Melting Ice Sheets Now Largest Contributor To Rising Sea Levels: Study

Ice sheets are now the largest contributor to rising sea levels, a new report has found. If ice sheets continue to melt at their current rates, sea levels may rise over 12 inches in the next four decades.

The study was conducted over the course of 20 years, and the results will be published in the journal Geophysical Research Letters. The group of researchers examined monthly satellite measurements between 1992 and 2009, using climate model data. The research shows that in 2006, Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes -- this ice loss can raise the global sea level by 1.3 millimeters per year.

Unfortunately, 2006 was not just a fluke occurrence. As ScienceDaily explains, ice sheets are melting at a steadily increasing rate. Over the course of the study, the ice sheets lost about an additional 36 gigatonnes per year, compared to each year before.

Melting ice caps have often taken the spotlight, but melting ice sheets are now dwindling at a faster rate than the ice caps and glaciers. While ice sheets extend for over 20,000 square miles, ice caps are defined as areas of less than 20,000 square miles. Though melting ice caps are certainly worthy of concern, their rate of loss has been three times smaller than the acceleration rate at which ice sheets are melting.

The report’s lead author, Eric Rignot of NASA’s Jet Propulsion Laboratory, is not surprised that ice sheets will now contribute the most to sea level rise. But, Rignot remarks, “What is surprising is this increased contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate Change in 2007.” The trends suggest that by 2050, melting ice sheets could raise sea levels by nearly six inches -- this amount is then added to predictions for melting ice caps and ocean thermal expansion. The resulting calculations find that sea levels could rise 12.6 inches by 2050.

How would these rising sea levels affect us? Another recent study, reported in the journal Climate Change Letters, shows that rising sea levels may threaten 180 U.S. cities by 2100. This study was based on projections that sea levels will rise by about three feet within the next century. Cities such as Miami, New Orleans, and Virginia Beach are expected to lose over 10 percent of their land. New York and Washington D.C. are also expected be impacted, though to a lesser degree.

U.N. reports have predicted that because of climate change, the world will have 50 million environmental refugees by 2020. That’s less than 10 years from now.

Climate change not only leads to rising sea levels, but it also is linked to droughts, flooding, and food shortages. As ice sheets melt at a faster pace, environmental refugees flee their homes, and major cities sink underwater, will climate change finally be taken seriously by everyone?

Comments

[MikeWebster]

11:28 PM on 04/13/2011

Certainly means that the IPCC estimates in their last report are vastly under the actual figures. Their estimates of around 60cm by 2100 will clearly be dwarfed. BTW: The 60cm was predicted based on thermal expansion, they excluded consideration of ice melt, because of uncertainties.

After how ever many metres we get by 2100, we still have a more than 70m rise, just with the melting of Antartica and Greenland.

[Howard Pearlman 13]

04:05 PM on 03/23/2011

The Volcanic Dust released by the Icelandic Eruption coated the Ice in the Northern Hemisphere with a dark coating. The surface now absorbs light instead of reflecting it back into space at a much greater rate.

[alteredstory]

08:54 AM on 03/24/2011

Source?

[MikeWebster]

11:29 PM on 04/13/2011

The study is over 20 years. Clearly a large amount of volcanic fallout would make the ice that it lands on absorb more heat.

[dragonmaster]

05:58 AM on 03/20/2011

Considering that in 2007 the IPCC predicted that we would not see an ice free arctic till 'around 2060' in late summer, and that in fact may happen this year or next, the predictions here are probably underestimate the real rate of sea rise.

James Hansen sees 2-3 meters by 2050, and up to 5 meters by 2100.

[alteredstory]

09:09 AM on 03/21/2011

All sea level rise and temperature increase models are inherently conservative because they rely on past data in a situation where the unprecedented (in our species existence) is becomign commonplace.

All the predictions go out the window if there's a sudden clathrate destabilization, or if we get a long series of droughts in the Amazon, or if the permafrost suddenly ups its emissions, or any other of a number of possible feed-backs strengthen.

They would go out the window because they're too small. It's clear that the IPCC undershot in 2007, and we can hope that Hansen isn't doing the same.

[MikeWebster]

11:34 PM on 04/13/2011

Most predictions from the IPCC and other credible sources are being exceeded. The IPCC in particular has various political issues to deal with that made it extremely conservative.

It appears that there are many more sources of postive feedback than though. The clathrates are a problem, and certainly bubbling methane is present in parts of the Arctic ocean now. Permafrost, as you say, and even soils are emitting more CO2. Once the ocean becomes saturated, we can expect some huge rises.

That's not all of it though, as the Ocean ecosystems are in danger of total collapse as the phyto-planckton populations plummet.

Resilient naturat systems have thresholds. In fact all sufficiently complex systems behave chaotically, and prediction of turning points is impossible. Turning points can be very sudden and catastrophic though, and that is exactly where we are heading with climate change.

[johuyik]

08:18 PM on 03/16/2011

We can save trillions of dollars and millions of lives if we act in a rational and decisive manner.

In other words, we're screwed....

[alteredstory]

09:09 AM on 03/21/2011

Never give up, never surrender.

[Daniel Hicks]

03:24 PM on 03/16/2011

I've posted this before, but, please, deniers, have a go:

Carbon dioxide concentrat­ions have increased dramatical­ly in the past two centuries, at a rate much rapider than any in the geologic record. THIS IS FACT.

Carbon dioxide is a greenhouse gas, meaning it absorbs radiation (heat) leaving the Earth and emits some of it back. The net result is that some of the heat that would have left the Earth instead remains on it. THIS IS FACT.

Therefore, increases in carbon dioxide in the atmosphere warm the Earth overall. THIS IS FACT.

Human beings take carbon out of the ground in the form of oil, natural gas, and coal. We burn it for energy. THIS IS FACT.

Burning fossil fuels turns the carbon it contains into largely gaseous carbon dioxide and water, which enter the atmosphere­. THIS IS FACT.

But it ISN'T fact that humans are warming the Earth? Refute ANY ONE of these things, and this simple proof fails. But, no truly objective considerat­ion of scientific evidence can do even this.

Therefore, attempts to stop limitation of carbon dioxide emissions DIRECTLY results in further warming of the Earth. If warming the Earth so quickly has negative impacts on the people on it, such actions are unconscion­able, selfish, and worthy of blame.

[droog1]

05:33 PM on 03/30/2011

The fossil record only goes back as far as fossils go back, around 550 million years out of the 4+ billion years of the earths history. Hard to really say how CO2 concentrations over the last two centuries compare to CO2 concentrations over much more than the last couple of hundred thousand years. Beyond that, it seems like the sources that could be used to infer CO2 concentrations get a little sketchy. So while I agree that CO2 concentrations are significantly higher now than over the last couple of hundred thousand years, I can't necessarily agree that we know that much about CO2 concentrations over the last 4.6 billion years that the earth has been around.

[jimboy71]

03:13 PM on 03/31/2011

Paleoclimatology, dendrochronology, paleozoology, paleobotany, stratigraphy, mass spectrometer analysis...and it does go on.

[MikeWebster]

11:40 PM on 04/13/2011

It simply doesn't matter whether we know the whole history of CO2 levels over 4.6 billion years. We know the levels now. We know a range of levels that are compatible with human survival, or at least civilisational survival. We know that we are heading in a direction that is outside of that range.

In other words we know that we are headed for climate conditions that are signigicantly different to the conditions in which the human species evolved. We know that we are heading there quicker than we or most other species can adapt to the changes.

In the past temperatures have been hotter. Other times much colder. In past extremely hot, and extremely cold climates, humans would not survive.

[mamacat]

07:19 AM on 03/16/2011

This is supposed to be new news? I thought this was pretty much accepted science for the last twenty years.

[Publicola]

12:21 PM on 03/16/2011

Info here:

http://www.sciencedaily.com/releases/2011/03/110308150228.htm

[alteredstory]

09:13 AM on 03/21/2011

On top of publicola's link, I'll just add a brief summary. The IPCC's projections were based on the thermal expansion of the ocean, and that has been a significant contributor to recent sea-level rise. It's difficult to measure exactly WHAT is making the oceans rise, and so it's taken time for researchers to get a good bead on the impact of ice sheets vs expansion, mountain glaciers, etc.

With ice sheets confirmed as the largest contributor (assuming nobody finds a serious flaw in this research), we can expect MUCH higher sea levels much faster than the IPCC predicted, simply because thermal expansion will continue, on top of the now-confirmed influx of water from Greenland and Antarctica.

[Robearbeach]

10:20 PM on 03/15/2011

2 years ago Al Gore said there was a 75% chance that the ice caps would be gone in 5 to 7 years. I already wrote them off.

[realpolitic]

02:40 AM on 03/16/2011

Where did he say that?

[Robearbeach]

09:08 AM on 03/16/2011

Dec. 2009 Copenhagen Climate Change Conf.

http://www.youtube.com/watch?v=MsioIw4bvzI

[Publicola]

12:02 PM on 03/16/2011

"Dec. 2009 Copenhagen Climate Change Conf."

That's not what Gore said.

Did you even listen to what Gore said, Robearbeach?

Ice CAPS aren't the same as ice SHEETS in any event, which is to say you've incorrectly confused things here on two levels.

[Publicola]

12:11 PM on 03/16/2011

Why did you write the Greenland and Antarctic ice sheets off, based on Gore NOT saying that they'd be gone in a few years?

[US National Legal]

06:28 PM on 03/15/2011

Global Warming is a true concern and it so not be taken for granted.

[constitutional 1]

03:12 PM on 04/04/2011

Its not called Global Warming anymore, its Climate Change.

[MikeWebster]

11:59 PM on 04/13/2011

If you want to talk about the warming of the atmosphere due to anthropogenice emissions from burning fossil fuels, then global warming is an appropriate term. Climate change just puts in in a context of a set of processes that have happened over the lifetime of the planet.

[StephenBP]

07:15 AM on 03/15/2011

Well, once again Richard jr has parroted the witless wisdom of MP Graham Stringer!

Graham used to work in a plastics lab. Graham has a lot of gall as a former plastics technician saying that climatology barely qualifies as science! but what is worse, rich jr is particularly disingenuous for claiming that climatologist keep their work secret from other scientists!

There is plenty of source code available if you bother to look.

And all that the denialists would have to do to make their case would be to write code that can do better simulations than the climatologists can currently do. Why can't Exxon Mobil with all their billions just get some climatologists to write some code that can show that there is no problem from carbon dioxide? Why? Because they can't do that without faking it! That, to me, is the real smoking gun in this argument. The absence of that code screams at us.

So once again dik2 makes a science free argument to help keep humanity hooked on lethal carbon energy.

What on earth can motivate someone to be so stubbornly, inhumanly, backward?

$$$$??????

[Richard2]

06:45 PM on 03/14/2011

"We now know that the work done at Climatic Research Unit barely qualified as science; they kept it secret to stop other scientists checking it; thus breaching one of the foundation­s of the scientific method."

Labor Member of Parliament Graham Stringer, from his article in Manchester Confidential.

[ILoveFiction]

09:11 PM on 03/14/2011

Cool. Right next to it on the front page is "Dish of the week: Tripe"

No kidding.

[Galong]

09:27 PM on 03/15/2011

That's far from the only source of scientific evidence to support this reality.

[wild1a]

04:56 PM on 03/14/2011

The theory of global warming is not a recent scientific development. In 1824 Fourier theorized the “greenhouse effect”. In 1896 Arrhenius made the connection between atmospheric temperature rise and increased concentration of CO2 in the atmosphere. He predicted man made global warming due to the extensive burning of fossil fuels beginning with the industrial revolution. Measurements during the 20th century by scientists have validated his prediction. The greenhouse effect is enhanced by increased evaporation of water. The ability for plants, trees and ocean to maintain a balance by absorbing carbon dioxide and releasing oxygen is diminishing. The seas are warming and acidified by carbonic acid, destroying marine life and losing CO2 absorption capability. Carbon sequestration in the earth’s crust by natural processes for millions of years provided the viable surface for the plant and animal species of today. We are rapidly reversing the trend. Peer reviewed information is available to anyone. Do we still have time to change to non- carbon related energy sources before the problem becomes unsolvable? We won't be the first species to go extinct due to uncontrolled expansion and overuse of our resources. But in our case as an intelligent species we are supposed to have the brains to try to take corrective action. This does not seem to be the case.

[ClimateHawk]

06:40 PM on 03/14/2011

Exactly.

[chachachamp]

01:44 PM on 03/16/2011

i agree wholeheartedly and im on your side; however, i still think that the square of the hypotenuse is equal to the square of the two adjacent sides--

[sunsetter]

03:55 PM on 03/14/2011

If I am not mistaken NASA found that the largest contributor to rising sea level is Michael Moore, taking a dip at the beach.

[busterbrownthefirst]

02:39 PM on 03/14/2011

There are so many climate change deniers in the column that it's sort of breathtaking. So far I've seen the sun did it, and glaciers are growing unless maybe it's ice sheets, and I'm not even trying.

So climate deniers, before you post, save us some time. Here's a site with commonly-used skeptic arguments and how they're debunked: http://www.skepticalscience.com/

Please look up your argument before posting and don't post it if you can't also reply as to why it's not true. This will save us all inordinate time.

By the way, this site has IPhone and android and even a Nokia app. You don't even have to memorize those specious arguments and the accompanying contradictory scientific facts. You can take it all with you and crib on the go.

And for those of you with a more technical bent, see realclimate.org

It would be nice not to have to read through so much drivel.

[PsyGuy24]

03:39 PM on 03/12/2011

Did you guys know that the rise in global temperature is directly correlated with solar cycles? Here, have a dose of real science.

http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt

[alteredstory]

07:53 PM on 03/12/2011

It's not the sun.

http://www.skepticalscience.com/solar-activity-sunspots-global-warming-intermediate.htm

Global temperature is HISTORICALLY correlated with solar cycles, however there has been a distinct divergence in recent years.

In addition, if it were the sun, we would expect to see warming throughout all of earth's atmosphere, and we're NOT. What we ARE measuring is that LESS heat is escaping the atmosphere at the same time as the earth is warming - this indicates an insulating effect that is consistent with the theory of anthropogenic climate change.

A thickening blanket of CO2 around the planet is having the same effect as adding more blankets on top of a person in bed - more heat is trapped inside.

[PsyGuy24]

10:13 PM on 03/12/2011

To bad you're wrong. Here, educate yourself...

http://onlinelibrary.wiley.com/doi/10.1002/qj.776/full

[PsyGuy24]

10:14 PM on 03/12/2011

And how about you use a legitimate scientific sources next time..

[ClimateHawk]

02:09 PM on 03/13/2011

Your link says nothing about solar cycles.

[StephenBP]

03:21 PM on 03/12/2011

Notice how when the authoritarian mind receives data that is not consistent with its pre-approved RW data set, it uses nervous laughter, derision, and often, utter falsehood to protect the sanctity of its rigid value system.

I picture the process as going something like this…..”Scientists? What do they know! If a scientist believes something that is counter to my corporate/religious/political/economic/ideological view of reality, it must be wrong.”

Only the authoritarian doesn't know this. It is all just a bunch of feelings to them, grounded, unfortunately, on misinformation.

So they will come back with their knee jerk insults, but rarely anything resembling science.

If you look at satelite images of the shrinking Arctic Ice Cap, the rate of loss each year is unmistakable, even to the naked eye.

By the way, the word is "bupkis", not "bumpkiss" mr. biggs....