Crystal Serenity

In 1981 James Hansen and colleagues published research in the prestigious peer-reviewed journal Science titled “Climate Impact of Increasing Atmospheric Carbon Dioxide.” They discussed the result of basic physics, that carbon dioxide in the air inhibits Earth cooling off, thus heating the planet. They also reported the results of computer simulations of Earth’s climate in a world with ever-increasing CO2.

Hansen81


In that research they stated some of the more notable results, both for the long term (if we double the amount of CO2 in the air), and some of the changes expected by the year 2010 if CO2 kept increasing the way it had been (because of our burning fossil fuels). These include:

  • Doubling the atmosphere’s CO2 would raise Earth’s overall temperature by 2.8°C (5°F).
  • By 2010, Earth’s temperature would rise about 0.4°C (0.7°F).
  • The Arctic will warm considerably faster than the globe as a whole.
  • There will be a reduction of sea ice in the Arctic.
  • There’s a chance we might see the opening of the fabled “Northwest passage” during late summer.
  • Naturally one wonders, how did things turn out?

    First on the list is climate sensitivity, the global warming we expect from a doubling of atmospheric CO2. We don’t know how accurate the 1981 result is, because climate sensitivity is still one of the more troubling uncertainties of climate science, but modern estimates put it somewhere in the range of 2 to 4.5°C (3.6 to 8.1°F). The width of that range testifies to just how uncertain we are about this, but all plausible values are a serious threat to mankind.

    It’s also important to emphasize that when it comes to climate sensitivity, uncertainty is not your friend. In fact the opposite is true: uncertainty is your enemy. We’ll be extremely lucky if sensitivity is only 2°C (3.6°F) because that will only be a lot of trouble. But if sensitivity is on the high side — if doubling CO2 (which we’re on track to do before this century is complete) raises global average temperature by 4.5°C (8.1°F) — then we are way beyond serious trouble. The consequences of that kind of global warming would be apocalyptic. That’s not exaggeration or “alarmism,” it’s just the truth.

    How much has Earth actually warmed since 1980, when the paper was written (although it was published in 1981)? Here’s the annual average global temperature each year from 1970 through 2016 (data from NASA, and the 2016 value is incomplete because the year isn’t over yet):

    globtemp1

    The values for 1980 and 2010 are circled in red. The difference — an estimate of the warming since then — is 0.44°C (0.79°F), very close to (in fact a little higher than) their estimate of 0.4°C.

    An even better estimate is one which removes the influence of random year-to-year fluctuations. We can do so by fitting a straight line to the data, to estimate the underlying trend, which gives this:

    globtemp2

    The values for 1980 and 2010 are circled in red. Their difference is 0.55°C (0.99°F), more than 35% higher than the projected increase from Hansen et al. in 1981.

    They also predicted that the Arctic would warm faster than the planet as a whole. NASA also reports the temperature for various regions of the Earth, and here’s a comparison of the warming since 1970 for the globe as a whole in blue, to that for the Arctic (in this case, the Earth north of latitude 64°N) in red:

    arctic_temp

    The Arctic has indeed warmed faster than the global average, by a lot. Since 1970, it has warmed nearly three times as fast.

    What about their projected decline of Arctic sea ice? Here’s the annual average extent of Arctic sea ice since we started observing with satellites in the late 1970s (data from the National Snow and Ice Data Center, with a trend line in red):

    arcice

    Finally, what about the Northwest passage? There is no single specific “Northwest passage,” it’s a generic term for crossing between the Atlantic and the Pacific oceans by sailing over the northern part of North America. It has been attempted many times, and was finally accomplished when Roald Amundsen reached Alaska via that route in 1906. But by no means was it smooth sailing; departing in 1903 it took him three years, including winters being frozen into the ice.

    What is really meant, in practical terms, is just that smooth sailing which would enable passenger and cargo ships to make the journey — without having to take three years to do it. Because of global warming, it has already happened. On this very day, a cruise ship called “Crystal Serenity” is departing Alaska with over 1,000 passengers, bound for New York with a scheduled passage by Greenland. It has real risks, and I wish them a safe journey, but there’s also no getting around the fact that the prediction that we might see the Northwest passage actually practical during summer is no longer a dream or a slogan, it’s a reality.

    The upshot of all this is that, 35 years after the fact, the expectations expressed in Hansen et al.‘s 1981 paper have come to pass. They’re all things that, frankly, could not have happened without real, significant climate change. Actually predicting them, without a good reason to expect unnatural climate change, would have been lunacy. But predicted they were, and more important they have come to pass. And those who tell you that all computer simulations of climate are utterly useless are either more than three decades out of date, or are spinning a web of lies.

    Global warming and its dangers isn’t a “hoax invented by the Chinese.” It’s a threat. We’ve been warned, for decades now, and it’s time for us to act.


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    79 responses to “Crystal Serenity

    1. Well, as for sailing the NWP, it is worth to mention two brave Norwegians and another brave crew of Russians sailing both Northern sea route (north of Siberia) and NWP (north of America) in within one season – in very small yachts in year 2010. The climate is changing and we can almost feel it on our backs.

    2. Record-breaking rainfall is being reported all across the world.

      Our unusually warm oceans

      are rapidly evaporating

      which results in massive volumes of water vapor being carried to nearby low pressure systems where it’s dropped as record rainfall

      and deadly raging flood waters.

      Thousands of independent sources of climate data from around the world strongly suggest the devastation will continue to rapidly escalate –

      at an ever-increasing catastrophic pace.

    3. In the middle of a discussion over at And Then There’s Physics, I was reminded of a similar calculation, not strictly peer reviewed like Hansen, et al, but a blue ribbon (National Academy of Sciences) one nonetheless. This was the commission in summer of 1979 whose report has become known after its lead, the Charney Commission Report after its lead, Jule Charney. Their ECS2x estimate was 3°C ± 1.5°, right on top of Hansen, et al.

      So, the thing is, as was mentioned by mt at And Then There’s Physics, we’ve basically known what has been needed since 1979-1981, independent of Exxon or anyone, and perhaps even a bit earlier with Wally Broecker’s 1975 article. And the response has been essentially nothing, even if the object lesson is, as Brandon Gates said, Shut up and mitigate already.

      So, I’m kind of sympathetic to the viewpoint which (the late) Hermann Scheer made several times in his talks and books, and which Kevin Anderson presently repeats, that the UNFCCC seems to be a stage to make pious pronouncements, and, then, when everyone goes home, after flying across the skies for working groups, sub-meetings, and editing meetings, continuing to do pretty much business-as-usual.

      • Anderson, the same guy who thinks a majority of climate scientists seriously understate risks and bamboozle the public without providing any evidence to support his point? I’ll take science from Michael Mann

        • Kevin Anderson is an engineer specializing in policy. He’s not addressing the climate science or forecasting at all. Indeed, he agrees wholeheartedly with the consensus.

          But what he is saying is that the emperor has no clothes in that the UNFCCC projections and plans are vastly inconsistent with getting to a +2°C world and that, moreover,, in order for the OECD countries to comply with their stated goals they would have had to peak their CO2 emissions yesterday (2015). What he is saying is that, by remaining silent regarding the inconsistency between these plans and emissions reality, scientists are complicit. Moreover, given that reducing the generations side is less effective than reducing the demand side, the best and quickest thing that can be done is launching a large campaign for energy efficiency and energy usage reduction, which, because of Sankey efficiencies, has a huge effect upon the amount of fossil fuels that are needed to be burned and harvested upstream.

          And, consistent with that, Anderson argues this implies lifestyle changes which those who are most knowledgeable about the effects of climate disruption should pursue, in order to set a proper example. He’s endeavoring to pursue that in his personal choices. He laments that the physical sciences community flits about from international meeting to international meeting without considering the impacts of their behavior as leaders. And, while the American Geophysical Union and, I believe, the American Meteorological Society both have instituted a means of attending conferences by using Internet video and chat participation, which is good, this is far too rare in practice.

        • spotsylvania

          And he is to be applauded for that. We need more people like him, but so of the things he says are a bit questionable.

        • Anderson simply uses other’s people’s climate science (mostly IPCC) to point out that given stated objectives and carbon budgets there is a massive disconnect between rhetoric/agreements and actual policy. All current govt targets assume massive BECCS or other sequestration, which is not necessarily at all feasible, and at the very least should be made very clear to people as an assumption (which doesn’t happen).

          So far as I can see he’s absolutely spot on that there is a lot of mealy-mouthedness about how serious the situation is, a total lack of urgency at govt/policy level, way too much hypocrisy amongst academics and politicians, and a need for _major_ demand reductions for at least the next decade amongst the rich.

          I’d make the man president/prime minister forthwith and that should greatly improve civilisation’s chances of survival in its current form.

          If you’ve not heard him, then this is a well-spent 45 mins: http://earth101.is/kevin-anderson/

        • Ah no, he’s not spot on all the time. He lied about the CAT 2.7C study being based on negative emissions (it’s not). He also thinks developing countries should be given a free pass on reducing emissions whike promoting draconian and unrealistic cuts on developed countries, which don’t have nearly as much population as developing ones.
          He also falsely claimed that most scientists self-censor themselves and seriously downplay the risks to the public without offering proof. I’ve talked to about 20 climate scientists, and they don’t agree with this statement at all.
          As far as your making him chief executive, I suggest you try becoming President of the United States and see how easy it is to get things done. Hint: Obama’s doing everything he can through executive action. It’s not his fault idiots in Congress hold up legislative action. I would also suggest looking at Clinton’s policies:
          https://www.google.com/amp/www.vox.com/platform/amp/2016/5/9/11548354/hillary-clintons-climate-and-energy-policies-explained?
          Glen Peters, a climate scientist specializing in tracking emissions and who works with Anderson, has called her policies “detailed and good”. Like it or not, Anderson’s talking about making unrealistic changes overnight. Incrementalism is needed to make changes happen first with a policy in place, ans then the big changes will start to happen, a policy Gavin Schmidt has promoted.
          I would point you to Glen Peters’ talk here: http://m.youtube.com/watch?v=529Og_YR0IU
          It’s a good summary of where we are and our prospects without sitting through 45 minutes of Anderson’s arrogance and condescension.

    4. There aren’t many forecast-centered science papers that would hold up so well in so many areas 35 years later. Note that the authors also included discussions of anthropogenic aerosols, volcanic eruptions, industrial gases, drought in western North America and central Asia, heavy rainfall near coastal regions, and potential rapid loss of ice from the West Antarctic Ice Sheet, all of which hold up well too.

      It’s stunning to think that cretinous bloggers and politicians from Washington to Canberra to London are still arguing about whether the planet is even warming.

    5. We’re way above 2C –

      The data shows we’re more than 5C –

      I’ve calculated it three times.

      Stop believing what they say and what they write –

      monitor the temperatures and calculate the anomalies –

      so you can see it with your own eyes.

      It’s not difficult.

      Record-breaking rainfall across the world corroborates the temperatures reported by local sources.

      The devastation is going to get much worse.

      The trajectory of the climate data strongly suggests worldwide devastation will soon be upon us –

      I already packed and left.

    6. Reblogged this on Don't look now and commented:
      Hansen’s predictions were right in 1981. Will his prediction for 300 mph storms happen? https://www.youtube.com/watch?v=L_FTR8E91RU

    7. Furthermore, I consider that a worldwide cap on emissions has to be put in place, decreasing with time in a sensible manner, and that to put local or regional caps into place can be a viable route to this aim, and that word has to be spread about it as much as possible, questions about it have to be asked as much as possible to the persons in power and the press.

    8. Good post..
      Hansen has obviously been right before, but I hope that the worst scenarios in Hansens latest masterpiece (2016) will not come true, i e “All Hell will break loose”.

      Another point, Gistemp loti may underestimate the changes due to the use of SST and the thermal inertia of the oceans. Hansen 1981 used the Gistemp dTs index (which on the other hand may overestimate the change)
      The recent dTs data looks like this:

      Table data behind this chart show an increase of 0.58 C between the annual values of 1980 and 2010, or 0.55 C with a 5 year LOWESS smooth.
      The true change in global temperature is likely somewhere between that of Gistemp loti and dTs..

      • Sorry, the link to the chart ceased to work after I finished my session with Giss new plotter page. The dTs chart was essentially the same as this standard one: http://data.giss.nasa.gov/gistemp/graphs/graph_data/Global_Mean_Estimates_based_on_Land_Data_only/graph.png

      • Yes. It took me months to read Hansen2016, because every time I progressed a few pages, I was hit by a desperation which was close to unbearable. And I still kept going, hoping that I would find a clear flaw in the reasoning.

        But I didn’t. Either they are in areas, I’m not sufficiently specialized in, or all hope of a softer climate response is in the parts where Hansen et al. report that further research is needed.

        And that, as much as I try to keep emotional responses out when I consider scientific claims, that prospect is terrifying.

        • Your experience is hardly unique. I’ve felt it, too, and repeatedly. I could not get through deGrasse Tyson’s _Cosmos_ episode “Lost Worlds of Planet Earth” without breaking down into tears, or watch episodes of “Years of Living Dangerously” without the same. I’ve compared notes on this with people who are far more professional climate scientists than I am, and _they_ have the same experiences, and it limits how much they want to confront these issues in public. For the public, it seems, the matter needs to be _soft_ _peddled_ and that’s _just_ _too_ _hard_ at times. Some of them, unfortunately, just want to disengage from the public, because it is too hard to do this, knowing what they do, and the *pathetic* *response* of governments (especially our own) and of people. (Obama made a pitch on climate last Saturday and today his administration approved additional leases for drilling oil wells in the Gulf of Mexico. _Really?_) I look to the bright side of things, and have focused upon the solar revolution, and its plummeting energy costs as a sign of hope. It does not involve government or people. It involves technology and greed. It may not be fast enough. But, in my book, it’s the most successful thing we have, combined with energy storage.

          It’s upbeat.

          And the other thing that helps, in my experience is _hanging_ _out_ with people who feel the same way as you do and acting on it.

        • And for those of you who do not yet feel as arnebab and I do, I suggest you watch this: https://www.youtube.com/watch?v=uWPj6CxtsGo

        • spotsylvania

          Hyper,
          You’re going off anecdotal evidence again when it comes to climate scientists and their associating with the public along with their emotions. I can easily counter your claim of these scientists feeling despair and not engaging with the public. I’ve talked with at least twenty of them, such as Michael Mann, Glen Peters, Paul Overduin, Ben Bond-Lamberty, and many others. They’ve expressed some hopen and optimism and have no problem engaging with the public, so your evidence is not representative by any stretch.

        • I wasn’t speaking for them. I was speaking for me. Ask them, next time you see them, if they’ll be optimistic if it is inevitable that we get to +3°C warming.

        • Who says we will? A lot needs to be done with emissions, but it looks like Paris will be ratified this year, and the range for that is 2.6-3.1C. And that’s also leaving out the looming idea of SRM. It’s getting more attention as time goes by, and it will probably be implemented at some point. Again, necessity is my main point. It frustrates me when people don’t mention SRM when it comes to keeping temperature down. Climate change is a big problem and we need to consider every option

        • Pierrehumbert isn’t an expert on SRM! Ken Caldeira is: “An interesting question is the extent to which the scoping team will want to include solar geo-engineering, which is probably the most feasible method of stabilizing at 1.5 degrees Celsius, at least in the short term,” climate scientist Ken Caldeira said by email; Caldeira’s own work has examined the scenarios in which artificially boosting the planet’s reflectiveness in an attempt to cool it down might make sense. Meeting the 1.5-degree target without these controversial methods, Caldeira wrote, is “physically possible but highly unlikely when viewed through a sociopolitical lens.”

        • What is your definition for being “an expert on SRM”? It’s never been done. Just because one person is investigating it, and another rejects it out of hand does not make either of them any more or less an “expert”.

          You can pick and choose experts all you like …. There’s a principle in Jewish law that you can pick whatever sage you like, but if he advises, you are bound to take the advice and not hop to the next sage, shopping for a better answer.

          The point is that SRM does not keep warming to 1.5°C. At best, assuming it works, and sweeping the possible complications under the rug, it postpones the consequences. At some point, those consequences need to be embraced, even if it is 500 years down the road when Carbon emissions have zeroed. And you get the consequences altogether, essentially overnight (within a couple of years) as soon as SRM stops. And we don’t know if it can be gradually dialed back, or of the side effects, or of the consequences of inhomogeneities in distribution. We do know the natural consequences of dialing back CO2 emissions.

          There are no human consequences of going to zero CO2 emissions for the developing world. The only social groups who would “suffer” from the actions and costs of rapidly decreasing CO2 emissions are the energy pigs and Carbon worshippers who are responsible, in direct use and by consumption of products, for most of these emissions, and those are the OECD countries, including us.

        • So you would completely eliminate the possible use of a tool that could alleviate catastrophic warming? That seems pig-headed to me. And Caldeira’s studied it for many years and produced many publications on it. It’s not some science you can just be a willy-nilly expert in. Besides, we know it works. Look at the case of Mount Pinatubo.

        • I am afraid I really don’t understand the advocates of SRM. They seem to want to base our mitigations of climate on forcings we understand least (e.g. aerosols) instead of those we understand best (e.g. greenhouse forcing).

        • SRM appears to be solar radiation management. I suppose it is better to break out the geoengineering out into sub-categories, but that’s a poor name for it. I’m much more interested in using geoengineering to lower the carbon dioxide levels in the atmosphere.

        • michael sweet

          Spotsylvania,

          Volcanic eruptions are associated with drought in many parts of the globe. While the temperature is reduced from the reduction of incoming sunlight, the evaporation of water from the ocean is also reduced. How much drought are you willing to put up with instead of more global warming? Increased acid rain and ocean acidification are also an issue with sulfate aerosols. How strong will these effects be? Are you willing to trust a model? How will the people stuck with the drought be compensated? Will they agree to go along to help your scheme, or will it be forced upon them against their will? If the people stuck with the drought cause the geoengineering to be stopped there would be a sudden heating. Is that really better?

          There are many unknowns with this type of intervention and a history of failure

        • Michael,
          What history of failure? Something like this has nevery been tried before.
          As far as precipiration goes, the decrease globally would be minimal: http://www.nature.com/nclimate/journal/v2/n2/fig_tab/nclimate1328_F1.html

          Acid rain is not really a problem in teS of SRM. Also, if a country like China, the US, or Russia wants to do SRM, they’re going to do so and no one will stop them.
          And the effects might be more uniform than you might think: http://www.slate.com/articles/technology/future_tense/2016/01/an_interactive_simulation_of_geoengineering_using_data_from_geomip.html
          I think the more important question is: do you want to risk 4C when SRM could possibly prevent that?

        • There is a lot of stuff available on Caldeira and Keith’s SRM. Really, it’s Keith and others, with Caldeira weighing in once in a while. For those interested …

          http://belfercenter.ksg.harvard.edu/files/160700_horton-keith-honegger_vp2.pdf

          Interestingly, in the above the authors agree with Anderson that COP21 targets cannot be met without some kind of negative emissions or SRM.

          http://keith.seas.harvard.edu/researchareas/solar-geoengineering?page=1

          http://keith.seas.harvard.edu/files/tkg/files/172.macmartin.caldeira.keith_.solargeoengineeringtolimittherateoftemperaturechange.pdf
          The above survey is pretty good and puts forth Keith’s primary proposal: Using SRM in a closed-loop based upon global temperature measurements. Unfortunately, they don’t even mention the problem of unexpected consequences, or how we might collectively do quick attribution of these. After all, and for instance, in a medical trial, the team is highly sensitive to the possibility of adverse effects and is poised to discontinue when there is evidence of excess morbidity or mortality. In my book, any SRM deployment, however limited, should be held to the same standard.

          http://keith.seas.harvard.edu/files/tkg/files/176.horton.keith_.liabilityforsolargeoengineering.pdf

          Oy! Legal liability concerns. Maybe Horton and Keith meant to make it “not so bad”, but it looks like a hornets nest to me. We can’t even get countries to comply fully with INDCs! Also, as I’m sure has been mentioned elsewhere, SRM, if understood, could be used as a weapon.

          This discussion http://dge.stanford.edu/labs/caldeiralab/Caldeira_research/MacMynowski_Test.html is not optimistic about the profile of even an SRM experiment.

          http://harvardpolitics.com/world/engineering-climate/
          This is an overview of the conference in Germany.

          Caldeira outlines prospects here:
          http://issues.org/27-1/caldeira/

          As a dynamicist, I worry a lot about nonlinearities in the climate state-space. It seems incredibly unwise to me to couple another another strong forcing into the climate system without really deep knowledge of what it will do. We don’t even know what the rate of forcing we’re applying now will do, let alone another.

        • A lot of this stuff is several years old, which makes the assumptions a bit outdated. Also, none of this precludes anything I’ve said. I’ve told you this before, necessity trumps everything.

    9. You should check Broecker, 1975
      Climatic Change: Are We on the Brink of a Pronounced Global Warming?
      in Science… Is scary in it’s accuracy.

    10. In the paper Hanson talked of amplified temperatures at “high latitudes” not just in arctic. No polar temperature amplification in antarctic. Uncheck that one.

      • Nice, isn’t it, that we don’t have to worry about amplified warming in the only continent without permanent human habitation?

        • Actually, we’d better check that box again–in West Antarctica at least, there is very considerable warming going on:

          “In West Antarctica, however, the significance of the trend is above 97.4%, and its magnitude is between 0.08 and 0.96 degrees C per decade. We argue that the persistent temperature fluctuations not only have a larger impact on regional warming uncertainties than previously thought but also may provide a potential mechanism for understanding the transient weakening (“hiatus”) of the regional and global temperature trends.”

          http://cel.webofknowledge.com/full_record.do?product=CEL&search_mode=CitingArticles&qid=1&SID=2DAz7CMnQdrdIOYM7jS&pReturnLink=&pSrcDesc=&page=1&UT=WOS:000333815700002&doc=1

        • Sorry, here’s a permanent link:

          http://dx.doi.org/10.1007/s00382-015-2582-5

          The main point of the paper is that the AR1 model is inappropriate because the data show longer-term persistence.

        • Michael Sweet

          Spotsylvania,

          Rignot is also on record as saying that there is a small chance that Hansen’s high estimate of 5+ meters of sea level rise by 2100 is possible. I could provide a link but the fact that Rignot coauthored Hansen’s paper speaks for itself. There is a difference between what Rignot thinks is most likely and what he thinks is the worst case sea level rise. Unfortunately, in several areas of climate science what has come to pass is worse than scientists expected.

          We know that the glaciers in West Antarctica have retreated enough so that “unstoppable” (according to Rignot) decay has started. We do not know how fast that decay will proceed. If it proceeds at the highest rate currently thought possible Hansen will be correct. It is more likely that the collapse will not be the highest rate possible. Obviously the rate will depend on how much carbon is emitted.

          Five years ago many scientists said there was no known mechanism for the rapid sea level rise that Hansen has suggested is the maximum possible. With the discovery of the instability of West Antarctica a method of melt has been found. Hopefully these glaciers do not collapse rapidly, but I have not seen data to support either a fast or slow rate of collapse (If you have a cite I would like to read it).

        • Michael,
          I don’t disagree with that. I tend to think such scenarios are unlikely, but they definitely should be planned for.

      • Hansen 2016 isn’t reassuring for the case of Antarctica not warming. The Climate Dynamics paper indicates that west Antarctica is likely warming but let us consider the possibility that Antarctica isn’t. The ozone hole deepened after Hansen’s 1980 prediction. This factor could account for some of the cooling. Winds and currents tightened up around Antarctica. If this happened as a function of the ozone hole or a pretty much cyclical process it may be reversible but:
        Melting of Antarctic ice from below by intermediate water at a depth of 100 meters has been observed and it’s causing a buoyant fresh water layer at the surface. The fresh water layer has slowed deep water formation in key locations such as the Weddell sea. The southern half of the global thermohaline circulation has weakened. Less heat is lost to space in the cold Antarctic winter because the Weddell sea polynya won’t stay open after it is briefly formed by intense winter storms.
        This situation allows more heat to build up in the global oceans.

        • Fish, what kind of idiot said Antarctica wasn’t warming? Everyone knows that, and Hansen’s sea level rise predictions have taken a lot of flak, including from a Eric Rignot himself.

        • michael sweet

          Spotsylvania,

          Riignot was a co-author on Hansen’s last sea level rise paper. Presumably that means that he thinks there is a possibility that high rates of sea level rise are possible.

        • Michael,
          Rignot is on record as saying the sea level rise of six feet by Deconto and Pollard is very reasonable. I’m more than happy to provide the link.

    11. Reblogged this on Global Initiative for a Sustainable Economy and commented:
      In this case, it would have been better if the predictions had been wrong.

      • Yeah, and that’s the odd thing about those who argue (without basis in reality) that CO2 increases are “from natural sources”. Well, if they were from natural sources, they could not be controlled, and we’d still have the effects. From my understanding, the primary problems of a +3°C or higher world is that there are natural reservoirs of Carbon which would begin to be tapped in a warmer world, and, so, controllability of the problem would diminish, compared to having strong reduction of fossil fuels burning as a principal option. That is, of course, setting aside clear air capture of CO2 as an option.

    12. Climate sensitivity has recently been upgraded to 5.1 – 5.6. I suspect that its still far too low.

    13. Excellent article, Tamino. Thank you.

      There was also this article from 1974, which was probably before there were any half decent global surface temperature data sets, but has a lot of information that would still hold up today, 42 years later:

      Kellogg, William W., and Stephen H. Schneider. “Climate stabilization: For better or for worse?” Science 186, no. 4170 (1974): 1163-1172. DOI: 10.1126/science.186.4170.1163

      http://science.sciencemag.org/content/186/4170/1163

    14. That the new CO2 is artificial was first demonstrated by Hans Suess in 1955, and confirmed by Revelle and Suess in 1957. It has to do with the radioisotope signature of the new carbon.

      14C has a half-life of 5570 years (5730, they thought in Suess’s time). And plants preferentially absorb 12C over 13C. The new CO2 is deficient in both 14C–completely lacks it, in fact–and in 13C. This means the source of the new carbon is A) very old, and B) from plant matter.

      What is made of very, very old plant matter that is just now being introduced to the atmosphere? The numerical answer is left as an exercise for the student.

    15. I still find it interesting that no one mentions anthropomorphic waste heat as a mechanism that is driving the warming. From my research it seems to be the largest driver of global warming and carbon dioxide is just exacerbating the problem.

      [Response: The reason we don’t mention it, is that it’s not.]

    16. Techknowledgest

      Human civilisation generates 1.5*10^16 Watts/year.

      The energy imbalance due to anthropogenic CO2 increase is increasing heat content by 3*10^22 Watts/year.

      The two are not remotely comparable.

    17. gotta put a lot of carbon back in the ground or face the consequences

    18. “The upshot of all this is that, 35 years after the fact, the expectations expressed in Hansen et al.‘s 1981 paper have come to pass. They’re all things that, frankly, could not have happened without real, significant climate change. Actually predicting them, without a good reason to expect unnatural climate change, would have been lunacy. But predicted they were, and more important they have come to pass. And those who tell you that all computer simulations of climate are utterly useless are either more than three decades out of date, or are spinning a web of lies.”

      Very good point, Tamino. This is a point I myself have used to rebut denier nonsense that this is all natural. What are the chances that all of these events would be happening due to some unknown, natural warming, given the fact that the events we are observing are 100% in line with projected anthropogenic global warming. Obviously, that probability would be very, very close to zero.

    19. One of the reasons the papers have stood up is, at the global scale, the physics, while not simple, isn’t that complicated. And, unfortunately, we have stayed on the same increase path for fossil fuels since that time.

      It’s about time to bend the curve.

    20. Sorry folks. I must drink my coffee before posting in the morning.

      Those figures should have been Joules/year.

      • I think that “before” is important. I would not recommend drinking coffee while reading the unintentional comedy posted by techknowledgest. Perhaps he should change his moniker to techknowled-jester.

    21. Keith McClary

      @techknowledgest
      Heat is not cumulative like CO2. If we were just making heat (and no CO2) we could turn it off and the warmth would be gone after a few months. It’s like turning off a heater in a greenhouse.

    22. I remember as a young pup seeing a pamphlet that described an oil tanker, the SS Manhattan, making the trip through the Northwest Passage. Sure enough, there’s a Wikipedia entry that said the ship was escorted by icebreakers in 1969, sailing from the east coast to Prudhoe Bay where it took on a barrel of oil and returned. A subsequent attempt in winter was not successful.

    23. SRM – Not reasonable considering the Earth system as a whole. Every proposed technology has side effects, that can make the cure as bad as the problem. The advocates of SRM are not folks that consider how the side effects propagate through the system. SRM should be considered in context of agricultural, food production, and ecological systems. SRM advocates tend to have a profound ignorance of marine biology and systems science. And, marine biology strongly affects our atmospheric CH4, CO2, and H2S concentrations — which affect agricultural (e.g., fiber), food production (e.g., wild fish), and ecological systems.

      Any paper advocating SRM should contain a full description of the microbiology of the affected volumes of ocean. : ) Marine Biological Laboratory. “Ocean microbe census discovers diverse world of rare bacteria.” ScienceDaily. ScienceDaily, 2 September 2006. .

      To advocate dropping (SO4) into a system that one does not understand is the height of hubris.

      • Have you read any of Caldeira and Keith’s work on the subject? I gather not.

      • Thanks. (Aaron Lewis, your comments are often insightful and to the point.)

        SRM, a panic station for people who don’t see how or don’t want to make the wholesale changes that need to be made, has scads of dangerous consequences. Naomi Oreskes mentioned them in her Collapse of Western Civilization, and it comes up in various forms of science fiction (The Sheep Look Up might give you a cauld grue about the range of pollutions we are willing to countenance in the name of possessions). Once you start compounding manipulations that have to be permanently maintained, you are in trouble, because all systems break down.

        Of course it’s hard to envision the dangers with which we flirt by our heedless consumption, the envy of less prosperous earthly neighbors who would adore to have clean hot and cold running water, heat, A/C, light, and easy transport, let alone jobs, but magic thinking is not the answer.

        • Susan,
          Who says it’s magic thinking? People in favor of SRM research are not advocating it as a replacement for reducing emissions, but as a complement. And the work of various scientists has shown it to be very technologically possible.

    24. These shorts are staggeringly well done, wish they were as ubiquitous as automobile adverts:

      This is a wealthy organization with priorities that are a little constrained. I’d like to see more wholesale ambition given the quality of its production.