On Not Being Certain About Uncertainty–Or, Why You Can't Downplay Global Warming

By Chris Mooney | June 2, 2011 12:25 pm

This theme is coming up a lot lately. I am noticing more and more that some very thoughtful people, like Michael Shermer, are willing to accept that global warming is real and human caused, but neverthless don’t think we have to worry about it because it won’t be that bad. And now here’s Michael Lind of the centrist New America Foundation, writing in Salon.com:

The scenarios with the most catastrophic outcomes of global warming are low probability outcomes — a fact that explains why the world’s governments in practice treat reducing CO2 emissions as a low priority, despite paying lip service to it….

In one sense, this is obviously true. In another sense, it’s completely off base.

First, uncertainty cuts both ways, so it makes no sense to be confident that change will be on the low end. This is something about which Kerry Emanuel recently testified:

In soliciting advice, we should be highly skeptical of any expert who claims to be certain of the outcome. I include especially those scientists who express great confidence that the outcome will be benign; the evidence before us simply does not warrant such confidence.

But more generally, you can really only make Lind’s argument if 1) you’re paying enough attention to global warming to understand that there’s a real scientific consensus that it’s happening, but 2) you’re not paying enough attention to realize what global warming really means for Planet Earth.

Fundamentally, global warming means adding more heat to the system. Physics dictates that planet wide changes are then inevitable, and while the speed at which they will occur may be debatable, if you keep adding heat and don’t stop then we know what eventually happens–because we know what the Earth was like at earlier points in its history, when temperatures and carbon dioxide concentrations were higher.

One of the most obvious things that happens is that land-based ice melts, and sea level rises. This is not only because global warming is adding heat, but because the amount of heat added is amplified at the poles, where the ice is located. And indeed, we know that global warming is already destabilizing Greenland and West Antarctica, although we don’t know for sure how much or how fast this is occurring, or how catastrophically it could occur. (For a good discussion of this, see Joe Romm.)

But eventually, add enough heat, and the ice melts and goes back into the ocean. It has to. It is ice. And then sea levels rise dramatically, and many places where we have currently established human civilization–we like to live near water, dangerous though it is–become uninhabitable.

It’s really that simple. We don’t know the timeline, but if we don’t stop it, we know the eventual outcome–and it is intolerable and unacceptable on any timeline. And that’s why any attempt to minimize worry about global warming by citing “uncertainty” about the projections just doesn’t make sense.

CATEGORIZED UNDER: Global Warming
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Comments (33)

  1. Somite

    The large uncertainty is what is so scary to me! At skepticblog Shermer is famous by insidiously (and not so insidiously) downplaying climate change due to a libertarian bias. Obviously Shermer and others are not fans of the adage: wish for the best, prepare for the worst.

  2. Chris Mooney

    “The large uncertainty is what is so scary to me!”

    Exactly. Because you know what is at stake. If ever there was a case for precaution is it this one.

  3. Did you say that Michael Shermer thinks we don’t have to worry because the effects of climate change won’t be that bad? That’s very concerning. With whom has he been conferring?

    Granted, the United States will not suffer similar catastrophic changes faced by countries like Indonesia, given a 2-3 degree increase in global temperature, but to say we need not worry is very troubling. Are we not a global community? Shall we not concern ourselves with the plight of others who suffer because of our actions (largest producer of GHGs)?

    I am thankful you finished this post the way that you did. I hope Shermer rethinks his position on this.

  4. Chris Mooney

    Shermer’s view is here. I should have linked before. We talk about this in the upcoming POI episode, which airs Monday.

    http://skepticblog.org/2010/11/16/throwing-cold-water-on-a-hot-topic/

  5. Then, when Andrew Leonard mildly rebukes Lind, but does NOT call him a “global warming denier,” Lind defensively responds by implying Leonard DID!

    http://socraticgadfly.blogspot.com/2011/06/michaellind-liar-on-peakoil-and.html

    And, yes, Jamie, in his first column, Lind says the same as Shermer.

    That said, per the latest from Lord Stern in England, a 50-50 chance of a 4C rise by 2100, I figure that’s a 50-50 chance of a 3F rise by 2050, when many of us will still be alive.

  6. Valid points. But omitted are the data to suggest that Global Warming could be due to solar flair increase due to our sun eventually dying. Or that ice core data suggest that global warming is a regular trend and that if we as humans by introducing carbon have made an insignificant effect on the overall cycle. Or that Global Warming is more accurate discussed as Climate Change as not everywhere in the world is getting warmer.

    Now before you jump all over me for bringing up these points. My point is the same as the authors, that we can’t be sure of anything. As research goes we are far from definitive about practically anything regarding Climate Change accept the potential effects if it does go to a worst case scenario. And those are only domino projections.

    I think most people (I say most because unfortunately some of the aforementioned individuals would happy to watch the world burn if you payed them enough) can agree that pollution is bad. And that the honest to god “least likely scenario” is that releasing trash into the environment is good for us.

    I wish we everyone could simply get behind the idea that preserving our natural resources, and reducing our footprint is in everyone’s best interest with or with the topic of Climate Change because we really don’t know squat about what is ACTUALLY going on. All we have are a variety of very expensive theories.

  7. Susan Anderson

    Niggling away about the problem of what science is and is not, and the perception disconnect, I remembered some conversations about scientific reductionism and its limits. Those of you who know what you’re talking about, please correct and be patient, as this is a layperson’s view, albeit with exposure to scientists and lifetime interest.

    We are all assuming that scientists can actually measure and define climate change due to global warming and other causes. But in fact they can only measure what they can measure, and define what they can define. Seems obvious, but we’ve been filling in the blank by assuming that what they are not measuring and defining is by intention rather than being a limitation on discipline and humanity. We are simply not omniprescient.

    The general public is assuming those uncertainties mean the material isn’t there. And scientists are failing to see something so obvious it makes the ground they stand on. They won’t guess and mostly won’t talk about what they understand as opposed to what they can prove and measure as scientists. Lately, things have gotten so bad that some are straying from this narrow path, but unfortunately they are being attacked rather than praised for stating the obvious but unprovable. This conflict is very distracting and provides fuel for propagandists.

    Those wishing to exploit this, knowingly or unknowingly, are not interested in the limits to their humanity. They work with a single purpose, having eliminated the possibility that what they don’t know or understand fills our lives. The recent spate of catastrophic events (whether you count decades or just a few recent years) can be removed from the conversation by relying on scientific uncertainty, but this basic fact escapes the conversation.

    Is there something that can be done about this? Religion fills most people’s need to live with things bigger than they can understand, but in fact they need to face life and death on a much more fundamental and practical level at this present. Unfortunately, issues of faith can seriously interfere with facing reality.

  8. Susan Anderson

    Reductionism and gaps in knowledge are also confusing for professional reporters. Depending on their natural biases and tendencies (Andy Revkin, for example, doesn’t like strong statements and downplays clustering of extreme events) they may think they are providing imbalance but in fact fail to identify the uncertainty at the core of knowledge. This uncertainty doesn’t mean that we can’t make clear statements about what we think is going on, but it limits understanding by allowing unclarity to rule where quite a bit of clarity is available. Fear also plays into this; many people are simply unable to face what is happening and won’t until it cuts off their power, water, or other essentials.

    Those reporting on this issue have been deluged with plausible looking material that discredits mainstream climate science. I think this cumulative battering and the exhaustion of trying to stay open-minded takes a toll. Over time, volunteer commenters like myself get exhausted and it never stops. It is always front and center, in a very organized way. Many of my friends and colleagues over the years, for example, have abandoned DotEarth and what remains is a consistent barrage of people who seem less black than they are painted but never go off message.

    In response, there is nothing on the reality side of the discussion to make a bulwark. Outright dishonesty and delusion are hard for someone with faith in humanity to see for what it is. Experts will continue to say what they know and don’t know, but the hardworking reporter is stuck with trying to provide answers, many of which are incorrect in a field where 97.4:2.6 is shown to be more like 50:50. The many gaps in science and “tricks” that help us look at what we do know (such as adjusting for changes in observations and measurements over time, and global differences in ability to measure, which becomes extremely hard at the poles, or proxies that don’t “perfectly” match and are certainly not perfectly understood) can be exploited by those who just want us to concentrate on what we don’t know.

  9. Susan Anderson

    TJ Anderson, your standard talking points are well answered here:
    http://www.skepticalscience.com/argument.php

    “Skeptic Arguments and What the Science Says

    “Here is a summary of skeptic arguments, sorted by recent popularity vs what science says. Note that the one line responses are just a starting point – click the response for a more detailed response. You can also view them sorted by taxonomy, by popularity …”

    You stake a claim by saying people may “jump all over you” but none of your arguments are either new or unanswered. The many thousands of times these points have been brought up distract from skilled people doing their work. You appear prepared to assume that any answer is biased, but those who have seen these in different forms for years should be forgiven for getting a little impatient.

    If you are referring to the new published solar article it is dealt with in detail with great technical background at RealClimate. Yes, your “friends” may have told you RC is biased, but please take a look for yourself, and insofar as you are able, try to understand what is being said instead of dismissing it without a trial. In general, the standard of patience there from people with extensive education and qualifications is admirable.
    http://www.realclimate.org/index.php/archives/2011/05/an-incremental-step-blown-up

    It turns out these conclusions were based on evidence created in a lab – isn’t that just what fake skeptics claim is the problem with other science they’d prefer to dismiss? Real skeptics question all “sides”.

    Please don’t parrot these talking points without considering the possibility that most of the world’s best scientists for decades have been telling the truth to the best of their ability.

  10. Colin

    For a counter argument, economics means that limits on using the most efficient means of energy production slow down development. When a resource becomes restricted, only the privileged can get it. It also means that less is available to put toward less important goals to business leaders, such as research. Without research, other known viable energy alternatives can’t be exploited to be made cheap enough for a mass market appeal and other unknown viable energy alternatives can not be developed. For example, how long do you think that the funding by the government for the ITER project will last if the U.S. economy reacts unfavorably to a cap and trade system? We will still have obligations to pay welfare assistance to states, pay back loans from the Social Security Administration, meet our debt payment obligations, and pay for the DoD, even if at a reduced capacity.

    Tampering with the economic output of the US for something that most models predict to be fairly low order does not seem like a good choice to me. Environmental protection should focus on things that are proven to be damaging, like overfishing (which most fishing companies have NO problem with), river and lake pollution, air toxins, etc and continue pushing the science forward as fast as possible on things that are likely to be damaging, like fracking, AGW, etc.

  11. JMW

    @1 Somite: The large uncertainty is what is so scary to me!

    Exactly. John Ralston Saul, in his “Voltaire’s Bastards”, criticizes the modern elites government, business and mililtary who have been trained by rational methods – because they forget two things. The first is ethics. The second is uncertainty. Elites…experts…get “street cred” by providing answers to problems. By being certain. It has, in the author’s view, created a ruling class of our society that is manifestly incapable of dealing with, and uncomfortable confronting, uncertainty.

    Recall the line of dialogue from Spider-Man 2, when Peter Parker visits the doctor and tells him of a “dream” he had where is Spider-Man, and loses his power. The doctor says, “Nothing is worse than uncertainty.”

    One thing we need to become more at home with is uncertainty. Because it is the natural environment in which we live. Somite, I don’t say you are, but I suspect many anti-science activists are doing metaphorically this: standing in the middle of the room with their eyes closed, their fingers in their ears, and yelling “la la la” as loud as they can because they simply cannot tolerate the idea that we just don’t know for sure.

    And you can tell who they are because they are the ones who say that they “know”.

  12. Chris Mooney

    @10 “Tampering with the economic output of the US for something that most models predict to be fairly low order does not seem like a good choice to me.”

    You’ve done it again….

  13. Nullius in Verba

    “Fundamentally, global warming means adding more heat to the system.”

    Do you really think so?

    Heat enters the system from the sun, and leaves it by thermal radiation to the cold of space. Even in the conventional tale, global warming means losing less heat from the system, not adding more. The sun, they say, does not change. And from a more precise point of view, the heat escaping is almost exactly balanced by the heat arriving. The change in temperature is not due to any imbalance between the two.

    The fundamental reason for the contribution to change in temperature arising from the greenhouse effect is that it is being lost from a different place.

    Even after seeing it so many times, I still find it astonishing that this, the central tenet of a global movement, the most serious issue facing mankind, the end of the world itself, is still not understood by so many people. How is it possible, after thirty years of being continually lectured on it, that people could not understand how it works? Not just sceptics, but believers?

    “And indeed, we know that global warming is already destabilizing Greenland and West Antarctica, although we don’t know for sure how much or how fast this is occurring, or how catastrophically it could occur.”

    It’s not destabilising it. Have you checked how small the change is in comparison to what is there? Have you checked over how short a period this has been observed for?

    “For a good discussion of this, see Joe Romm.”

    You should check with him for his advice on mobile phones, too.

    “But eventually, add enough heat, and the ice melts and goes back into the ocean. It has to. It is ice.”

    Ice caps are a balance between multiple inputs and outputs – precipitation, flow under gravity, evaporation (sublimation actually), and – yes – melting. If you increase snowfall the ice grows. If you increase humidity the ice grows. If you increase temperature – from let us say from -40 C to -38 C – what precisely do you think happens?

    Raising temperature only leads to melting in certain special circumstances – when it was previously just below freezing, and is now just above. Otherwise, it stays where it is. It has to. It is ice.

    “And then sea levels rise dramatically, and many places where we have currently established human civilization–we like to live near water, dangerous though it is–become uninhabitable.”

    I think I’ve already explained this one, several times. We build civilisations on land that rises and falls with the sea – the geological processes that make it so fertile and desirable to people are exactly what dictate its proximity to sea level. The coast is a dynamic place, always changing.

    “It’s really that simple.”

    The Earth’s atmosphere and oceans are complex. Your explanation is simple. Don’t be so certain. By telling people the explanation is simple, you set them up for a fall when they run into someone who knows it to be complex, and can show them so.

    What you should do is to tell them that it is complex, that here is a simplified explanation, and if they wish to study the complexities they can do so. Then when they run into sceptics, they are prepared, they are armed with the knowledge that the explanation they have been given is not the true story of AGW, so its disproof is not the disproof of AGW.

    It is the same with all dumbing down of science. Don’t tell people science is simple. Tell them that it is understandable, with sufficient effort. Show them the first step. But don’t tell them that they have already arrived as soon as they make the first step.

    But congratulations on giving evidence and reasons for belief, instead of authority. Genuinely, I think that’s an improvement. No sarcasm intended.

  14. Sean McCorkle

    Allow me to add a point of certainty to the discussion:

    If you increase temperature – from let us say from -40 C to -38 C – what precisely do you think happens?

    If you increase the ice temperature from -40 to -38C, then it will take less additional heat to actually melt it.

  15. Nullius in Verba

    #14,

    Yes, that’s true.

    Your point?

  16. Sean McCorkle

    I wanted to clarify a point: as temperature increases, its easier for ice to melt.

  17. Nullius in Verba

    Now, that statement does not follow from your first, and indeed isn’t true. As the temperature rises from -40 C to -38 C, it is not easier for it to melt. It does not melt. It cannot melt. It is at -38 C.

    Would you agree that if you increase the temperature of steel, or concrete, or the ground on which we stand, then it will take less additional heat to actually melt it? Yes? No? Is it your assertion that global warming makes it “easier” for the ground to melt? How could it try?

  18. Sean McCorkle

    Its easier to melt in the same sense that its easier to reach the summit of a mountain or hill if you start from part of the way up. Easy as in “requiring no great labor or effort”, effort as in “work”, work as in energy. If you have ice at equilibrium just a degree or less below the melting point, its still ice, but it could be melted simply by breathing on it (pretty easy) compared to ice in equilibrium at -40C (not as easy).

  19. Nullius in Verba

    Are you talking about how easy it is for the ice to melt, or how easy it is for something to melt the ice? Like what?

  20. Sean McCorkle

    I wasn’t really distinguishing between the two, in the strict subject-object sense. The ice’s point of view, “gee if I only had another calorie or two, maybe I could melt” may seem like an outlandish anthropomorphic projection, but sometimes that can be a very useful metaphor for understanding or explaining the physics.

    Another way to look at it is, the closer to melting the ice already is, the more likely an environmental temperature fluctuation will push it over the top.

  21. Nullius in Verba

    And would you agree, as I said earlier, that the same can be said of steel or concrete?

  22. Sean McCorkle

    For steel, yes, If you are trying to melt steel and starting from a higher environmental temperature, it will take less heat to do so, although the melting point is so high, a few degree starting advantage would be miniscule and would be hard to notice. Concrete is composed of all kinds of different materials with different melting points etc. Not sure what would happen – I suspect it might combust in the atmosphere before actually melting. The ground is even more varied – some refractory materials, but a lot of volatiles as well, organic compounds etc. Its difficult to imagine it melting before burning, to be honest.

    I’m quite confused by your question. Are you asking if I think AGW will cause buildings to melt? No I don’t. But it will cause cause more rapid polar ice melting. The ice is not all at -40C. The ice which is melting at any time, at the edges of sheets and glaciers, is at the melting point and is at the interface of a warmer exterior environment and interior ice which is below that temperature. If that interior ice temperature is raised, the “melting front” or interface will propagate more rapidly through the ice.

  23. Nullius in Verba

    “I’m quite confused by your question.”

    Well, I was confused by where you were going with this. The post above argues that adding heat via global warming will eventually melt the poles – that this is some sort of physical inevitability due to the properties of ice. I was pointing out that this applies only to those parts just below zero, a tiny fraction; to the bulk of the ice that is a long way below zero, it makes no difference. Combined with precipitation adding ever more layers of snow on top, and the supply of ice to warmer altitudes being driven by gravity and hence ice mass, a little heat will likely have no effect. At the very least, you cannot claim it to be inevitable, or simple.

    There are, of course, several points on which I could be challenged. There was my allusion to the greenhouse mechanism, or the claim that it wasn’t widely understood. Someone could cite data on ice sheet destabilisation, or the physics of glaciers, or discuss the formation of river deltas and Darwin’s views on coral atolls. You could definitely have got a shot in about my wisecrack on Joe Romm – that he is wrong on one topic does not mean he is wrong on others. We could have had all sorts of fun.

    But you seemed to be trying to get me to agree to a point that I hadn’t denied, nor relied upon. Ice at -38 C takes less extra heat to melt it than ice at -40 C. But given that such extra heat is not going to be forthcoming, so what? Unless you was about to claim it could? Or that the ice had some moral property of ‘meltiness’ that was increased by the higher temperature, which was in itself a moral wrong brought about by global warming.

    The question didn’t seem relevant to the point I had made, and it didn’t seem up to your usual high standards of challenge – which I generally enjoy – so I was confused as to what you actually intended. I asked myself, had I misunderstood?

    Yes, some of the ice is close to zero – every year in high summer there are pools of meltwater form on the top of the plateau, in places where dirt and debris results in dark patches that absorb a little extra sunlight, and it runs down into cracks called moulins. There always have been – and a few feet of meltwater on top of two kilometres of cold ice is not going to make much difference anyway, but we could have an interesting talk about it. Can an extra few weeks in summer exceed the accumulating snows of the far longer Arctic winter? Haven’t we said that they expect it to snow more in a warming world? Is it really that “simple”?

    More interesting, though, is what the response should be to Chris giving his reasons for concern about global warming – and again, well done to him for doing so! – and me pointing out that there are some problems with what he says. Should he answer my points? Should they be answered at all, if they’re not obviously wrong? Given that Chris has blogged on the dangers of trying to doggedly defend a position out of motivated reasoning, and called on his opponents to reconsider with more open minds, would he not expect us to expect the same of him? If you were to do unto others as you would want them to do unto you, as they say, what should you do?

    Hypothetically, of course, in the event that I ever did make a point that was worth acknowledging?

  24. Sean McCorkle

    But you seemed to be trying to get me to agree to a point that I hadn’t denied, nor relied upon. Ice at -38 C takes less extra heat to melt it than ice at -40 C. But given that such extra heat is not going to be forthcoming, so what?

    That heat is not only forthcoming, its going into the Greenland Ice Sheet at this very moment. Temperature maps. here and show the temperatures over and on the surface of the ice sheet which are something like 10-20 C cooler than those outside the sheet. What does that mean? The ice sheets are cooler than the neighboring environment , so heat is therefore flowing into the ice from the air (and land and water). That means that the ice sheet is sucking heat out of the environment around it. Even precipitation—even snowfall—will add heat to the sheets if the falling snow is warmer than the ice (and snow is usually a lot warmer than -40c) And until the ice melts or evaporates, it can’t get rid of the heat, so the remaining ice is therefore warming up. We may infer this simply from the observation of those temperature maps. And it is true regardless of any increase in average global temperature. Furthermore, the surrounding temperatures are above 0 C in that map; were the ice to reach equilibrium with those surrounding temperatures, it would melt.

    How much heat would it take to melt Greenland? Its a useful exercise to do a back-of-the-envelope estimate. Taking 3e21 cm^3 for the volume, 2e12 m^2 for the area and 2 J/gm/K, a density of 1gm/cm^3 for ice, and assuming your number of -40C for the current temperature, I get that it will take about 2.4e23 J to melt the whole thing. To put that in context, the Earth gets about 300 W/M^2 on average from the sun, so the equivalent area of Greenland would get about 6e14 J/s. If we could pump all that into the ice sheet, it would last only 4e8 seconds, or 3 years!

    Furthermore, there are more than a few observations showing the ice sheet is loosing mass (GRACE gravimetric). Chris is perfectly correct here. The interesting (or worrisome) questions are how fast the is melting occurring and if its accelerating and if so, by how much.

  25. Sean McCorkle

    Sorry about the screwup with the links in the previous (didn’t get an editing pass that time). The two temperature map links are
    http://www.uni-koeln.de/math-nat-fak/geomet/meteo/winfos/arcisoTTPPWW.gif
    http://www.esrl.noaa.gov/psd/map/images/fnl/sfctmp_01.fnl.html
    and ice sheet numbers are from
    http://en.wikipedia.org/wiki/Greenland_ice_sheet
    also I should have said “a heat capacity of 2/J/gm/K”, and make a correction from 3 years to a few years (its an order-of-magnitude estimate)

  26. Nullius in Verba

    #24,

    “Temperature maps. here and show the temperatures over and on the surface of the ice sheet which are something like 10-20 C cooler than those outside the sheet. What does that mean?”

    I’m not sure what you mean by that. Do you mean to point out that the centre of the Greenland ice sheet is 10-20 C colder than the coast and seas around it?

    There’s a very good reason for that.

  27. Sean McCorkle

    The surface temperatures are cooler over the whole ice sheet. Of course there’s a very good reason for that—that’s my point: the ice is pulling heat out of the air over it, causing the air to cool.

  28. Sean McCorkle

    I see where you’re going with this – the adiabatic cooling of 2km can explain the temperature difference. Fine. But that doesn’t protect the sides of the mass and there’s plenty of area not blocked by high mountains. Heat is flowing into the ice; measurements show that it’s shrinking.

  29. Nullius in Verba

    #28,

    Very good!

    But now you’ll have to say why you think the sides of the mass don’t correspond to the temperature gradient around the ice sheet. (The sides are not vertical.)

    Measurements show that it’s shrinking? What percentage per year? With what error bars? Over what period?

  30. Sean McCorkle

    arrgh I can’t now locate an aggregated resource for works on this subject which plotted numbers and error boxes from various measures over the last couple of decades in a time plot. The take-home number I remember from that is about 200 gigatons per year mass loss. Here’s one example of analysis from GRACE gravimetric data: Pritchard, et.al., there have been other publications of analysis of GRACE as well. If that rate holds, the sheet lifetime will be in the order of tens of thousands of years, but as the Romm link above discusses, there been some analysis showing possible acceleration (i.e. Velicogna)

  31. Nullius in Verba

    Thank you.

    So if the sheet lifetime is on the order of tens of thousands of years, we have something like a 0.01% variation over a time interval 0.1% of the time for which consistent change would have to be sustained.

    So you tell me, do you really consider that to be evidence that the ice sheet is already being “destabilised”? Might it not be random noise?


    This isn’t intended as a game of “gotcha!” (Not much, anyway.) But I hope you can see why this has an importance beyond the simple scientific point. People on both sides of the debate make frequent errors, hold many misconceptions, make bold and confident-sounding statements that can’t be backed up, and quite often know less than they think they do. But Chris still acts as if it is a peculiar and terrible thing that political and media figures on the other side of the debate should sometimes make erroneous and unscientific statements, and not even be bothered by the fact – while appearing to do the same himself. Whether or not that is actually a problem, do you see how others less sympathetic are liable to see it?

    What effect do you think it will have on what people think?
    From your side’s point of view, what could be done about it?

  32. Sean McCorkle

    So you tell me, do you really consider that to be evidence that the ice sheet is already being “destabilised”?
    This isn’t intended as a game of “gotcha!” (Not much, anyway.)

    Don’t worry, you didn’t get me. I’m not sure about “destabilized” but I do consider GRACE observations, among other things, to be good evidence that the Greenland Ice sheet is melting.

    The small baseline “lever-arm” from these observations that you note in no way rules out a much shorter lifetime if the mass loss rate is increasing, as has been claimed by more than one work. Rignot, et.al. claim the rate is accelerating by about 10% per year. If that acceleration were to hold, starting with the present rate of 200 Gt/y, and a present mass of 3e6 Gt, the resultant quadratic mass loss would hit zero in around 500-600 years. That Greenland could completely melt in 5 centuries is perfectly consistent with these observations.

    Might it not be random noise?

    No. This is indicative of what appears to be an interesting mindset on your part, to attribute randomness in physical systems where not appropriate.

    What effect do you think it will have on what people think?

    To be honest, I haven’t got a clue. I haven’t got a clue what the majority of the population thinks about most scientific issues. I’m often shocked at widespread attitudes about evolution and such,and thats one of the reasons I follow this blog.

    From your side’s point of view, what could be done about it?

    I can’t speak for my “side”, but I will say that continued gravimetric observations of the Ice sheets are a high priority and should be continually monitored. Continued satellite imaging of the sheets is also in order, as are surface and subsurface observations.

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About Chris Mooney

Chris is a science and political journalist and commentator and the author of three books, including the New York Times bestselling The Republican War on Science--dubbed "a landmark in contemporary political reporting" by Salon.com and a "well-researched, closely argued and amply referenced indictment of the right wing's assault on science and scientists" by Scientific American--Storm World, and Unscientific America: How Scientific Illiteracy Threatens Our Future, co-authored by Sheril Kirshenbaum. They also write "The Intersection" blog together for Discover blogs. For a longer bio and contact information, see here.

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