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Greenland Ice Cap Melting Faster Than Ever

Satellite observations and a state-of-the art regional atmospheric model have independently confirmed that the Greenland ice sheet is loosing mass at an accelerating rate, reports a new study in Science. Collaborating on the paper were scientists from Utrecht University, the Netherlands Royal Meteorological Institute, Delft University of Technology, Bristol University (UK) and the Jet Propulsion Laboratory (USA).

The researchers used the Regional Atmospheric Climate Model (RACMO2/GR) at high (~11 km) horizontal resolution to calculate surface processes over Greenland, satellite radar measurements to determine iceberg production and ice sheet mass loss from the Gravity Recovery and Climate Mission (GRACE) satellites.

They found that the mass loss is equally distributed between increased iceberg production, driven by acceleration of Greenland’s fast-flowing outlet glaciers, and increased meltwater production at the ice sheet surface. Recent warm summers further accelerated the mass loss to 273 Gt per year (1 Gt is the mass of 1 cubic kilometer of water), in the period 2006-2008, which represents 0.75 mm of global sea level rise per year.

It is clear from these results that mass loss from Greenland has been accelerating since the late 1990s and the underlying causes suggest this trend is likely to continue in the near future. We have produced agreement between two totally independent estimates, giving us a lot of confidence in the numbers and our inferences about the processes.

—Professor Jonathan Bamber, University of Bristol, co-author

The Greenland ice sheet contains enough water to cause a global sea level rise of seven metres. Since 2000, the ice sheet has lost about 1500 Gt in total, representing on average a global sea level rise of about half a millimeter per year, or 5 mm since 2000.

At the same time that surface melting started to increase around 1996, snowfall on the ice sheet also increased at approximately the same rate, masking surface mass losses for nearly a decade. Moreover, a significant part of the additional meltwater refroze in the cold snowpack that covers the ice sheet. Without these moderating effects, post-1996 Greenland mass loss would have been double the amount of mass loss observed now.

Resources

  • Michiel van den Broeke, Jonathan Bamber, Janneke Ettema, Eric Rignot, Ernst Schrama, Willem Jan van de Berg, Erik van Meijgaard, Isabella Velicogna, Bert Wouters (2009) Partitioning Recent Greenland Mass Loss. Science 326, 984. doi: 10.1126/science.1178176

Comments

richard schumacher

[Oddly enough "loosing" is appropriate here, but I'd guess that "losing" was intended.]

Time to start unloading real estate in The Netherlands, south Florida and New Orleans.

JN2

0.75mm per year = 75mm per century (approx 3 inches). Not good, but not catastrophic.

HarveyD

Some will claim that the sun is getting bigger an hotter sooner than expected.

If that is so, the universe must have jumped one billion years lately.

Either way, sun-made or man-made, south Florida, New Orleans, Maldives Islands and other similar low land places may not be the best places to buy real estates for the grand children.

Sean Prophet

Don't get too complacent about the slow speed of sea level rise. Ice melting is an accelerating process. And it's not just Greenland, but the big daddy Antarctica. I'm becoming increasingly convinced that people would rather stay on the path to melting all the ice than do anything about it. Check the latest American polling.

http://www.greencarcongress.com/2009/11/ras-cc-nov-20091115.html#more

You can watch American "belief" in human caused climate change dropping like a rock in response to the prospect of doing absolutely anything at all to stop it. As if nature cares one whit what anyone "believes" or professes to "believe."

Mark_BC

"0.75mm per year = 75mm per century (approx 3 inches). Not good, but not catastrophic."

If Greenland goes, it won't be anything like linear trend. Actually, a large chunk of Green"land" is ocean. A bunch of islands that amalgamated together under an ice sheet. Therefore, if it breaks up, it could go very quickly.

Antarctica is fairly safe from melting now, but may go in the future as well.

Arne

"Time to start unloading real estate in The Netherlands"

Richard, Richard. A bit of faith in our dikes would be appreciated. Thank you. ;-)

Arne

JN2, I second Sean Prophets remark that the melt will not stay constant, but most likely accelerate.

Jer

I am thinking that some of the key issues are:

If there is the equivalent of 7m of worldwide ocean rise (average) in the entire Greenland icepak, how long would it take to completely melt the entire mass at 'just better' than status quo emission reductions (i.e. some legislative and technological improvements, but limited)? 100 years? 50 years?
-- some may argue that that is more than enough time to prepare the most important shorelines of developed countries.

Does it matter, at this point, whether we drastically cut manmade climate-change emissions? The effect of the current 'blanket' may mean that much of the melting is inevitable, and that incremental warming compounds' (CO2, methane) drops would maybe remove the last few metres of the 7m and add a few decades to this.
--some may argue that this would only little alter our success at adapting.

The point is whether to focus (because we have likely limited time and resources) on adaptation or prevention -- technology or conservation (and how should these be balanced)??

((i am allowed to play devil's advocate for the purposes of discussion))

danm

The worst case scenario for climate change is very worrisome. If rainfall patterns change we could have trouble growing food (e.g. corn belt). This is a much greater threat than Hitler & japan, in WW2. Yet back then we initiated the Manhattan project, which at one point consumed 10% of all electricity in U.S. (just an amazing fact).
-
We need to get off our duffs and start taking some action. Perhaps even try to extract CO2 already in the atmosphere. This is not sci-fi.
All it takes is political will and a populace that does not have its head buried in the sand (who still believe the earth is flat).

Henry Gibson

When there were few or no humans on the earth, there were no worries about rising sea levels. The Dutch decided centuries ago to protect the land that they had and to take more from the sea. They have stopped taking land for the moment, but it is an example how the human creature will deal with his environment. It is known that the Mediterranean was dry at one time because the Atlantic was too low to flow into it.

I propose that various small islands around the world have their human populations removed, even the so called indigineous populations that have only been around for a few tens of thousand of years. First the Hawaiian Islands then Australia. Eventually all humans should move to the moon so that the Earth is left to nature. ..HG..

Nick Lyons

@Jer--

I'll bite. Adapt we will have to do, even if we succeed in reducing GHG emissions and stabilize CO2 at some new, higher level. The question is do we adapt to a less friendly world with persistent droughts, slowly rising sea levels and more violent weather or do we try to adapt to all that plus the collapse of ocean food chains, meters higher sea levels with billions of refugees, etc. Going back to the world of 1950 is not an option, but avoiding Armageddon may still be.

Roger Pham

We have the technology to remove CO2 from the air to produce cellulose, and then turn the cellulose into charcoal (carbon), and then sequester the carbon in the ground. That technology is known as agriculture and forestry.

But first, we must completely wean ourselves off fossil fuel by building more solar and wind energy collectors. Then, instead of leting waste biomass rot in the ground and turned into CO2 again, the biomass must be collected and heated at the right temperature under low O2 concentration. This will burn off the Hydrogen and the Oxygen in the biomass, leaving behind charcoal, or carbon, to be sequestered in the ground. The heat of this limited combustion can be used by steam turbine to generate electricity. Ditto for forestry products. Computer technology can be used to markedly reduce paper consumption, or paper recycling can save a vast number of trees. And, the wood from razed-down houses can also be turned into charcoal for carbon sequestration.

Engineer-Poet originally suggested a variation of this scheme.
As Al Gore stated in his latest book, we have the technologies, we only need the will power to choose the right path in order to save our future generations.

richard schumacher

Anne, I trust your dikes as they are now, but not if they were 10m taller (10m, not only the additional 7m of sea rise because the deeper sea will make dis-proportionately higher storm and tidal surges). Also, at a guess they'll have to be twice as long as they are now. Would you trust them?

Bad as the loss of the Greenland ice sheet shall be, it is a mere wake-up call against the loss of the East Antarctic ice sheet. We still have time to prevent that 10,000 year catastrophe.

Jer

@ Nick Lyons:

Well, of course. The more sophisticated of us recognize that 'something' must be done. But what? The devil is, as always, in the details. Everyone seems to dwell within useless generalities and unrefined predictions (but of course, even the PhDs cant' agree on a way of approach or even the underlying calcs, much less how to convince people to follow through).


The point I am trying to thrash out is what happens in the interim as we prepare for/ adapt to/ confront the future. How much of a sacrifice, if we indeed need to go that route, has to be made and can that be quantified? To cut to the chase: I want the numbers so that we can attach lifestyles (and their potential) to them. In an article in the Economist several months ago, 1 reader had calculated what the total annual energy use of a typical family in the north US (perhaps minnesota) and one in the south would use. That reader then tried to reasonably optimize that lifestyle (not giving up anything completely, just smart energy use - car, house, etc). Then the reader spread this new optimized value across all american families -- sort of imposing an energy quota on everyone -- and you know what was found -- only a 5% reduction across the board - likely less reduction in emissions depending on the energy source. Of course, who knows the assumptions -- it may be 0%, it may be 15%. My argument: is this reduced lifestyle enough? -- unlikely. Now, i suppose it is easier to 'scare' people (legitimately) into reducing their levels below, not only daily usage, but to a level that is mildly uncomfortable or restrictive -- but would even that be enough?? - i have my doubts. The point is: people seem obsessed at only looking at the big picture/end result(possible) -- of course we need to look at that and then the small, grassroots picture. We may not like what we see - maybe London World War 2 rationing- type of sacrifices?? Who knows? Do we consider the possibility? Many would argue that the end of the world (or Armageddon, as you refer to it) is not worth living like starving peasants for a few generations. It is easy to say: 'we must stop 4C temp rise and searise above 1m or 2m at any cost'. Famous last words: 'At any cost'. Contrary to what many people would claim: 'Quality of life does indeed have some value'.

Answers?: Determine what emissions from each country are. Determine how much they need to be reduced to achieve a reasonable goal (maybe, max 2C increase over 100 years) - some of these numbers have been calculated. Of course based on an acceptable lifestyle per capita worldwide (whatever that is) -- which likely means that US needs to go down but India and China can go up-ish (or the US way down and these other 2 marginally down). How do these then play down to the individuals and families? Policies, it seems to me, need to be based on what level of sacrifice (or technological advancement) need to be taken on at the grassroots level. We have limited tools (calc your personal emissions websites). We need to be given a emission behavior and consequences list and then make the personal decision about what level of lifestyle emissions we believe is a reasonable compromise. Maybe 1500sq.ft home + 1 car half-days + travel and entertainment = certain emissions load -- is this too high, low, what technologies can be brought in or reductions done to bring it to that 'golden' number (without imposing quotas or rationing, if that is unpalatable to the population). Endline: More info. Less rhetoric. More process-based thinking. Maintain some results-based thinking. More bringing the emission numbers down to real life. Less 'do all that you can and hope it works out'

sulleny

Sections of the Greenland cap seem to be growing:

http://sermitsiaq.gl/klima/article30834.ece?lang=EN

But more important is fully 90 percent of all the ice on planet Earth is contained in the Antarctic. Fully 80 percent of all the fresh water on Earth is locked in the Antarctic ice cap. The Antarctic continent has been increasing in overall size by 4-5% since the start of the satellite record (1970s). NASA scientists acknowledge this fact and have no confirmed explanation.

Adapting to the three inch sea level rise per century appears to be reasonable. But I am considering an investment in an inflatable dingy.

HarveyD

Jer:

A lot more than 5% can be achieved without seriously reducing your standard of living. In the last 10 years we managed to reduce our e-energy consumption for the house from 65+ Kwh/day to 22.5 Kwh/day and our gasoline consumption by more than 50%.

Our place is very comfortable with the new ultra high efficiency Inverter type heat pump + 50 CFL + higher efficiency frige, washer, dryer, dish washer etc and we still travel about 25 000 Km/year by car.

We hope to further reduce gasoline consumption with a mid-size PHEV by 2012 or so.

All our bills and pay checks are handled in a paperless way thru our bank with a few exceptions like city taxes and school taxe.

The per capita carbon foot print could easily be reduce by 50%+ if everybody do the right things over the next 10 years.

ToppaTom

My brother has a roof full of PV panels, he bikes everywhere and plants trees.

The per capita carbon foot print could easily be negative if everybody did the right things over the next 2 months, AGW would be stopped 8 months, reversed in 2 years, ice age in 3.

Reel$$

I'm nearly 70 years old and cannot bike everywhere nor afford PV panels on my roof. I do plant vegetables in my backyard. Or is that not enough?

ToppaTom

Plant peas and beans and harness the methane
- win the Nobel Peas Prize.

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