Global sea levels have risen six meters or more with just slight global warming

July 9, 2015
Icebergs near Timiamuit, SE Greenland (left) and modern reef in the Seychelles (right) where fossil corals record global mean sea level 7.5 m higher than present during a previous warm period 125,000 years ago. Credit: Anthony Long/Dan Zwartz

A new review analyzing three decades of research on the historic effects of melting polar ice sheets found that global sea levels have risen at least six meters, or about 20 feet, above present levels on multiple occasions over the past three million years.

What is most concerning, scientists say, is that amount of melting was caused by an increase of only 1-2 degrees (Celsius) in global mean temperatures.

Results of the study are being published this week in the journal Science.

"Studies have shown that both the Greenland and Antarctic ice sheets contributed significantly to this rise above modern levels," said Anders Carlson, an Oregon State University glacial geologist and paleoclimatologist, and co-author on the study. "Modern atmospheric carbon dioxide levels are today equivalent to those about three million years ago, when sea level was at least six meters higher because the ice sheets were greatly reduced.

"It takes time for the warming to whittle down the ice sheets," added Carlson, who is in OSU's College of Earth, Ocean and Atmospheric Sciences, "but it doesn't take forever. There is evidence that we are likely seeing that transformation begin to take place now."

Co-author Peter Clark, an OSU paleoclimatologist, said that because current , or CO2, levels are as high as they were 3 million years ago, "we are already committed to a certain amount of ."

"The ominous aspect to this is that CO2 levels are continuing to rise, so we are entering uncharted territory," Clark said. "What is not as certain is the time frame, which is less well-constrained. We could be talking many centuries to a few millennia to see the full impact of melting ice sheets."

Andrea Dutton surveying the position of modern sea level at Anse Source d'Argent, La Digue, Seychelles. Fossil corals at this site record a global mean sea level that was 7.5 m higher than present during a past warm period at 125,000 years ago. Survey staff is 4 m tall. Credit: Jody Webster

The review, which was led by Andrea Dutton of the University of Florida, summarized more than 30 years of research on past changes in ice sheets and sea level. It shows that changes in Earth's climate and sea level are closely linked, with only small amounts of warming needed to have a significant effect on seal levels. Those impacts can be significant.

Six meters (or about 20 feet) of sea level rise does not sound like a lot. However, coastal cities worldwide have experienced enormous growth in population and infrastructure over the past couple of centuries - and a global mean sea level rise of 10 to 20 feet could be catastrophic to the hundreds of millions of people living in these coastal zones.

Much of the state of Florida, for example, has an elevation of 50 feet or less, and the city of Miami has an average elevation of six feet. Parts of New Orleans and other areas of Louisiana were overcome by Hurricane Katrina - by a surging Gulf of Mexico that could be 10 to 20 feet higher in the future. Dhaka in Bangladesh is one of the world's 10 most populous cities with 14.4 million inhabitants, all living in low-lying areas. Tokyo and Singapore also have been singled out as extremely vulnerable to sea level rise.

"The influence of rising oceans is even greater than the overall amount of sea level rise because of storm surge, erosion and inundation," said Carlson, who studies the interaction of ice sheets, oceans and the climate system on centennial time scales. "The impact could be enormous."

The Science review is part of the larger Past Global Changes, or PAGES, international science team. A working group known as PALSEA2 (Paleo constraints on sea level rise) used past records of local change in sea level and converted them to a global mean sea level by predicting how the surface of the Earth deforms due to changes in ice-ocean loading of the crust, along with changes in gravitational attraction on the ocean surface.

Independently, Greenland and Antarctic volumes were estimated by observations from adjacent ocean sediment records and by ice sheet models.

"The two approaches are independent of one another, giving us high confidence in the estimates of past changes in sea level," Carlson said. The past climates that forced these changes in ice volume and sea level were reconstructed mainly from temperature-sensitive measurements in ocean cores from around the globe, and from ice cores.

Explore further: On a tropical island, fossils reveal the past—and possible future—of polar ice

More information: Sea-level rise due to polar ice-sheet mass loss during past warm periods, www.sciencemag.org/lookup/doi/10.1126/science.aaa4019

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31 comments

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Ironwood
1.9 / 5 (13) Jul 09, 2015
How much has sea level risen in the past fifteen years? Must be a whole lot since we've had all these warmest years on record and all the glaciers everywhere are melting.
docile
Jul 09, 2015
This comment has been removed by a moderator.
Gimp
2.7 / 5 (12) Jul 09, 2015
Can we get Al Gore to go back and retroactively tax the culprits from previous global warming events? We could use that money to print more books and discuss current warming.
denglish
2.5 / 5 (14) Jul 09, 2015
This article jumps the AGW article shark.

Great Title: 9/10

Immediate Reference to cyclic natural earth processes that will be easily mis-read by the plebs: 8/10

"we are already committed to a certain amount of sea level rise."

Pleb Terroristic Threat: 9/10

"The ominous aspect to this is that CO2 levels are continuing to rise, so we are entering uncharted territory,"

Appealing to the CO2 Gods: 9/10

This is not a science news site.
Vietvet
3.9 / 5 (15) Jul 09, 2015
"It takes time for the warming to whittle down the ice sheets," added Carlson, who is in OSU's College of Earth, Ocean and Atmospheric Sciences, "but it doesn't take forever. There is evidence that we are likely seeing that transformation begin to take place now."

"The ominous aspect to this is that CO2 levels are continuing to rise, so we are entering uncharted territory," Clark said. "What is not as certain is the time frame, which is less well-constrained. We could be talking many centuries to a few millennia to see the full impact of melting ice sheets."

Read more at: http://phys.org/n...html#jCp

The time frame might not be certain but the rise in sea levels is certain.
SamB
2.3 / 5 (6) Jul 09, 2015
How much has sea level risen in the past fifteen years? Must be a whole lot since we've had all these warmest years on record and all the glaciers everywhere are melting.

You are right!. I just lost my dock and the patio is under 3 mm of water.
Shootist
2.7 / 5 (9) Jul 09, 2015
six meter rise was caused by an increase of only 1-2 degrees (Celsius) in global mean temperatures
According to the IPCC's averaged temperatures warmed roughly 1.53°F (0.85ºC) from 1880 to 2012 - so we should have three meters rise by now. Whereas during period between 1870 and 2004, global average sea levels are estimated to have risen a total of 195 mm...


Who actually believes you can measure the mean temperature of the planet to within 3 significant figures? You cannot measure the mean temperature of a space suited astronaut to within 3 significant figures.
thingumbobesquire
2.3 / 5 (6) Jul 10, 2015
Thus, the amazingly accurate revelation in that lovable Beatles' ditty. I, of course, refer to Ringo Starr's "We all live in a yellow submarine." What must he have been smoking? I'll bet these "researchers" have gotten into something similar...
MrLuigiVercotti
1.5 / 5 (11) Jul 10, 2015
Do you really believe that a coral island provides some kind of sea level reference? How utterly stupid
antialias_physorg
4.2 / 5 (15) Jul 10, 2015
How much has sea level risen in the past fifteen years? Must be a whole lot since we've had all these warmest years on record and all the glaciers everywhere are melting.

You are right!. I just lost my dock and the patio is under 3 mm of water.

According to the IPCC's averaged temperatures warmed roughly 1.53°F (0.85ºC) from 1880 to 2012 - so we should have three meters rise by now

Did you even bother to read the article? Why don't you do so before posting next time. Might spare yourself the embarassment.

(Hint: arctic melting is neither linear not instant)
Returners
2.3 / 5 (8) Jul 11, 2015
I calculated that if the rate of acceleration continued indefinitely, then Greenland land ice would melt completely within 400 to 500 years.

Fortunately, none of us will be alive to see half the state of Florida and 3/4 the state of Louisiana submerged in salt water by the time the new equilibrium happens.

CO2 is not the main culprite, BTW.

The world's waste heat from human activities is enough to explain the arctic sea ice melt and the greenland land ice melt, on average.

The albedo changes from concrete and asphalt roads, parking lots, drive ways, and sky scrapers, black shingles on rooftops, glass heat traps of automobiles and actual "greenhouses" also contributes a significant amount of excess heat.

All of this more than explains the total melting in the northern hemisphere, before you even consider CO2 or other supposed greenhouse gases.

This doesn't even count second order feedbacks from these NON-POLLUTANT related sources of human warming melting snow lines.
Returners
2.1 / 5 (7) Jul 11, 2015
I did not take into consideration the amount of body heat produced by our metabolism and that of our livestock and pets. While this number is certainly much smaller than the waste heat of all of our machines, it is still not negligible.

Every billion humans produces 0.1 PPM CO2 each year just from breathing. There are 7.25 billion humans on earth right now, which gives 0.725PPM per year just from breathing of humans. That figure represents nearly 1/3rd of the annual average excess on the Keeling Curve.
Returners
2 / 5 (8) Jul 11, 2015
If humans were to become carbon negative, such that the Keeling Curve's slope became negative, it would not stop the Arctic warming, even if the Keeling Curve returned to pre-industrial levels, because the waste heat alone from our technology is enough to explain the entire northern hemisphere melting.
antigoracle
2 / 5 (8) Jul 11, 2015
Can we get Al Gore to go back and retroactively tax the culprits from previous global warming events? We could use that money to print more books and discuss current warming.

He's more likely to use that money to buy himself an even bigger beach front mansion, closer to the water.
cjones1
3 / 5 (4) Jul 12, 2015
I read that according to the 'Panama hypothesis' that before roughly 2.5 mya there was no ice in Iceland or a North Polar ice cap. The closing of the isthmus disrupted a current flowing between the Pacific & Atlantic, changed the salinity, the course of the Gulf Stream, and led to more fresh water flowing from moisture into the Article Ocean, leading to the Northern ice cap. I don't know what caused the warming periodically that led to the melting and higher sea levels. I suspect the sunspot cycle and/or Milankovitch solar orbital cycles had an influence. CO2 concentrations may be an after effect.
marko
3 / 5 (2) Jul 12, 2015
Can you please convert 6 metres into something that Americans understand - like 20 feet.

Another confounding factor is the predicted lowering of solar activity in the next 50 years due to lower sun spot activity.

However this buys just a little more time to get the worlds greenhouse in order.

If you want to keep throwing stones then be prepared to hold your breath for some time.
leetennant
4.6 / 5 (9) Jul 13, 2015
Geez, Returners, do you have any more comments based on completely-made up physics or are you done?
Vietvet
4.5 / 5 (8) Jul 13, 2015


Moreover, it seems to me that for them is more important to make a revision of their mental ecology and think what they do and for what fight because time for repentance ran and soon will be the second coming of the Son of God with his army of angels.


LMFAO! You religious zealots have have been making that claim for 2,000 years. Ain't gonna happen.
gkam
2.6 / 5 (15) Jul 13, 2015
This is a science site, but since he brought it up: Ren, why does god inflict the most deadly tornadoes on Earth on the Bible Belt?

Is it because of his omniscience?

Good judgement?
OdinsAcolyte
1.5 / 5 (8) Jul 13, 2015
It won't happen. We are cooling.
Get a real job.
john_mathon
1.6 / 5 (7) Jul 13, 2015
This is so bizarre. They are warning us about something 500 years from now? Seriously?

People do understand that virtually the entire world was built in the last 100 years. For most of that 100 years most people were deadly poor. If we had to rebuild it all over the next 100 years it would not be expensive because we ARE going to rebuild it all over the next 100 years anyway and again and again and again before 500 years.

But what they didn't mention is that all of that melting ice will expose and make habitable vast regions of iced land. They don't mention the death rate would decline by 15% (just from warmer temps. The earth is about as cold as it has ever been. Flying over you will see an ice covered ball. When it melts the real "earth" that existed for most of time will be revealed. California is covered under ice during the ice ages. Would you prefer to go to that? Would you prefer stasis? Guess what you can't get stasis. Things change. Get used to it.
john_mathon
1.7 / 5 (6) Jul 13, 2015
It's like these people are talking to a bunch of morons. People do understand that the earth hasn't been like it is today right now forever? It's so pathetic to think that this is a surprise to many. We live on a fragile ball. It's going to change whether we like it or not. Whether we are complicit in it or not.

The author pretends like this melting wouldn't have happened anyway. As long as we are above the temp that ice melts there is going to be melting. It's been melting for 100s of years. During the 19th century sea levels rose 7". They melted another 7" in the 20th century and they will likely melt maybe 7" in the 21st century. Global warming is going to have virtually zilch effect and if we cut ALL Co2 production and temps return to 1880 level ice will still melt. We have to deal with this anyway children. We don't want to go to the temp ice doesn't melt. That would be incredibly deadly, really bad 1,000,000 times worse than global warming.
leetennant
4.5 / 5 (8) Jul 13, 2015
Pace and rate of change.
For the seventy billionth time.
Pace. And. Rate.
mbee1
2.3 / 5 (3) Jul 15, 2015
We already know the actual trend in the ocean rise from the NOAA tidal gauge data. If you go out to the pacific islands far from continental borders which go up and down a lot due to various factors like the last ice age buckling from the ice sheets and subsequence rise when they melted, the current trend is 3 inches in 100 years (Johnston Atoll). that is with a claimed rise of 1.5 degrees in the last 150 years. To rise 20 feet in the next 100 years would require an increase of thousands of a percent or 8000 years. Since it was hotter than today in the recent past, 1000 AD or 3000 BC from trees found under glaciers or north of the present tree line I will take the 8000 year number.
mbee1
2.3 / 5 (3) Jul 15, 2015
If you look at the picture and claim about a rise 125000 years ago one has to wonder a bit about the agw claim. That warm period was not caused by CO2 levels, something else warmed the world, most likely the changes in earths tilt and orbit increasing solar gain or simply more solar output. Models of earths current tilt and orbit have the world warming for the next 25000 years if one assumes the solar output is stable which is a wild guess.
leetennant
4.4 / 5 (7) Jul 15, 2015
Shorter mbee1: you can get cancer anyway so there's no way smoking is harmful. Ipso facto.
Vietvet
4.2 / 5 (5) Jul 15, 2015
Revelations---- the dude writing that must have had some really, really good mushrooms because LSD hadn't been invented yet.
gkam
2.4 / 5 (14) Jul 15, 2015
" I guess you understand that without God's justice there will be no justice in this world. "
----------------------------------

Show me. I want to see him to make sure you are right.

Nobody would just believe these silly stories from the Age of Ignorance without proof, . . . would they?
antialias_physorg
4.5 / 5 (8) Jul 15, 2015
Nobody would just believe these silly stories from the Age of Ignorance without proof, . . . would they?

I thinkRen doesn't even get that this is a question aimed at him to answer.

So I'll put it a bit more plainly:

Nobody would just believe these silly stories from the Age of Ignorance without proof, . . . Why do you Ren? Where's your proof? (Hint: A book ain't proof. Other people also believing it ain't proof, either. Your momma saying so ain't proof either. Give some HARD evidence or just admit you just believe what you want. I.e. that you're just a total egocentric individual.)
Captain Stumpy
4.4 / 5 (7) Jul 15, 2015
I encourage you to read the last book of the New Testament
@renTROLL
i suggest you read the whole thing... as i have shown that you are woefully deficient in your "biblical knowledge", from your claim of "pairs" of animals on the ark to your ignorance on your own biblical laws (which you've been caught violating repeatedly)
without God's justice there will be no justice in this world
you mean like the justice the religious folk in ISIS are giving? how about those female sexual mutilations? child/women slavery? kill thy neighbor if they aren't of your particular sect?

THAT is the message of the bible... your "law"... and you wonder why people are running away from it now?
and before you complain: muslims/jews/christians have the same BOOK OF LAWS!

as AA_P says above
Hint: A book ain't proof. Other people also believing it ain't proof, either
you had better leave it out of the conversation, considering i know more about your own bible than you do
Water_Prophet
2 / 5 (4) Jul 15, 2015
As usual, "science" articles demonstrate they have little understanding of science.

I am sure the scientists are better, but:

If the Earth's temperature rose five degrees tomorrow and stayed that way for say three days, freak solar storm, or CO2 fans exhaling all at once, say, what would happen?

Not much, the Earth would go back to normal once that phenomenon stopped.
What if it were prolonged? Well the Earth would respond, ice would melt, heat would transfer more quickly and the Earth would lose those five degrees to some new equilibrium.

The point is, that temperature does not melt ice, or cause sea level rise. Temperature pretty much remains constant. It's the heat.

For example, imagine a Copper bowl with water and ice in it.
What temperature is the water?
0C.

Now we raise the air temperature above the bowl-5 degrees, what temperature is the water? Well ignoring surface effects and other non-conceptual realities, the water remains 0C, the ice melts.

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