Study: Greenland ice sheet larger contributor to sea-level rise—melting faster than expected

[OKIsItJustMe]

http://www.uaf.edu/news/news/20090611122526.html

Study: Greenland ice sheet larger contributor to sea-level rise

Submitted by Marmian Grimes
Phone: [phone]
06/11/09

The Greenland ice sheet is melting faster than expected according to a new study led by a University of Alaska Fairbanks researcher and published in the journal Hydrological Processes.

Study results indicate that the ice sheet may be responsible for nearly 25 percent of global sea rise in the past 13 years. The study also shows that seas now are rising by more than 3 millimeters a year--more than 50 percent faster than the average for the 20th century.

UAF researcher Sebastian H. Mernild and colleagues from the United States, United Kingdom and Denmark discovered that from 1995 to 2007, overall precipitation on the ice sheet decreased while surface ablation--the combination of evaporation, melting and calving of the ice sheet--increased. According to Mernild’s new data, since 1995 the ice sheet lost an average of 265 cubic kilometers per year, which has contributed to about 0.7 millimeters per year in global sea level rise. These figures do not include thermal expansion--the expansion of the ice volume in response to heat--so the contribution could be up to twice that.

The Greenland ice sheet has been of considerable interest to researchers over the last few years as one of the major indicators of climate change. In late 2000/early 2001 and in 2007, major glacier calving events sent up to 44 square miles of ice into the sea at a time. Researchers are studying these major events as well as the less dramatic ongoing melting of the ice sheet through runoff and surface processes.

Ice melt from a warming Arctic has two major effects on the ocean. First, increased water contributes to global sea-level rise, which in turn affects coastlines across the globe. Second, fresh water from melting ice changes the salinity of the world’s oceans, which can affect ocean ecosystems and deep water mixing.

“Increasing sea level rise will be a problem in the future for people living in coastal regions around the globe,” said Mernild. “Even a small sea level rise can be a problem for these communities. It is our hope that this research can provide people with accurate information needed to plan for protecting people and communities.” CONTACT: Sebastian H. Mernild, postdoctoral fellow, at 907-474-2787 or [e-mail]. Jenn Wagaman, research outreach coordinator, at 907-474-5082 or [e-mail].

ON THE WEB: http://www3.interscience.wiley.com/journal/89013836/issue

JW/6-11-09/183-09

[Bigmack]

1. "which can affect....deep water mixing." -

and deep water mixing can - will? - affect the thermohaline (sp?) current...... Ms Bigmack

[Systematic Chaos]

2. K&R - and hoping for the inevitable response from XemaSab.

Seriously, I wonder how much longer it will be before we're discussing sea level rise in "millimeters per month", or even "millimeters per week"?

Fuck.

[XemaSab]

12. I opened this after three days incommunicado

and sure enough...

[JohnWxy]

3. We have 6 to 10 years (hopefully) to achieve some appreciable reductions in GHGs.

What are the options? We don't have 20 years to wait. Dreams and expected savings don't get us reductions NOW.

(growth industry in the future manufacture of Scuba diving gear.)

(TRied to recommend but was too late.)

[The Croquist]

5. I differ

The study also shows that seas now are rising by more than 3 millimeters a year--more than 50 percent faster than the average for the 20th century.

3.1 millimeters a year is about half of what it has AVERAGED for the last 20,000 years. To say that we are on the brink of disaster is a bit of a push.

[pscot]

6. The problem with that average

is that it smooths out the difference between periods of relative stability, like the last 8500 years, and periods of dramatic sea level rise. Eighteen thousand years ago it was possible to walk from Helsinki to Dublin. In 8000 BC Britain was a peninsula. By 6500 BC it was an island. For most of the history of human cultural development climate and sea levels have been pretty stable. All that is changing before our eyes. The writing is on the wall, but like Belshazzar, we seem to be unable to parse its meaning.

[The Croquist]

7. So what you are saying here is that

even though it has averaged twice as much per year over the last 20,000 years that was natural but because it is currently half that amount per year over 30 years it is a concern now.

Question: If averaging it over 20,000 years smooths out instabilities doesn't that mean that short periods can be even LESS stable and not be detected compared to our 30 year record?

Question: If it is mankind's fault now what caused it 20,000 years ago?

Question: If most of it happened in less then 20,000 years (I've seen a figure of about 13,000 years) wouldn't that mean that for 13,000 years it was averaging three times as much per year as it is averaging now instead of two times as much?

Question: If it averaged three times as much per year then it is averaging now what caused it then?

Question: Is thirty years enough data to compare to a trend that has been going on for 13,000, 18,000 or 20,000 years?

[pscot]

8. My point was that averages are deceptive.

and not all that helpful in describing what's actually happening. Between 18,000 and 6500 BC, sea levels rose almost 300 feet. Primitive folks, living in widely scattered bands, simply moved out of the way as the waters rose. There was very little change from 6500 to the present, during which period of stability civilization occured. Now, after a hiatus of 8500 years, it looks as if the game is on again. This time, moving out of the way is going to cause some serious inconvenience.

[The Croquist]

9. My understanding is that it rose 400 feet not 300 feet

but regardless, why is it considered natural that it rose so much and at a much faster rate prior to man-made global warming then currently?

Maybe "the game is on again" or maybe not. 30 years is too small a time to measure. Do you really think that in the last 8,500 years sea level hasn't moved by as much as it has, over a 30 year period, either up or down, as it has in the last 30 years?

If it continues I agree that moving out of the way will be inconvenient but it has been so for the last 20,000 years. The ancient Metropolis (4 huts and a stockade) of Croquistvillia may not have been as large as NYC but it probably represented as much dedication, history and hard work of the inhabitants that the current residents of New York City have, after providing for food for their families.

Whole islands have been submerged along with any records of human habitation. Think about how many Islands 300 (400?) feet of sea level rise has submerged. We hear news stories that blame submerged islands on "Man-Made Global Warming" when the truth is that during the time that these islands were submerged sea level rose less then an inch. Think about what kind of an island gets sunk when sea level rises a lousy inch. The Great Lakes and Niagara Falls didn't exist 20,000 years ago nor did Long Island...

Somehow man managed to survive.

[vincna]

19. Great questions

You have summarized the problem I have with the climate change alarmists: For the most part, their focus seems to be limited to the past 30 or so years and the fact the sea levels and global temperatures have varied greatly (higher and lower than today, over thousands and millions of years) are largely ignored. I'm still skeptical.

And 3 mm per year? That's about 10 feet in a thousand years. Is that really worth getting excited about? In any case, there would be plenty of time for affected people to relocate

[JohnWxy]

22. Averages are definitely deceptive if the average person doesn't consider that the warming is

accelerating. Accelerating warming makes it difficult to extrapolate future temps. (especialy when we're not sure just what the rate of accelleration is. It is apparent that the warming is increasing faster than the models have predicted.

i.e. let's not pretend that we are faced wilth a linear rate of change.

[The Croquist]

28. I don't think the warming is accelerating

There are only 30 years of accurate data and the temperature peaked 10 years ago. It is warmer today then it was 30 years ago but cooler in 2008 then 1998 or even 1980. The earth's temperature bounces.

It is absolutely not true "that the warming is increasing faster than the models have predicted.
"unless you pick and choose a specific model from the dozens out there. That's like deciding that a handicapper at a horse track is a genius because he has a good day. They all show warming temperatures over the next 100 years but none showed cooling temperatures over last decade. Frankly I think that 10 years is too short a time period to get a warm and fuzzy but I also think that 30 years is to short.

Look at the predicted sea level rise. the IPCC 2007 estimates it to be anywhere from 0.6 feet to 2 feet in the next hundred years. What kind of wiggle room is that?

I agree that we are not faced with a linear rate of change. I just don't know what the rate of change is or in what direction.

[JohnWxy]

26. If we do not get some reductions to GHG emissions started in 6 to 10 years the warming will

get 'ahead' of us. The "disaster" (depending on how you define it, or where you live, say India or Bangladesh vs the United States) won't be experienced perhaps for 20 to 40 years from now. But the stage, likely, will be set for such a scenario by what we do in the next 6 to 10 years.

For one specific: The permafrost is beginning to defrost. As it it does, the organic material making it up, will begin to decay. This will generate CO2 and methane and speed up the warming process. A 15% to 20% reductiion in CO2 emmissions achieved within 8 to 10 years will mean more in terms of slowing the warming down than a considerably larger reduction in say 20 - 30 years.
At some point the warming will be building to a degree that we actually won't be able to produce large enough reductions in GHG emissions to slow the warming down. That's how I define the disaster - Global Warming getting to the point that we will not be able to slow it down or reverse it.

We need to start getting some appreciable reductions in GHG emissions soon, or it won't matter how big the reductions we MIGHT acheive later are. NOw, I don't know exactly how much reductions (in the next 6 to 10 yrs) we need, nobody does for sure (but estimates can be made). But we are going to have to do better than we are so far.

Doing something is likely a better approach than sitting on the pot contemplating the aroma of your own effluents.

[Fotoware58]

4. Hmmmm

I just had a thought. The saltier the water is, the lower the freezing point. Could it be that one mechanism for rebalancing sea ice is an ocean with decreasing salinity? An interesting thought but, ultimately, probably a non-issue. Our world is still very complex and many things regarding weather are still beyond our comprehension. This world has many self-compensating controls but, millions of years of historical data say that an icy globe is the default here.
.
.
.
Then again, some people think that I think too much....heh

[wuvuj]

10. Have no data to back it up...

...but I'm guessing that melting ice has cooled the rest of the earth (non-polar)...for awhile and after this is overcome...we will see a serious warming cycle?

[The Croquist]

11. I understand what your saying but I don't think so

If you put an ice block in your room with the doors and windows shut it will cool it while it slowly melts but if you freeze it in the room with a 100% efficient freezer (I know that doesn't exist) and then pull it out there will be no difference in the temperature of the entire room (including the freezer.

Melting ice can certainly slow the increase in the world's temperature and has been for 18,000 - 20,000 years. Keep in mind that back then much of North America had 1 - 2 miles of ice sitting on it. That was a lot of slowing of temperature change.

Fortunately we still have lots of ice to go. May of 1979 had 25.20 million kilometers of sea ice. May of 2009 had 23.80 million kilometers of sea ice. That is a drop of about 6%. 6% over 30 years may be a lot but we really don't know.

[jimlup]

13. But the earth isn't a closed system.

Also in your second example the room would initially heat up as the heat was extracted from the water in order to freeze it. Then the room would cool back down in a hypothetical zero entropy increase cycle. My point is that at the point in time when the ice starts to melt the room then proceeds to cool. I guess there may be some truth to the argument that melting glacier and sea ice could cause a temporary atmospheric cooling but I'm not enough of a climatologist to really judge.

[The Croquist]

14. Either I wasn't clear, you missed my point or

probably both. If I had been clear you wouldn't have missed my point.

When I talked about the room I included the freezer. The freezer, freezing ice will warm the rest of the room but the freezer / room combination will stay the same (remember I claimed 100% efficiency).

I also said that "Melting ice can certainly slow the increase in the world's temperature" that is not the same as "melting glacier and sea ice could cause a temporary atmospheric cooling". Maybe I niting picks but I think there is a difference.

You are absolutely correct however saying that "the earth isn't a closed system". But lets talk about the surface of the earth. It is even less of a closed system. It receives energy from the sun (directly and indirectly from the moon and other planets), stars and the interior of the planet. It looses heat into space. Sometimes it gains energy and sometimes it looses energy. It appears that we've been gaining energy off and on for the last 18,000 - 20,000 years, long before man started significantly increasing the CO2 in the atmosphere.

[jimlup]

15. Right, right...

But the problem isn't that I don't get the 1st or 2nd laws of thermodynamics (I'm actually a Ph.D. physicist). Perhaps we don't understand each other. But I still stand by my point - melting ice could have the effect of lowering the apparent temperature. I have a hunch that this is what is going on in the Antartic. Yes, I agree that melting ice can slow the increase in the world temperature, certainly it functions as a thermal buffer. But I claim it could also reduce atmospheric temperatures in a non-equilibrium state (our current planet).

We are both saying it is a negative feedback. Apparently I'm just saying it could have a temporary depression affect on atmospheric temps because thermal energy could be transferred from the environment to warm the newly melted water. My post was confusing because it made two points. First that the earth is not a closed system (which I said just to point out that this problem is complex) then that yes, sea ice could lower (apparent) temperature though not total heat content. Given my level of expertise on this it is (from my position) just idle speculation of course.

If you put a block of ice in a closed refrigerator it will melt and lower the temperature of the air in the refrigerator but the total heat content will stay constant. Maybe my only point is that we are not in an equilibrium state because we are both using the same thought experiment to explain our reasoning.

[Fotoware58]

16. Weather

Man has been studying weather for millenia but, today's meteorologists still cannot correctly predict TODAY'S weather. The variables involved in predicting weather are complex enough even without including modern man's contribution to the system. We do understand more about individual variables but their interactions seem to be beyond our present comprehension. Personally, I think we should focus on real sources of obvious pollution and not worry about variations that stay within the historical (and pre-historical) record. After we have reduced most of the sources of obviously bad pollution, then we can re-evaluate and see what else is needed. While I don't believe that runaway global warming is possible (ala Hansen), I also believe that mankind cannot continue to damage the earth in exchange for cash.

Just my 2 cents.

[jimlup]

18. Er eh...

You miss the point of the global warming models. Sorry that you don't get the science yet. Study up and you might find some interesting things. You're about a century behind so you have a lot of work to do.

[Fotoware58]

21. I understand science just fine, thank you!

I've seen the claims, pro and con and I conclude that I'm somewhere in the middle. Yes, I know that both sides do not want me there but, I choose not to follow the extremists. Hansen says the ocean will boil off and THAT sounds quite extreme to me. There is evidence that both CO2 levels and temperatures were much higher, historically, than Hansen's preferences but yet, the oceans still persist! On the other hand, we cannot continue to extract coal and oil from underground and burn it with no environmental ramifications. Models are simply models and they are probably wrong 90-100% of the time in human history. In fact, your precious models don't even include forest fires, with the IPCC COMPLETELY ignoring those impacts on our atmosphere.

So, don't try to lecture me about science. Today's science is more about who funded it and less about scientific truth.

[jimlup]

24. ????

Wow!

[guardian]

29. Oh noooooooo

"Today's science is more about who funded it and less about scientific truth."

You are about to be slammed by the GW zealots. Didn't you know that only CORPORATE money corrupts. Academic money is and those whose living relies on it are pure as the driven snow.

[guardian]

23. Agreed

Let's put our money and resources into making real improvements to the environment and stopping real pollution.

[The Croquist]

20. "I'm actually a Ph.D. physicist"

Oh yeah? Well I flunked Differential Equations, had to switch majors and ended up a banker so we're practically even (well maybe not practically). So there! x(

I do agree with you about that were not too far from each other regarding ice melting.

There are several reasons why I question that man-made global warming is significant. One reason is that the data just sucks. Nobody really knows how much the earth has warmed up in the last 100 plus years. If you look at the temperature record you will see just how questionable it is. Here is a map of what they claim January 1880 to be.

http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2009&month_last=05&sat=4&sst=0&type=anoms&mean_gen=01&year1=1880&year2=1880&base1=1951&base2=1980&radius=250&pol=reg

I'm sorry for just the link but I don't know how to post an image.

They claim that January 1880 was 0.50 C. above average. Last February they claimed it was 0.47 C. above average. I know because I saved a copy of the data then. Now maybe they get improved data but I watch it change on a monthly basis and I doubt that they find new data every month, blow dust off and use it. Since they are using a static base of 1951 - 1980 that shouldn't matter.

If you look at the map you will see two stations in Africa and zero in both South America and the Antarctic. The only two continents that are covered worth a darn are Europe and North America yet they claim to know accurately what the temperature was back then to two decimals. We haven't even touched on the quality of the data. As a Scientist, would you list out to two decimals a number based on this?

Now I chose the "least options". That includes no sea temperature and only grids within 250km of a temperature record. They have the world divided into 16,200 grids each 2 degrees latitude by 2 degrees longitude and of them they have data for 913 of the grids and I question even that many.

If you look at the map you will see a record near the equator just off the west coast of Africa. That, I believe, is the Island of Sao Tome. From that one record they assigned temperatures to 12 grids totaling 294,368 square kilometers. That's about 50% bigger then a 250 km diameter drawn around Sao Tome and about 50% bigger then Great Britain,. Do you think that makes sense? What do you think it would be like if you use their default 1,200 kilometers option?

[jimlup]

25. Honestly, I wasn't ...

talking about my Ph.D. because I wanted to show off. I just wanted you to know you were talking to someone who understands thermodynamics. Frankly, I try to keep my degree out of conversations but feel it is sometimes important when the discussion turns to
science because I do have kind of an "unfair" advantage and a certain built in academic bias. :hide:

Anyway, yeah I have not looked at the "GISS" data myself with that particular question. It is astounding to me that they have temperature records that are that accurate yet I know that the peer review process tends to shoot down anything that isn't rigorous so I have a fair amount of confidence in the data going in. Apparently more than you do.

I'll take a more careful look, thanks! I'm working to become more educated about climatology just like everyone else. It isn't my field so anything I do in it is just playing. It is true that more of us have to now become experts. If Hansen is correct - we're in trouble.

[The Croquist]

27. No offense taken

Anyone who can do Differential Equations I have to respect. It was the first major failure in my life. Peggy (last name withheld) was bad too but bailing out of physics was a real bummer. Math was so easy up to that point that it was a shock to me.

Please do take a look at the data. I truly think it is just lacking. That doesn't mean that significant man-made global warming doesn't exist. It just means that we don't know.

[wuvuj]

17. A pic....

As the poles take the brunt of temp increases...they will eventually lose their effectiveness as heat sinks...possibly causing a serious bump up in global temps?

Still a lot of ice...but it is 60% as thick at the N pole?





This feedback might explain some of the shorter cycles? Interesting bump up during WW2?