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Earth Science

Arctic Ice Extent Understated Because of "Sensor Drift" 823

Posted by samzenpus
from the give-it-a-few-taps dept.
dtjohnson writes "The National Snow and Ice Data Center (NSIDC) has been at the forefront of predicting doom in the arctic as ice melts due to global warming. In May, 2008 they went so far as to predict that the North Pole would be ice-free during the 2008 'melt season,' leading to a lively Slashdot discussion. Today, however, they say that they have been the victims of 'sensor drift' that led to an underestimation of Arctic ice extent by as much as 500,000 square kilometers. The problem was discovered after they received emails from puzzled readers, asking why obviously sea-ice-covered regions were showing up as ice-free, open ocean. It turns out that the NSIDC relies on an older, less-reliable method of tracking sea ice extent called SSM/I that does not agree with a newer method called AMSR-E. So why doesn't NSIDC use the newer AMSR-E data? 'We do not use AMSR-E data in our analysis because it is not consistent with our historical data.' Turns out that the AMSR-E data only goes back to 2002, which is probably not long enough for the NSIDC to make sweeping conclusions about melting. The AMSR-E data is updated daily and is available to the public. Thus far, sea ice extent in 2009 is tracking ahead of 2005, 2006, 2007, and 2008, so the predictions of an ice-free north pole might be premature."
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Arctic Ice Extent Understated Because of "Sensor Drift"

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  • Rocket science? (Score:3, Insightful)

    by foobsr (693224) on Thursday February 19, 2009 @09:01AM (#26915219) Homepage Journal
    Obviously not, too cold. The more astonishing the fact they can make such errors.

    CC.
    • Re:Rocket science? (Score:5, Insightful)

      by jellomizer (103300) on Thursday February 19, 2009 @09:20AM (#26915339)

      Science isn't an exact science, people are involved and people make mistakes. Scientist need to remember that they are human too and they will make mistakes. Data can be off or altered, I remember a local weather channel use to use a point for the local temperature until they built a Dunin Donuts next to it, and heat escaping the building or cars or something (it was a long time ago) raised the temperature 5 or 6 degrees warmer then the actual weather.

      Climate Scientists are trying to make very accurate predictions where they don't have the data to do so. We can probably say global warming is real, however that is a very broad statement. But to say The Polar caps will be gone in 2008 or by 2012 NYC will be flooded, is grossly misunderstanding the complexity of the earths environment.

      Granted that most of the fear mongering worst case scenarios stuff isn't from the people doing the real science but from activists groups who pick and choose data to make people afraid so they do what they want. But still the Scientists don't like saying to people Hey I could be wrong, but thats OK because with the scientific process being wrong takes us the next step closer to the real answer. They want to in general portrait themselves like the Sci-Fi scientist who know what is going on and is always right.

      • Re:Rocket science? (Score:5, Insightful)

        by Anonymous Coward on Thursday February 19, 2009 @10:02AM (#26915747)

        There is no question that data analysis and prediction is subject to errors, sometimes quite large ones. The real question is whether these errors are due to researcher bias. Unfortunately climate data and predictions are apparently more motivated by political beliefs and biases than hard facts.
        Many people have strong feelings that disaster is about to occur. Perhaps this comes from childhood recollections of maternal warnings about running with scissors or touching hot stoves. These fears can be reinforced by religious beliefs that portend the end of the world. Because this psychological factor is so prevalent we need to be especially skeptical of predictions of future disasters.

        • Re:Rocket science? (Score:5, Insightful)

          by jellomizer (103300) on Thursday February 19, 2009 @10:30AM (#26916101)

          I think it goes back to the showing the DDT is a harmful chemical (other then the old commercial "DDT its good for you and good for me!") it was widely used and was considered safe and effective a marvel in scientific advancement. Then it was shown to have effect on the eagle population and perhaps humans as well. So we had to stop using the chemical, but that opened peoples minds to think other things will have such problems, and to question every advancement and study the effects of it. In general it is a positive thing but it has lead to fear mongering and a belief that we should stop advancements as every advancement has some cost to it (however in my opinion they usually forget to factor in the benefits). Such as the immunization and the possible link to autism, lets say it creates a 1% increase in autism how ever it saves 25% from death, the benefits out weigh the risks and the parents who avoid this are poor judges on risk assessment.

          • Re:Rocket science? (Score:4, Insightful)

            by macxcool (1370409) on Thursday February 19, 2009 @10:47AM (#26916333)

            I think it goes back to the showing the DDT is a harmful chemical ... So we had to stop using the chemical

            It's too bad that DDT helped to eradicate Malaria in places where it was used. DDT Needed to Control Malaria [www.cbc.ca] Perhaps the answer wasn't to eliminate its use but to manage it to limit the harm it could do. Certain countries in the world could use some mosquito control.

          • Re:Rocket science? (Score:5, Informative)

            by tick-tock-atona (1145909) on Thursday February 19, 2009 @11:22AM (#26916837)

            Such as the immunization and the possible link to autism, lets say it creates a 1% increase in autism how ever it saves 25% from death, the benefits out weigh the risks and the parents who avoid this are poor judges on risk assessment.

            Arrgh!
            Speaking of fear mongering, it has been repeatedly shown [sciencedaily.com] that there is absolutely no link between autism and vaccines.
            Please, can't this FUD just die already? It's already caused deaths in the UK from a loss of herd immunity!

        • Re:Rocket science? (Score:4, Insightful)

          by Rary (566291) on Thursday February 19, 2009 @10:56AM (#26916471)

          Because this psychological factor is so prevalent we need to be especially skeptical of predictions of future disasters.

          Or, arguably, because the danger is greater if we're wrong, we need to be especially sceptical of attempts to downplay predictions of future disasters.

          • Re:Rocket science? (Score:4, Insightful)

            by jadavis (473492) on Thursday February 19, 2009 @01:30PM (#26918769)

            because the danger is greater if we're wrong

            That is far from certain. Our attempts to fix something we don't really understand could cause far more damage.

            This is how ideas like blood letting became fashionable in medicine.

              1. Someone is sick.
              2. We only vaguely understand how people work.
              3. We have to "do something".
              4. Conclusion: let's drain their blood.

            Then, if they don't die, then the doctor must have saved their life.

            This reminds me of the stimulus bill.

        • Re:Rocket science? (Score:4, Insightful)

          by Renegade Iconoclast (1415775) on Thursday February 19, 2009 @11:58AM (#26917455)

          The real question is whether these errors are due to researcher bias. Unfortunately climate data and predictions are apparently more motivated by political beliefs and biases than hard facts.

          The Earth is getting warmer and our ice is melting, and that's not in dispute. If the warming trend continues, all of the ice will melt eventually, this is dictated by physics.

          Your implication of overwhelming political bias in climate science is simply contrary to the facts. The fact that these researchers seem to have been biased is not relevant to the science as a whole.

          The "think tanks" who criticize climate science don't do any actual science. They cherry pick data from scientific papers, and attempt to refute CO2 vs warming trends with typical logical fallacies, but they do no research, make no predictions, and advance no falsifiable claims.

          Science is about making better predictions from the data. Climate scientists projected a 1-degree rise in temperature, and a 1-foot ocean level rise, many decades ago. Overall, they were pretty close. Anti science people said there was no such thing as global warming until recently when it became too clear to ignore.

          These fears can be reinforced by religious beliefs that portend the end of the world. Because this psychological factor is so prevalent we need to be especially skeptical of predictions of future disasters.

          So what does your idea of caution boil down to? Doing nothing? How can that be considered erring on the side of caution?

          Your argument is nonsensical on its face. Belief in the inevitability of end of the world leads people to sit on their respective asses and do nothing about it, not for them to write specious science papers predicting the end of the world. The very opposite is true, there is a very strong correlation between belief that climate science is a hoax, and being a religious American.

          • Re:Rocket science? (Score:4, Insightful)

            by russotto (537200) on Thursday February 19, 2009 @12:32PM (#26917899) Journal

            The Earth is getting warmer and our ice is melting, and that's not in dispute.

            Actually, that last bit is in dispute, if you RTFS.

            If the warming trend continues, all of the ice will melt eventually, this is dictated by physics.

            If you feel comfortable doing linear extrapolations on a highly nonlinear system, anyway.

            • Re:Rocket science? (Score:4, Informative)

              by Renegade Iconoclast (1415775) on Thursday February 19, 2009 @03:12PM (#26920331)

              Actually, that last bit is in dispute, if you RTFS.

              Nonsense. The data from this particular survey are in dispute, and people here are conflating this to all of climate science. That the earth is warming, and that globally, ice is melting at an alarming rate, is not even disputed by the oil industry any more.

              If you feel comfortable doing linear extrapolations on a highly nonlinear system, anyway.

              If the atmosphere heats up, physics predicts that the ground will heat up as well, and that ice will melt.

              You're correct that the system is more complex than that, because, for example, melting ice can trigger other mechanisms that are too complex to model, currently. This doesn't refute the very basic fact that adding global heat to the atmosphere tends to melt ice.

              I'd also point out that we know all of this because we've studied it scientifically, just the same way that we know that CO2 tends to heat the atmosphere, and ice tends to melt with warmer air.

        • Re:Rocket science? (Score:5, Informative)

          by catchblue22 (1004569) on Thursday February 19, 2009 @12:19PM (#26917735) Homepage

          To quote TFA:

          Sensor drift is a perfect but unfortunate example of the problems encountered in near-real-time analysis. We stress, however, that this error in no way changes the scientific conclusions about the long-term decline of Arctic sea ice, which is based on the the consistent, quality-controlled data archive discussed above.

        • Re:Rocket science? (Score:5, Interesting)

          by wytcld (179112) on Thursday February 19, 2009 @12:21PM (#26917767) Homepage

          Unfortunately climate data and predictions are apparently more motivated by political beliefs and biases than hard facts.

          That's an empty assertion, apparently motivated by the conflict between the conclusions from overwhelming climate data and the writer's ideology.

          Where is the sociological data to support it? All these claims about "political beliefs and biases" among climate scientists are working backwards from a desire to reject the conclusions of science to ad hominem attacks on the scientists themselves - attacks which make presumptions about the politics of scientists which are naive in the extreme. A great many - perhaps most - scientists are not political at all. They're too busy with their science to worry about politics outside of their own university departments, and anyway consider most politicians and commentators a bit too stupid to concern themselves with one way or the other.

          So where's your data on "political beliefs and biases" among climate scientists? As most of them are funded by governments, can you show an example from any scientific community of a pronounced pattern of biting the hand that feeds it? Consider the scientists funded by drug companies. Do their results cut against their funders?

        • Re:Rocket science? (Score:4, Informative)

          by Obfuscant (592200) on Thursday February 19, 2009 @02:53PM (#26920027)
          There is no question that data analysis and prediction is subject to errors, sometimes quite large ones. The real question is whether these errors are due to researcher bias.

          At the heart of the issue is usually the measurements themselves. Bias should never be part of a measurement, but failure to completely understand the system being measured often is. Since many measurement systems today are not direct measurements but indirect, and many are "remote sensing", it is often a failure to understand both the system being measured AND the proxy for the desired measurement that causes failure.

          For example, several years ago it was determined that the satellite-based sensing of ocean surface temperature was off by several degrees, because the atmospheric effects on the IR radiation being used to measure the temperature weren't being correctly corrected. It is no surprise to hear that any proxy measurement has been found to be off with a biased error.

          What? Bias? Well, "biased error" is the technical term for an error in measurement that is wrong in a consistent manner. For example, a thermometer that has been miscalibrated so that it always reads high. But please do not mention this possibility of measurement error to anyone involved in global warming research. They are right, everyone else is wrong.

          Don't EVER ask why they assume that CO2, a gas that is soluble in water to a great extent, cannot diffuse out of air bubbles in ice that have been trapped for millenia. It is the measurement of CO2 in those bubbles that global warming scientists use to tell us what the level of CO2 was ten thousand years ago -- even though there is no recorded measurement from then, and only the proxy of "trapped bubbles" to rely on.

          Many people have strong feelings that disaster is about to occur. Perhaps this comes from childhood recollections of maternal warnings about running with scissors or touching hot stoves.

          Today's strong feelings of disaster are prompted by catastrophe-based science and the scientists who are paid to find solutions to catastrophes. Scientists who warn us that a stray comet could obliterate life on this planet don't get paid to deal with comets that don't come anywhere near us. Scientists who predict gloom and doom from global warming don't get paid if they report that there really isn't a problem. I am repeatedly fascinated by global warming scientists who dismiss studies that contradict their cries of alarm as the product of people who are being paid to say there is no problem. Why would the only scientists who lack ethics be the ones on one side of an issue? (The state of Oregon just created a group to deal with global warming issues. Do you think that the head of this group is someone who doesn't toe the line regarding the causes and results of global warming? He's getting paid, so why aren't his ethics questioned?)

          • Re:Rocket science? (Score:4, Informative)

            by Tycho (11893) on Thursday February 19, 2009 @07:04PM (#26923223)

            For example, several years ago it was determined that the satellite-based sensing of ocean surface temperature was off by several degrees, because the atmospheric effects on the IR radiation being used to measure the temperature weren't being correctly corrected. It is no surprise to hear that any proxy measurement has been found to be off with a biased error.

            What? Bias? Well, "biased error" is the technical term for an error in measurement that is wrong in a consistent manner. For example, a thermometer that has been miscalibrated so that it always reads high.
            But please do not mention this possibility of measurement error to anyone involved in global warming research. They are right, everyone else is wrong.

            I am unaware of the experiment and controversy surrounding it, have a link to a peer reviewed journal article?

            Really, even if a bias is discovered later in an experiment and if that bias can be estimated, whether the added error is constant or variable, corrections to the old data can be made and the corrected data would be accurate. This assumes the supposed error is actually an error and not some global warming denier's fantasy. One correctable error does not mean that all of the data from the experiment is useless, and the same conclusion from the experiment can still hold.

            Even if the data from an experiment has uncorrectable errors and the data is faulty, GW deniers have one experiment discredited, and only have a whole truck load more valid experiments showing Global Warming to discredit. GW deniers still have still shown no credible alternate to explain the trends in the world's climate. Thus, GW deniers are just that, in denial, they are not advocating their own hypothesis by using accepted scientific practices and existing data.

            Don't EVER ask why they assume that CO2, a gas that is soluble in water to a great extent, cannot diffuse out of air bubbles in ice that have been trapped for millenia. It is the measurement of CO2 in those bubbles that global warming scientists use to tell us what the level of CO2 was ten thousand years ago -- even though there is no recorded measurement from then, and only the proxy of "trapped bubbles" to rely on.

            Water, in its solid crystalline form, ice, has no capability to hold CO2 in solution, only liquid water can hold CO2 in solution. It would seem to follow that when trapped in a gas bubble in ice, CO2 does not diffuse because water ice is not permeable to CO2 at any of the temperatures or pressures that the ice has been at since it formed.

            Many people have strong feelings that disaster is about to occur. Perhaps this comes from childhood recollections of maternal warnings about running with scissors or touching hot stoves.

            Today's strong feelings of disaster are prompted by catastrophe-based science and the scientists who are paid to find solutions to catastrophes. Scientists who warn us that a stray comet could obliterate life on this planet don't get paid to deal with comets that don't come anywhere near us. Scientists who predict gloom and doom from global warming don't get paid if they report that there really isn't a problem. I am repeatedly fascinated by global warming scientists who dismiss studies that contradict their cries of alarm as the product of people who are being paid to say there is no problem. Why would the only scientists who lack ethics be the ones on one side of an issue? (The state of Oregon just created a group to deal with global warming issues. Do you think that the head of this group is someone who doesn't toe the line regarding the causes and results of global warming? He's getting paid, so why aren't his ethics questioned?)

            I'm not sure how to respond, I am nearly certain that over many the years as corporations like Phillip Morris, Exxon, and alike sponsored anti-GW groups, that at least some research was done at least one sound and valid published study should still be available. No

      • by Lord Ender (156273) on Thursday February 19, 2009 @10:40AM (#26916261) Homepage

        If they want to be seen as scifi scientists, they need to offer solutions, not just point out problems. When was the last time a climate scientists suggested rerouting the goo-on particle stream through the deflector dish using just the right frequency to reverse global warming? I WANT ANSWERS, DAMN IT.

      • Re:Rocket science? (Score:5, Informative)

        by Cally (10873) on Thursday February 19, 2009 @10:45AM (#26916313) Homepage
        Denialists, stop your engines now...

        there was a significant problem with the daily sea ice data images on February 16. The problem arose from a malfunction of the satellite sensor we use for our daily sea ice products. Upon further investigation, we discovered that starting around early January, an error known as sensor drift caused a slowly growing underestimation of Arctic sea ice extent.

        So, to be clear, this issue has arisen over the last 4-6 weeks. The records for the last decade, clearly showing a significant trend towards less sea-ice, are unaffected.

        • Re:Rocket science? (Score:4, Insightful)

          by burning-toast (925667) on Thursday February 19, 2009 @11:29AM (#26916965)

          Some of us tend to target the methods and data used as being the weakness in the arguments for climate change. We will point to the fact that they have been using faulty data at all no matter how hard people say "Nothing to see here, move along!". Logic dictates: If their data was wrong under their nose once in a ridiculous manner, it could have been wrong all along or in different ways. We (rightfully) will want a further look at the data used all along regardless.

          I don't know of very many people who would openly deny that any climate change has happened over the last millennium in general. However, I know plenty of people who are (rightfully) skeptical of a bunch of "scientists" claiming "end of the world as we know it" apocalyptic scenarios. This is about the sixth major time in 40 years? Humanity has had to deal with everything from disease, insects, plague, war, famine, and politicians/lawyers. We want to know why this requires special attention. Having a major controversy surrounding it just polarizes people and brings into doubt the validity of the claims as stories like this come out.

          After all, we have had a lot of these sorts of openly public fears about the end of the world throughout human history. And without concrete and testable data that our fears are founded on fact (as was shown with things like DDT, Mercury, Lead, etc.) there are a lot of people tired of living in an open ended state of panic about shit we don't feel we have too much direct control over let alone shit we have to "believe in" in order to support. Especially if we can't be sure that it is happening as people say it is because the data keeps coming into question in what outwardly appears to be ridiculous oversights.

          As a person who is relatively concerned about their own energy usage and relative impact on the Earth in a more basic "because I want to be a good custodian of the earth" sort of way, I want to know really whats going on and really what I can do about it which will really make a lick of difference. I'm tired of the fact that even basic descriptions of localized problems which should be easy to demonstrate are awash in arm waiving and proselytizing instead of actual demonstrations of proof (note I didn't say making up facts). People like me just want confidence that what we are "believing in" is going to be actually functional for a greater good and won't make us part of a hysterical crowd when it's not warranted.

          - Toast

          P.S. The fact that there are "Denialists", "Believers", "Supporters" and "Followers" makes this area of science look a lot like religion. The fact that it also includes politicians, corporations, lawyers, and lots of appeals to emotion ("Someone think of the cuddly polar bears!") makes it look a lot like pork. Those two things alone removes much of it's potential appeal to me as I heavily devalue things of that nature as a waste of my time.

          The phase of scientific research going on now, where the data is still under heavy scrutiny and the methods untested or unverified really should be taking place outside of the mainstream media involving every last person who watches the 6:00 news. The general populace would be much less polarized if the hypothesis was better tested before becoming politicized as it was. At least we would have less of a panic approach and look a bit less like the boy who cried wolf for the umpteenth time.

          • Re:Rocket science? (Score:5, Insightful)

            by Cally (10873) on Thursday February 19, 2009 @11:45AM (#26917229) Homepage

            We (rightfully) will want a further look at the data used all along regardless.

            OK, here you go [nasa.gov], have fun. All the data in modern climate science is freely available in massive quantities. (The GISS datasets are just one example.) It's certainly true that there's a lot of crap journalism around climate change; please don't confuse the finger pointing at the moon for the moon itself. Go read RealClimate, or Scientific American (hell, even New Scientist if you like comics) or (better yet) search out the specialist journals.

          • by tgibbs (83782) on Thursday February 19, 2009 @11:59AM (#26917461)

            If their data was wrong under their nose once in a ridiculous manner, it could have been wrong all along or in different ways.

            This is a prime example of the sort of rationalization that passes for denialist reasoning. When confronted with a huge mass of evidence supporting an unpalatable conclusion, they cherry-pick any error, no matter how small or irrelevant to the conclusion, and insist "if this is wrong, then maybe it is all wrong." Since in any human endeavor, there are always errors, it is always possible to rationalize away any conclusion that you prefer not to confront.

            This is of course quite typical. The data in question is real-time, raw data. In most scientific enterprises, such data is kept private by the researchers until it can be cross-checked and validated. But in climate research there is a level of openness and public access that is almost unparalleled in science, with even preliminary data publicly available. Of course, the actual scientists know that such data is subject to revision and do not base important conclusions upon it. So the error has no impact on the conclusion that there is a long-term decrease in Arctic ice due to global warming. But that won't stop denialists from talking about it as though it invalidates everything.

      • Re:Rocket science? (Score:5, Insightful)

        by Chris Burke (6130) on Thursday February 19, 2009 @10:50AM (#26916387) Homepage

        But to say The Polar caps will be gone in 2008 or by 2012 NYC will be flooded, is grossly misunderstanding the complexity of the earths environment.

        Yeah, but climatologists don't suffer from that misunderstanding. They're the ones who have to actually slog through that complexity.

        Granted that most of the fear mongering worst case scenarios stuff isn't from the people doing the real science but from activists groups who pick and choose data to make people afraid so they do what they want.

        An astute point, and really it was both the activists and the -- well, whatever the opposite of an activist is, someone who wants to do nothing is called -- who with the help of the media took the scientists claims of a chance for a minimum and an ice free north pole (just the pole, btw, not all arctic ice gone entirely) and run with it as if the scientists are saying it's a sure thing. The activists to cry doom and gloom, and the inactivists to pounce on as proof the whole thing is bunk if the results come out on the "wrong" side of the scientist's claimed 60:40 odds.

        But still the Scientists don't like saying to people Hey I could be wrong, but thats OK because with the scientific process being wrong takes us the next step closer to the real answer. They want to in general portrait themselves like the Sci-Fi scientist who know what is going on and is always right.

        They didn't just say "Hey I could be wrong", they attempted to quantify the chances of them being wrong. Then they voluntarily report on censor errors that briefly screwed up their data, while I'm sure knowing that this would be blown way out of proportion and used to "prove" that they never know what they're talking about at all. In other words, the opposite of trying to appear like they can't be wrong. So I'm not buying it at all.

        Just because news headlines omit the qualifiers does not mean they do not exist.

      • Re:Rocket science? (Score:5, Insightful)

        by goodmanj (234846) on Thursday February 19, 2009 @01:53PM (#26919127)

        to say The Polar caps will be gone in 2008 or by 2012 NYC will be flooded, is grossly misunderstanding the complexity of the earths environment.

        We climate scientists try to give a sense of the certainty of our predictions, but our discussions of certainty are almost always deleted when the news is presented to the public. The two predictions you mention are vastly different -- we're pretty sure about ice, but flooding New York has a gigantic pile of "ifs" in front of it.

        Scientists don't like saying to people Hey I could be wrong, but thats OK because with the scientific process being wrong takes us the next step closer to the real answer. They want to in general portrait themselves like the Sci-Fi scientist who know what is going on and is always right.

        Real scientists *do* say "I could be wrong" all the time, and try to estimate the odds of being wrong. We're happy with greater certainty, but we know that 100% guarantees don't exist.

        The confident, absolutely certain authoritarian scientists you see on TV are just talking heads: they may have PhDs, but they're not acting as true scientists.

  • Not consistent? (Score:5, Insightful)

    by mccalli (323026) on Thursday February 19, 2009 @09:04AM (#26915239) Homepage
    From the summary:'We do not use AMSR-E data in our analysis because it is not consistent with our historical data.'

    What's the point of being consistent with a flawed methodology? I would have thought the thing to do would be to collect the new data, base newer model off that and then perform a statistically weighted correction to the older dater. Both data sets can be maintained if required.

    Am not sure I see a point in consistency for consistency's sake, when you in the light of newer information you now know the original measurements are flawed.

    Cheers,
    Ian
  • by s31523 (926314) on Thursday February 19, 2009 @09:05AM (#26915243)
    FTA, "Some people might ask why we don't simply switch to the EOS AMSR-E sensor. AMSR-E is a newer and more accurate passive microwave sensor. However, we do not use AMSR-E data in our analysis because it is not consistent with our historical data. Thus, while AMSR-E gives us greater accuracy and more confidence on current sea ice conditions

    OK, I can see their point, but using the EOS sensor may have given pause to researchers doing a comparison to current conditions using the traditional sensor, i.e. cross-reference current conditions to be more confident that your data is correct. Nothing like screaming "the sky is falling" due to bad data. Any science experiment, especially one that can produce sensationalist news, should not just rely on one piece of data.
    • by chr1sb (642707) on Thursday February 19, 2009 @09:43AM (#26915567)
      From TFA:
      <i>"Sensor drift is a perfect but unfortunate example of the problems encountered in near-real-time analysis. We stress, however, that this error in no way changes the scientific conclusions about the long-term decline of Arctic sea ice, which is based on the the consistent, quality-controlled data archive discussed above."</i>

      If the media outlets and attention seekers sensationalise the real-time output, then unreasonable conclusions might well be drawn. What's the alternative though? To not make this real-time data available? Scientific hypotheses will be tested against the corrected data, so this sensor drift doesn't affect them. These are preliminary measurements only, not full-blown experiments with scientific conclusions. The polar bears are still going to have to become better swimmers.

      It's a little ironic that this data will have been used by one group with an agenda to sensationalise climate change, and now will be used by the (perhaps overly) sceptical amongst us to poo poo it. Some have an agenda to sensationalise both. All serve to cloud the real message.
      • by smoker2 (750216) on Thursday February 19, 2009 @12:07PM (#26917585) Homepage Journal
        In the end (or even the beginning) the only reasonable thing to do is to keep an eye on the current scientific situation yourself. I have the NASA Earth Observatory [nasa.gov] in my RSS feeds and if you take the time to read what's going on, you find that they occasionally do find inconsistencies and report them openly. Relying on the mass media for accurate conclusions is stupid at the best of times.

        There are many issues at work with climate change, and for any one group to suggest hard conclusions based on the data we already have is disingenuous. Most any sane person accepts climate change. When you take into account historical records, geological records, fossil records, the precession of the equinoxes, the solar cycle, biological fluctuations and many many other factors, to simply state that we are causing global warming is way too simplistic an approach.

        Before you get all huffy and call me a denier, of course what mankind does has an effect on the climate. But so does what plankton does. Of course being an intelligent species, we can recognise our part and try to minimise our impact. But that alone will not stop global warming. Why should we assume that because we think we can stop it, we should do so ? Because too many of us live near coastal areas ? That seems a little self important to me. And to risk a flame, that attitude is directly derived from the "earth is ours to do with as we will" notion which religion has ingrained in society. Do we believe everything else that religion demands ?

        My suspicions about the climate change lobby were somewhat vindicated a little while ago when the BBC reported on some work by the Institute of Mechanical Engineers which takes as read, that we must stabilise average temperatures. I can't find the original document now, but the European Commission has stated that "The commission aims to limit the world's temperature increase to 2C." [bbc.co.uk] This is no longer about limiting CO2, it has become all out climate control. And we certainly do not know enough to experiment with that. Even if we could do it safely, do we really want to live in a world where commercial interests control whether your region gets rain today, this month, this year ? Fuck me, it's bad enough dealing with the MAFIAA !

        In short, yes reduce our impact on the planet, but that's it - at least until we have a LOT more data. We can not hope to go back in time. And this has been my position all along, as any /. subscribers can easily check. What are we aiming for, the average 1940's temperatures, earlier, later ?

        Just remember that the diversity on this planet has arisen BECAUSE of climate change, not despite.
  • Historical error (Score:4, Interesting)

    by Potor (658520) <.farker1. .at. .gmail.com.> on Thursday February 19, 2009 @09:10AM (#26915281) Journal

    Am I to understand that they will continue to measure (and predict) ice conditions based on less accurate sensors simply because these measurements tally better with older measurements, which themselves are less accurate?

    Or have I missed something?

    • by cnettel (836611) on Thursday February 19, 2009 @09:35AM (#26915487)

      Compare it to a game benchmark or whatever. You keep a standard, even if it's flawed, because that's the only way you get comparable results. You can't take a raw number for MIPS or millions of polygons/second or transactions per second or whatever the metric of choice is in your field (here, one is obviously ice sheath coverage) and use numbers from wildly different methods to even try to devise a historical trend. The value observed might not correlate exactly (or even very well) with old ones, but unless the flaws in the method cause great variability within that framework, the historical trends will still be accurate, or at least more accurate compared to what would happen if you changed your methodology each year and still tried to extract longer trends.

      It might not be a good choice, and suggestions to run double series over the (short) timespan where overlapping data is indeed available would of course be better, but you can't just switch to the latest and greatest if you want some kind of consistency in your data.

      • Except... (Score:3, Insightful)

        by DG (989)

        ...that consistancy with historical data is worthless if that data is wrong.

        Using your game analogy, assume that the metric for video card speed was a specific timedemo for Game X. There exists framerate data for Game X going back 10 years, so it is nice for showing historical trends.

        Then a bug is discovered in the game rendering engine that causes actual delivered framerate to be understated by somewhere between 20-50%.

        Well guess what - your test is WRONG. And all that lovely historical data is worthless,

  • Confusing (Score:3, Insightful)

    by Andr T. (1006215) <andretaff@gmailP ... minus physicist> on Thursday February 19, 2009 @09:12AM (#26915299)
    This is _very_ confusing. By the IJIS website, 2002 and 2003 were in average:
    http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm [uaf.edu]

    But, then, look at this:
    http://www.nasa.gov/centers/goddard/news/topstory/2003/1023esuice.html [nasa.gov]

    The result has direct connections to NASA-funded studies conducted last year that found perennial, or year-round, sea ice in the Arctic is declining at a rate of nine percent per decade and that in 2002 summer sea ice was at record low levels. Early results indicate this persisted in 2003.

  • Good, but.. (Score:3, Informative)

    by MadMidnightBomber (894759) on Thursday February 19, 2009 @09:33AM (#26915465)

    still plenty of data from other sources, NASA in this case showing a trend of ice melting... http://earthobservatory.nasa.gov/Newsroom/view.php?old=2006101923416 [nasa.gov]

  • Tosh. (Score:5, Insightful)

    by Anonymous Coward on Thursday February 19, 2009 @09:33AM (#26915467)

    "n May, 2008 they went so far as to predict that the North Pole would be ice-free during the 2008 'melt season,' "

    No they didn't.

    They said it was a remote possibility.

    This was taken up by the anti global climate change, altered, and then used to "prove" that global warming wasn't happening when it didn't happen.

    The fact it is presented that way by the story submitter shows which way they think, and thus how reliable the overall story is.

  • Typical spin job (Score:5, Informative)

    by itsdapead (734413) on Thursday February 19, 2009 @10:05AM (#26915781)

    In May, 2008 they went so far as to predict that the North Pole would be ice-free during the 2008 'melt season,'

    Er, no, they said it was possible and later quote "a 59% chance of a new record minimum this year". How the media chose to report this is another matter... Oh yes, note the date: May 2008.

    Today, however, they say that they have been the victims of 'sensor drift' that led to an underestimation of Arctic ice extent by as much as 500,000 square kilometers.

    And if you read TFA, the sensor drift started in January 2009, was spotted within a few weeks and only affected their daily images which are effectively "live" and hence haven't gone through QA.

    So how exactly does an error which occurred in Jan/Feb 09, was almost immediately spotted and declared affect a (misreported) prediction made last May?

    <irony>Meanwhile, I'm sure the little fairies are hard at work ensuring that the geological era's worth of sequestered CO2 we're in the process of releasing back into the atmosphere magically changes its physical properties. After all, it is made from special carbon that God put there in 4004BC for us to burn, unlike that nasty communist CO2 that exhibits the greenhouse effect in godless laboratories.</irony>

    • by MarkusQ (450076) on Thursday February 19, 2009 @10:59AM (#26916501) Journal

      And if you read TFA, the sensor drift started in January 2009, was spotted within a few weeks and only affected their daily images which are effectively "live" and hence haven't gone through QA.

      So how exactly does an error which occurred in Jan/Feb 09, was almost immediately spotted and declared affect a (misreported) prediction made last May?

      Congratulations. You appear to have been the first person here to read beyond the flamebait summary and respond to the actual content. On a site full of people conditioned by years of rickrolling (and worse) to never RTFA, you sir, are a member of a rare and vanishing breed.

      Keep up the good work.

      --MarkusQ

      P.S. I used to be skeptical of global warming myself (years ago), until I realized that the best the anti-HCGW crowd could offer as counter case was crap like this--the scientific analog of "Marty look, your shoe's untied."

      On the one hand, tons of data, much of which is easily checked, and all of which hangs together to form a consistent picture, and on the other a hodge podge of nonsense that doesn't stand up to a moments scrutiny glued together with this sort of BS. They've gotten as bad as the anti-evolution people.

      Coming up next, I fear:

      GLOBAL WARMING WEBSITE ISN'T W3C COMPLIANT
      How can we trust their climate data when
      they can't even get their HTML/CSS right?

    • Re: (Score:3, Informative)

      by javelinco (652113)

      Er, no, they said it was possible and later quote "a 59% chance of a new record minimum this year". How the media chose to report this is another matter... Oh yes, note the date: May 2008.

      To be perfectly accurate (unlike the measurements :)), from the article (linked to in the summary):

      Taken together, an assessment of the available evidence, detailed below, points to another extreme September sea ice minimum. Could the North Pole be ice free this melt season? Given that this region is currently covered w

  • by slick_shoes (881437) on Thursday February 19, 2009 @10:26AM (#26916031)
    Clearly some oil company executives have been to the Arctic and moved the sensors, just to discredit the campaigners.
  • Slashdot Drift? (Score:4, Insightful)

    by TheGuapo (864659) on Thursday February 19, 2009 @11:11AM (#26916659)
    It's been interesting to track the Global Warming/Climate Change drift over the years on Slashdot. A couple years ago, it seemed prevailing opinion (measured by high moderation scores and # of comments) favored the "consensus" Anthropogenic Global Warming view of the scientific community.

    However, looking at the more recent global warming related threads, the posts moderated with 5's seem to be more and more in the "Open-minded but skeptical" camp regarding the "consensus" view.

    Is this due to a miscalibration in the sensors, or are we talking about a real opinion shift here?!?

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