 / -3 )

On the one hand, the ice is melting and this contributes to the rising of the sea level. But on the other hand the liquid water is evaporating, and this contributes to the lowering of the sea level. The latter effect is more rapid and powerful then the former, so the net effect for the long range is the lowering of the sea level.

-7 ( +1 / -8 )

Checkout The Water Will Come by Goodell if you are interested in the topic.

0 ( +3 / -3 )

@YGHome The latter effect is more rapid and powerful then the former,

Do you have any references to this 'fact'?

I'd be very interested to see them.

0 ( +3 / -3 )

Do you have any references to this 'fact'?

The answer lies in elementary physics. At a certain point all of the ice will melt away, so the contribution to the rising of the sea level will cease completely. At the same time the evaporation process will continue (and accelerate) with the rising of the temperature.

-5 ( +2 / -7 )

 But on the other hand the liquid water is evaporating, and this contributes to the lowering of the sea level. 

That is not correct, evaporation can accelerate or intensify the water cycle, but without that water being captured outside of the ocean there is no mechanism where it would lower the sea levels.

https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=2438

*Increased temperatures cause changes in atmospheric circulation and increase evaporation and water vapor, resulting in precipitation increases, more intense precipitation, more storms and sea level rise.*

-2 ( +3 / -5 )

without that water being captured outside of the ocean there is no mechanism where it would lower the sea levels

The water is captured in the atmosphere. Simple physics: When the humidity increases there is more water in the atmosphere. Sometimes a part of the water falls down as fierce precipitation when there is a downwards oscillation of the temperature. However, these oscillations will cease at a certain point, and the temperature will rise in a steep monotonous curve.

-2 ( +2 / -4 )

Al Gore's Inconvenient Truth "Documentary" from earyl 2000s is still available to watch on Youtube.

Back then all the "experts" were claiming that all the coastal cities would be flooded by now.

Beachfront property on the Maldives is selling for record prices.

-3 ( +5 / -8 )

It is happening, just ask people in the S. Pacific whose islands are disappearing into the oceans and where NZ and Australia are having to step up and offer these people homes for life, and before that happens, they are having to transfer their island's treasured cultural artifacts with them.

Some other islands in fear to be gone in the next 20 to 50 years Tonga, Samoa and more along with Jakaratta.

0 ( +3 / -3 )

Who cares what Al Gore said in 2006. He is not a scientist

Renée Montagne has given you the following answer: "Gore is a lay person, he is not a scientist, and he's careful to say that. But that said, he does get the big picture very well. Most scientists say he really can see the forest for the trees." And she continues: "I saw Al Gore give a talk at the American Geophysical Union meeting in San Francisco last December. He was cheered by this enormous audience of scientists, who were really excited to hear his message that it's time to take global warming seriously."

2 ( +4 / -2 )

 In a city where sea level is projected to rise between 8 and 30 inches by 2050, subsidence further increases its vulnerability to coastal storms.

Coastal storms are a natural occurrence. Taking place as far as history records.

-1 ( +5 / -6 )

The water is captured in the atmosphere

No, it is not, it is released with increased speed as the reference clearly proves, that is not what a reservoir would need to do to have an effect on sea levels, the increase in precipitation do not require at any point for the temperature to drop. The US environmental agency explicitly contradicts your unsubstantiated claims (exactly zero references of that claim) that means you need to prove them wrong before trying to repeat that claim.

l Gore's Inconvenient Truth "Documentary" from earyl 2000s is still available to watch on Youtube.

Much better yet, the hundreds of papers published in the scientific literature are also available, and they prove beyond any reasonable doubt the conclusions of the scientific consensus.

Coastal storms are a natural occurrence. Taking place as far as history records.

But having an increase on the frequency, potency or reach of the storms thanks to human activity derived climate change is not natural by definition. That is what is becoming a more serious problem year with year.

-3 ( +1 / -4 )

the increase in precipitation do not require at any point for the temperature to drop

Precipitation occurs only when the temperature drops.

-2 ( +1 / -3 )

Precipitation occurs only when the temperature drops.

No. But what is true is that hotter air can hold more moisture than cool air. THAT is why you have rain. Antarctica is very cold and also very dry. Don't let all that ice fool you. Relative humidity in Antarctica is typically single digits. Many parts qualify as desert but because it is so cold what precipitation that does fall doesn't melt fast or often it never melts. It just builds up year after year, century after century.

I have experienced rain with over 35C temps simultaneously in the Philippines. Heat rises. Hot moist air rises and as it does, it cools to or below the dew point and you have precipitation. But without the rising column of hot moist air you do not get that big thunderstorm. Increasing temperatures increase humidity and accelerate the process making the storms more intense.

1 ( +2 / -1 )

Precipitation occurs only when the temperature drops.

But the increase in precipitation because of climate change will still happen even with higher temperatures thus it can't be considered a reservoir that would increase in capacity, this is the reason the US environmental agency explicitly calls this a reason for sea levels rise, not a decrease as you claimed. You have still not brought any refence where an institution supports your claim, so at this point the USEA is a much more trustworthy source about the final effect of the increase of temperature.

-3 ( +2 / -5 )

it cools to or below the dew point and you have precipitation.

That's right. It has to cool at least a little bit, and only then precipitation can occur.

0 ( +2 / -2 )

That's right. It has to cool at least a little bit, and only then precipitation can occur.

Which still contradicts your point, condensation in air do NOT reduce sea levels but instead contribute to their rise because increases in temperature do not make it hold more permanently, it just makes the cycle faster and stronger. This according to a scientific authority in the reference provided.

-2 ( +2 / -4 )

But having an increase on the frequency, potency or reach of the storms thanks to human activity derived climate change is not natural by definition. That is what is becoming a more serious problem year with year.

Actually storms such as hurricanes are less frequent now than 100 years ago, and fewer of them are even reaching land,

-2 ( +2 / -4 )

Actually storms such as hurricanes are less frequent now than 100 years ago, and fewer of them are even reaching land,

Hurricanes are now more destructive thanks to climate change, there is nothing positive on more people dying and more infrastructure lost because of it.

https://www.npr.org/2023/08/30/1196865225/whats-the-connection-between-climate-change-and-hurricanes

New research shows that over the past 40 years, storms within a few hundred miles of coasts have become about three times more likely to intensify fast.

https://www.c2es.org/content/hurricanes-and-climate-change/

Climate change is worsening hurricane impacts in the United States by increasing the intensity and decreasing the speed at which they travel. Scientists are currently uncertain whether there will be a change in the number of hurricanes, but they are certain that the intensity and severity of hurricanes will continue to increase.

-1 ( +1 / -2 )

Hurricanes are now more destructive thanks to climate change, there is nothing positive on more people dying and more infrastructure lost because of it.

So you admit hurricanes are declining.

And if there are more deaths it would go in line with the increase in population on the coasts. Simple to figure that one out.

Hurricane numbers are decreasing in every ocean basin except for one, study finds

https://www.cnn.com/2022/06/27/weather/tropical-cyclone-frequency-21st-century-climate/index.html

-2 ( +1 / -3 )

So you admit hurricanes are declining.

The source do not make such claim that is you, and it completely refutes the claim that this is in any way better since they become even more destructive and last longer even with the same frequency.

Your reference does nothing to disprove the one I provided, so the consequence is still as negative in the short and long term.

New research shows that over the past 40 years, storms within a few hundred miles of coasts have become about three times more likely to intensify fast.

Climate change is worsening hurricane impacts in the United States by increasing the intensity and decreasing the speed at which they travel. 

-1 ( +0 / -1 )

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