Rising Oceans - Too late to turn the tide?

This article brings up a good point not many people think about. Expansion by heat, not just rising levels. And also, the fact it's only 3 feet by the end of the century? So much for entire cities being wiped out. It also talks about how the ocean isn't warming as fast as the atmosphere, and the caps aren't melting as fast as they have in the past. New twist on an old topic.

Rising Oceans - Too Late to Turn the Tide? LINK TO ARTICLE


By Daniel Stolte, University Communications July 14, 2011
Melting ice sheets contributed much more to rising sea levels than thermal expansion of warming ocean waters during the Last Interglacial Period, a UA-led team of researchers has found. The results further suggest that ocean levels continue to rise long after warming of the atmosphere levels off.

Thermal expansion of seawater contributed only slightly to rising sea levels compared to melting ice sheets during the Last Interglacial Period, a University of Arizona-led team of researchers has found.

The study combined paleoclimate records with computer simulations of atmosphere-ocean interactions and the team's co-authored paper is published in Geophysical Research Letters.

As the world's climate becomes warmer due to increased greenhouse gases in the atmosphere, sea levels are expected to rise by up to three feet by the end of this century.

But the question remains: How much of that will be due to ice sheets melting as opposed to the oceans' 332 million cubic miles of water increasing in volume as they warm up?

For the study, UA team members analyzed paleoceanic records of global distribution of sea surface temperatures of the warmest 5,000-year period during the Last Interglacial, a warm period that lasted from 130,000 to 120,000 years ago.

The researchers then compared the data to results of computer-based climate models simulating ocean temperatures during a 200-year snapshot as if taken 125,000 years ago and calculating the contributions from thermal expansion of sea water.

The team found that thermal expansion could have contributed no more than 40 centimeters – less than 1.5 feet – to the rising sea levels during that time, which exceeded today's level up to eight meters or 26 feet.

At the same time, the paleoclimate data revealed average ocean temperatures that were only about 0.7 degrees Celsius, or 1.3 degrees Fahrenheit, above those of today.

"This means that even small amounts of warming may have committed us to more ice sheet melting than we previously thought. The temperature during that time of high sea levels wasn't that much warmer than it is today," said Nicholas McKay, a doctoral student at the UA's department of geosciences and the paper's lead author.

McKay pointed out that even if ocean levels rose to similar heights as during the Last Interglacial, they would do so at a rate of up to three feet per century.

"Even though the oceans are absorbing a good deal of the total global warming, the atmosphere is warming faster than the oceans," McKay added. "Moreover, ocean warming is lagging behind the warming of the atmosphere. The melting of large polar ice sheets lags even farther behind."

"As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming, the oceans would keep warming, the ice sheets would keep shrinking, and sea levels would keep rising for a long time," he explained.

They are absorbing most of that heat, but they lag behind. Especially the large ice sheets are not in equilibrium with global climate," McKay added. "

Jonathan Overpeck, co-director of the UA's Institute of the Environment and a professor with joint appointments in the department of geosciences and atmospheric sciences, said: "This study marks the strongest case yet made that humans – by warming the atmosphere and oceans – are pushing the Earth's climate toward the threshold where we will likely be committed to four to six or even more meters of sea level rise in coming centuries."

Overpeck, who is McKay's doctoral advisor and a co-author of the study, added: "Unless we dramatically curb global warming, we are in for centuries of sea level rise at a rate of up to three feet per century, with the bulk of the water coming from the melting of the great polar ice sheets – both the Greenland and Antarctic Ice Sheets."

According to the authors, the new results imply that 4.1 to 5.8 meters, or 13.5 to 19 feet, of sea level rise during the Last Interglacial period was derived from the Antarctic Ice Sheet, "reemphasizing the concern that both the Antarctic and Greenland Ice Sheets may be more sensitive to warming temperatures than widely thought."

"The central question we asked was, ‘What are the warmest 5,000 years we can find for all these records, and what was the corresponding sea level rise during that time?'" McKay said.

Evidence for elevated sea levels is scattered all around the globe, he added. On Barbados and the Bahamas, for example, notches cut by waves into the rock six or more meters above the present shoreline have been dated to being 125,000 years old.

"Based on previous studies, we know that the sea level during the Last Interglacial was up to 8.5 meters higher than today," McKay explained.

"We already knew that the vast majority came from the melting of the large ice sheets in Greenland and Antarctica, but how much could the expansion of seawater have added to that?"

Given that sea surface temperatures were about 0.7 degrees warmer than today, the team calculated that even if the warmer temperatures reached all the way down to 2,000 meters depth – more than 6,500 feet, which is highly unlikely – expansion would have accounted for no more than 40 centimeters, less than a foot and a half.

"That means almost all of the substantial sea level rise in the Last Interglacial must have come from the large ice sheets, with only a small contribution from melted mountain glaciers and small ice caps," McKay said.

According to co-author Bette Otto-Bliesner, senior scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., getting the same estimate of the role ocean expansion played on sea level rise increases confidence in the data and the climate models.

"The models allow us to attribute changes we observe in the paleoclimate record to the physical mechanisms that caused those changes," Otto-Bliesner said. "This helps tremendously in being able to distinguish mere correlations from cause-and-effect relationships."

The authors cautioned that past evidence is not a prediction of the future, mostly because global temperatures during the Last Interglacial were driven by changes in the Earth's orbit around the sun. However, current global warming is driven by increasing greenhouse gas concentrations.

The seasonal differences between the northern and the southern hemispheres were more pronounced during the Last Interglacial than they will be in the future.

"We expect something quite different for the future because we're not changing things seasonally, we're warming the globe in all seasons," McKay said.

"The question is, when we think about warming on a global scale and contemplate letting the climate system change to a new warmer state, what would we expect for the ice sheets and sea levels based on the paleoclimate record? The Last Interglacial is the most recent time when sea levels were much higher and it's a time for which we have lots of data," McKay added.

"The message is that the last time glaciers and ice sheets melted, sea levels rose by more than eight meters. Much of the world's population lives relatively close to sea level. This is going to have huge impacts, especially on poor countries," he added.

"If you live a meter above sea level, it's irrelevant what causes the rise. Whether sea levels are rising for natural reasons or for anthropogenic reasons, you're still going to be under water sooner or later."

People need to move a little farther away from the water. The earth changes.....We (people) put permanent structures on a changing land............Then cry when it is changing.

Then they blame it on us, I don't even live by the beach

I noticed alot of we, and blame it on us, propaganda in this article.

ETA: I gave you a star and a flag, because I feel a little guilty.........I must have scared them off

The earths oceans have risen about 330 feet in the last 14k years. We know this because underwater archeologists have found prehistoric settlements deep under water. Some settlements were discovered at the bottom of the english channel, which hail from a time period where the brittish isles were a penninsula off western europe. There were several other sites discovered off bermuda (what some call the bimini road) which was an ancient harbor or sea port before the ocean overtook bermuda, which 14k years ago had also been a penninsula in eastern north america,

One such paleo-archeological site were the seven temples on the southern coast of India, 6 of which are now sunken, yet one megalithic structure, carved out of the bedrock remains intact. Civilization has been around LONG before the ancient Sumerians began building cities. Some Biblical archeologists theorize that where Eden orignally was, now lies deep under the Persian Gulf. Whatever the case, coastal cities need to pull up anchor and move farther inland, because the earths oceans are not going to stop rising.

Many people laughed and scoffed at Kevin Costners movie "Waterworld", however that movie was not very far off from the truth. Within the next 200 years, the earths oceans will rise enough and move far enough inland that states like arkansas, will be half underwater, this will include, Georgia,Alabama, Mississippi and Texas. Louisiana will be totally underwater, and New Orleans will go the way of so many other paleolithic settlements, sleeping forever under the waves of the gulf of mexico.

reply to post by liejunkie01

OP no offence to you but, I never see these articles talk about one of the most obvious ways and reasons, NOT related at all to AGW, that make the oceans expand and that is debris from space and rivers which are constantly adding to the depths. It is not a surprise that this happens when you consider the layers of soil over ancient ruins. We tell their age normally by how deep they may be. Then these same articles seem to avoid the elephant in the room, volcano's under/around the poles are active and melting the caps. No way in hell AGW is causing volcano's. The themes of these stories lead me to conclude we're getting pissed on and someone is trying to tell us it is rain. Throw in the evidence of planetary changes on the outer planets and wa la, we have a trend that suggests something outside the Earth is working it's magic. I suspect TPTB are playing a game of suppression of that data to maintain the carbon footprint scheme that threatens to bankrupt modern society and is causing people to starve now IMHO. The media shills are parroting the story so they can keep their sex habits, swimming pools, country clubs and yachts. They can rock the boat maybe once at their own career's stake or enjoy the ride by perpetuating a lie. Most of us might do the same if we could be rich or hang out with the rich.

"Turning the Tide"

You crafty devil

Never mind....

perhaps any noticeable sea level rise is due to the existence of under water volcanoes.. that constantly are erupting increasing the height of our ocean floor as their magma rushes out and very quickly solidifies forming new islands and more layers on the ocean floor.. kinda like putting sand into a glass of water.. the water in the glass will start to overflow as more sand is introduced to the base of the glass. Just an interesting thought to add to this thread.

reply to post by JaxCavalera


I agree - water displacement has to be happening with all the junk we have added. Another post I did was the thousands of miles of junk in the middle of the Pacific. Thing is, there are 4 of these areas in the world in different oceans. Not all of it floats. In fact, the article states that 70% sinks! There has to be some sort of displacement from all that crap out there.
And yes - not to mention the accumulation of sand, silt, etc.

Here we go - just to add to it (though a little 'out there') ... SKIN! How much skin/hair to humans, animals shed, only to add to the ever growing land? Just one more thought I mean seriously - the average human sheds 1.5 lbs of skin per year. Currently, there are 6,852,472,823 people on earth. At 1.5 lbs per year, that equals 10,278,709,235 lbs (or 5,139,354.6175 TONS) of skin just in 2010 alone!! It's got to go somewhere.

Where I live on the California coast,I tell young people that the coastline used to be 100 yards further out than it is today 35 years ago when I first came here.

It was 50 yards farther,30 years before that.

I have seen old aerial photographs that prove that.

It is as much from the eroding away of the coast line from damning of the rivers and streams that deposit sand on the beaches which was a natural process.

Now the winters storms pound away with no replenishment of sand.

If the sea level were to rise because of the glaciers melting, then why haven't they from the water flowing into the oceans from all the rivers that empty continually in to it?

I am fairly confident that Mother Earth on its own will solve this dilemma.

Have you ever wondered where all the rubber from vehicle tires as they wear down go?