Sea levels rising in parts of Indian Ocean, according to new study

Jul 13, 2010
Rising sea levels in parts of the Indian Ocean appear to be at least partly the result of rising greenhouse emissions. Credit: University of Colorado

Newly detected rising sea levels in parts of the Indian Ocean, including the coastlines of the Bay of Bengal, the Arabian Sea, Sri Lanka, Sumatra and Java, appear to be at least partly a result of human-induced increases of atmospheric greenhouse gases, says a study led by the University of Colorado at Boulder.

The study, which combined sea surface measurements going back to the 1960s and satellite observations, indicates anthropogenic likely is amplifying regional sea rise changes in parts of the Indian Ocean, threatening inhabitants of some coastal areas and islands, said CU-Boulder Associate Professor Weiqing Han, lead study author. The -- which may aggravate monsoon flooding in Bangladesh and India -- could have far-reaching impacts on both future regional and .

The key player in the process is the Indo-Pacific warm pool, an enormous, bathtub-shaped area of the tropical oceans stretching from the east coast of Africa west to the International Date Line in the Pacific. The warm pool has heated by about 1 degree Fahrenheit, or 0.5 degrees Celsius, in the past 50 years, primarily caused by human-generated increases of greenhouse gases, said Han.

"Our results from this study imply that if future anthropogenic warming effects in the Indo-Pacific warm pool dominate natural variability, mid-ocean islands such as the Mascarenhas Archipelago, coasts of Indonesia, Sumatra and the north Indian Ocean may experience significantly more sea level rise than the global average," said Han of CU-Boulder's atmospheric and oceanic sciences department.

A paper on the subject was published in this week's issue of Nature Geoscience. Co-authors included Balaji Rajagopalan, Xiao-Wei Quan, Jih-wang Wang and Laurie Trenary of CU-Boulder, Gerald Meehl, John Fasullo, Aixue Hu, William Large and Stephen Yeager of the National Center for Atmospheric Research in Boulder, Jialin Lin of Ohio State University, and Alan Walcraft and Toshiaki Shinoda of the Naval Research Laboratory in Mississippi.

While a number of areas in the Indian Ocean region are showing sea level rise, the study also indicated the Seychelles Islands and Zanzibar off Tanzania's coastline show the largest sea level drop. Global sea level patterns are not geographically uniform, and sea rise in some areas correlate with sea level fall in other areas, said NCAR's Meehl.

The Indian Ocean is the world's third largest ocean and makes up about 20 percent of the water on Earth's surface. The ocean is bounded on the west by East Africa, on the north by India, on the east by Indochina and Australia, and on the south by the Southern Ocean off the coast of Antarctica.

The patterns of sea level change are driven by the combined enhancement of two primary atmospheric wind patterns known as the Hadley circulation and the Walker circulation. The Hadley circulation in the Indian Ocean is dominated by air currents rising above strongly heated tropical waters near the equator and flowing poleward, then sinking to the ocean in the subtropics and causing surface air to flow back toward the equator.

The Indian Ocean's Walker circulation causes air to rise and flow westward at upper levels, sink to the surface and then flow eastward back toward the Indo-Pacific warm pool. "The combined enhancement of the Hadley and Walker circulation form a distinct surface wind pattern that drives specific sea level patterns," said Han.

The international research team used several different sophisticated ocean and climate models for the study, including the Parallel Ocean Program -- the ocean component of NCAR's widely used Community Climate System Model. In addition, the team used a wind-driven, linear ocean model for the study.

"Our new results show that human-caused changes of atmospheric and oceanic circulation over the Indian Ocean region -- which have not been studied previously -- are the major cause for the regional variability of sea level change," wrote the authors in Nature Geoscience.

Han said that based on all-season data records, there is no significant sea level rise around the Maldives. But when the team looked at winter season data only, the Maldives show significant sea level rise, a cause for concern. The smallest Asian country, the Maldives is made up of more than 1,000 islands -- about 200 of which are inhabited by about 300,000 people -- and are on average only about five feet above sea level.

The complex circulation patterns in the Indian Ocean may also affect precipitation by forcing even more atmospheric air down to the surface in Indian Ocean subtropical regions than normal, Han speculated. "This may favor a weakening of atmospheric convection in the subtropics, which may increase rainfall in the eastern tropical regions of the Indian Ocean and increase drought in the western equatorial Indian Ocean region, including east Africa," Han said.

The new study indicates that in order to document sea level change on a global scale, researchers also need to know the specifics of regional sea level changes that will be important for coastal and island regions, said NCAR's Hu. Along the coasts of the northern Indian , seas have risen by an average of about 0.5 inches, or 13 millimeters, per decade.

"It is important for us to understand the regional changes of the , which will have effects on coastal and island regions," said Hu.

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3432682
1.8 / 5 (16) Jul 13, 2010
"Regional sea rise changes" is an impossibility, unless they are tiny. Gravity and all that. No measures are cited. Considering that there are no credible reports of sea level rise elsewhere, we can conclude this is either just a tiny local effect, or BS. Of course, they attribute it to global warming. However, the actual worldwide rise in temperature for the last 150 years has been only about 1/2 degree F, and that was from the cool period called the little ice age. This story is linked to global warming only for propaganda purposes. Science should stick to facts and figures, not stretch to link to leftist political fabrications.
Donutz
2.7 / 5 (6) Jul 13, 2010
"Regional sea rise changes" is an impossibility, unless they are tiny. Gravity and all that. No measures are cited. Considering that there are no credible reports of sea level rise elsewhere

OR, (and I'm not saying this IS so, just a possible explanation) they are reporting the rises in India alone because they've only done the measurements in India. If you're honest about your reportage, you would say "measurements in India are up", not "measurements everywhere are up", the assumption being that at some point someone is going to check elsewhere.

GSwift7
4.7 / 5 (12) Jul 13, 2010
Actually, regional sea levels change constantly. The sea is not uniformly distributed around the earth. If you look at sea level on either side of the Panama isthmus, for example, there is a huge difference in sea level caused by many factors, such as wind, current, tides, the shape of the coastlines, etc. The Oceans 'slosh' back and forth quite a bit.

What they call a "tidal surge" (actually a misnomer) on the front of a hurricane is a good example of how stustained winds can "pile up" water against a coastline in a region.

Trying to model this is exceedingly difficult. Tide tables are used for coastal water levels most of the time, which are based on historical data. The current predictive model used by NOAA/OFS is based on National Weather Service predictions. They say that it's only accurate for two day predictions and it's accurate to within 6 inches 90% of the time, while extreme variations from predictions may occur a small percent of the time. (from the NOAA site)
Parsec
4.2 / 5 (13) Jul 13, 2010
"Regional sea rise changes" is an impossibility, unless they are tiny. No measures are cited. ... the actual worldwide rise in temperature for the last 150 years has been only about 1/2 degree F ... Science should stick to facts and figures, not stretch to link to leftist political fabrications.

If you simply assume that AGW is a leftist fabrication as your starting point, all of your points make complete sense. However, interpreting data using such a strong bias is wrong. Heard of the kettle that called the pan black?

Of course your absolutely wrong on the rest of your points. Measured temp change in the last 50 years is more like 1.5 F. Sea level changes have been measured in lots of places and while there are inconsistencies because of the large effects of the wind (mentioned in the article), overall sea levels are up.
Pyle
4 / 5 (9) Jul 13, 2010
The tidal effects on coastal areas are significant. Go to the beach and build a sand castle at low tide. Now, you ask, how does one inch make a difference when the tide is fluctuating 2 or more feet each day based on the position of the moon? Well, if you are several million people living below five feet of sea level you have less than 60 inches to play with. Add to that "storm surges" caused by monsoons. The wind effects of the mentioned circulations could have devastating effects. Yes, the "tiny" local effects are significant. To think, guys a mile from sea level in the middle of a continent are studying this. Kind of funny.
GSwift7
4 / 5 (4) Jul 13, 2010
Well, down here in South Carolina, we have Fort Sumter sitting in Charleston Harbor. It began construction in 1827, shortly after the end of the war of 1812. There hasn't been any noticable change in sea level here in nearly 200 years. High tide and low tide are just where they've always been. It's easy to see the evidence when you look at a 200 year old fort. The rise must be somewhere else I guess, or it's just not noticable.
Skeptic_Heretic
4.3 / 5 (6) Jul 13, 2010
Well, down here in South Carolina, we have Fort Sumter sitting in Charleston Harbor. It began construction in 1827, shortly after the end of the war of 1812. There hasn't been any noticable change in sea level here in nearly 200 years. High tide and low tide are just where they've always been. It's easy to see the evidence when you look at a 200 year old fort. The rise must be somewhere else I guess, or it's just not noticable.

Might want to read this then?
http://epa.gov/cl...ter4.pdf
GSwift7
2 / 5 (4) Jul 13, 2010
like i said... "or it's just not noticable"

There are plenty of historical photographs of the area. The sand bars around the fort and the fort itself are a good measuring stick, with plenty of reference points still remaining today. If it's risen inches then surely the gradual beach and sandbar around the fort would be gone.

Sorry, but I don't believe the report you linked to. They are claiming a nearly two foot rise. That would be visible when comparing water level to land features. The nice thing about Fort Sumter is that there are many actual photographs from before the civil war. It's hard to argue with a photo.

Just goes to show that you can't believe everything you read. I seem to recall EPA reports on acid rain from back in the 80's which have now been shown to be grossly exagerated or just plain wrong. I don't know how old you are, but the acid rain thing was a big deal back then.
PaddyL
2.3 / 5 (9) Jul 13, 2010
"The key player in the process is the Indo-Pacific warm pool, an enormous, bathtub-shaped area of the tropical oceans stretching from the east coast of Africa west to the International Date Line in the Pacific. The warm pool has heated by about 1 degree Fahrenheit, or 0.5 degrees Celsius, in the past 50 years, primarily caused by human-generated increases of greenhouse gases, said Han."

What a bunch of horsepucky. Prove it without repealing the laws of physics.
Dan_K
3 / 5 (6) Jul 13, 2010
"appear to be at least partly a result of human-induced increases of atmospheric greenhouse gases"

It's unfounded declarations like this that detract from the AGW proponents case. The article only mentions that local sea levels are rising, then states that it's greenhouse gasses that are causing it. One would have to show global sea level rises before you could even begin to link it to global atmospheric properties.

I'll be so glad when all of this goes away just like "the Earth is entering another ice age" warnings from scientists of the 1970s. Then again, politicians and scientists didn't have trillions of dollars to gain/lose in the ice-age scare of the '70s.

Dan K
ppnlppnl
3.7 / 5 (6) Jul 13, 2010

Dude, scientists didn't believe that we were entering another ice age back in the 70s. It just isn't true. Its a lie. A stupid one. Its as stupid as when a creationist asks "If we evolved from monkeys then why are there still monkeys?"

And if you believe that its all a plot to grab power then how is fear of an ice age less useful than fear of warming?

And scientists are going to gain "trillions"? Really? Well then we need to band together and apologize to Exxon and BP for the actions of those evil scientists. Poor oil companies can barely keep their family fed. Lets reduce their liability to protect the "mom and pop" oil companies. Let them get their life back.
GSwift7
2 / 5 (4) Jul 14, 2010
"And scientists are going to gain "trillions"? Really?"

Yes, the space missions alone account for a good portion of a trillion dollars just between the ESA and NASA, not to mention actic expiditions, permanent research stations in remote areas of the world, full time dedicated research ships, vast agricultural studies around the globe. The total is easily in the trillions, and "big oil" pays for a good portion of it.

The EPA "study" sited above is a great example of a good deal of money being wasted on this trash. You can easily go down to the Charleston harbor and look at brick steps leading down to the water that were built two hundred years ago, which still lead down to the water (not under the water). That report was blatant fearmongering and clearly wrong. Most of the climate predictions from just a few years ago have already become impossible. They are "revising the models in response to observations". Liars.
GSwift7
2.3 / 5 (4) Jul 14, 2010
This AGW thing is just like the acid rain thing from twenty years ago. Don't be slow. Think for yourself and question the "experts". If the acid rain scare people were correct, then every lake from Ohio to Quebec would be dead by now. Obviously nothing like that is happening, so the acid rain scare died. There was never any big cry of "OOOPS, I was wrong", those people just quietly shifted their work to climate change, and they are doing it again. They are leading the masses on a wild goose chase and the masses love it. Nothing is more fun than chasing wild geese apparently. Forget the global cooling thing, that was a failed attempt. People never bought into it. The acid rain scare was much more widely accepted and then conveniently forgotten. The Michael Crichton book "State of Fear" has an interresting theory about why there is always some big scary thing everyone talks about. I'm not sure he's right, but it's interresting.
joefarah
3 / 5 (4) Jul 14, 2010
13 mm per decade measured... wow - please show me the physics that doesn't make this this 13mm +/- 500mm per decade. Show me the effects of the planets orientation, impact of solar flares, precise tidal measurements and errors, wind speeds, etc. that permit you to measure a difference of 13mm per decade. Oh yes, temperature may have a minute effect as well. But you can exclude that if you include earthquakes, volcanic activity and seasonal variations, all which will drown out these numbers.

In short, if you're trying to fear monger, you'll have to have a more credible story.
GSwift7
2.3 / 5 (3) Jul 14, 2010
Nah, they don't need credibility. If you say enough stuff, no matter how silly, most people will believe some of it, and some people may even believe all of it. People especially like to believe bad news.
thermodynamics
5 / 5 (2) Jul 14, 2010
3432682: You said: ""Regional sea rise changes" is an impossibility, unless they are tiny. Gravity and all that." That is not true. The reason is that a column of water that is warm weighs less than a column that is cold. There is an experiment that can be done with graduated pipets. Connect them at the bottom, fill both with water, and heat one side. The height of the two sides will not be the same even though the same gravity is acting on them. The reason is that the heated column is lighter and less dense. You can see the same thing by not having the pipets communicate by watching the heated side expand. The reason for the communication is to show that even connected regions will have different heights. That is why satellites are measuring ocean height as a proxy for column temperature. The ocean is not at one height even without wind or waves - even though the parts communicate.
Husky
not rated yet Jul 15, 2010
arabian sea? persian gulf, like in gulfwar
barakn
4.2 / 5 (5) Jul 18, 2010
Gswift7 - thanks for the revisionist history of acid rain. However, much like the Holocaust deniers, you are trying to deny something which has been thoroughly and exhaustively researched and documented. Acid rain was a problem, there were dead lakes and dead forests (and still are). The reason that acid rain is no longer on the radar is not because scientists overhyped the issue. The reason is because Congress (in the US) actually did something about it. Amendments to the Clean Air Act resulted in a decline in sulfur dioxide emissions of 40%. Oddly, much of this was accomplished via a cap-and-trade system.
GSwift7
1 / 5 (2) Jul 18, 2010
lol, that is so far from true that it's not even funny. The Clean Air Act stopped acid rain? Hardly. The PH of precipitation is the same now as it was then. The truth is that natural rain isn't really supposed to have a PH of 8. It never has been before. The Clean Air Act was immeasurably effective in regard to acid rain. Your faith in the environmental movement is ill-informed. Can you even tell me what the PH of rain is now and what it was before the industrial revolution? I bet you havn't looked it up.
GSwift7
1 / 5 (2) Jul 18, 2010
p.s. if you are comparing me to a Holocaust denier then you are being unreasonably obtuse and offensive. That is a very emotional and irrational response. I'm not the one re-writing history or science to support my emotional or rhetorical beliefs. Your comparison of me to a Holocause denier is like calling me names. Surely you are kidding. My grandmother's family name on my dad's side is Spellerberg.
thermodynamics
4 / 5 (1) Jul 19, 2010
GSwift7: First, let me be very clear. I agree with you that a comparison with the Holocaust deniers is an exceedingly serious step over the bounds of decency. There is no excuse for using comparisons like that and I do hope you get an apology from barakn.

However, I do have to take exception with your fast and loose interpretation of the acid rain situation. I have provided you with an EPA site with the progress reports from each year on the impact of the Cap and Trade approach. It is in disagreement with your view it has had no effect.

http://www.epa.go...rts.html

These are measured data including pond acidification and loading of sulfates per square area. Having said that, the approach could have done a lot better. One of the add-ons to the legislation was the "grandfathering" of existing equipment for power plants. Many have never had to make the conversion. Take a look and then see how far off you are.
Mayday
not rated yet Jul 19, 2010
Reading this article & thread on a "science" site on a Monday morning has put me off my Toasties. If this is reasoned discourse, well, then we are in trouble, aren't we?
barakn
5 / 5 (3) Jul 19, 2010
Gswift7 - I did have to look it up. I thought the pH of rain was 5 because of the reaction of CO2 with water, but it turns out to be 5.5 or 5.6 - it's been quite a few years since I took that environmental chemistry class. However, in 1989 the most acidic rain (in Pennsylvania) averaged 4.08. By 2000 the most acidic rain was at 4.3. Considering that the pH scale is logarithmic, the difference is considerable.

Also, I don't care about the names of your ancestors. I didn't say you were a Holocaust denier, I said that you had the same mentality, which is to deny and ignore the obvious evidence. Acid rain has been carefully monitored because it ignores international borders, and countries tend to get upset when their neighbors start killing their lake and forests. Your ignorance of the science behind acid rain does not reflect a problem with the science but with your own self.
GSwift7
1 / 5 (1) Jul 20, 2010
Well, I think this is a reliable resource in regard to acid rain. It is titled "National Acid Precipitation Assessment Program Report to Congress":

http://www.esrl.n...rt05.pdf

It remains one of the largest government environmental studies of all time. They found that acid rain caused by humans has only a small effect on the environment. Only one kind of tree was affected by acid rain, and that effect was small. Only a few lakes were acidic and most of that was from natural causes. I can't site the whole report here, and I haven't read the whole thing (it's huge).

Comparing your example from the EPA to my example from NOAA shows an apparent difference of opinion between official sources in regard to the danger of acid rain. I can site additional credible sources supporting the exageration of the acid rain scare of the 80's if NOAA and the National Science and Technology Council aren't good enough for you. Funny thing about the EPA. Self Funded.
GSwift7
1 / 5 (1) Jul 20, 2010
I could also site plenty of paleolimnological data showing a history of acid lakes in the north atlantic coastal area which goes back thousands of years. Most lake acid comes from decaying vegitation and seeps through the soil to reach the lake. Soil is the controling factor, not rain. Most lake water, especially in steep terrain, is runoff not direct precipitation.

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