Less Ice, More Accuracy: Ice sheets in Greenland and Antarctica are now shrinking three times faster than they were in the 1990s.
Image: Flickr/ilovegreenland
Ice sheets in Greenland and Antarctica are shrinking three times faster than they were in the 1990s, and their contribution to global sea level rise is growing, according to a new study by many of the world's top ice experts.
Melting of the two massive polar ice sheets raised the world's oceans 11.1 millimeters between 1992 and 2011, or just under half an inch, accounting for about one-fifth of the total sea level rise during that period.
The study represents a major scientific advance that could help improve projections of future sea level rise, experts said. It reconciles earlier, seemingly contradictory analyses of polar ice sheet behavior, finding strong agreement in observations gathered by 10 satellites using three different measurement methods.
"Our new estimates of ice sheet losses are the most reliable to date," said lead author Andrew Shepherd, a professor of Earth observation at the University of Leeds. "They also end 20 years of uncertainty concerning changes in the mass of the Antarctic and Greenland ice sheets, and they're intended to become the benchmark data set for climate scientists to use from now on."
Forty-seven scientists at 26 research institutions wrote the paper, which was published yesterday in the journal Science.
Richard Alley, a glaciologist at Pennsylvania State University who did not contribute to the new research, called it "a spectacular achievement."
A boost to making more accurate models
Prior analyses used satellite data to examine different parts of the ice sheets during different time periods, making it tough to compare those results, he said. The new paper has found a way to work around those difficulties, developing methods to make "apples-to-apples" comparisons of data from 10 different satellites by using common locations and time frames.
"The remarkable result is that the different techniques agree closely," Alley said.
Waleed Abdalati, a polar ice expert who is NASA's chief scientist, said the research "strengthens our understanding of how and why the ice is changing, which in turn can inform models and help us understand what the future may look like."
The study shows both Greenland and Antarctica losing ice, a pattern scientists said was caused by man-made climate change. But the similarity between the two poles ends there.
Greenland has experienced the most dramatic shrinkage. It is losing ice five times faster than it was in the mid-1990s. Overall, it shed 2.94 trillion metric tons of ice during the 19-year study period.
"It's very clear now that Greenland is a problem for the future," Shepherd said, referring to the ice sheet's growing contribution to sea level rise.
Antarctic melts more slowly
Antarctica, which is significantly larger than Greenland, shed less than half as much ice from 1992 to 2011: 1.32 trillion metric tons. There was wide variation across the continent, with West Antarctica and the Antarctic Peninsula losing ice and East Antarctica making a smaller gain.
The new study does not project how ice sheet behavior may change in the future and what the consequences might be for global sea levels, but experts said there is reason for concern.
The Greenland and Antarctic ice sheets store enough water to raise seas by nearly 200 feet. Current projections suggest only a tiny fraction of that ice will melt during this century, but that would still be enough to wreak havoc on many of the world's coastal areas.
"As the climate warms, we're going to lose more mass, and the losses will be higher by the end of the century," said Ian Joughin, a glaciologist at the University of Washington. "We can't at this point extrapolate, but we can see that the trend is toward increases, and that's something we need to worry about. If we really want to have meaningful information that planners can use to build sea walls and things, there's going to have to be a big push to improve our projections of sea level rise using models."
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28 Comments
Add CommentThe headline from the propaganda machine known as Scientific American states: Polar Melting is Accelerating, So Is Sea Level Rise
Reply | Report Abuse | Link to thisThe truth is:
Polar Melting was higher in 2012 than in prior years for about 3 months in the summer.
There is ZERO evidence that the rate of sea level rise (which is the only real reason we care about arctic ice melt) has accelerated. http://sealevel.colorado.edu/
Lets see, 11.1 mm SLR over two decades = 5.55 mm per decade due to melting ice, when we are warming. So in 100yrs or 10 decades, we will have to accommodate an additional 55.5 mm of SLR (about 2 inches/century or 20 inches/millennium). Even snails can get out of the way of that.
Reply | Report Abuse | Link to thisThat is, of course, if the planet continues to warm, which is presently stalled at a insignificant level. With decreasing solar activity, which may or may not indicate a protracted cooling cycle... I find it increasingly difficult to be alarmed at such hype. GK
I have a question, guys. Where do I sign up to get paid to write anti-global-warming screeds against every article in Scientific American that mentions hard data on global warming?
Reply | Report Abuse | Link to thisIs that where Shell Oil is spending its advertising dollars now that it's stopped putting its propagandistic "surveys" on the SciAm website?
For those of you who are so derisive over these figures re sea level rise, I feel a little enlightenment is in order.
Reply | Report Abuse | Link to thisFrom the mid nineties through 2002 those of us working in the coastal areas of the SE Atlantic coastal region of the US were optimistic concerning rising sea level. The general consensus was that if we could eliminate or mitigate the other stressors caused by human activities, our coastal marshes might be able to adapt to rising sea levels. At that time we were using 1 inch per decade of mean rise, which had been constant for three to four decades. And this, by the way, extends to all sand based barrier islands, which accounts for roughly half or more of the eastern coast of North America.
In the case of the marshes associated with these islands, a 3 inch difference in relative elevation can span a whole botanical community, thereby displacing large numbers of vertebrate and invertebrate species. Among these are 30-50% of harvested marine food species, commercial and recreational. Notice that I stipulated the marshes, not the islands. Without intervention the islands would erode. But the natural processes include erosion and replacement (of course interuption of along shore sand movment is one of those stressors.)
Understand that references to us or we are inclusive of gov. employees (fed., state, county, city, ect,) private enterprise, NGO’s, and individuals. Also remember that our optimism was based upon near perfection of effort and outcome; yet we retained optimism, we refused to succumb to pessimism, cynicism or defeatism.
Somewhere between 2002 and 2005 it became obvious that our base rate of rise was substantially less than what was being observed (as I stated earlier, single digit changes are substantial.) Did we throw up our hands and wail? No, we raised our fists and shouted!
You idiots who crawl out from under your bridges every time new information is disseminated truly should all go away, as you in no way have anything constructive to add to the effort.
Let me guess, the solution to the problem is:
Reply | Report Abuse | Link to this1) Higher taxes
2) More government spending.
3) Larger government, more regulation.
Oddly enough, the very same solution for problem such as poor public education, poverty, pollution, racism, endandered species, drug abuse, crowded prisons and I assume, male pattern baldness.
Ahhhh, it is refreshing to see that the usual peanut gallery is still camping here. I haven't missed any intelligent commentary, clearly.
Reply | Report Abuse | Link to thisJust an observation. I live near a lake. This particular lake happened to be 12 inches higher than normal last spring. This caused very extensive damage to many roads, flooded a considerable number of dwellings (including an entire neighborhood), etc. This is just a lake, there are no tides or large waves or storm surges. Those of you who think a few extra inches of water level is trivial clearly don't spend much time by the water...
Speaking of the "peanut gallery", just how do you equate a 12 inch rise in lake level over 30 days, with 2 inches over 100 years of SLR, due to ice melt?! Even a "peanut" should understand the difference. GK
Reply | Report Abuse | Link to thisWhat if we flooded the Dead and Caspian Seas?
Reply | Report Abuse | Link to thisIf the Dead Sea were filled to sea level, the basin would pull about 20.6 cubic miles from the oceans (86 cubic kilometers). 11 mm of sea rise in the past twenty years (per the article) is 50 cubic miles per year. So filling the Dead Sea would sadly only mitigate 5 months of glacial melting at current rates. The Dead Sea basin is rather small (~80 square miles at sea level, -1388 feet), so let's look at the vastly larger, by surface area, Caspian Sea (143,200 square miles, or 1790 times larger).
The Caspian Sea is only -92 ft below sea level, but it's really big. If its basin is filled to sea level, it could hold an additional ~3170 cubic miles of water by my rough calculations (which include the Garabogzakoi Basin and Volga Delta regions which would be inundated by the sea rise). That translates to ~63.4 years of glacial melt storage at current melt rates. NOT BAD AT ALL!
Do note that the city of Baku (2.2M residents), which is officially at -92 feet, would lose it's entire downtown region and Astrakhan, a city of 520,000, would be entirely submerged. So there's that...
-BigWu
Both of you fail to understand my point entirely. Not surprising really...
Reply | Report Abuse | Link to thisAgain, the point is 12 inches of rise in water level in a body of water IS actually a big deal. Even a couple inches extra when the level is already rising is a big deal. The lake example simply illustrates that. Get it now?
Also, the further point there was that a lake is a mild example. The water is relatively still, all you get is passive marginal flooding. With the OCEAN you have higher surges and tides and etc which means you have effects further inland where these higher waters will now reach during these events. You also have more and faster erosion and deposition which means lots of shifting island, beaches, sandbars, etc, all causing property damage and disruption.
So, where exactly is the peanut gallery? Do you people have ANY reading comprehension at all? I am beginning to seriously doubt it.
In regards to reading comprehension, Karst lacks it. In his attempt to use math he failed to recognise that:
Reply | Report Abuse | Link to this"Melting of the two massive polar ice sheets raised the world's oceans 11.1 millimeters between 1992 and 2011, or just under half an inch, accounting for about one-fifth of the total sea level rise during that period."
There Sisko goes again -- cherry picking -- pointing to short-term data as evidence for his long-term projections:
Reply | Report Abuse | Link to thishttp://sealevel.colorado.edu/files/2012_rel4/sl_ns_global.png
Sisko just knows his gut feeling is correct; and he'll mine the data to prove it. Did Sisko even read this SciAm news article or the original study?
http://www.sciencemag.org/content/338/6111/1183
Sisko always seem to frame his analysis in error.
When there's an article/comment about increased VOLATILITY of observed short-term data, Sisko closes his eyes to that volatility and only looks at long term trends (e.g. 100 year datasets of rainfall in Nebraska and Colorado to disprove the significance of recent droughts).
When there's an article/comment about long-term temperature and sea level TRENDS focusing on projections to the year 2100 AD, he only concentrates on volatile short-term data for the last ten years.
------
Links given by Sisko:
Sisko's use of long-term trends (when others are looking at short-term volatility):
http://www.hcn.org/blogs/goat/on-droughts-and-fires-past
http://www.ianrpubs.unl.edu/live/g1551/build/g1551.pdf
Sisko's use of short-term volatile data (when others are looking at long-term trends):
http://rankexploits.com/musings/2012/adding-multi-model-means-to-model-v-observations-graphs/
http://sealevel.colorado.edu/files/2012_rel4/sl_ns_global.png
Some graphical data from the Shepherd et. al. study showing an accelerated ice melt in a relatively short time frame (1992 to 2011):
Reply | Report Abuse | Link to thishttp://www.sciencemag.org/content/338/6111/1183/F5.medium.gif
Went to the beach last July in North Carolina and did not notice any difference in sea level. Also, as an earlier commentator noted, how does sea ice melt at the poles during winter periods when temperatures are typically sub-zero?
Reply | Report Abuse | Link to thisI don't understand why Sysco, Karsk, "Scienceproofreader," etc. aren't extending their penetrating insights to other data collecting and analysis reported by SA.
Reply | Report Abuse | Link to thisFor instance their incisive commentary is desperately needed on these current propagandistic reports:
DNA--Microbiology Cult conspirators have made the ridiculous claim that they can tell what DNA looks like with their phony "electron microscope" gadget.
Planetary "science"--The "Planetary Propagandists" are actually claiming they can "see" water deposits on Mercury. Anyone can look up at night and observe there is no "Mercury," no less water deposits on it.
Moons-- The astronomer cult fanatics claim their "models" show moons may form from Saturn-like rings. Ha! Anyone can see that a moon cannot form from something that fits on your finger. And who is this Saturn dude anyway?
Flame retardants-- The Anti-Flame Retardant conspiracy are, once again, trying to sabotage the chemical industry with dissembling propaganda. They should spend less time sniffing sofas and more time getting sober.
Look at any article in this propaganda rag and you will find countless deliberate deceptions by countless conspiracies which need to be rebutted with full force.
Sysco, Karsk, et al. Don't waste your valuable time on the climate conspiracy. More important ones need to be quashed. Cult conspiracies are everywhere in science, and they're all out to get YOU (and your employer).
I guess when someone who is actually doing the work responds you can ignore.
Reply | Report Abuse | Link to thisSisko, what forms will the robust infrastructure take that solve the problem of coastal ecosystem collapse? How about those needed to prevent the displacement of populations worldwide w/in 10km of oceanic coast? And on a personal level, how will we save Florida for my grandchildren?
GKarst, it doesn’t matter how fast the snail crawls; if his niche has disappeared he dies. You’re cherry picking. I would expect better from you after an absence.
Proofreader, “Fortunately more and more people are dismissing…” Which multiverse do you live in, Opposite World?
Duderino, “duh,, government bad”
Does this mean I need to find my own bridge to hide under? I feel like such a troll.
Seriously, in the long run when you start stacking up fractions they pretty soon become whole numbers, and in this case problems. Discounting human cause/aggravation it will still be in our own best interest to conserve and diversify; it will save resources and expand the industrial base.
Johnny Cash "Five Feet High and Risin'" is a good instruction on this.
Reply | Report Abuse | Link to thisPractically every other branch of science is studied & reported with more rigour than climate science.
Reply | Report Abuse | Link to thisFunny, because most branches of science are a part of climatology. Troll elsewhere.
Reply | Report Abuse | Link to thisClimatology is a new word, which has appeared only recently. It is not a "hard" science and mostly consists of manipulated statistics used to construct a flawed model.
Reply | Report Abuse | Link to thisMany refuse to acknowledge it as a recognized discipline as it has been unable to predict anything (basic requirement).
Even the great advocate Ben Santer’s latest model/observation comparison paper in PNAS, finally admits, what climate realists' have been been saying for years — climate models are exaggerating warming.
http://landshape.org/enm/santer-climate-models-are-exaggerating-warming-we-dont-know-why/
Moss Boss will admit to nothing because his advocacy is based in ideology not climatology. GK
Karst:
Reply | Report Abuse | Link to thisThank's for putting words in my mouth.
As an aside: If climatology is not a "'hard' science and mostly consists of manipulated statistics used to construct a flawed model", then why do you suggest I adhere to it rather than adhere to my "ideology"? Can't have it both ways, bro.
Here is an example that refutes your post (yours giving false credence to Ross McKitrick who is an economist for the Fraser Institute (laugh), and Stephen McIntyre who is a minerals prospector):
Models vs. Observations:
http://www.skepticalscience.com/climate-models.htm
You have shown yourself to be exactly what we have suspected and seen in the past: a cherry-picking "denialist".
Oh so things like the famous hockey stick & the notorious emails meet your standards of rigour?
Reply | Report Abuse | Link to thisWhat a joke to put WUWT up against sceptical science & declare the latter the winner. By the way, Einstein was a patents clerk so I guess we should not give any credence to anything he wrote outside his field?
Reply | Report Abuse | Link to thisWUWT is a blog which retains funding from, among others, the Hartland Institute. Einstein had, among other credentials that were much more acclaimed need not be mentioned, a PhD in physics. I doubt that, if asked, most people would identify Einstein as a patent clerk.
Reply | Report Abuse | Link to thisNice try, but pretty weak.
Ha. You have just been debunked. What a tool to accuse others of being unscientific while you are prepared to swallow fairytales. Billions of dollars are spent by governments & big business in support of AGW while those outside the tent have to be content with a few crumbs yet they are winning the war.
Reply | Report Abuse | Link to thisWho do you think builds all the solar farms & windmills around the world? Big business. Who do you think funds it or substantially funds it. Government. This is why big business is only too happy to fund AGW proponents & programs.
Reply | Report Abuse | Link to thisEvery time you open your mouth you expose your brain to those equipped with a microscope.
When I hear or see fools denying man caused global warming I remember Buddha’s statement that among humans on all worlds the fools are many and the wise are few. When I was an undergraduate assistant in a University Zoology dept. in the late 60’s I remember some of my Professors saying that with increasing pollution and deforestation there would be a big increase in droughts and floods in the world, that the weather would become more and more unstable. It’s not just the Climatologists that have proof of the role of CO2 in climate warming. I remember a Zoology professor in the late 60’s being asked if there was more jungle in the time of the dinosaurs. His response was that the world was warmer then because the CO2 was higher. This is clear in the geological record, more CO2= world warmer, less CO2= world cooler. I have the Buddhist belief and intuitive knowledge that it is not some unchanging Self or “Soul” that is reborn after death but that it is the mental force of our ever-changing mental process that is reborn for life after life until we conquer our Self-illusion. You who deny global warming are earning some really bad karma. When it is the sphere of ethical and philosophical thought, wrong view leads to future suffering. You’ve been warned! Ignorance of the laws of the Universe is no excuse. It is a condition of ignoring truth.
Reply | Report Abuse | Link to thisThe moral of your story is that more CO2 = more life & bigger fauna, not disaster. Also it was a warmer wetter Earth. There has been no increase in extreme weather events. In fact there has been less in recent decades. There has been an increase in doomsayers because instead of holding out their hands for alms, now some of them earn enough to own private jets. The new priesthood with hordes of followers. The trouble is, rather than just fleecing their flocks, they now fleece everyone, like it or not.
Reply | Report Abuse | Link to this"This is clear in the geological record, more CO2= world warmer, less CO2= world cooler."
Reply | Report Abuse | Link to thisThat is only what you want to believe. Please indicate where in the geographical record, there is support for your assertion.
http://deforestation.geologist-1011.net/PhanerozoicCO2-Temperatures.png
Even during our current ice age where there does seem to be correlation, you have things ass backwards. First temperatures rise, then oceans degas CO2, and finally (much later) the CO2 conc. rises. Saying things with conviction doesn't make them true. Always check the data first. Cheers GK