Artic ice melting … melting … melting … gone?

On 1 May 2007, the online edition of Geophysical Research Letters will publish a study by a combined team from the National Center for Atmospheric Research (NCAR) and the University of Colorado’s National Snow and Ice Data Center (NSIDC). study report will show, in yet another way, how the Intergovernment Panel on Climate Change (IPCC) report is overly optimistic and is likely understating the risks and impact of Global Warming.  In this case, the to-be-published study: ‘

Arctic Sea Ice Decline: Faster Than Forecast?

This study examined the 18 different computer models used by the IPCC and compared the models’ predictions about Artic sea ice coverage with actual data.

The study team

 compared model simulations of past climate with observations by satellites and other instruments. They found that, on average, the models simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006. The fastest rate of September retreat in any individual model was 5.4 percent per decade. (September marks the yearly minimum of sea ice in the Arctic.) But newly available data sets, blending early aircraft and ship reports with more recent satellite measurements that are considered more reliable than the earlier records, show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953-2006 period.

“This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections,”

In the graphic, the red line shows the actual Artic ice melting.  The blue area represents the range of melting predicted within the 18 different IPCC climate models.

In short, Artic ice melting (ice-free Artic) looks to be “30 years ahead of schedule”.

A critical gap in IPCC modeling is the basic absence of “positive feedback cycles” …

The Arctic is especially sensitive to climate change partly because regions of sea ice, which reflect sunlight back into space and provide a cooling impact, are disappearing. In contrast, darker areas of open water, which are expanding, absorb sunlight and increase temperatures. This feedback loop has played a role in the increasingly rapid loss of ice in recent years, which accelerated to 9.1 percent per decade from 1979 to 2006 according to satellite observations.

Now some might take this report in the following way:

“Well, see, the models are wrong. We don’t know enough.  We must study the problem more before we take action.  Let’s pay the scientists some money and go back to other things.”

This type of thinking and argument, which has been so prevalent in Global Warming Skeptic/Denier rhetoric, sabotages our ability to move toward a saner energy policy.  In fact, this data should be driving us (US) toward more aggressive action. 

It is correct: we don’t know enough. And, in this case, it looks like what we don’t know might very well kill us faster …

42 responses to “Artic ice melting … melting … melting … gone?

  1. So, arctic ice still was declining from 1953 to 1975, even though average temperatures were declining from 1953 to 1975?

    I see the graph tailing off at a greater downward slope from 1975 to present, but there was still a downward slope to the yearly extent of pack ice even when average temperatures were sliding downward prior to 1975.

  2. CO2 eats Ice… it’s like yeast eating sugar during fermentation; except at the molecular level.


  3. Oh, I see.

    It’s like CO2 “drys” the ice out. That’s why they call frozen CO2 “dry ice”.

    Wow. Informative.

  4. Darren,

    53-75 was “average” global temperatures rather than, necessarily, Artic temperatures. [note: this is not my expertise but …]

    And, Darren/Jimmy — there are many other causes to Global Warming than ‘simply’ CO2. CO2 has become the poster child and surrogate for many other GHGs.

  5. Yeah… but it’s the only one that hangs the albatross around the neck of industrial America in a way that is impossible to correct sans adoption of uber-radical economy-crunching environmental conservation dogma.

    Funny how things work out that way.

  6. Jimmy,

    You love throwing around words, “framing” things in a way to make them seem simply unacceptable:

    * Energy efficiency — bad or good? To me, this is a strengthening the economy activity that also benefits the environment which we all live in …

    * Fostering moves to renewable power — while ‘higher’ current accounting costs, wind is lower cost if one factors in health & other free rider costs of using coal

    “Economy-crunching”??? Perhaps if everyone were mandated to go to subsitence famring overnight but that is not what is being called for …

    And, going energy efficiency/renewable energy route strongly & discovering 10 years later that it wasn’t really required by Global Warming? Okay, that .0001% chance … economy is strengthened.

    Not going this route and continuing BAU (business as usual) and worsening the situation? Okay, that 99+% chance, being deep in the hole and digging it deeper with the dirt falling around us as the rain clouds threaten to fill it in with water.

    Truth be told — “industrial” America will be strengthened if it pursues an ever more energy-efficient and pollution-reducing path toward profit-making.

  7. Then the dry ice melts into the water causing a cloud (al la Halloween witches cauldron)… which is the negative feedback loop that explains Global Dimming.

    It’s probably a pretty blue color when it evaporates like the standard deviation band in the graph above.

    The red line represents the way evil-capitalist America is torpedoing gentle Mother Earth toward flat-line status.

  8. I’m sorry A.S. … just messing around a bit.

  9. I think history shows that we will proceed in a way that makes Earth a better place to live [because of our excesses], A Siegel.

    We don’t need Al Gore evangelizing us about the environment any more than we need Street Preachers on Beale Street in Memphis to makes us a generally moral and generous society.

  10. You have to admit, though, that if we could somehow have temperatures similar to the 1953-1975 graph for the next 22 years, that would be a good thing. It would also completely torpedo any thoughts of dramatic action to lower CO2 emissions, because in doing so we might allow temeperatures to drop too far — but that’s another novel by Niven, Pournelle & Flynn, and another topic.

    Even with temperatures falling the ice sheet receeded, is my point. Yes, it’s warmer than it was 10,000 years ago, when the ice sheet got to Cleveland or so. It would be instructive for the data to encompass 1900-2000, to include the last warming period before 1953 to compare to the current warming period. I don’t know if that data is even available, that certainly predates satellite surveillance and aircraft monitoring. But picking an arbitrary start date would seem to be doing a study to prove a point rather than to get an answer.

    I wonder how much the pack ice receeded in that last warming period, and if the rate of change is different now than it was then. From the data presented, there is no way to tell.

  11. A. Siegel –

    Maybe you’d get more productive responses if you honestly characterized GW skepticism.

    ‘ “Well, see, the models are wrong. We don’t know enough. We must study the problem more before we take action. Let’s pay the scientists some money and go back to other things.”

    This type of thinking and argument, which has been so prevalent in Global Warming Skeptic/Denier rhetoric, sabotages our ability to move toward a saner energy policy.’

    And that is the kind of rhetoric – calling someone a ‘denier’ that ‘sabotages’ sane energy policies, while inaccurately characterizing the counter-arguments – setting up the straw-man – that is the kind of rhetoric that tells me you’re not actually interested in working with ‘THOSE PEOPLE’, to bring about ‘sane’ energy policies.

    There are a lot of good reasons for reducing all types of pollution, improving efficiency, etc. We simply don’t agree on the gov’t role in getting there, or the immediacy (or necessarily irreversible existence) of GW.

  12. J Frey — evidently you’d be shocked on who I’m willing to work and to what extent.

    On the other hand, sadly, that ‘strawman’ is not such a strawman. Has there not been a tremendous amount of rhetoric that ‘we do not know enough … invest in research … act in the future’?

    I am sorry … there is a mass (and we do mean mass) of scientific analysis that lays out the realities of Global Warming … now, we can have productive and meaningful discussions and debates over what are the best paths forward, on the varying/balancing role of government versus the market, on what are the balancing advantages of various options, etc … The most productive, major, cross-party discussion that we’ve had was the Kerry-Gingrich debate a few weeks ago. There is fact … and then there are policy debates to figure out how to deal with facts.

    According to John P. Holdren, Director of Woods Holes Research Center (

    “To be credible, the skeptics about human causation of current global climate change would need both to explain what alternative mechanism could account for the pattern of changes that is being observed, and explain how it could be that the known, human-caused buildup in greenhouse gases is not having the effects predicted for it by the sum of current climate science knowledge (since by the skeptics’ assumptions, something else is having these effects). No skeptic has met either test.

  13. Can I just say that, while I enjoy Pournelle’s writing so much that I named my son “John Christian,” that doesn’t mean I lend any credence to the science behind “Fallen Angels.” That book is 50% Jerry grinding his personal axes, and 50% pandering to the hard-core con going fans (which isn’t exactly a formula for great fiction).

    Too many people can’t make out the difference between some imagined “buncha granola crunchers who want to stop the world” (never met them) and making reasonable choices that allow us to move forward with reasonable assurance that we’re not about the screw the pooch. I work in the energy industry — in the coal business, actually — and I’ve been there long enough to remember all the gnashing of teeth that went on back when the Clean Air Act was being drafted. Industry guys rushed up the hill every day showing charts that predicted the end of civilization. Energy was going to cost so much Americans would “freeze in the dark.” Funny thing was, once the law passed, it turned out that meeting the goals could (and was) done. Every single goal for SO2 and NO2 production was met ahead of schedule and at a tiny fraction of predicted costs.

    You’ll have to excuse me if, when confronted by the same kind of “oh, if we try to reduce CO2 it’ll ruin everything!” moaning today, I’m not so quick to listen.

  14. Doug Snodgrass

    Devilstower, nice to see you here. You’re a blogger whose writing I’ve admired for quite some time. Please don’t be a stranger.

  15. J Frey:

    We simply don’t agree on the gov’t role in getting there, or the immediacy (or necessarily irreversible existence) of GW.

    For those insisting on engaging in the experiment of putting more greenhouse gases into the atmosphere in order to test the validity of the climate modelling … to test whether they are accurate regarding the impact of that experiment … how do you propose to insure the rest of us against the risk that the experiment will turn out as the climate modelling predicts?

    Indeed, why should you not be governed by the will of others when you seek to take that gamble? By what right are Greenhouse Gas emitters taking a free ride by dumping by-products of their activities into the common atmosphere?

    If the argument is that dumping the by-products of these activities into the common atmosphere is harmless, the burden of proof is on those who wish to be global greenhouse gas emitters to prove beyond reasonable doubt that the activity is irreversibly harmless.

  16. Jimmy,

    Do you have the numbers showing that reducing energy consumption is “impossible to correct sans adoption of uber-radical economy-crunching environmental conservation dogma?”

    In the meantime I have some numbers for you.


    6th largest economy in the world.
    $1.6 trillion GDP, representing 17% of the entire US GDP.
    576,000 new jobs in the last 3 years.
    $576,000 (strangely enough) is the median house price.

    And here’s the real kick in the pants:

    Since the mid-70’s California has reduced C02 emissions by 30% compared to the rest of the US.
    California is the 3rd lowest per-capita energy consumer in the US.
    Per capita energy consumption is 33% below the US national average.
    Average family pays $800 less for energy compared to the rest of the US.

    Yep, sure sounds like that “uber-radical environmental conservation dogma” is an economy crusher to me.

  17. Devilstower,

    I did note that Fallen Angels is a novel, and it’s over a decade old now. I didn’t mean for it to be presented as a scientific text, much as I do not take (nor expect others to) Footfall as a literal warning to Earth of a pending invasion of aliens that resemble small elephants and drop asteroids on the Earth to subjugate humanity.

    The thing that’s not being discussed is that global cooling is considerably worse than global warming, was my point. Shorter growing season, less arable land, more water locked up in ice, etc. Too cold kills more people than too hot. I don’t anticipate a scenario where humans will be able to cool the earth, other than other science-fiction gewgaws such as Kim Stanley Robinson’s ‘soletta’ from the Red-Green-Blue Mars series.

    What is possible, and is being predicted by some solar observers, is that the level of solar activity is going to decrease and temperatures will come back down. If this occurs, the penalty for CO2 in the atmosphere will turn out to be rather small, and the buffer it creates for declining temperatures driven by the sun will actually be a bit of a bonus. It would suggest that the time horizon for drastic action on CO2 is not as significant as the majority opinion believes it to be.

    There are still reasons to lower CO2 emissions, though those reasons are primarily about controlling energy usage and the CO2 decrease is a side-effect. We’re still overly dependent on a finite mineral, the easily-accessable and remaining deposits of which are located where people are better at making car bombs than cars. Wind, solar and nuclear power emit no particulates, the first two are pollution-free past the manufacturing phase. There are still issues to be worked out in the battery field that will impact everything we do that runs on electrical power.

    But having to Do Something Now presents us with the reality that in the Good-Fast-Cheap relationship you can only pick two, and materials sciences is still not entirely there on the “Good” for solar or cellulosic ethanol. And in bypassing “Cheap” for “Fast”, we’re also passing up the ability to do some other things that are also important. There is a literal opportunity cost in lives of people in the developing world that die every year for lack of safe drinking water. I guess you’d have to classify me as a Bjorn Lomborg-type skeptic, in that I believe there are higher priorities than making the concetration of a trace gas in the atmosphere decrease at whatever cost is necessary.

  18. Actually I think particulate reduction best explains the spike over the last 30 years upon which the doom-saying models all seem to base their progressive warming predictions. It’s a helluva lot better explanation than CO2.

    As A. Siegel noted earlier it’s not just CO2 but CO2 is the poster child for the movement. Why? Because it’s a natural by-product of our industrial advancement. It’s the perfect enemy.

    If you were crusading against sulfur or nitrogen oxides, etc. then we can just engineer our way out of the problem. CO2 however is the ultimate boogey-man… a kick in the n*ts to industrial America that forces conservation.

  19. Darren — RE CO2, perhaps you should spend some time considering the implications of acidification of the oceans due to growing CO2 levels and the impact (already observed and considered scientific thought about future trends) of that acidification. (Can start with Wikipedia:

    Jimmy: Your focus on particulates remains frustrating. You have an interesting point that the reduction of particulates might (MIGHT) mean that the temperature trend growth lines might flatten … that we are experiencing a sharper slope upwards right now due to the removal of the ‘shade’ effect of the particulate pollution. But, the removal of the man-made particulates nor the relative low level of volcano activity at this time is not the cause of global warming.

    CO2 is the “poster child” not in an effort to kill industry … it is the ‘poster child’ because (a) it is the largest single factor of manmade contributions to GW and (b) there is a complexity of discussion that is simply past the vast majority of people in the world. GW is an extremely complicated, systems-of-systems issue (as should be a thoughtful response to mitigating future impact and reducing man’s contributions to GHG & warming) — speaking mainly to CO2 is a surrogate for the complexity of contributing aspects of GW. And, tackling CO2 starts us (US) down the path toward a comprehensive, system-of-systems solution.

    And, well, “conservation” (prefer work efficiency, but I’ll use yours) has proven very profitable in the past for business and society. See notes above … California doing poorly by not having increasing electricity use per capita even in the face of personal computers, large-screen TVs, etc …?

  20. I’m sorry facts frustrate you A.S. but you’ve can’t just ignore what particulate reduction does to both the trend-lines of warming predictions and the case for anthropologic global warming in the first place. The CO2 concentrations are historically a trailing trend to the warming so using it as the poster child is not only inaccurate… it harms the case.

    Nitrogen oxides, given their potency; and the fact that we’ve not already reached saturation points in the atmosphere; and the fact that there is actually something we can do about them; are the low hanging fruit for effective GHG reduction as it pertains to global warming. Again, though, the crusade, led by Prince Al, is against CO2.

    I think California is a bubble economy where regulation and taxation has inflated the cost of living to the point of a mass exodus of those who can leave… hindered only by the fact that most of the middle class is upside down in their mortgages because of the real-estate correction.

  21. From reading the link (and a couple of others), global cooling will accelerate CO2-mediated acidification. Cold seawater holds more CO2, and therefore more acid. This would seem to be bad for things that live in the sea and can’t easily adapt to a pH change. Global warming will, at some point (according to the article, predicted to be in 2100), stop the influx of CO2 into the ocean. At this point, we’re in a bit of a bind because the carbon sink that had been buffering atmospheric CO2 will be full; however, by 2100 we will have long-since changed to more carbon-neutral systems out of exhaustion of carbon-producing energy feedstocks — or so Peak Oil predicts. Carbon-neutral alternatives will become more economically-feasible as the other energy alternatives become less economically-feasible.

    Average energy costs being lower in California has not been the complaint of the last several years, though I suppose that brownouts do lower energy utilization. California has high gas prices, which alone serve to decrease utilization, and a moderate climate where most of the people live. It’s a beautiful place, no doubt, but if the rest of the country also had a Mediterranian climate then our energy usage would be considerably lower as well. There are obviously deserts in California, I understand that, but outside of Arizona there aren’t a lot of people who choose to live in deserts in the United States. There are some, but not many. The relative few who live in the California desert would seem to me to be more than counterbalanced by the much more populated temperate areas.

  22. Darren — Key point about California — past 30 years, rest of nation has seen major increase in per capita use of electricity. California has been flat and certainly not because Hollywood doesn’t have big plasma TVs or computers in homes.

    Jimmy — note that re particulates I was at least meeting you part way …

  23. I caught that A.S. I’m just tweaking you a bit.

    I REALLY appreciate your knowledge and passion for this topic. The format of these comment threads comes off a bit terse at times. I hope though that we’ll both end up benefiting; if nothing more than a ‘know your enemy’ kind of way🙂

    I enjoy the debate… please let me know if I’m coming off as just an adversarial troll.

  24. If California’s electrical consuption has been flat, why is California having electrical supply problems it didn’t in the past?

    According to this list of electrical energy demand by year in California since 1980, from the California Energy Commission, electrical use in California went up 66%. That would seem to be a, er, slanted definition of “flat”.

    It may be flat or decreased relative to the increase in population, or the increase in GDP, but as a raw number it’s not flat, and GDP is fudged by inflation. You don’t get 1-2% more kWh a year from an electrical grid for inflation, while GDP will grow with inflation.

    If you include transportation in energy, then the higher gas prices in California may be enough to drop the overall energy usage to “flat”, but I’d like to see the numbers on that.

    On the positive side, “private supply” (which I take to be solar, etc.) has increased by a factor of ten, so that’s good. The problem is that the demand has increase by a factor of ten over “private supply”, so that’s not so good.

  25. Jimmy — Actually, in terms of paths forward, I believe that we have a tremendous amount of overlap. As I’m sure that I’ve stated before, believe that we could come up with a sensible plan for the coming 10 years or so that would drastically change America’s (and the globe’s) energy future while enabling the development of Knowledge to change the path accordingly. A “Carbon” fee — which you feel is misguided focused on Carbon — could help drive down fossil fuel energy use and lead toward an overall more energy efficient economy, strengthening the economy while reducing CO2. That last you don’t think is required, but the vast majority of scientific opinion believes is necessary. You might be right … might … but isn’t it prudent to be acting, even if solely in “economically profitable ways”, as if you are wrong?

    Second, the back/forth with you is valued.

    With Darren as well.

    I appreciate that both of you do check links/references and put thought into your responses.

    And, CO2 “trailing”, by the way, remains a very interesting interacting cycle over the long-term history. But, we are into the science lab of ‘knowledge’ that CO2 is a GHG (that is simply fact) and that CO2 levels are significantly higher than they have been in a million years and that we are entering uncharted territory. Without man’s impact, perhaps (for a variety of reasons), CO2 is a trailing indicator of heating for other reasons, but now we have man’s CO2 and other emissions. Do you discount that being at 400 ppm rather than the historical record (million years/so) 175-285 ppm is irrelevant and nothing to be concerned about?

    And, by the way, if it were solely “temperature”, there are plenty of interesting options out there. How about, for example, global mandating of high-reflective white roofs to improve the albedo factor of all man-made structures? That would provide a notch downwards in heating trends. But, it would still leave minor things like acidification of the oceans …

  26. I’m going to just knee-jerk a bit here on the term ‘Global Mandate’.

    A white roof on my house would be ugly as heck plus I think the dark roof benefits me in the winter.

    Going back to CO2… it’s well known that you reach a saturation point with each of the gasses because the gas only absorbs certain wavelengths of the reflected radient energy. If we are at 400ppm already then we’ve already hit the point of diminishing returns where even doubling the amount of CO2 will have very little effect on green house related temperature. You can fall back on positive feed-back loops, etc. but in this article [ ] an excellent case is made that CO2 cannot and will not be the cause of hockey-stick-like progressive warming.

  27. Fine … see … you see “black helicopters” when I use the term ‘global mandate’ where I see simply a phrase for starting a discussion. How would you describe international agreement re CFCs?

    Re white roof — studies show that the benefits from white roof far (FAR) outweigh the marginal positive impact in heat gain in the winter. (Let’s take those bleeding hearts, Wal-Mart — they’ve mandated white roofs on all their structures since the financial benefits were so overwhelmingly positive.)

    RE style … well, style changes … and, there are code restrictions in most parts of the United States about what can/can’t be done … and there are codes abotu what must be done in buildings … living in society, we accept some form of restraint on our behavior. Now we are into a debate (fine) about what is legitimate extent of that.

    RE diminishing point … my “experts” tell me otherwise (e.g., talks that I’ve been in, conversations), but I am not expert. I am not ‘conceding’ the point but simply stating that I don’t have the time to crunch out on something for which I have limited knowledge.

  28. BruceMcF –

    “If the argument is that dumping the by-products of these activities into the common atmosphere is harmless, the burden of proof is on those who wish to be global greenhouse gas emitters to prove beyond reasonable doubt that the activity is irreversibly harmless.”

    I’d have much less problem with some regulation of GHG emissions if the proposed regulations were reasonably distributed. By exempting nearly everyone outside of Europe, the USA, Canada, Japan and Australia from regulation, and even then attempting to put the most stringent controls on the USA (while Europe/Canada fail to meet their goals), then I confess that I don’t really take the GHG/GW proponents very seriously, because they obviously and demonstrably don’t take their own cause very seriously.

    At the same time, President Bush negotiates a treaty to share technology that will reduce GHG (and other) emissions and improve technology transfer to the countries that need it, between six of the largest GHG producing countries in the world, including 2 (more?) that were specificaly exempted from Kyoto (1/3 of the world’s population), and he is attacked by GHG/GW proponents.

    So from my perspective, when you look at the way the politics has unfolded, it appears that it is more about politics and power, and a struggle between the haves and have nots, than it is about environmental concerns and mitigating or reversing GHG/GW effects.

  29. “To be credible, the skeptics about human causation of current global climate change would need both to explain what alternative mechanism could account for the pattern of changes that is being observed, and explain how it could be that the known, human-caused buildup in greenhouse gases is not having the effects predicted for it by the sum of current climate science knowledge (since by the skeptics’ assumptions, something else is having these effects). No skeptic has met either test.” YET


    In any case, the whole challenge is absurd on its face. The “known, human-caused buildup in [GHG] is not having the effects predicted for it by the sum of current climate science knowledge.” That is a statement of fact. That’s why they have to keep revising their predictions – downward. Telling a skeptic to explain a phenomenon that IS NOT OCCURING AS PREDICTED, as though the predictions are true is bogus.

    As for alternative theories on warming… mmmm… the sun comes to mind, which explains why Mars shows roughly the exact same temperature increase over the last three to four decades.

    Combine that with jimmy’s particulate theory/clouds, and we’ll at least have a better model to understand what’s really happening. And that answers the challenge posed.

  30. Doug Snodgrass

    Just a quick sidebar. For quite some time I’ve been wanting to propose that J Frey have his Caps Lock privileges revoked.

  31. Doug –

    Figures you would want to censor my free expression. I’m just too lazy to type code so I utilize OTHER METHODS of expressing emphasis.

    If you want to provide formatting buttons, I’ll be more than happy to use them.

  32. Doug Snodgrass

    It’s a joke, lighten up my friend. Trust me, growing up with the last name Snodgrass, I don’t take myself too seriously.

  33. We’re starting to debate the Bloomberg thing over at if anyone wants to jump in.

  34. Here at A Siegel’s invitation…

    jimmy and J Frey have made statements presented as facts here which, while they may be popular among right-wing blogs like “junkscience” are simply not true.

    The most authoritative source of climate information available now are the IPCC reports – working group 1 just released their final report that provides comprehensive details on the science issues, extensively reviewed and, as A. Siegel mentions in the original article here, very conservative in their analysis.

    Contrary to J Frey, the human-caused buildup of CO2 is having precisely the effect the models predict – thousands of physical and biological variables, both global and regional, have been studied for changes that would be expected as predicted under the models, and the overwhelming majority (about 90%) are in the direction predicted. Quantified magnitudes match as reasonably as could be expected. There is no longer any legitimate scientific argument against human causation of warming through our CO2 buildup.

    The variability in solar radiation is also easily quantified since we’ve had satellites, and its recent variability is at least a factor of 10 too small to justify the observed temperature changes in the last 2 decades.

    Contrary to jimmy’s statement that CO2 saturates in the atmosphere, the fact is that it does not. The climate impact of additional CO2 increases roughly logarithmically with the CO2 concentration, so every doubling gives about the same temperature increase. Thanks to the feedbacks (primarily water vapor) each doubling is expected to add about 3 degrees C, or 5.4 degrees Fahrenheit to global average temperatures, and much more at the poles.

    The aerosol effects jimmy talks about (particulates) are real, but they are hard to measure. The best estimates are that up to about 1980 the (human) aerosol impact was close to but opposite to the CO2 (and other GHG) impact, but since then the (human) aerosol contribution has stayed about the same or been slightly reduced, while the CO2 impact has considerably increased. See this wikimedia picture for a rough idea of the state as of early 1990s:

    Other sites with good facts on climate issues:

  35. Arthur Smith –
    thanks, but…
    Why is the IPCC revising their estimates downward if CO2 is having “exactly” the effect the models predicted? Thanks, but, try again.

    And the doubling you cite for CO2 has NOT resulted in the expected temperatrure increases, to date. Which is why the IPCC is revising their estimate downward.

    The funny thing is, people who cite the IPCC report – which was edited by politicians and social scientists prior to publication – get really torqued when politicians review gov’t positions on scientific knowledge. Just pointing out the hypocrisy – not saying it’s right or wrong.

    However, you did get close to the answer when you started talking about satellites. 1) Were you aware that April was the hottest April in France since 1950? Wow – France is now as hot as it was 57 years ago. Thanks global warming. But the kicker…. 2) 1950 was the year reliable temperature measurements from 22 stations across France were begun.

    Oh boy. Now we’ve done it. Now we’ve got to begin recognizing that a) we don’t have significant amounts of accurate data with which to guage our current vs. historic ‘total energy’, and b) ice cores tell ‘a story’, but are a local snapshot, and thus are somewhat imprecise in the information we derive from them, and inaccurate as a means to describe conditions over the entire globe.

    With satellites we can actually get a good handle on accuracy and general vs. local conditions – but that data is only 30 years old and even then wasn’t comprehensive.

  36. I question the presumed absence of bias in the environmental science community. They’re environmental scientists for heaven’s sake… of course they’d see their myopic specialty environmental decline as the most important thing ever; even if it didn’t affect their pay checks.

    It’s a recipe for chicken-little alarmism of biblical proportion. And then there’s the UN political spin.

    Sorry guys… I’ve lived through hysteria like these before. I’ll place my bet on History over Science here.

  37. J Frey – The IPCC did not “revise their estimates down”. Some estimates of changes have gotten more precise, and therefore the 90% confidence interval is narrower – that means the upper limit is lower than it was, the lower limit is higher. That’s increased precision, not “revising down”, despite the misinterpretation in numerous media reports.

    And the most important estimate – the estimate for temperature change with a doubling of CO2 – has not been “revised down” at all. The 2001 report had a range of 1.5 to 4.5 degrees C. In the 2007 report the estimate for this is 2 to 4.5 degrees C.

    But perhaps you have some other number you saw “revised down”? Details?

    You can argue about the accuracy of the scientific data all you want – that’s certainly the job of the scientists to evaluate the accuracy of the measurements they’re using. Anybody who has a good argument can publish a paper – it’s the sort of controversial thing journals love to publish – but as you can probably tell, there’s no sound argument along these lines at all any more. Go and actually read the IPCC report – the full technical report on the science is available online, free. There’s no excuse not to understand how sound the science is now on this.

  38. Jimmy — Why retreat to arguments of “they are all biased because they get money”? That is, after all, what you are doing with your points. Do you really want to bet your future on that?

    J. Frey — This is about Global Warming, not specific data points about specific locations. Fine, I’ll buy your statement, France April 2007 is cooler than April 1950. So? We are talking about global trends and global patterns …

  39. A Siegel –

    In your response to Jimmy that he is retreating, it is the same argument that is used to discount or completely dismiss scientists who have theories contrary to global warming, based on their supposed (however thinly sourced) ties to energy companies.

    What he’s proposing is, why should he bet his future on one persons’ bought and paid for opinion over another persons’ bought and paid for opinion? The only reason is the science, and he hasn’t found the science for global warming to be compelling enough to justify the drastic actions some are proposing.

    As to your response to me – I can say the same thing about the ice cores, you realize that, yes? Now, all that ice core data is reduced to “specific data points at specific locations”. Virtually all of those locations are around the poles.

    My point was that it’s only in the last 30 years that we’ve been capable of even somewhat accurately quantifying the ‘total energy’/mean temp of earth’s system. I seriously question the presumption that we’ve accurately characterized the ‘total energy’ for the preceeding millenia to any degree of accuracy that can be useful to us now.

  40. Arthur Smith –

    We’ll have to agree to disagree. The numbers I saw recently suggested that we’ve achieved a doubling already and that the increased temp (now) is lower than projected by the models.

    The upper estimate for sea level rise by ~2100 I believe was ~halved, which means that the mean MUST have been reduced.

    The IPCC report is only as accurate as the models used to support their conclusions, and even then you’re depending on the assumptions of the modelers. And this is where we get to bias, because those assumptions are dependent on the judgement of the scientists doing the modeling.

    There are plenty of sound arguments that address possible inaccuracies in the modeling, including lack of accurate and precise data even for the last 150 years that actually spans the globe, the models’ failure to accurately model the impact of clouds and/or airborne particulate influences, etc.

    These are complex systems. We have trouble marshalling the computing power necessary to model (relatively) simple chemical reactions that take place in our bodies, where the factors and variables are known quantities. When it comes to atmospheric and total energy modeling, we don’t even have a complete handle on all the variables. I’ve seen some scientists talking about the noise in the data being significant enough to affect the conclusions which means our models aren’t precise enough to give us an accurate picture of what’s really going on.

  41. J Frey

    Read the IPCC report. I particularly recommend the Technical Summary. It answers every single one of your complaints in detail with references to the full report which further has references to the original literature. For example, on the 150 year temperature record, there is extensive analysis on how reliable that is – the complaints about “heat island” effects are demonstrated to have a negligible effect on the temperatures used in analysis, for instance. And there is extensive discussion of the models. If the models “depend on the assumptions” of the modelers, then you would expect there to be plenty of models from people who assume that global warming will have no effect (because there are a huge number of people who seem to still believe that, and there were many scientists who believed that too until a few decades ago). But there are, in fact, no detailed numerical climate models that match those assumptions – every model shows a temperature response of at least 1.5 degrees C to doubling CO2, and the many other consequences that have been discussed as well.

    Yes some results are uncertain – the IPCC report goes into extensive detail to quantify uncertainties, and reports these in an extremely clear manner: some things are “likely”, “very likely”, “almost certain” etc. depending on the percent likelihood of the condition in question, based on the data we have to this point. That’s a translation of the “noise in the data” into quantifiable statements of facts. It’s not that hard to do.

    And no, humans have not doubled CO2 yet. We’re up by 40% from pre-industrial levels. Also, the response to doubling that is reported is a long-term response; the “transient” (short-term) response is expected to be slightly lower because of delays from things like the heat capacity of the oceans. The temperature rise so far of about 1 degree C is exactly on the order of what the models expect for this transient response to a half-doubling, if the full response is about 3 degrees. Look at the numbers, read the report yourself. It’s not that hard to understand.

  42. Oh, you also mentioned the sea level rise issue. The mean for the sea level rise estimate did indeed decrease – but that was almost entirely because the IPCC removed from the new report estimates of ice-sheet melting acceleration which had raised the upper-bound in the third report. There’s actually strong evidence for acceleration in melting of the major ice sheets, but instead the main estimate in the new report was a “Model-based range excluding future rapid dynamical changes in ice flow” as you can see in table TS.6 (p. 70 of technical summary).

    There were also a few technical changes – the date range for the estimates is different, and the number of standard deviations used to describe the range was different. As the fourth report states in reference to the third report (TAR) – “The TAR would have had similar ranges for sea level projections to those in this report if it had treated the uncertainties in the
    same way.” (p. 70).

    So, again despite misleading media reports, there was actually no change in the sea level projections in the new report from the 2001 version.

    I wonder why various media outlets insist on announcing that the IPCC has reduced their estimates for things, when that’s simply not true?

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