ICE Satellite Maps Profound Polar Thinning

xp65 writes "Researchers have used NASA's Ice, Cloud and Land Elevation Satellite to compose the most comprehensive picture of changing glaciers along the coast of the Greenland and Antarctic ice sheets. The new elevation maps show that all latitudes of the Greenland ice sheet are affected by dynamic thinning — the loss of ice due to accelerated ice flow to the ocean. The maps also show surprising, extensive thinning in Antarctica, affecting the ice sheet far inland. The study, led by Hamish Pritchard of the British Antarctic Survey in Cambridge, England, was published September 24 in Nature."

Comments

What is the net effect?

[msevior]

I'm no climate change skeptic, but from just looking at the images it's not clear that the reduction in some places is not balanced by the increase in others. What is the net effect? Can these data be compared to model predictions?

Re:What is the net effect?

[blind biker]

Yes for Antarctica - there does, indeed, seem to be a balancing between areas with thinning and those with thickening ice. But not for Greenland, which appears to be pretty much on a dramatic thinning regimen.

Re:What is the net effect?

[should_be_linear]

if net effect was positive, that would be great surprising news. It seems, instead, situation is getting worse so quickly that we are heading towards geoengineering (desperate) solutions.

Re:What is the net effect?

[psyph3r]

Irrespective of humanity's perceived impact, does this not happen throughout history in a cyclical fashion? I would look at this type of activity as the main source of evolutionary change. The species that are equipped to survive the conditions will prevail.

Re:What is the net effect?

[msevior]

Sorry, I didn't mean the net effect of climate change, I meant the net amount of ice in Greenland and Antarctica. From the data provided it's not obvious that Greenland and Antarctica are losing ice. For example there are very large blue/green regions (gaining ice) that by eye could be bigger than the red regions (losing ice).

The other question is regards climate model predictions. One of the catastrophic outcomes of climate change are large sea level rises due to ice melt in the polar regions. Presumably there are models that predict how this could occur with global warming. So the question is, do these data agree with these models?

Re:What is the net effect?

[khayman80]

One of the catastrophic outcomes of climate change are large sea level rises due to ice melt in the polar regions. Presumably there are models that predict how this could occur with global warming. So the question is, do these data agree with these models?

The last article I read in Science compared model prediction of sea level rise, and found that observations showed the sea levels rising even faster than the models predicted. Perhaps this was just short-term weather, though: more recent measurements may indicate agreement with the models.

Re:What is the net effect?

[siddesu]

It is really simple. It all depends on how much kick are you getting out of the environment as we know it.

It is true that so far whenever cataclysms occured and species died out there was a subsequent re-population with new flora and fauna. It is also true that whenever such events have occurred, nearly all of the prevalent species have disappeared, and the subsequent re-population has taken millions of years to happen.

So, if you really, really don't care about your species disappearing in famine and diseases and other niceties those bring then yeah, life will eventually adapt to the new equilibrium that will prevail, and there is little to worry about in the long run.

If you are one of the neo-conservatives who want to keep living as we like it (a.k.a. tree-huggers), without disruptions and without need to die out and re-adapt, then you understand there are things that better be done sooner than later.

Re:What is the net effect?

[khayman80]

It's a better idea to get your science from scientists rather than politicians. The CO2 emissions by living organisms are part of a closed cycle, and those isotopes don't match the composition of the atmospheric CO2 that's currently ~26% higher than it's been in the last 650,000 years. Other sources such as volcanoes emit 100x less than humans do. Also, water vapor isn't relevant because it has a short lifetime in the atmosphere and isn't well-mixed to the top of the atmosphere. I've discussed all these issues at length.

Re:What is the net effect?

[EsbenMoseHansen]

They have never been able to accurately predict what the weather will be tomorrow. It is arrogant for Al Gore (who incidentally also invented the Internet) to claim he knows what the effect will be decades from now. The largest cause of CO2 emissions is natural activity. The most abundant greenhouse gas is water vapor. http://en.wikipedia.org/wiki/Greenhouse_gas#Greenhouse_effects_in_Earth.27s_atmosphere

3 myths in one go? Not bad. First link on google for climate myths gives 3 rebuttals: Chaotic systems are not predictable, CO2 isn't the most important greenhouse gas and finally CO2 isn't the most important greenhouse gas

Re:What is the net effect?

[khayman80]

According to a recent survey, about 10% of scientists believe that the current warming is natural, 4% believe there is no warming, and 84% believe the current warming is caused by humans. So, yeah, some scientists are skeptical of global warming.

But stop trying to count heads on each side of the debate. As I've repeatedly stressed in that last link, science isn't democratic. It's about evidence. When I see some convincing evidence against the existence of abrupt climate change, then I'll be interested.

And of course the IPCC doesn't conduct original research. They compile previously peer-reviewed research into reports that summarize the best scientific evidence available.

Do they know if this is unusual?

[n2rjt]

I see on the maps that some areas are thinning, near the coasts, and other areas are thickening.
I wonder if that is the usual pattern, or if they are seeing something unusual.
The article didn't mention that, as far as I could tell.

Re:Do they know if this is unusual?

[Beryllium Sphere(tm)]

Qualitatively, what you'd expect from climate change is more precipitation (because there's more evaporation) and therefore thickening at high elevations where the snow stays cold, while lower warmer regions flow faster or even melt.

Re:Do they know if this is unusual?

[khayman80]

Exactly. I've described my research into Greenland's ice sheets. My most recent estimates show that Greenland as a whole is losing ~100 Gtons of ice every year, but my advisor believes my estimate is too low by a factor of 2. As you say, northern Greenland is gaining mass, but southestern Greenland is losing much more mass. Climate change is a very serious problem, and I'm really annoyed that health care is currently distracting the Senate from an issue that affects the future of the entire human race.

Re:Do they know if this is unusual?

[khayman80]

Higher average global temperatures imply higher upper ocean temperatures, which imply a higher water vapor pressure. Thus more water vapor will evaporate into the atmosphere. Yes, Roderick 2007 showed that wind speed had a stronger affect on the evaporation rate than changes in temperature, but I doubt that affects the expected theoretical equilibrium vapor pressure from basic thermodynamics. When that more humid air is carried across a tall mountain range, its temperature decreases and the water precipitates.

Re:Do they know if this is unusual?

[BrokenHalo]

and I'm really annoyed that health care is currently distracting the Senate from an issue that affects the future of the entire human race.

Well, this doesn't help, but I can see why health care is the focus of attention: it is one thing the government can do something about. Climate change is a serious problem, but it is now too big to fix, since no-one has the will to adopt a policy amounting to more than "business as usual" and "let's have another toke on that big ole' oil-pipe".

A lot of political mileage is being made of proposed emissions trading schemes, but it's too late for that. They are just accounting exercises - like pushing food around on the plate to make it look like you're eating less.

I'm sorry if that sounds defeatist, but I'd be happy to hear an alternative. People will not change until they're forced to.

Re:Do they know if this is unusual?

[khayman80]

Assuming that large scale warming is already well under way (And that's a big assumption given the major cooling trend we have been in for the last 10 years.)

I've discussed this claim before. Short version: there hasn't been a cooling trend over the last ten years, major or minor.

It is likely, in fact nearly guaranteed that not only can't we do anything about it now, we probably NEVER were able to do anything about it.

The climate varies naturally on long timescales but Meehl 2004 shows the current warming can't be accounted for by natural forcings. Greenhouse gas emissions are the only way we can explain the temperatures over the last ~40 years.

Don't matter...

[The Master Control P]

Those who demand "proof" of climate change before we do anything to fight it will find some way to ignore this. They'll keep pretending there's "no evidence" and that it's a "librul conspiracy" until it becomes undeniable (I'm betting til the dams surrounding a port city fail) because they don't believe in doing anything proactive.

Then when the engineers say it's too late to do anything except build a 300 foot tall dam around every coastline in the world, it'll be their fault for not fixing it.

Re:Don't matter...

[icebike]

We have been warned for years on end that coastal inundation would be the direct effect of polar melting.

But inundation should not be a delayed effect. It should appear immediately, and in direct proportion to the melting.

So where is it?

Re:Don't matter...

[MartinSchou]

Well, with what is usually being proposed, like reducing carbon emissions by driving more fuel efficient cars, no leaving lights on everywhere, how is that POSSIBLY a bad thing?

If we're talking about some of the more harebrained ideas like having hundred of thousands of ships sucking up cold water from the the ocean and spraying it as high into the atmosphere as possible, yes I agree - that could easily do serious long term damage that we don't realise.

But conserving energy cannot do that, as we are simply choosing to reduce the energy input into a system that had previously had a moderately stable equilibrium before we started burning all those fossil fuels.

Re:Don't matter...

[khayman80]

Okay, yes. Technically I agree. The political/economic ramifications of our response to climate change aren't completely within the domain of physical science, so they're not facts in the way that the anthropogenic origin of abrupt climate change is a fact. For example, our technology could suddenly jump forward very quickly, rendering adaptation very simple and cheap.

But we're talking about the future of the human race here. Let's choose the safest option, and try to avoid the worst effects by moving from coal power to modern nuclear power. As technology advances, solar, wind, tidal and geothermal power can play an increasing role. We've stagnated and become complacent in a world powered by cheap oil; another industrial revolution is long overdue.

Re:Don't matter...

[Idiomatick]

Fixing CO2 emissions is a few trillion dollar problem. Having water raise a foot and having temperatures change globally will be many many trillions. As lang changes there will be massive wars. You can already see parts in the Arctic. With the US claiming up to half of it (Including islands to the south Canadian's have claimed for almost 100years.). Dealing with food shortages, massive natural disasters. This will be many trillions of dollars over a long period of time.

And I'm sure the number of possible problems is significantly greater with the surface of the planet changing compared to retiring old coal power plants and converting to more electric cars.

Re:Don't matter...

[khayman80]

The NASA Earth Observation site has measurements of the ice coverage at the north pole. While their text speaks of massive ice loss and continuing doom, the actual graph they provide of the data shows that while the minimum ice cover is less than the average of a decade ago, there is actually more minimum ice cover than last year, and last year had more cover than the year before. Why do they not mention this at all ? Maybe the point is to mislead?

Yes, 2008 and 2009 had smaller ice extent minima than 2007. But the point is that climate models had previously predicted larger ice extent minima than were observed in 2007. So the last several years tend to confirm that the previous measurements were due to short-term weather variability rather than a flaw in the climate models.

If they were to publish the proper figures for 1979 to 2000 instead of just a vague average, we could maybe see whether there is a regular fluctuation, instead of guessing that the decline has been constant.

Ask, and you shall receive. No serious scientist is actually "guessing" that the decline has been constant, and no climate model that I'm aware of makes that prediction. Short term variability is expected, but the data shows a clear downward trend over the last 30 years.

Re:Good-bye ice, it was nice knowing you.

[icebike]

Where is the massive coastal flooding that was promised to be caused by this?

I have beachfront property. Or I will have as soon as the much promised flooding arrives.

Re:Good-bye ice, it was nice knowing you.

[EsbenMoseHansen]

That would be sensationalism. So far, it is measured in cm; by the turn of the century (90 years from now) it is projected to be a few meters,

Carbon Credits?

[retech]

I thought carbon credits would have someone parked on the poles with a couple of ice making machines (perhaps like they use in a hotel but not as loud) and they'd be scooping fresh ice out to keep it topped off... why is this not happening? Have we been lied to? Where did all that carbon credit money go to? Just when I thought for sure I could sit in my apt and do something really fucking meaningful from a distance to help save all those future generations by buying offset credit every time I got on WOW and played for two days... this just has destroyed my entire weekend and trust in humanity.

Re:Hide in the mountains!

[PinkyGigglebrain]

Congratulations!! You just explained by analogy how melting ice pack (ice cube), that is ALREADY floating in the water, will have no meaningful effect on sea level.

Now try this, take that same full cup and put two chop sticks side by side across the top of the glass. Now place a few ice cubes on the chop sticks and watch them melt, what happens to the water level in this case?

What is worrying is ice that is currently NOT floating is showing signs of melting, which will have an impact on sea levels.

The climate is changing, it doesn't mater if its caused by humans or some natural cycle, we have to start thinking about how we are going to adapt now if we are going to survive long term.

Remember that what happens elsewhere in the world DOES have an effect on you, it may be slight but it does. Ever notice how milk costs more when petrol prices go up because of political unrest in the middle East?

Re:"man made"

[khayman80]

Wrong.