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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 1 to 50:

Timothy Chase at 15:07 PM on 23 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Congratulations! I believe this is well-deserved.

Given the role of free market ideologies in all this, I believe it is worthwhile to keep in mind the following points:

The fossil fuel industry receives massive subsidies.
Power utilities are typically government regulated monopolies, and both solar and wind that generates power sold back to the grid offers a more decentralized approach - an approach that is already supported by some libertarian and tea party groups.
Carbon taxes can be revenue neutral, and with an "across the board" approach in which carbon taxes are entirely offset by reductions in other taxes there is no reason why they can't be implimented on a local level while the regions that apply them remain competitve with those that have yet to do so. (British Columbia seems to be doing quite well at $27.88 per ton with corresponding reductions in income tax.)

Personally? I was a libertarian of sorts (Objectivist, actually, for about a decade and a half), and I am still quite sympathetic towards that sort of world view. I also recognize industrial climate disruption as the single greatest issue facing humanity of our time. Failing to address it will make people impoverished and desperate, and the freedom of the individual tends to be greatly discounted under such conditions.

Riduna at 10:30 AM on 23 April 2014

Climate dollars and sense – preventing global warming is the cheap option

Dana – Lucid as ever. That’s quite a fruit salad you’ve got there, apples, oranges and bananas.

And talking of bananas, I have never been able to understand Lomborgs’ persistent preoccupation with the strange notion that its not only OK to do nothing when it comes to mitigation but desirable. Rather like his misplaced advocacy for global warming and claim that increased CO2 emissions are beneficial for us - at least until 2070.

Clearly, both contentions are nonsense, unsupported by climate science and unsupportable by economics, or for that matter common sense.

KR at 04:12 AM on 23 April 2014

Climate dollars and sense – preventing global warming is the cheap option

I've had this very discussion on a few of the pseudoskeptic blogs (such as here), pointing out that mitigation is far less expensive than adaptation to climate change under a Business as Usual (BAU) economic strategy. And that if the pseudoskeptic is concerned about economic consequences, BAU is probably the worst choice possible.

The usual responses are sputtering (often accompanied by links to something by Lomborg, whose work has issues such as discussed above) or changing the subject. Sigh.

jsam at 23:43 PM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Better than a bloggie, I guess. :-)

Well done all.

CBDunkerson at 21:33 PM on 22 April 2014

2014 SkS Weekly Digest #16

The objection that distributed solar users get to use the electricity grid while paying less than other customers (or nothing if they generate more power than they use) is theoretically valid. The 'proposed solutions' to this 'problem' have all been utter nonsense.

As Michael noted, ALEC was pushing for monthly fees of between $50 and $100 in Arizona. At those rates we'd have to believe that a majority of every electric bill goes to grid maintenance rather than power generation. Even the $5 monthly fee Arizona settled on is almost certainly more than the utilities are spending on grid maintenance... $5 * ~100 million residential households in the U.S. = $500 million per month. That'd work out to $6 billion per year spent on grid maintenance, and that's not counting non-residential customers.... yet most of the U.S. grid equipment is more than a century old and huge sections go offline for weeks every time a major storm rolls through.

The reality is that actual grid maintenance costs are miniscule. The utilities should split out a flat charge (I'm guessing less than a dollar per month) to apply to every customer and reduce the cost per unit of electricity accordingly. Nice simple solution to the 'problem' requiring no legislative action at all. They aren't doing that because the 'problem' is purely a pre-text for attempts to place absurd extra charges on solar. If they succeed then they will simultaneously slow the growth of solar and steal profits from people who do install solar power on their homes.

That being said... there is now a real chance that in a few more years the cost of solar and/or electricity storage will have fallen enough that customers will be able to go off grid entirely and still save money. Either solutions like that or states which refuse the 'maintenance charge' nonsense will lead to solar becoming extraordinarily successful in some areas... which will eventually result in voters demanding the same nearly everywhere.

CBDunkerson at 21:13 PM on 22 April 2014

Breathing contributes to CO2 buildup

Of course, increasing human population requires occupation of land which would otherwise have been occupied by other life forms. The 'extra sequestration' in humans would thus also be offset by a decreased sequestration of carbon in non-human life forms. The net result would vary by the type of land taken over by the human population, but (as Tom noted) the values in play are so small that the entire exercise is meaningless.

michael sweet at 19:52 PM on 22 April 2014

2014 SkS Weekly Digest #16

Tom,

There will undoubtedly be long arguments about what is a fair rate for net metering. The article linked references the attempt by ALEC and the Koch's to make solar users pay up to $100 just to link to the net. Since this is more than many people pay for delivery of electricity that seems much too high. The Koch's are trying to make solar uneconomic by raising the net metering. As rkrolph says, in Claifornia the net metering is so low that I have heard (no cite) of many peoploe installing smaller systems so that they produce no excess electricity since the utility makes all the money on it.

The utilities have realized that solar is cheaper than buying their product and they are trying to keep out solar by increasing fees. Hopefully voters will wise up to this strategy.

rkrolph at 14:58 PM on 22 April 2014

2014 SkS Weekly Digest #16

I read the Times article and thought it was pretty misleading in saying that solar users are getting a big advantage and attractive prices for power they produce using net metering. I have solar panels on my roof in the LA area, and the cheapest rate I have to pay is 13 cents per kWh for Tier 1. But for any net excess my panels produce that goes out on the grid for other consumers to use, I am only credited at the wholesale rate of around 3 cents/kWh. I don't get how that is taking adavantage of the utility company.

Chris McGrath at 11:53 AM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Congratulations John and the SkS team.

Bob Loblaw at 10:24 AM on 22 April 2014

Breathing contributes to CO2 buildup

Tom:

No dispute about the significance of the increased carbon sequestration.

The storage approach to determining the source/sink question has a huge advantage over the flux approach, however. The flux approach can be argued to have relatively large error bars on individual components, which make it difficult to determine the net result when the individual fluxes are much larger than the change in storage. The storage approach is a direct measure of the net result.

As an objection, the "humans breathing" is an utter fail.

The same bogus argument is applied to the denial that the rise in atmospheric CO2 is the result of burning fossil fuels, when pseudoskeptics compare the fossil flux flux to natural fluxes. The "humans breathing out CO2" fails for the same mass balance reason you expressed in your Climate Change Cluedo post a couple of years ago.

Tom Curtis at 07:10 AM on 22 April 2014

Breathing contributes to CO2 buildup

Bob Loblaw @28, using the 3 billion increase in human population since the 1970s, and the global average adult mass of 62 Kg, we can calculate that human population growth represents a sequestration of not more than 0.034 Gigatonnes Carbon. That is, it represents less than 0.0007% of anthropogenic emissions over that period, and indeed, less than 0.6% of annual industrial emissions. The numbers are irrelevant except as trivia, but when you work them out it becomes absolutely plain that all these "objections" to AGW have never been worked out. They are mere thought bubble objections - and yet they are treated seriously by many so-called skeptics of AGW.

Bob Loblaw at 05:07 AM on 22 April 2014

Breathing contributes to CO2 buildup

Tom's statement that

"Therefore, the direct effect of the increase in human population is only to sequester an amount of carbon equal to the amount of carbon in the bodies of the additional population."

is key. I was going to point this out, but taking a quick glance over the existing comments I see that I already made such a comment two years ago, at #18.

Ignore the fluxes in and out - the change in storage is all you need to look at to know if humans population growth is a biological carbon source or sink.

climatehawk1 at 05:01 AM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Great stuff. I'm wondering whether there is some way to illustrate the fact that it's a coterie of fossil-fuel-funded propaganda outlets who are driving the "debate," rather than a stubbornly ignorant public. I guess the graphic that has appeared elsewhere comparing the 97% with the percentage of Republican members of the U.S. Congress who concur with AGW does some of the job, but perhaps something that looks formally at pronouncements or reports of Heartland, CEI, Cato and others?

CBDunkerson at 02:31 AM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Nice! Apparently they also have a '25 highlights of 2013' with this study at the top of the list. Some interesting reading in those other articles and the papers citing the consensus study.

Paul D at 01:27 AM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Congratulations.

Nice one!

Magma at 01:05 AM on 22 April 2014

Skeptical Science consensus paper voted ERL's best article of 2013

Ouch. Members of the Deniosphere aren't going to like this.

Why must the world gang up on them so?

ranyl at 18:46 PM on 21 April 2014

The consequences of climate change (in our lifetimes)

"For me human behaviour is the most frightening aspect of climate change."

Yes, but is it possible to change this?

VictorVenema at 08:53 AM on 21 April 2014

Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change

Tristan, yes. If you have a measurement of the minimum and maximum temperature, they are simply averaged to get the daily mean.

In the time before minimum-maximum thermometers were invented other averaging schemes have been developed where temperature measuremens were made at 2, 3 or 4 fixed hours and then averaged to get the daily temperature. For example, in Germany it was costum to measure at 7, 14 und 21 hours. And then compute the average temperature from Tm = (T7+T14+2*T21)/4.

Nowadays we have automatic weather stations that measure frequently and the average temperature is computed from 24 hourly measurements or even measurements every 10 minutes.

Changes from one method of computing the mean temperature to another can produce biases. How large such biases are can be computed from high frequency measuremens, for example from automatic weather stations.

Tom Curtis at 08:11 AM on 21 April 2014

2014 SkS Weekly Digest #16

michael sweet @1, the issue of feed in tarrifs is slightly vexed. With to high a feed in tariff, it pays the person installing solar panels to change their energy consumption habits so that they consume most electricity at night time. Indeed, when we were sold a solar panel at our house (in Qld, Australia), we were actively encouraged to do so by the salesman, in order to maximize our return from the solar panel. The effect, if we had followed his advise, would be to minimize the mitigation advantage of the solar panel. It also maximized the costs to the distribution network. On the other hand, any feed in tariff lower than the mean wholesale price of electricity to the power company represents an implicit subsidy of the power company (and indirectly of other consumers) by the person buying the solar panel. Indeed, any price less than the wholesale price of renewable power, where that is marketed at a premium, represents such a subsidy.

It follows that ideally the feed in tariff should fall between the wholesale and retail prices of electricity. That does represent a subsidy of the person with the solar panel installed - but that is a good thing. We want to subsidize renewable power to mitigate climate change. Treating all subsidies as bad is equivalent to saying that the market should determine all prices - and the unrestrained market has a good chance of turning the Earth into a place that cannot sustain advanced economies, or a global population in excess of 2 billion. Therefore pointing out that a pricing structure represents a subsidy is not, by itself, an argument to remove that pricing structure.

Having said that, if there is large scale take up of solar panels, distribution costs will represent an ever larger proportion of electricity company costs. The suggestion that bills should be broken into two components - a connection fee plus a rate on electricity consumed is reasonable, provided it is done to all customers, not just those installing solar power. If done, however, it should be legislated that profits from the connection fee not exceed those from the electricity tariff; and that companies not providing a discount on the connection fee to households using solar panels also not be permitted to count the solar power generated by that household towards renewable energy targets. Lacking the first, companies will have a perverse incentive to inflate the connection fee so as to deflate the impact of the tariff on their total earnings. Absent the later, or some equivalent measure, the effective subsidy for domestic solar power will deflate as it is taken up by more and more people.

Tom Curtis at 07:45 AM on 21 April 2014

Breathing contributes to CO2 buildup

hlpump @26, Vitousek et al (1986) calculated that with a population of 5 billion, and assumed global average caloric intake of 2500 kcal per person, per day, that humans directly consume 0.76 Pg of organic material (0.35 PgC) annually. The global populatin has since expanded to 7.2 billion, and and global average caloric intake is now estimated as 2940 kcal per person per day (2015 estimate). Scaling accordingly, humans now directly consume 1.29 Pg of organic material (0.59 PgC) per annum.

That represents just 0.5% of terrestial (not global) net primary activity, and 10.6% of emissions from fossil fuel use and cement manufacture. Of course, all of that Carbon is drawn from the atmosphere originally, as noted in the OP. You argue that the increase (< 0.025% of net terrestial productivity, and < 0.53% of antropogenic industrial emissions) represents a true increase in emissions. However, the CO2 emitted in human respiration is still drawn from the atmosphere first by photosynthesis. Therefore, the direct effect of the increase in human population is only to sequester an amount of carbon equal to the amount of carbon in the bodies of the additional population.

TD (inline to your comment) notes that the impact of increased human population is to increase substantially anthropogenic emissions both through industrial (fossil fuel and cement manufacture) and non-industrial (Land Use Change) emissions. That is correct. Indeed, the increased sequestration in human bodies is almost certainly exceeded by reduced sequestration in forests. However, all of those changes are already included in the accounting of anthropogenic emissions. They are not additional, unaccounted for changes. And they are not changes from human respiration.

michael sweet at 06:57 AM on 21 April 2014

2014 SkS Weekly Digest #16

Today (April 20) the Los Angeles Times ran an article about conservatives, including the Koch brothers, trying to get net metering chnaged to make rooftop solar less economical. The utilities have figured out that rooftop solar challenges their business model and are trying to charge people exorbitant amounts of money to be connected to the grid. These arguments will undoubtedly continue for a long time. Progressive countries, like Germany, will lead the implementation of disbursed generation.

hlpump at 02:45 AM on 21 April 2014

Breathing contributes to CO2 buildup

Your argument is not wrong. It does, however, fail to account for the population explosion from 1800 thru today (from approximately 1B persons to now over 7B persons). While the CO2 is in a different form when exhaled from the human body (roughly 5-6% of total exhaled volume), it requires time for each molecule of CO2 to be absorbed and returned to plants, oceans, etc. How much time is actually a variable based on numerous factors. That is one of the primary changes that has taken place over the last 200 years. Now with that said, should we all (including China and India) be responsible with how we manage our common resources? Of course! Let's just not take the approach that some have taken for the sake of publicity, wealth and fame (we all know who I'm talking about). Rather, let's work together to ensure our home can be enjoyed for all the years to come.

The other huge factor that I don't have time to go into depth about today are solar cycles. It's a very big deal and it should be included in all our equations when we responsibly discuss global climate conditions. Here's the bottom line - we need to learn as much as we can about the things that affect our environment. But none of us have a handle on the enormity of components that make up the final equation. Responsibly pursuing knowledge (not reacting to actors and politicians) is where we will find our long term solutions. Let's start there and see how we do.

Moderator Response:

[TD] The counterargument to the myth does indeed account for the increased population's CO2 exhalation, because the increased population's food grown also has increased to feed those people. But you are correct that increased population increases net greenhouse gas emissions, because of large fossil fuel use to produce, process, transport, and cook/prepare the food for consumption, and in some cases replacement of carbon-sequestering plants (e.g., old forests) with cropland.

Regarding the Sun: The Sun's "cycles" indeed are included in all our equations. As a start, read the counterargument to the myth "It's the Sun." After you read the Basic tabbed pane there, read the Intermediate and then the Advanced tabbed panes. If you want to comment on that topic, do so over there, please.

Alun at 16:09 PM on 20 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

Unusually, I chose to read Mr Lu's paper to see what it was all about. I must commend the Skeptical Science authors on their restraint in assessing the paper and commenting on it. I have never trusted papers that resort to emotive hyperboles in describing the state of knowledge and their findings. They always smack of ego exceeding intellectual capacity and rigour and almost always indicate serious amounts of confirmational bias. Snide negative commentary about others (yes Albatross his paper is much like his rebuttals) just reinforce my lack of trust.

Mr Lu clearly has a favourite topic which is CFCs and he seems to think they rule the world and much of what goes on in it. His purpose appears to be more one of proving just how important they are - and by inference how important he is because he knows more about them than others do. A clear case of FIGJAM.

I found his comments about CFC processes related to ozone reasonably well argued and supported. I haven't taken the time to check out all the references though, but this appears to be his area of speciality and possibly expertise.

The leap from these analyses to climate impacts is less than impressive. He makes the most basic, amateurish mistake of implying causality from statistical correlation. I am quite surprised that any journal with aspirations of professionalism could allow this type of reasoning to be presented as scientific - especially one that purports to be about physics.

Lu's proposition is entirely dependent on his bald statement that the warming effect from CO2 is saturated. The statement looked suspicious and the arguments and analyses presented to support the statement are so clearly and obviously flawed that all following inferences must be rejected. So I was pleased to hear that the proposition was debunked long ago.

Mr Lu may well know lots about CFCs, but he needs to improve his methods of analysis and inference.

WebHubTelescope at 15:33 PM on 20 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

I side with HughBat. The figure you show does suggest that the fluorocarbons contribute around 0.15C of warming, leveling off since 2000. How much extra warming would these have caused if their concentration had continued to rise since 2000?

There are grains of truth in all research. The tricky part is scaling back the exaggeration. This one required a scaling back to perhaps 1/5 of the claim?

HughBat at 06:45 AM on 20 April 2014

Global warming can't be blamed on CFCs – another one bites the dust
All that not withstanding, flurocarbons are potent, and quite long lasting, green house gasses, and "ABC" issues should not prevent us from working mightily to reduce their use. They tend to be 'invisible' in discussions, but with the escalating growth of air-conditioning ("it's a human right to have A/C" !!) - we will see increase in the release of these refrigerants - sure they are not major GHG's - but their contribution is significant, and growing. Attempts to get non-flurocarbon refrigerants into common use (primarily iso-propane and its relatives - which have miniscule GHG forcing ability (2??) - are making headway - against the strenuous lobbying efforts of duPont and other fluro manufacturers. But there are enormous amounts already in systems - often in abandoned facilities - which will eventually leak out unless recovered and destroyed. (and we must not forget automobiles and transport systems!) Because of lobbying, here in Australia (and I suspect elsewhere) the destruction process (plasma arc) has slowed - and with the poor administration of the carbon tax, the incentive to recover flurocarbon refrigerants is not very high - even though collection is mandated by the Fed Gov't. We forget - once refrigerant is put into a system, it eventually enters the atmosphere - unless active steps are made to recover and destroy them.. (and if we are not paid to do that... why bother.. psssssssst.. )So we mustn't let our reactions to Lu and his ilk, blind us to the fact that flurocarbons are a serious contributing factor.

Albatross at 05:50 AM on 20 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

Magma @3,
Agreed. It is unfortunate that the journal permitted Lu's vitriolic remarks to stand-- allowing such strong language in a journal is unusual.

I shudder to think what his papers read like. IMO, Lu's snarky and angry replies are consistent with the fake skeptics' tendency to try and obfuscate criticisms of their work with bluster and Gish gallops and to never, under any circumstances, admit fault or wrong doing. Lu had a potentially novel idea, it was wrong, and he now needs to accept that and move on (difficult as that may be).

Dumb Scientist at 09:17 AM on 19 April 2014

The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

We start with the HadCRUT4 surface temperature data. We fit it with a 6th order polynomial over the entire period of 1850-2011, instead of just over the period 1979-2011 as DS did. This produces the observed 0.17 C per decade of warming after 1979, the same as in DS. But in contrast, the warming here exists over the entire period, not just after 1979. The polynomial is smoothed by a cubic spline so that the trend is monotonic before 1979. This anthropogenic component will be called human. It is denoted by the red curve in Figure a. To create the AMO the-above-obtained human is subtracted from HadRUT4 data. The difference is smoothed with a 50-90 year wavelet band pass filter. This is the AMO (note: not the AMO Index). This is called nature (denoted by the purple curve in Figure b) and is the counterpart to DS's 70-year sinusoid. [KK Tung]

I'm sorry for the long delay; my day job has consumed my life. I like your new simulation, and tried to reproduce it in R, though I used a Fourier transform band pass filter instead of wavelets. Regardless, the human and natural influences look similar to those in Dr. Tung's plots (which are sadly no longer visible in his comment).

My first tests had 10,000 Monte Carlo simulations each:

0.132±0.012°C/decade, 19% contain the true trend.
0.156±0.012°C/decade, 100% contain the true trend.
0.137±0.012°C/decade, 70% contain the true trend.
0.159±0.012°C/decade, 100% contain the true trend.
0.168±0.012°C/decade, 100% contain the true trend.
0.125±0.013°C/decade, 2% contain the true trend.
0.140±0.012°C/decade, 86% contain the true trend.

They varied so much that I ran a few tests with 10,000,000 simulations each:

0.129±0.012°C/decade, 42% contain the true trend.
0.121±0.012°C/decade, 2% contain the true trend.

I also tried matching ARMA(p,q) noise parameters to those of the real residuals.

I still don't know why the mean trends vary so much when using 10,000 Monte Carlo simulations. I agree with Dr. Tung that millions of runs shouldn't be necessary, but for some reason "merely" 10,000 runs yield wildly varying results. More disturbingly, none of the trends in either of the 10,000,000 runs overlap with the mean trend in some of the 10,000 run cases. Maybe I'm not using the random number generator correctly?

Without seeing how Dr. Tung's code differs from mine, I don't know how he was able to specify the percentage of 10,000 simulations that contained the true trend to two significant digits ("91%") when my estimates vary from 2% to 100%, and most of those 20,070,000 white noise simulations don't include the true trend.

First, attribution is not necessarily a thermodynamics problem. The method adopted by IPCC AR4, the "optimal fingerprint detection and attribution method". "is based on a regression of the observation onto model simulated patterns and relies on the spatio-temporal response patterns from different forcings being clearly distinct... The global energy budget is not necessarily conserved and observed changes in the energy budget are not considered". This quote came from Huber and Knutti, 2012. [KK Tung]

That's a fair point; I should've qualified those statements as my opinion to avoid implying that everyone agrees. Personally, I read Huber and Knutti's statement as a criticism of the optimal fingerprint method because it doesn't consider or conserve the energy budget. This is an unusual situation where I've criticized fingerprints used by the IPCC and many researchers while agreeing with Dr. Pielke Sr. that ocean heat content is a better diagnostic than surface temperatures or stratospheric cooling fingerprints, etc. In my opinion, diagnostics more closely related to conservation of energy are more compelling. But you're right, this is just my opinion.

Towards the end of the paper, the authors compared the 50-year linear trends derived from unforced control runs in the CMIP3 models with the observed 50-year trends. These models do have internal ocean variability. ( DS, please note, this part is not based on a thermodynamic argument, but the result was what you referred to as from a thermodynamic argument.) [KK Tung]

Why isn't this part based on a thermodynamic argument? Since CMIP3 models have internal ocean variability, aren't they're simulating heat transfer between the deep ocean and surface (i.e. thermodynamics)?

The authors concluded "For global surface temperature it is extremely unlikely (<5% probability) that internal variability contributed more than 26+/-12% and 18+/-9% to the observed trends over the last 50 and 100 years, respectively". So the "upper bound" is 38% for the last 50 years and 27% for the past 100 years, respectively. [KK Tung]

Attribution over the last 50 years is based on Fig. 3(c) from Huber and Knutti 2012:

Given mean radiative forcings (etc.), the upper bound on the post-1950 surface trend due to internal variability is 26%. The lower bound is -26%, implying that internal variability actually offset surface warming. Regarding the "+/-12%" Huber and Knutti state "The probabilistic ranges presented here account for uncertainties in the observations, radiative forcing, internal variability and model inadequacy (see Methods)."

Since the upper bound in Huber and Knutti is itself given as a probabilistic range, I don't see why Dr. Tung's singular estimate of "40%" should be compared to the upper bound of the upper bound rather than the best estimate of the upper bound.

Given the uncertainty in the model's oceans, I do not think these upper bounds rule out our ~40% and ~0% contribution of internal variability to the 50-year and 100-year trends, respectively. [KK Tung]

Even if we compare your estimate to the upper bound on the upper bound of Huber and Knutti 2012, the probabilistic range on that upper bound at least attempts to account for "model inadequacy." And 38% here is the upper bound on the upper bound of all modes of natural variability summed together. Even if this upper bound on the upper bound is appropriate and needs to be expanded because it didn't fully account for model inadequacy... doesn't this leave very little room for the PDO (for instance) to affect surface temperatures (at the same phase)?

On Isaac Held's blog#16 that DS refers to as providing an upper bound of 25% for the contribution of internal variability to the surface warming for the past 50 years: We need to recognize that Held is using a very simple two-box ocean model to illustrate the process of energy balance that can be used to constrain the contribution from internal variability. The exact figure of 25% as the upper bound should not be taken too seriously, and it could easily be 40%, given the fact that there is at least a factor of two variation in climate sensitivity in the IPCC models and he picked one particular value of climate sensitivity from one of the GFDL models for illustrative purpose. There were many other simplifying assumptions so that an analytic result could be obtained. [KK Tung]

Yes, all thermodynamic estimates involve simplifications but in my opinion simplifications are preferable to not mentioning energy or heat altogether. And 40% here is the upper bound of all modes of natural variability summed together. Even if this upper bound needs to be expanded... doesn't this leave very little room for the PDO (for instance) to affect surface temperatures (at the same phase)?

Magma at 04:33 AM on 19 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

"The journal also allowed Lu to respond to that critique."

Allowing authors to reply to comments is standard practice, of course. What is unusual is the angry and personal nature of Lu's replies, at least judging from the abstracts. This is particularly the case in the reply to Müller and Grooß.

Albatross at 03:46 AM on 19 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

Fantastic job to all involved! Well done.

Lu has been pushing this pet hypothesis of his for a while now, so it is good to see it soundly refuted in the peer-reviewed scientific literature. Another fake skeptic myth busted, and another influential SkS journal paper too :)

Magma at 03:31 AM on 19 April 2014

Global warming can't be blamed on CFCs – another one bites the dust

I would have thought Lu's paper unpublishable, but I suppose it falls into category #2: flawed paper in off-topic journal.

A selection from one (of many) lists of impact factors for 2012 journals (physics)

Nature 38.6
Science 31.0
Physical Review B 34.3
Physical Review Letters 7.94
Applied Physics Letters 3.79
International Journal of Modern Physics B 0.32

Rob Honeycutt at 02:08 AM on 19 April 2014

The consequences of climate change (in our lifetimes)

Tom @10 is, as always, correct. We're talking about large mammals which could not survive at the tropics.

Sherwood and Huber 2010 is a good read on the human aspect of this topic. They state:

We conclude that a global-mean warming of roughly 7°C would create small zones where metabolic heat dissipation would for the first time become impossible, calling into question their suitability for human habitation. A warming of 11–12 °C would expand these zones to encompass most of today’s human population.

So, the broader point is that, the fact that "the earth has seen such conditions" in the past, doesn't preclude the catastrophic nature of such conditions on humans. Going back to PETM conditions would reduce the carrying capacity of the earth down to a small fraction of today's human population.

michael sweet at 21:50 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

To me the issue with it beng "too hot" is can agriculture continue. If it is too hot for cattle they cannot be raised. It is impossible to provide shelter to large scale agriculture animals. Can agriculture continue with goats? Will enough plants grow for the plants to live all year as food? Can food crops continue to be raised? If only weeds will grow few humans will be able to live there

Humans could devise shelters so that they can continue to live in areas that are too hot for them without shelter. Humans cannot live where they cannot raise food. It takes a lot of locally grown food to support a city. We see the interior of Australia does not support any cities because it is too hot to grow enough food. Even in the wet north they cannot support cities because the climate is hostile to cities.

bill at 18:40 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

Another great potholer video, and the caveat at the end is a classic! (Make sure you hang around for it.) I'll just add that I would have liked to see more attention to Ocean Acidification...

localis at 17:46 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

For me human behaviour is the most frightening aspect of climate change. Not only the denial that it is happening but the breakdown of civilized society when food and water become inadequate to sustain a population growing at a rate of 200,000 a day. At what point you call it a catastrophe much depends on how well fed you are.

BojanD at 16:47 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

Therefore the use of CAGW, implying as it does a belief in a certain, or almost certain catastrophe from AGW, is a strawman. I have only ever seen it used for rhetorical effect by AGW deniers.

Tom, @7, I agree totally, that's why I like (C)ostly, because I could just refuse to play their game by acting obtuse and use costly instead.

KR at 14:20 PM on 18 April 2014

Climate contrarian backlash - a difficult lesson for scientific journals to learn

WRT Marco's comments - interaction was essential to the development of conspiratorial ideation, the very thing being studied. This includes variations on "spammed responses", the two day "IP blocking" theory, the self-sealing extentions to UVA and some kind of world order, all the various reactions to additional information.

If you are studying the development of recursive conspiracy theories, you are studying them in the context of reactions to additional information, to corrections of previous conspiracy theories.

So yes, it's entirely consistent and in fact required to include interaction responses in this study. Complaints to the contrary seem to add up to (as somebody put it on one of the various blog discussions) a contrarian claim that "...Lew made me do it!".

From Peru at 14:19 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

Siberian gas venting and the end-Permian environmental crisis

Are you not comfortable with 10% chance of catastrophe?

Even 1 ppm (i.e. 0.0001% ) of chance of triggering the greatest massacre in human history (and possibly in all the planet history) would me be very very anxious if I were a policymaker.

To give one idea of what I am talking about, see this paper [insert link here] (moderator, please put my link inside the [])

It is about the most likely cause of the so-called Great Dying (officially Permian-Triassic extinction): a massive flood basalt eruption inside a oil and coal field in Siberia, the Tunguska Basin.

Basically the magma ignited the oil and coal releasing 100 000 Gt of CO2 (and some methane). Sounds familiar?

chriskoz at 14:18 PM on 18 April 2014

Heartland logic: More people have heard of Fidel Castro than Michael Mann, therefore global warming is false.

I'm realy amused by that report. To confirm my amusement, I just wated to make sure: is it the same type of annual conference by Heartland that we used to see in previous years? Those bygone conferences I recon have been held in exquisite venues, like Hilton hotels and attreacted hundreds of people together with mainstream medias and I've seen them reported on i.e. my ABC news the same day.

If so, the Heartland collapse is finally imminent (although long overdue).

chriskoz at 13:56 PM on 18 April 2014

Climate contrarian backlash - a difficult lesson for scientific journals to learn

Tom@11,12

Thanks for this important clarification. After that, I still maintain that Marco@4 intentionaly misleads readers like myself by avoiding to provide a clear context of his claim, therefore he tries to muddy the issue rather than to explain it. So I still maintain that he tells us demostrably false information in his comment@4.

By the same token, the climate science deniers, claim e.g. that "CO2 lifetime [of individual molecule] in the atmosphere in merely 5 years". Which is "right" at the molecular level according to the Henry's law and dynamic equilibrium with the ocean but which has nothing or very little to do with the actual issue at hand of the excess CO2 persistance in the atmosphere. With such worldview, you can produce "right" claims that deny the reality ad infinitum.

Another argument raised by Marco has not been addressed in this discussion yet:

While the conclusions and analysis may be sound, in my opinion it was improper for several of the authors to interact with their study objects. I don't buy the "psychopathological characterization", but I also don't buy the paper to be an objective analysis. Lewandowsky should have known better and asked a third party to do the analysis.

I find it at adds with Dana's assertion that "Frontiers [and UWA] had found no academic or ethical problems with the paper". Surely, they should have found claimed a bias of "interraction" or acquiantance, if there was one. Should the study been "double blindfolded" to be unbiased?

Tom Curtis at 13:49 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

Rob @9, I think the claim that the tropics were uninhabitable by complex organisms is overstated. What is true is that the tropics were seasonally uninhabitable by large mammals, where large means anything larger than a labrador. It would also have been extremely restrictive for some large cold blooded creatures, and for some small warm blooded creatures. Further, all warm blooded creatures would have been at a competitive disadvantage relative to cold blooded competitors, and relative to todays conditions. On top of that, small animals would have been at a competitive advantage relative to large animals, and relative to todays conditions.

That set of restrictions applies once you get sustained wet bulb temperatures of 35 C or more. In contrast, to truly limit complex organisms in general, you need sustained dry buld temperatures above 50-60 C.

Rob Honeycutt at 13:20 PM on 18 April 2014

The consequences of climate change (in our lifetimes)

Tom... What also often gets missed in the statement that the earth has seen similar conditions is the fact that those conditions were such that the tropics we uninhabitable by complex organisms.

Going back to those conditions would, indeed, be catastrophic... And very expensive along the way.

michael sweet at 11:13 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

Tom,

What an extraordinarily depressing graph! If positive feedbacks are bad (say a bunch of Arctic Methane) what will it look like? Hopefully renewable energy will continue to go down in price and replace fossil fuels more rapidly.

Tom Curtis at 11:07 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

BojanD @1, my preffered acronym is AGW, but I am happy to go with PCAGW, ie, Potentially Catastrophic Anthropogenic Global Warming. The point, however, is that catastrophic effects from global warming are not certain. Depending on what you consider to be catastrophic, they are even unlikely (0-33% chance) or very unlikely (0-10%). Therefore the use of CAGW, implying as it does a belief in a certain, or almost certain catastrophe from AGW, is a strawman. I have only ever seen it used for rhetorical effect by AGW deniers. Having said that, I, and I hope global policy makers, am not comfortable with even a 10% chance of a global catastrophe, and think we should do something about it.

Tom Curtis at 10:54 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

Harry Twinotter @3, Rob Honneycutt @5, for some impacts of climate change (eg, extinction rates), rate of change in temperature is the most important factor. For others (eg, melting sea ice), it is absolute temperature that is the most important factor. For the potential of a runaway greenhouse effect it is the later. Of course, neither you nor I think the later is at all likely, and on current best evidence is not even possible in the coming millenia.

Having said that, it is possible that the Earth will soon face absolute temperatures conditions never faced before while complex life has existed on Earth. Below is a modified graph showing the radiative forcing due to CO2 concentration and insolation over the history of the phanerozoic (last 550 million years). The original is from Royer (2006). I have drawn in lines representing the radiative forcing in 2011 (2.23 W/m^2), and the expected radiative forcing for RCP 8.5 for 2100 (8.3 W/m^2) and 2300 (12 W/m^2).

As you can see, even in 2100, radiative forcing is expected to exceed any in the past 550 million years due to changes in insolation and CO2 concentrations. Those are not the only factors effecting radiative forcing, and the resolution of the graph is low. It is likely, therefore, that for shorter intervals than shown radiative forcing has exceeded that expected fro 2100, and possible that it has exceeded that expected for 2300. It is, however, by no means certain that worst cast BAU scenarios have ever been matched in the Earth's past.

Rob Honeycutt at 08:51 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

Harry Twinotter... I don't want to give any credence to the boiling oceans idea, but I don't believe the earth has had similar conditions as today. This is specifically because the rate at which we're introducing CO2 into the atmosphere is greater than even the Siberian Traps could have achieved.

I would also add that, eventually the oceans on earth will boil away. It's just not likely to be because of human carbon emissions.

KR at 08:20 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

Harry Twinotter - If you listen just a few seconds past that point Peter points out that boiling oceans aren't going to happen. That statement by Hansen is often taken out of context; the context that Hansen notes that while physically _possible_, it's not going to happen on Earth as the result of our emissions.

Context context context...

citizenschallenge at 07:33 AM on 18 April 2014

Heartland logic: More people have heard of Fidel Castro than Michael Mann, therefore global warming is false.

Narahani,

Nicely written!

As another who could find himself described as a "grumpy-looking old white guy" I still liked your article. :- ) I thought it was well written and it painted a vivid image.

Also thanks to SkS REPOSTing policy I'm able to reproduce it at my blog.

Thanks for a job well done.

http://whatsupwiththatwatts.blogspot.com/2014/04/heartland-logic-financial-interests.html

Harry Twinotter at 06:05 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

I discount the possibility of the oceans evaporating based on the fact that it did not happen before when conditions on the earth were similiar.

johnthepainter at 02:59 AM on 18 April 2014

The consequences of climate change (in our lifetimes)

Hansen's 2012 statement, shows in the video, that we could get to a condition where the oceans would begin to boil was unfortunate and opened him to ridicule by the deniers. It shows the danger of simplifying complex matters for the public. In his most recent paper he was more careful in assessing the possibility of such an occurrence:

"In principle, an extreme moist greenhouse might cause an instability with water vapour preventing radiation to space of all absorbed solar energy, resulting in very high surface temperature and evaporation of the ocean [105]. However, the availability of non-radiative means for vertical transport of energy, including small-scale convection and large-scale atmospheric motions, must be accounted for, as is done in our atmospheric general circulation model. Our simulations indicate that no plausible human-made GHG forcing can cause an instability and runaway greenhouse effect as defined by Ingersoll [105], in agreement with the theoretical analyses of Goldblatt & Watson [128]." http://rsta.royalsocietypublishing.org/content/371/2001/20120294

Mike at 01:09 AM on 18 April 2014

Heartland logic: More people have heard of Fidel Castro than Michael Mann, therefore global warming is false.

As I grumpy-looking old white guy I protest your denigrating grumpy-looking old white guys! I know you are being tonge-in-cheek, but deniers will use anything they can agianst this site. Might be better to leave out the racial humor.

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