Slashdot Mirror
Antarctic Ice Loss Big Enough To Cause Measurable Shift In Earth's Gravity
An anonymous reader writes: Contrary to what we were sometimes taught in high school physics, the Earth's gravity is not constant. It actually shows slight variations on different parts of the Earth's surface, and the variations correlate with the density of the material on that surface. The European Space Agency has been measuring gravity for four years, mapping these variations and recording the changes those variations have undergone. Its data indicates "a significant decrease [in gravity] in the region of Antarctica where land ice is melting fastest. Further analysis is, of course, planned so that the whole of Antarctica can be taken into account and "the clearest picture yet of the pace of global warming" can be determined on that continent.
http://en.wikipedia.org/wiki/F...
http://en.wikipedia.org/wiki/F...
The Gutenberg Discontinuity, is the boundary, as detected by changes in seismic waves, between the Earth's lower mantle and the outer core about 1800 miles below the surface. It is also called the core-mantle boundary.
http://en.wikipedia.org/wiki/M...
I can't speak for all country, but in France you are taught 1) that gravity constant used varies and we get the values at equators, pole, (iirc 9.78 to 9.83 while we used 9.81) and our lattitude, altitude
2) but afterward to make it simpler we always assume it is a constant because we do not have the math tool to integrate with g(r,theta, rho) over complex surface.
At no point we were taught that gravity is a constant. What we were taught is to use it as constant in simplified problems. That is a difference. I would wagger it is the samer in the country of the submitter, only he missed the important semantic difference.
C. Sagan : A demon haunted world:
http://www.amazon.com/gp/product/0345409469/
visit randi.org
Freezing water expands and takes up more volume which makes it less dense, yes, but it still has the same overall mass as when it was liquid. The idea here would be that the water runoff goes into the surrounding oceans, so mainland Antarctica would be losing overall mass.
The Ice melts and the water physically goes elsewhere. Less stuff, less gravity.
The whole story is. 4 years != climate. Not by anyone's measure. If skeptics tried to debunk AGW on this board with a 4 year trend, everyone would be all over them like white on rice. But 4 years in favor of AGW in the summary? A O K!
The shift is small but the mass loss is real. Last three year average in the measured area has been 185 gigatonnes/year. It has an effect on the gravity, that's clear. The question is how much, and it seems it can actually be measured by instruments. Not anywhere in the world there's a constant loss of this magnitude, and as the trend goes on the change in gravity will also become more distinct.
The problem is that this is not intended or presented as a proof of climate change. It is merely measuring recent gravitational changes showing the affect of the reduction in ice. The article does pre-suppose that any melting of ice would be the result of climate change. You could certainly argue against that assumption.
But what you can't argue against is the fact that the ice is melting at all, although that doesn't stop some people here from cherry-picking one particular type of ice (sea ice), saying that it has expanded as if that is the complete argument against the total ice loss.
Ladies and gentlemen, the Gish Gallop.
In complete denial of the FACT that Antarctic sea ice is at the HIGHEST LEVEL in decades, these Global warming cult members keep spreading the blatantly false propaganda.
Does the expansion of sea ice mean that the total volume of sea and land ice has gone up? Does it even mean that the volume of sea ice has gone up or is it just being spread thin?
You have cherry-picked a single variable that has gone up and ignored the bigger picture, and then made the outrageous claim that it is the people who actually measure the total ice that are spreading false propaganda.
Answer one question: has the volume of land ice gone up or down? If the answer is down, why is it so unimportant for you to mention this inconvenient fact?
On second thoughts, we can ask an even easier question. Has the total volume of ice gone up or down? According to the article, the gravitational measurements show that it has gone down. Why are you in complete denial of this FACT?
What conclusions are we supposed to draw from that? Well, other than that you don't know the difference between "land" and "sea".
I'm getting tired of hearing about how all life on Earth will end in a few years unless we vote for just one political party and their pet doomsday cult.
I'm sorry that you are getting tired of this, but in this case you can rejoice! Because nowhere in the article did they state such an absurd line.
There is no point making up quotes to get offended by when you could just comment on the actual story at hand. Your entire post has absolutely nothing to do with measuring the gravitational changes of melting ice.
It is not necessarily as simple as that. For example the gravitation field near mountains is actually less that that further away from them. Mountains are areas of thicker continental crust and this displaces the denser underlying mantle meaning that there is actually less mass near mountains despite appearances to the contrary.
In this case it looks like the hots spots are right on the coast so is it possible that the ice has actually thickened and displaced more of the denser sea water? This might also cause a decrease in the gravitational field there. It would be nice if articles actually discussed some details of the science and some of the effects which researchers have considered.
There is no net change. Local gravity becomes weaker where the ice was and stronger where the melted ice now is.
The cryosphere page at University of Illinois-Champagne shows that we are currently seeing more sea ice than the average, and the levels have been sharply rising the last few years.
It is the same effect: The ice on the land is melting and flowing into the sea where some of it re-freezes.
The area of ice is increasing, the mass of ice is decreasing.
The whole story is. 4 years != climate. Not by anyone's measure. If skeptics tried to debunk AGW on this board with a 4 year trend, everyone would be all over them like white on rice. But 4 years in favor of AGW in the summary? A O K!
Yes but before the ESA satellite there were the GRACE satellites launched in 2002 that also showed West Antarctica losing ice and Antarctica overall is losing ice at a rate of almost 69 GT/year (graph). So it's more like 12 years of data. Even that is a rather short time period compared to the standard climatological period of 30 years. But the standard climatological variables such as temperature, precipitation and wind are very noisy compared the rate of ice loss so it takes longer to discern a significant trend with them than with ice. So 12 years may be long enough for significance. I'm not sure.
The suggestion that "being big enough to cause a measurable shift in earth's gravity" is something worthy of note is the anti science idiocy. This is not something that matters.
You don't understand. It is politically correct to tie this to global warming.
In complete denial of the FACT that Antarctic sea ice is at the HIGHEST LEVEL in decades, these Global warming cult members keep spreading the blatantly false propaganda.
This would be wrong. It has been known from the older GRACE satellites that Antarctic Ice has been losing mass from the ice sheet.
In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of 26 ± 14 Gt/yr2 in 2002–2009. (Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, I. Velicogna, Geophysical Research Letters, (2009))
You might be thinking of the Antarctic Sea Ice.
Now they are saying that if I don't drive a Prius, that the earths gravity will fail.
I don't think that that's what they're saying.
My reading of it is that they're saying that Antarctica and Greenland together are now losing 500 cubic kilometers of ice per year. They don't mention what will be the effect on that of you driving a prius, but I suspect not a lot.
This was measured using Gravity. I don't think that they say that gravity is failing.
The article barks at the wrong tree. The cryosphere page at University of Illinois-Champagne shows that we are currently seeing 1.3 million sq. km more sea ice than the average, and the levels have been sharply rising the last few years.
There is a fine balance between trying to increase awareness and being a downright propagandist. Unfortunately, this article doesn't help the cause. This is exactly the kind of thing that make people believe environmentalists are exaggerating and grasping at straws.
Wired: Stop. You are not helping.
Before you go on you really should learn the difference between ice sheets, ice shelves and sea ice. They are not the same thing. Talking about sea ice in response to this article about the West Antarctic Ice Sheet is a non-sequitur.
I'm getting kinda tired of the Global Warming doomsday cult
Good marketing there, mate. The PR professionals of the denialist movement like to throw around words like "cult" or "religion" for the scientific movement that they are trying to attack.
Casting the scientific position as religious attacks it's greatest strength, that it is scientific, and therefore our best guess of truth.
While I don't ignore the fact that man can alter the weather to some degree.
Okay.
I'm getting tired of hearing about how all life on Earth will end in a few years unless we vote for just one political party and their pet doomsday cult.
The article is about ice loss on the Antarctic. It doesn't discuss who you should vote for. It doesn't even assume the reader is in any country or democratic precinct.
Apparently, the sun has nothing to do with climate.
The current warming is not due to the sun. This can be shown because the current warming is occurring more in winter and night, as you would expect from greenhouse warming which slows the rate of heat loss. The sun would warm more when it is shining.
It can also be shown by the cooling of the stratosphere, showing that less heat is reaching the stratosphere from below. The sun would increase the temperature of the whole atmosphere.
But also Solar activity does not correlate with the current warming.
Also, all global warming and ice age events for that last 100 million years were caused by present day American pollution but non-American pollution doesn't do anything....especially is it comes from China and India.
I think that this would be wrong.
Do you have a source?
So just remember, Al Gore has a carbon footprint 10000 times larger than you and is swimming in millions of oil dollars from the Middle East.
I believe that Al Gore is carbon neutral.
Here's wapo [washingtonpost.com] two weeks ago telling me Antarctic ice is increasing — because of AGW.
I think you are confusing sea ice with the ice sheet.
The Antarctic Sea ice is the ice that is floating on the sea around Antarctica. It grows in winter, and nearly disappears in summer, because there's a big continent where the pole is.
The Antarctic Ice sheet is the much larger slab of ice sitting on Antarctica. It is about 60% of all the fresh water on the planet, and consists of 26.5 million cubic km of ice. This is losing mass at an accelerating rate. The study in the OP finds that it is currently losing 125 cubic kilometres a year.
Fuck off with your head games.
It's not that bad. Sea ice sits on the sea. Ice sheets cover the land.
I read just the other day that Antarctica has more ice than ever!
I suspect you read that there the sea ice around Antarctica is more than ever. Antarctica has been losing huge volumes of ice for some decades.
1. Global warming = the world getting hotter
2. Climate change = the changes to the climate due to the increased amount of energy due to warming
3. The land ice is melting, causing it to flow into the sea, where some of it re-freezes. It is expected if warming occurs.
4. Volcanoes release between 65 and 319 million tonnes of CO2 per year. Industry releases ~29 billion tonnes per year. So it takes ~19 hours for industry to release as much CO2 as all the volcanoes do per year.
Maybe people will keep "banging the bell" until people like you actually learn what's happening. You suck as a conscientious individual.
Stop being logical - society doesn't care as long as they have a 4 second headline for CNN's morning recap. Science is old school.
The whole story is. 4 years != climate. Not by anyone's measure. If skeptics tried to debunk AGW on this board with a 4 year trend, everyone would be all over them like white on rice. But 4 years in favor of AGW in the summary? A O K!
Not so. The scientific point of view is that the data speak for themselves; different theories try to make sense of the observed data. Theories are never perfect, but we can make theories better by using the scientific method - and this is where the debate invariably breaks down, not because a secretive conspiracy of climate scientists are suppressing facts, but because those suffering from 'skepticemia' are unwilling to accept reality.
Weather is what happens locally, in the short time span - the wind in your hair, the sun on your face - climate is the average of the weather over large areas and long periods of time. So, it is perfectly reasonable to observe that the weather has been unusually cold in Canada this summer, and then say that this goes against the idea of global warming, and the observation requires a theoretical explanation, of course. Climatologists have already given very plausible explanations; the problem is that climate deniers don't want to accept the explanation. But just as it is necessary to consider data that go against the theory, it is also necessary to accept the data that support the theory; hence it is reasonable to state that the loss of icemass in Antarctica supports the theory of global warming.
What I still haven't seen in is just 1 climate model that explains most of the observed current and historical data and doesn't end up concluding that climate change is happening and is caused by human activities. Produce just 1 theory that can stand up the critical efforts of more than a select group of handpicked believers; the truth is that the skeptics are unable to do so, and therefore talk about conspiracies instead. Meanwhile, I think the scientific consensus has moved on, because whether people like it or not, reality keeps happening.
Not exactly and no. When mass is redistributed (due to ice melting, plate tectonics, mantle convection, etc...) the shape of the geoid changes. However the total mass of the Earth is conserved. So if you are far enough away from the Earth to make it indistinguishable from a point mass, Earth's gravity remains constant.
But what you can't argue against is the fact that the ice is melting at all, although that doesn't stop some people here from cherry-picking one particular type of ice (sea ice), saying that it has expanded as if that is the complete argument against the total ice loss.
It's worse than that. They're actually claiming that extent is counterevidence against loss of ice mass. Some of them don't even realize that's what they're claiming. Either way, this finding proves them wrong.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
What I still haven't seen in is just 1 climate model that explains most of the observed current and historical data
The reality is that the world is too complex and weather too chaotic to come up with 1 model that you're going to be able to plug what we know of what happened in the weather into and get out a simulation that follows what actually happens. The proof of this is that weather forecasters are commonly completely wrong, and they're dealing with the best-quality records we've got (e.g. the extensive weather doppler radar network in the USA) and only have to make predictions about rainfall, temperature, and cloud coverage for a day or a week in advance.
Our maps are just barely up to the task of modeling global weather in the way that you want, where we get to make specific predictions. Our understanding of localized weather patterns is inadequate to the task. However, that still doesn't prevent us from being able to make broad, generalized predictions from what we know of physics. And given that what we do know broadly fits the global warming narrative which in turn agrees with what we know of physics, there's no particular reason to doubt the overall picture. The globe is warming, and we're doing things which physics says should warm it. There are natural mechanisms which will serve to bring the system back into balance, like for example spreading extent of sea ice, but these mechanisms have literally never had to clean up a mess like the one we've made and it's unclear whether we're going to make it through the reset process because we don't actually know what that looks like. We've perturbed the regular cycle that we could have expected to survive in a somewhat unpredictable way, but we can still make some predictions. Just as the world is not black-and-white in the way that denialists want it to be when they argue that it's colder where they are so there can't be global warming, our lack of complete certainty does not make us completely unable to make predictions. If it did, then we would never be able to do anything, because we often find that our understanding is superficial — yet our previous models still enabled us to make useful predictions.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Looks obnoxious doesn't it? That's because you fucking people who are like that are fucking obnoxious. No one takes fucking responsibility for their shit in anything, this included.
well since consensus is now that animal agriculture is responsible for most greenhouse gas emissions: http://www.nytimes.com/2009/11... One easy thing we can do is stop eating cows, then stop eating all animal products.
Also even though I bicycle to work, I need to convince my boss to let me work from home "to stop climate change" ;-)
At the time the scientists were saying that a 5,000 year old ice shelf had broken off. Okay if it was 5,000 years old what broke it off the last time? the egyptians using slave labor to build the pyramids?
Really?
1) Larson B had been a stable ice shelf 200 metres thick with a surface area of 3,250 square kilometres for at least 10,000 years. (source)
2) Even if that wasn't the case you can still attribute climate change to a cause, and that cause doesn't have to be the same cause as previous climate change.
2 b) Climate change one to two orders of magnitude slower than the current climate change would not be expected to have the same mechanism.
3) It is not believed that Egyptians used slaves to construct the pyramids.
The weather changes it goes up and down and side to side.
Yes. And the current going up is primarily due to the enhanced greenhouse effect.
looking for a .01 degree change is like looking for a penny to pay a $1,000 bar tab. it matters yes but come on.
On the other hand a 0.8 degree rise has put a number of species at extinction risk, has displaced tens of millions of people per year, and kills about 150,000 people annually.
"Overall, the agricultural sector contributed nearly 7% of total US GHG emissions in 2010"
that is from http://iopscience.iop.org/1748...; that's just the USA
but it's indicative that there's something a *little* wrong with your claim
While I'm not denying reality - global warming is happening - I'm questioning the models proposed by the scientists. Let them come up with a model that doesn't completely fall apart 10 years later. So far, all models produced before 2000 have proven to *not* forecast the reality of things.
I'm not saying those guys are charlatans, but if they try to convince me that the sea level will rise by 2m in 100 years I'll laugh, and pretty hard at that. Nobody is actually able to predict anything beyond a couple of years, so 100 years is well beyond their best effort so far.
Granted the climate is an extraordinarily complex thing to model and so to predict. What exactly are going to be the consequences of the global warming is yet a thing to discover.
Now, this doesn't mean that we should do nothing about it and wait & see. But shouting all over that in XX years, YY will change by ZZ is in my view discrediting the cause for the simple reason that those claims have always proved to be just plain wrong. So far.
Write boring code, not shiny code!
What I still haven't seen in is just 1 climate model that explains most of the observed current and historical data.
You could have ended this sentence right there and it would be accurate. So of course any additional clause that you append isn't going to change that. However, it does make the argument contained in that clause less compelling.
rgb
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
I can't speak on the first or third claims (nor can I recall ever hearing them) but I was recently researching various solvents for a particular application, some of which were CFCs, so I do have some information regarding those-
Although the Montreal Protocol limiting CFC use began to come into force in 1989, it is implemented gradually, and the last of the provisions won't come into effect until 2030. Then you have the fact that decades of damage will take decades of recovery; the recovery is estimated to be complete around 2050-2070. You're about half a century too early to start talking about "proven lies". Despite the timetable involved, as of 2010 the ozone layer had already began a measurable recovery.
Wikipedia is a good place to start researching these issues, particularly the article on the Montreal Protocol contains citations to primary sources on all the facts I have mentioned here. If the other two claims you take issue with aren't strawmen, I imagine you can find more information on those as well.
You aren't quite right that the satellite gravity scientists are just using climate as a "hook" to display their techniques. A major reason for the launch of these very precise gravity satellites is to use gravity to monitor the movement of water (not just ice) in and around the Earth. Hence the name of the GRACE satellite -- Gravity Recovery and Climate Experiment. The NASA GRACE fact sheet is at -- http://earthobservatory.nasa.g... with more details.