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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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Greenland is Experiencing a Sudden and Rapid Melt Season Onset by Pakalolo, The Daily Kos, July 9, 2015

william5331 at 06:28 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Fortunately China is working its toosh off converting to renewable energy. Her rate of construction of new fossil fuel plant is going down rapidly and she seems to always exceed any promises in this regard that she makes. Her motivations are not just climate change which will impact on her very hard. She doesn't want to be caught by the short and curlies, dependent on overseas energy. I wish the US of A would follow suit. Without sorting out PPCT, she never will.

http://mtkass.blogspot.co.nz/2015/01/ppct.html

Moderator Response:

[PS] link removed.

wili at 04:08 AM on 15 July 2015

Global warming is causing rain to melt the Greenland ice sheet

And part of the reason is that we just had the warmest June on record.

ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/jun_wld.html

Rob Honeycutt at 04:00 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

On a personal level, here is something I tell people that relates to stranded assets: Carefully consider your next vehicle purchase.

If you buy a big, gas guzzling SUV as your next new car, there is a strong likelihood that you will get next to zero resale value when you want to trade it in. Potentially that's true for many ICE vehicles as prices fall for EV's and their availability expands.

It'll be curious to watch what happens in the vehicle leasing market as the shift occurs. This could rapidly become a massive liability for those leasing companies.

Rob Honeycutt at 03:49 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Tom... Unfortunately, changes in social norms are unpredictable and erratic. That's the achilles heel to all the projections: How and when humans will actually respond suficiently to the challenge.

It's seems to me our response is going to be a little like the 100th monkey effect. At some point there will be a shift where people, en mass, will accept there is a problem and respond. Depending on when that actually occurs will dictate how rapidly the response is required.

I guess I just have a hard time imaging that in 2050 there are going to be very many people running around saying there's no problem. I think denial has its limits.

It also bears acknowledging, there a lot of positive things happening. Wind and solar are being built out at a rapid pace, and their costs continue to fall. The auto industry is showing great progress in shifting toward electric vehicles, with nearly every major company launching EV's in the coming years. This past year was the first year we saw carbon emissions decouple from economic growth, which was something many said was impossible.

It's definitely not enough and not fast enough, but these are the things that have to happen, and they are happening.

KR at 03:04 AM on 15 July 2015

2015 SkS Weekly Digest #27

Tom Curtis - Quite right, I must have been conflating AR4 and AR5, as you correctly point out that the IPCC didn't give an AR5 median/mode.

As it stands, the 1.5C lower sensitivity bound given in AR5 (as opposed to the 2C lower bound in AR4) is due almost entirely to the incorporation of short-term observational estimates such as the recent Lewis paper - and there are serious indications that such short-term estimates are biased low. I therefore consider (IMO) the AR4 bound of 2C on sensitivity (only a 5% chance of sensitivity being lower than that given current data) to be a more reasonable estimate.

Either way, the only 2% change in sensitivity to direct forcing over a +/1 5C range around current conditions is really negligible considering the uncertainties in feedbacks, and dispite Michael Fitzgeralds search for exactitude in that sensitivity delta it's just insignificant compared to the feedback uncertainties.

Tom Curtis at 02:47 AM on 15 July 2015

2015 SkS Weekly Digest #27

KR @42, the IPCC likelihoods for 1 C and 6 C show they still have a fat tailed probability density function for the climate sensitivity. It follows that their most likely (modal) value is less than 3 C, although it is possible (but not certain) that the most policy relevant value (the mean) is above 3 C. Unfortunately in AR5 they specified neither mode, median or mean of their implicity PDF.

PhilippeChantreau at 02:42 AM on 15 July 2015

2015 SkS Weekly Digest #27

Michael Fitzgerald at 38. This is the weekly digest, there is flexibility as to what's on topic, as was pointed to my attention recently.

My question is essentially why the egregious double standard? Why such heavy scrutiny and such high burden of proof on climate science, and why so little scrutiny and so little burden on other activities that have proved for sure how damaging they are. You ask a specific question indeed. My contention is that the question is misplaced, and that areas of activity with a proven track record of economic damage deserve at least as much questioning. You may not want to engage, and mods may decide it is OT, but it is a perfectly legitimate argument.

I think I agree with your take on precautionary principle. There is no reason why it should apply only to climate science and decisions made on its basis.

Tom Curtis at 02:41 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Rob Honeycutt @10:

"I feel fairly confident that humanity will be at or near zero carbon emissions by 2050"

I wish I shared that confidence. I think it is still at least an even chance that emissions in 2050 will be greater than current emissions. I don't expect the climate denial disinformation machine to pack it in anytime between now and 2050, and neither have we seen any major turnaround in the US, Australia or India that would lead to confidence of achieving zero emissions by 2050.

Tom Curtis at 02:36 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

ranyl @8, the IEA Outlook says:

"In its latest report, the Intergovernmental Panel on Climate Change (IPCC) estimated that to preserve a 50% chance of limiting global warming to 2 °C, the world can support a maximum carbon dioxide (CO2) emissions “budget” of 3 000 gigatonnes (Gt) (the mid-point in a range of 2 900 Gt to 3 200 Gt) (IPCC, 2014), of which an estimated 1 970 Gt had already been emitted before 2014. Accounting for CO2 emissions from industrial processes and land use, land-use change and forestry over the rest of the 21st century leaves the energy sector with a carbon budget of 980 Gt (the midpoint in a range of 880 Gt to 1 180 Gt) from the start of 2014 onwards."

For comparison, 3 000 gigatonnes of carbon dioxide is 817. 4 gigatonnes of Carbon, ie, about 20% less than the well known target of a trillion tonnes of carbon. More to the point, the energy sector target shown in the diagram above represents 980 GtCO2, or 267 GtC. These are figures based on the latest IPCC report, and hence are hardly "fictitious". Further, they are figures for a 2 C target.

More importantly, these figures represent emissions, not CO2 concentrations. The target scenario stabilizes at a CO2 concentration of 450 ppmv. That represents 360 GtC (1320 GtCO2) above preindustrial levels. In contrast, 592 billion metric tonnes of CO2 represents an atmospheric increase of 76 ppmv (ie 356 ppmv total concentration); and a total increase of 900 billion tonnes represents 116 ppmv, for a total target of 396 ppmv. That means if we accept the, presumably non fictional values from the quote from the article linked by JH we have already exceeded the target for 4 C; and that the climate sensitivity is 2.1 C per W/m^2, or 7.8 C per doubling of CO2.

I think such a prediction as the central estimate (50-50 chance) can safely be described as alarmist.

Rather than the scientists at the conference being so alarmist, it is more likely that David Biello is massively mistaken about what the scientists said. (Most likely he has mistaken emissions for CO2 content in the atmosphere).

Rob Honeycutt at 02:09 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

I'm with CBDunkerson here. Anyone investing in carbon emitting infrastructure is making a massively risky investment... Not even a risky investment, they're making an investment that is not going to return a profit.

Think about what's likely to happen over the course of the next 40 years. We are certain to see more and more extreme weather events. We're going to see more and more of exactly what scientists have been saying all along. It's going to become abundantly obvious, far beyond what it is already, that we have big trouble on our hands.

At some point it's not a question of who's going to make the decision to shut coal plants down. It's going to be, how fast can we shut them all down, and how much disruption are we going to see from the shut down?

I feel fairly confident that humanity will be at or near zero carbon emissions by 2050, one way or another. What I'm not certain about is whether we can do it in a methodical, systemized fashion designed to produce the least impact to people and economies.

What I think the world's capital investments (specifically, the world's capital investments in carbon production and use) are doing is pushing us toward a chaotic transition.

CBDunkerson at 01:20 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Actually, I'm with TomR on needing an explanation of the 'replacements clause'. As worded, it would appear to indicate that we could continue replacing existing old coal plants with new ones indefinitely and never hit 2C... so long as we stopped building 'non-replacement' carbon commitments by 2018. Which is certainly false and thus presumably not the intent.

Also, the 2018 figure is based on an assumption that any new carbon emissions sources will continue operating for their expected lifetime. I suspect that is unlikely to be true for many. In the US we have already seen coal plants being shut down prior to normal end of life because it has become more cost effective to build and operate new natural gas plants than continue running some old coal plants. As solar and wind power costs decline we are likely to see a similar result... with both coal and natural gas plants shutting down early in favor of cheaper renewable power. Indeed, the likelihood of fossil fuel plants becoming such 'stranded assets' is already causing a decline in investment in these technologies.

The point at which CO2 emissions must peak to meet the 2C target is inherently a factor of both total emissions up to that point and rate of reduction afterwards. Until we have some kind of handle on what rate of reductions is likely to occur it isn't possible to define 2018 or any other year as the 'necessary peak year'.

Moderator Response:

[JH] I have asked the author of the OP, Stephen Leahy, to chime in on this issue.

KR at 01:19 AM on 15 July 2015

2015 SkS Weekly Digest #27

Michael Fitzgerald - Given the various non-linearities along the range, I feel that it's really not useful to step from zero forcing to present conditions in order to establish slopes. Rather, since we're interested in how things will change from present conditions, look at the sensitivity to changes from the current conditions.

Rounding values just a bit for discussion, the sun provides 240 W/m² of input energy, and in steady state the Earths climate will emit an equal 240 W/m² to space at the top of the atmosphere.

From the Stephan-Boltzmann relation, P = emissivity * SB * T⁴, and rearranging for the effective Earth gray-body emissivity at 15C:

240/(SB_constant*(15+273.15)^4) = emissivity is 0.6139

Emitting 239 W/m², ie with a 1 W/m² forcing, and the effective emissivity becomes 0.6139 * 239/240 = 0.6114. The temperature required to emit 240 W/m² with that new emissivity is (240/(0.6114*SB_constant))^0.25-273.15 = 15.30094, so the temperature sensitivity to forcing at current conditions is ~0.301C per W/m².

This matches well with the predicted direct forcing of a doubling of CO2, 3.7 W/m2 leading to ~1.1C warming, with feedbacks expected to amplify it to ~3C.

Now calculating that sensitivity for different bounding scenarios, an ice age (~10C global average temperature) and an Eemian hothouse (~20C global average temperature, no polar caps, oceans 10s of meters higher), while retaining absurd precision:

At 15C, 1W/m² leads to 0.30094 C temperature change
At 10C, 1W/m² leads to 0.295718 C temperature change
At 20C, 1W/m² leads to 0.306162 C temperature change

The difference in temperature sensitivity per forcing watt between an ice age and a hothouse is less than 2%, far less than any uncertainties in feedbacks, so I think we can essentially treat that change as negligible. We can assume that direct forcing sensitivity is a constant for the purposes of evaluating climate change. Beyond that range the best response may just be "Uh-oh."

---

A far more interesting question is the level of feedbacks to a forcing change, which as summarized by the IPCC is in the range 1.5 to 4.5C, most likely value of 3C, per doubling of CO2.

ranyl at 00:10 AM on 15 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

"To avoid global warming of as much as 4 degrees Celsius by the end of the century, the scientists suggested civilization has a total budget of 900 billion metric tons of carbon dioxide in the atmosphere, and the world has already added roughly 592 billion metric tons since 1780."

From article @JH 5.

So less budget than the fictious 1000billion Tom C's diagram shows for 4C.

"The argument against CCS is strong. Critics, however, often overlook the fact that making steel and making cement—the fundamental substrates of all power plants, whether wind turbines and solar rooftops or new nuclear—spew copious CO2, as does making the fertilizer that has made more than seven billion humans on the planet today possible. If the goal is zero- or negative emissions, these emissions will have to be eliminated. The only proposal at present to do so is CCS."

CCS is very expensive and reduces power plant efficiency even if powered by biomass.

Although the carbon negative claims are theoretically possible, most massive biomass production production is heavily carbon emissions loaded due to industrial farming, land change, fertilizers (production), pesticides, processing and tansport, and if power plant less efficient you need more biomass to get the same power an therefore more potential conflict with food and biomaterials production.

I'm with Tom R all carbon negative asap, and call for chances of avoiding serious stuff 1:20 chnace which is common level for medical practioneers to consider thngs safe, i.e. there is a less than 1:20 chance that the treatment doesn't actually improves things.

If people keep contemplating a budget rather than a huge debt people will just do lots of fancy accounting and CO2 emissions will just keep on going up.

And don't forget the mass extinction event, implying the earth ecosystem needs repairing quickly as well, making things like pesticides, synthetic fertilizers, pollution, e-waste, rare earth metals, mining, deforestation and anything associated with toxic waste production kind of not sensible either.

Where do stand?

Let face it people are more worried about Scotish MP's voting on fox hunting than all this environmental stuff.

Someone recently said to me that they felt I had good points but prefered just to not take notice as it meant they just function in their lifes, which were hard enough without having to worry about enviromentlachange as well.

For me the only way to turn things arround on a tupence (as needed) is for everyone to want to.

But at present it seems everyone wants to maintain BAU at all costs, be it powered by fossil fuels or the alternative environmental and GHG associated energy production systems available; playing at being accountants and accountants can make anything look rosey if they try hard enough.

Wonder how many more extremely extrem weathe revents in a row will be needed before cliamte change is a high priority for everyone and not just a political tool to say the right thing about and hope for the children that its all been hot air?

Moderator Response:

[JH] Excessive white space eliminated.

Tom Curtis at 23:27 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

John Hartz @5, Schellnhuber is good company indeed. Thankyou.

@6:

In a previous thread I wrote:

"[It] is quite obvious that if it is acceptable, in 2018, to replace existing houses or to build carbon neutral houses, then it is also acceptable to replace an existing house with two 50% carbon neutral houses; or to modify an existing house to halve its carbon emissions, and build a new house with just 50% of current emissions per house, and so on. In particular, each 1% reduction in emissions from national electricity generation makes room for further economic growth.
Ergo, Stephen Leahy's formula sounds dramatic, it really represents only a formula for no more emissions growth from 2018. Rather than a cessation of emissions growth (and hence ongoing growth in CO2 concentration), what the world needs is the almost complete elimination of net anthropogenic emissions by 2050, and hence on the order of a 3% reduction in global emissions per annum. That is a doable target. Even with slow initial progression, a genuine attempt to move in that direction will allow very rapid strides in the near future. It is not, however, something on which we can delay - and each year that we delay - each year you win your struggle for inaction makes the cost of transition higher (because it must be more rapid), and the end benefit lower (because of increased global warming durring the delay)."

Obviously, even in context I agree with TomR's interpretation. As to his suggested strategy, I do not believe it is necessary or achievable as a globally averaged target. However, if we are to limit emissions on a per capita basis, as is required by simple considerations of justice, Western societies, and their citizens individually must indeed go net carbon negative as soon as possible, or purchase unused per capita emission credits from the third world to make up any overshoot.

John Hartz at 23:07 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Tom R: You are taking a phrase of a sentence out of context. Here is the context.

“By 2018, no new cars, homes, schools, factories, or electrical power plants should be built anywhere in the world, ever again unless they’re either replacements for old ones or are carbon neutral? Are you sure I worked that out right?” I asked Steve Davis of the University of California, co-author of a new climate study.

The above is the second paragaph of the OP.

John Hartz at 22:56 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Tom Curtis:

You are in good company...

In Paris Hans Joachim Schellnhuber, a climate physicist and chair of the German Advisory Council on Global Change, called for "an induced implosion of the carbon economy" over the next few decades, a shift he compared with efforts to end slavery in the last few decades of the 19th century. Without such a momentous shift in the global energy system, there is "not the slightest chance of avoiding dangerous, maybe disastrous climate change."

Zero Carbon or Bust: Scientists remind policy makers that CO2 pollution must end--and soon by David Biello, Scientific American, July 13, 2015

TomR at 22:56 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

"[U]nless they’re either replacements for old ones...." seems to suggest that replacing your fossil fuel dinosaur vehicle with another such fossil fuel vehicle is OK. Clearly, it is not. Great article although I am sure that with permafrost and methane clathrate emissions, which are already accelerating in the Arctic, it is already too late to prevent a 2C global atmospheric temp increase.

Please eliminate the "either replacements for old ones" part or explain to me what I am not understanding. We must each and everyone of us go carbon negative as soon as possible. No excuses.

Tom Curtis at 22:27 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Apposite to this post is this chart showing historical and projected energy related emissions, and the percentage of our carbon budget used consistent with a 50-50 chance of staying below 2 C at 2100:

I got the chart from John Baez, who in turn found it in the International Energy Agency report World Energy Outlook Special Report 2015 (Figure 2.3). It is clear from this graph that we need to halve current emissions by 2040, and (approximately) eliminate emissions by 2065 if we are to avoid overshoot on that less than ideal target.

In fact, the chart does not include Land Use Change (LUC) related emissions, which constitute approximately 20% of anthropogenic emissions even now, so those targets are generous and we should expect faster reductions than that if we are to meet the target. Indeed, it is dubious if all LUC emissions can be eliminated meaning some means of sequestring carbon is a necessity for the future. As it is unlikely to be cost effective, however, emissions reduction should be the first objective were possible.

Tom Curtis at 21:58 PM on 14 July 2015

2015 SkS Weekly Digest #27

Michael Fitzgerald @36:

"... which brings us back to my original question asking what is the sensitivity as a function of temperature so I can perform a definitive test.
The test starts in equilibrium at absolute zero and increases total forcing in 1 W/m^2 steps, allowing the system to stabilize after each step. The resulting change in temperature is the sensitivity to 1 W/m^2 of forcing at the current temperature. From the quantification of sensitivity as a function of temperature, calculate the expected sensitivity at the current temperature and increment the current temperature by that amount. After 239 steps, the resulting temperature must be around 288K at a sensitivity of 0.8C per W/m^2 or else the prediction fails."

I believe that unless you reduce the test to the trivial question as to the temperature response to total forcing plus feedbacks at the surface, in which case the response function is given by the Stefan Boltzman law applied at the surface, your test is entirely unsuitable. That is because:

1) The response function to forcing alone varies greatly with temperature as different feedbacks kick in and vary in strength and rate of change with temperature. That in turn means that to perform your test we would need to know for each of those feedbacks exactly at what temperature they kick in, and how they vary with temperature. In turn that is something we cannot know from observation, in that most of the relevant temperature range has never been experienced on Earth, and all of it except the last 1% of the temperature range has not been experienced when we could make instrumental observations. Further, we cannot know it from computer models because the relevant experiments have not been done, and even if they were the models would be operateing so far outside their design range as to make the responses almost meaningless. Combined, this makes your test analogous to determining the slope at an unspecified location on the mountain range by adding together the altitude change per kilometer from from the nearest coastline to ensure it gives the correct altitude, when there has been no detailed survey of the topography between the coast and your current location.

2) This difficulty is compounded by the fact that the temperature change with change in forcing differs in some circumstances depending on whether you are cooling or warming. This hysterisis in the atmosphere was certainly a feature of the (at least two) snowball Earth states experienced in the distant past and have been conjectured to be a factor on a smaller scale on time scales relevant to the modern. Ergo your whole of mountain range test of the current slope does not even have unique values for the slope at a given forcing.

In short, your "definitive test" is nothing of the sort. It is not even a doable test; and to the extent that we can approximate to it, the results are so uncertain as to be meaningless.

ranyl at 21:53 PM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

350ppm means at least 1.6C temperature rise (Pliocene temperature 2C estimated by Hansen 2011 and assuming 60% heating 100 years), and as the temperature for the early Pliocene (last time CO2 350ppm -400ppm), is most often estimated to be between 3C-5C this implies a more likely temperature rise of 1.8C to 3C, for 350ppm.

And 350ppm by 2100 means there hasn't been any carbon budget for some while and the atmospheric CO2 will have been >than 350ppm for >100 years even if 350ppm is achieved, therefore 60% of the warming by 2100, the 1.8C (luckiest result) to 3C(worst case scenario) is kind of inevitable.

Further stopping all carbon emission today and 350ppm isn’t achieved until 2200 even if all CO2 emissions stopped in 2010, if permafrost releases are counted, and that is not mentioning, forest fires, peat fires, and the reduced biosphere fertilizer affect if synthetic nitrogen fertilisers use is reduced.

Even further clean the air of sulphur dioxide emissions and the true CO2 levels at present called the CO2e is ~470ppm.

Can we afford to make anything more by 2018 considering associated carbon emissions?

How much carbon emissions and biodiversity losses are incurred by none native rubber plantations (mainly for tyres) in China say?

Nor do they include the carbon emissions from large scale hydro electric dams as these are deemed carbon negative, so a double whammy.

A couple of interesting articles on the overall effective emissions from renewables and the author's don't seem to be fossil fuel advocates.

Richard York1 Do alternative energy sources displace fossil fuels?

Nature Climate Change Volume: 2, Pages: 441–443, 2012

“Non-hydro renewable sources have a positive coefficient, indicating that renewables tend to simply be added to the energy mix without displacing fossil fuels.”

“Hydropower destroys river ecosystems and threatens the survival of anadromous fish and other aquatic species11.

Solar voltaic power and wind power, although representing less serious environmental threats than nuclear power and hydropower, require large amounts of material, some of it toxic and energy-intensive to produce, as well as large areas of land to produce substantial amounts of energy12.

In short, all energy sources have environmental costs.”

“A general implication of these findings is that polices aimed at addressing global climate change should not focus principally on developing technological fixes, but should also take into account human behaviour in the context of political, economic and social systems.”

Andrew K. Jorgenson1 Energy: Analysing fossil-fuel displacement

Journal name: Nature Climate Change Volume: 2, Pages: 398–399 Year published: (2012)

“Besides contradicting the proportional displacement assumption, York's research adds to the growing body of environmental social science that highlights how societies cannot only rely on technological solutions to reduce fossil-fuel use and thus anthropogenic carbon dioxide emissions6, 7, 8. To effectively reduce emissions, societies need to focus on reducing the consumption of energy at both the individual/household level9 and the system level, with strategies geared towards broader changes in the economic, political and cultural spheres10. More broadly, York highlights the importance of integrating research on the human dimensions of climate change — such as the role of individuals and collective human behaviour, the characteristics of social institutions and the complex interrelationships between the world's nations — with research on technological solutions to tackle greenhouse-gas emissions”

Can humanity get off fossil fuels?

Realistically considering the current situation is that actualy possible?

And as powering down is the only to actually prevent fossil fuels emissions, can this down and miantian well being and happiness?

Can we power down beyond efficiency gains (lots mahcines are very efficient already, people have working on this years, and replacing old inefficinet ones is of course adding to the carbon debt) or it that too much?

Wouldn't war have to cease to stop carbon emissions?

Moderator Response:

[JH] Excessive white space eliminated.

MA Rodger at 21:41 PM on 14 July 2015

2015 SkS Weekly Digest #27

Moderator [PS} @38.

While the the nub of the question is quite specific, I am not at all sure where it will lead. This interchange transferred here (being off-topic elsewhere) as it appeared to require an open thread to allow for all the ramblings. If it does resolve into a single point of discussion, that would be the time to consider transferring to an appropriate thread.

Michael Fitzgerald @38.

You say "After 239 steps, the resulting temperature must be around 288K at a sensitivity of 0.8C per W/m^2 or else the prediction fails." This is untrue. Firstly, a lot of the workings of climate are dependent on the existence of life which wouldn't survive the initial drop to 0 K and its absence would have a significant impact on the result (although not a massive one). For instance, there would not be an oxygen-rich atmosphere without life and the methane cycle is driven by life. Secondly, the state the planet ends up in could be a snowball earth. If this step-forcing you envisage results in a snowball shiny enough to keep CO2 as well as H2O as part of geology and not part of atmosphere, there will be no warm state to flip into. And further, that warm state could be a warm ice-free planet, not the 'small' ice version we have today. So what you envision by your 239 steps is more 'thought experiment' than the physics of an alternate world that you appear to imagine.

The thesis you present (if I read you right) is that the accepted estimate of ECS=1.5 to 4.5ºC would look silly and utterly incongruous if even a rough graph of ECS were drawn out for a planet Earth subject to differing levels of climatic warming from 0 Wm^-2 up to the present-day effective-solar-heating of 239 Wm^-2. Surely, you say, the physical guts of this is the Stefan-Boltzmann relationship as per the zero-GHG planet, and that is an inverse-quartic relationship. The stated 150 Wm^-2 of the GHGs might provide the planet with +33ºC of heating (and yes, something has to be responsible for that +33ºC), but (as you put it @28) for a planet at 15ºC a CO2 forcing of 1 Wm^-2 would require an extra 3.3 Wm^-2 of feedback to achieve the accepted central ECS=3ºC which is nothing near the ratio 150Wm^-2/239Wm^-2 = 0.6. This extra 3.3 Wm^-2 of feedback therefore has to be a fantasy and AGW with it. (Or is that "CAGW with it"?) Doesn't it?

Of course the Stefan-Boltzmann relationship applies to the planet at an effective temperature of -18ºC and the requirement is 2 Wm^-2 fo feedback for an ECS=3ºC. The 150 Wm^-2 of the GHG is not all feedback. And not all the feedback is GHG. The various GHG contributions are not additive but ignoring that, about half of it is a combination of water vapour (positive feedback) and lapse rate (negative feedback). Clouds produce about a quarter. CO2 provides about 20% and that isn't a feedback, but extra to the GHG feedbacks are the significant albedo feedbacks.

Now, as water vapour seriously kicks in at -20ºC, ice melts at 0ºC and vegetation above 0ºC, the feedbacks don't apply at cold temperatures. So does that amend this thought experiment? I think it would.

Moderator Response:

[PS] my concern was that whereever a discussion leads, it is better to take steps one at a time rather than leaping all over the place. Michael clearly thinks there is at least a possibility of low sensitivity which is why I would prefer discussion moved there. He also clearly needs to understand direct feedback before considering the more complex feedbacks of albedo, clouds, water/CH4 etc.

Tom Curtis at 21:33 PM on 14 July 2015

2015 SkS Weekly Digest #27

Michael Fitzgerald @38, you are discussing this topic here because all topics are on topic on the weekly digest posts. Therefore it is hardly possible that Philippe Chantreau's post is off topic. It may be non-responsive, but that it a different matter entirely (and I am far from convinced that it is). There may also be a more appropriate thread for his comments, in which case courtesy (and the comments policy) dictate that he should use it apart for brief responses, but I am not aware of that more appropriate thread and neither you nor the moderator have pointed to it.

With regard to the "next, inevitable ice age", I do not know whether or not you are referring to recent reports on Zharkova's conference paper (ably discussed by Sou at Hot Whopper); or to the next glacial (shown to be unlikely with more than 220 ppmv of CO2 in the atmosphere at any time in the next 50 thousand years by Berger and Loutre, 2002; and ably discussed by Sou again). If you would like to clarrify, please at the same time indicate (and post on) the appropriate thread, and attempt a rebutal of the relevant points raised by Sou and/or Berger and Loutre. I will only note that there does indeed appear to be a next, inevitable glacial some 50 thousand years from now; and it would be a great shame if the fossil fuel reserves that it could usefully be used to mitigate that eventuality are used up in the coming century when they harm the human condition rather than in 50 thousand years when they could concievably help.

MIchael Fitzgerald at 16:45 PM on 14 July 2015

2015 SkS Weekly Digest #27

PhilippeChantrea,

Your comment is both political (bad regulations vs. bad investment bankers) and OT, but with regard to the precautionary principle, understanding is always better then precaution arising from the unknown. A better understanding prevents costs arising from unnecessary precaution and improving understanding is a key feature of the scientific method. Wouldn't it be a good thing for the world if a better understanding of the climate led to a sensitivity low enough that we didn't have to worry about climate change, except for natural variability like the next, inevitble, ice age?

Moderator Response:

[PS] I am inclined to agree that Michael has asked very specific questions so it is preferrable to keep on topic. If someone wants to tackle his "inevitable" ice age, then please do so in appropriate place and post a link here to your comment.

PhilippeChantreau at 15:58 PM on 14 July 2015

2015 SkS Weekly Digest #27

Really, this is framing the issue all wrong.

Back in 2007 nobody was seriously questioning whether it was worth the risk to steer the financial and housing market the way the industry was. It wasn't even questioned, except by those who knew better, like Benoit Mandelbrot. The risks existed, and materialized into a trillion dollars (give or take, who cares at this point) of loss to the World economy. In the thick of it, there was no long lines to get soup in street kitchen or scores of homeless people like in 1929. The World has mostly recovered (except for Greece) and it hasn't been 10 years yet. This demonstrated that the US, and World economies could absorb this enormous, catastrophic loss without massive chaos. If it could be done for the sake of Wall-Street clowns gambling with others' money, surely it should be done for the sake of minimizing the immense risk posed by climate change.

Perhaps it will turn out that the science was all wrong; the likelihood of that is a lot less than that of people defaulting on their mortgage. But even if it does turn out to be wrong, it would still be a more defensible expense on the ground of principle than the loss occasioned by the pathetic incompetence of the entire financial industry at the beginning of the century. So why exactly are we quibbling in such excruciating detail about this? Why are our values so messed up? Why are enormous costs acceptable (since very few have gone to jail over the 2008 fiasco) when occasioned by certain unethical behaviors, but unacceptable when motivated by a principle of precaution rooted in science? This skewed cost/benefit analysis does not make any sense.

ubrew12 at 15:07 PM on 14 July 2015

2015 SkS Weekly News Roundup: End of the Series

Thank you for all the work of putting together this listing each week, its been a valuable resource. However, we all have to prioritize, its life. We do it and move on. Along with your links above I would also like to share that once a week Mary Ellen Harte (biologist) puts together a blog on 'Huffington Post' called 'Climate Change this week' that is a long news listing, with links, of events that week. Your readers may find it a valuable resource. Also Peter Sinclairs 'Climate Crocks' series should be sampled every few days because its full of useful information. Thanks again!

Moderator Response:

[JH] You're welcome and thank you for adding two other resources for our readers to use. As I stated in a prior comment, we are in the process of finding a suitable replacement for the Weekly News Roundup. Stay tuned for further developments.

MIchael Fitzgerald at 14:16 PM on 14 July 2015

2015 SkS Weekly Digest #27

MA ROdger,
My interpretation of what divides the two sides is not if AGW is valid, but whether the effect is large enough to justify expensive remediation, small enough to be nothing but a benefit to agriculture, or somewhere in between which brings us back to my original question asking what is the sensitivity as a function of temperature so I can perform a definitive test.

The test starts in equilibrium at absolute zero and increases total forcing in 1 W/m^2 steps, allowing the system to stabilize after each step. The resulting change in temperature is the sensitivity to 1 W/m^2 of forcing at the current temperature. From the quantification of sensitivity as a function of temperature, calculate the expected sensitivity at the current temperature and increment the current temperature by that amount. After 239 steps, the resulting temperature must be around 288K at a sensitivity of 0.8C per W/m^2 or else the prediction fails.

We've already established that for a zero feedback/unit gain climate, the sensitivity as a function of temperature is the slope of the Stefan-Boltzmann Law, which at 255K is about 0.3C per W/m^2 and at 288K is about 0.2C per W/m^2. Applying this test to any predicted value of temperature consequential to arbitrary input power unconditionally supports the ideal sensitivity function and serves as the existence proof that quantifying this relationship is not impossible. Starting from this tested quantification for a zero feedback, ideal black body, how does decreasing emissivity (effectively a gray body) and/or increasing the closed loop gain (net effect from feedback and open loop gain) quantifiably modify the underlying physics to support the predicted sensitivity at the required final temperature?

What I say is right or wrong about climatology is irrelevant, only the results from testing its predictions will answer your question about what, if anything, climatology has gotten right or wrong.

Michael

Moderator Response:

[PS] Just a note to participants, that list of talks at latest Ringberg workshop on climate sensitivity can be found here.

MIchael Fitzgerald at 14:14 PM on 14 July 2015

2015 SkS Weekly Digest #27

I'll remove the response to MA's comment from the preamble, as his comment about evidence of warming was OT anyway.

I also think that this is the more relevant thread, as I'm not claiming any specific sensitivity, high or low, and am just characterizing a test of the sensitivity.

Also, the sensitivity as a function of temperature I'm concerned with is strictly the ECS.

MIchael Fitzgerald at 12:08 PM on 14 July 2015

2015 SkS Weekly Digest #27

Moderator.,

My last post seemed to have dissappeared. I can repost it if necessary.

Michael

Moderator Response:

[PS] It appears it was deleted for sloganeering (not me). Try again without the preamble. I would also suggest that since you are proposing sensitivity might be low, that an appropriate place to post would "Climate sensitivity is low". (be sure to read the article). To answer the question as to whether climate might be sensitive enough to be damaging, then you need to look at ECS not just the instantaneous change.

PhilippeChantreau at 02:46 AM on 14 July 2015

Climate denial linked to conspiratorial thinking in new study

He would tell you he's part of "a lot of other scientists." Without, of course, getting anywhere near exactly how many is "a lot" and why that des not prevent every major scientific organization in the world to acknowledge AGW and its dangers. It doesn't really matter, since none of this wouldhave any bearing on the validity of his argument, if there was some clearly defined argument there whose validity could be assessed. Oh well...

jenna at 01:52 AM on 14 July 2015

A Hard Deadline: We Must Stop Building New Carbon Infrastructure by 2018

Unfortunately, the exact opposite is happening in the real world, mostly in developing countries. Please see this Vox article about coal infrastucture in the works. Very worrysome!

http://www.vox.com/2015/7/9/8922901/coal-renaissance-numbers

Moderator Response:

[PS] Fixed link. Please use the link button in the editor in future.

Jim Eager at 01:49 AM on 14 July 2015

Climate denial linked to conspiratorial thinking in new study

Up thread ryland identified himself as "a scientist with a PhD from the University of Western Australia who rose to become a Professor at Curtin University in Perth" whose "own field of interest, [is] the study of prostate cancer using molecular biological techniques"

Which means ryland's views and pronouncements on climate science are no more valid than any other layman's. He is not even part of the 3%, full stop.

Moderator Response:

[PS] It would be preferable to stick to any scientific points that Ryland has raised rather than offering opportunities for further trolling.

Tom Dayton at 00:00 AM on 14 July 2015

2015 SkS Weekly News Roundup: End of the Series

Bob, Hot Topic pointed out that Valentina Zharkova in an interview revealed she is a climate change denier. See the transcript near the bottom of Sou's post at HotWhopper. Good explanation of the reality is at And Then There's Physics, especially in the comments. See also Barton Paul Levinson's comments in the comment stream on the Rabbett Run post (but ignore that original post, because as its author says in the comments, it turns out that Zharkova's mention of "activity" means sunspots, not TSI).

bwilson4web at 23:46 PM on 13 July 2015

2015 SkS Weekly News Roundup: End of the Series

I fully understand the need to manage one's time but I probably won't be following via Facebook because it is so 'needy' of my attention. It is a Facebook issue that drives me nuts. Still, I appreciate the other three links.

Like mushrooms after a rain, another denialist-lite paper came up on July 9 by Valentina Zharkova on Sun spots. An unfortunate choice of words has been picked up by the usual suspect news sites to claim we're headed towards a 'mini-Ice age.' Sad because the paper probably has merit but poor word-smithing means the misleaders will ride it for all it is worth. <SIGH>

GOOD LUCK!

Bob Wilson

Tom Dayton at 23:23 PM on 13 July 2015

Water vapor is the most powerful greenhouse gas

arationofreason, SkepticalScience's comment threads are for scientific discussion, not repetitions of what "seems logical" to you personally regardless of the science. You started this discussion (rudely and vaguely), apparently without reading the original post of this thread, or at least without addressing any of its points. Several people then gave you more information, which you should have read and responded to, disagreeing if you desired. Instead you ignored all that information and merely re-asserted your personal belief. If you continue that behavior your comments will be deleted. Instead you need to respond specifically to the information you have been given.

arationofreason at 22:04 PM on 13 July 2015

Water vapor is the most powerful greenhouse gas

Moderator, My apology and thank you for your forebarance.

I fully appreciate all of the technical analysis that I have read over the years which shows the incredible complexity of the problem even without the confusion which often arises for people who are not accustomed to working with feedback let alone positive feedback. Yes all of these effects undoubtedly take place at different times and places throughout the atmosphere. I merely wanted to make the point that many are local temporarly and spatially. We may never have the measurements and computing power to untangle the physics with enough accuracy to settle the question and that we should look to nature for the solution.

The 10u window (negative FB ) aside. The only tool left to balance the radiation by NET radiation to space is water vapor. It has done a pretty good job (till now apparently). The only simple point that I was trying to make is that in spite of (local) positive FB effects of increased water vapor, it is the only cooling mechanism there is. As such its NET effect is cooling in response to increased forcing. How else can it keep up with variation in forcing and balance the earths radiation over the eons. It seems logical to me that increased water vapor will add cooling and is thus a net negative climate feedback in spite of all the complexities which are well noted and computed with our understanding of atmospheric physics.

Moderator Response:

[PS] This amounts to Argument from Personal Incredulity. Without supporting evidence, this is little better than sloganeering. "It seems logical to me that increased water vapor will add cooling" is an assertion that seems to me to reflect a poor understanding of the physics and should be supported by either data or references if you wish to persuade others of the value of your position.

Tom Curtis at 13:40 PM on 13 July 2015

Water vapor is the most powerful greenhouse gas

aror @207, consider the case where 100% of the IR radiation from the surface is absorbed by WV. If your argument had any validity it would be valid in this case. With an average surface temperature of 288 K, that means on average 390 W/m^2 of radiation will be absorbed by the WV. The energy is thermalized, and the WV rises through convection. As it does do it cools due to adiabatic expansion, with the temperature falling by approximately 6.5 K per Km. Suppose it rises by 2 Km, and then radiates its energy to space. Therefore, it will radiate to space at a temperature of 275 K (on average). At 275 K, the absolute maximum energy it can radiate to space is given by the Stefan-Boltzmann law, and is 324.3 W/m^2. Therefore in this simplified scenario, less energy is radiated to space because of the existence of the WV. As the temperature at altitude is governed by the surface temperature by the adiabatic lapse rate, and as Outgoing Longwave Radiation must equal incoming shortwave radiation to achieve equilibrium, that means the the Water Vapour warms the surface of the Earth. You only manage to think otherwise because you ignore the fact that the WV cools as it rises, and the consequences that has on the energy balance.

In real life, WV does not absorb all of the radiation. Some makes it to space from the surface. Equally, however, much of the radiation is from far higher altitudes than 2 Km. A warming Earth not only increases the WV, thereby reducing the radiation to space due to increased absorption. It also increases the altitude from which, on average, WV radiates to space thereby increasing the temperature differential between radiation from the surface, and radiation from WV, and hence increasing the strength of the greenhouse effect.

Note to the moderator. Last time I responded to aror I was reminded of the comments policy position on inflammatory tone. aror's name is obviously chose to suggest that they have what others lack, ie, that ration of reason. They are suggesting that they are adding a dose of reason to the discussion here that is otherwise lacking. Ignoring the massive irony of that claim given the quality of their posts, that means their name itself violates the provisions agains inflammatory tone. I request that you enforce the policy by requiring them to use a name without invidious implication.

Moderator Response:

[PS] Thank you for your positive contribution to the discussion. We do not have policy on pseudonyms to enforce. I thoroughly agree with the irony, but I think that it improves the chances of constructive discussion if we all resist provocation. We will see whether AROR is able to respond in conformance with comments policy.

Tom Dayton at 12:40 PM on 13 July 2015

Water vapor is the most powerful greenhouse gas

arationofreason, you did not ask an actual question, but I'm guessing that you were implying belief that the greenhouse gas effect of water vapor is saturated. If so, you should read the post about the myth of CO2's greenhouse gas effect being saturated, because although the details differ, the principles are the same.

Moderator Response:

[PS] Reading an accurate account of GHE eg as done here would help too.

arationofreason at 11:06 AM on 13 July 2015

Water vapor is the most powerful greenhouse gas

Let's see now. IR in intersepted by WV which immediatly thermalizes the energy. The increase in temperature evaporates more WV. Positive feedback in the lowest layers of the boundry layer, so far so good. Then this warmer air and WV convect to condensation altitudes where the heat is radiated away by the WV molecules. We know that this is true since it is the only mechanism by which 3/4 of the earth heat is sent to space. Additional warming by any forcing mechanism allways results in addition WV which compensate by radiating more heat to space. Now you are going to tell me that any increment to the amount of WV is going to cause additional heating. Are you all out of your 'cotton picken' minds? know, it is mind boggeling complex but mother nature worked this out eons ago and it still works. It is the only cooling mechanism that she has. Has she changed it just for you? Or has Michael Moor's suggestion of reversing the laws of physics suddenly taken effec?

Moderator Response:

[RH] Please watch the tone of your comments if you want a productive engagement.

[PS]

Please note that posting comments here at SkS is a privilege, not a right. This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

Moderating this site is a tiresome chore, particularly when commentators repeatedly submit offensive or off-topic posts. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.

Finally, please understand that moderation policies are not open for discussion. If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.

sidd at 07:57 AM on 13 July 2015

2015 SkS Weekly News Roundup: End of the Series

Thanks for the series, and all the other good work. I do appreciate the time and energy expended by the hosts of this site. Unfortunately since the Facebook page seems completely broken without javascript enabled, I doubt I shall visit there.

Moderator Response:

[JH] You're welcome.

ubrew12 at 03:05 AM on 13 July 2015

2015 SkS Weekly News Roundup #28A

Regarding the article "What will climate be like in 2100? Expect surprises, says new Met Office study", perhaps a similar study could be done in heavily forested areas of N America and Europe to see when these forests are likely to burn. As horrible as losing the forests as lumber would be, it would be worse if they burned due to the black ash deposits and released CO2 exacerbating Climate Change. Perhaps the Climate models could be tasks with giving a likely tipping point at which certain forests are likely to burn. Once those points are surpassed, permission could be given to log them. That way, we give the forest as long as possible to see if our own behavior can be changed in time to save them, but act to prevent 'insult to injury' once those limits are passed. (I'm not really being sarcastic here: it would be better to harvest the trees for construction lumber than have them burn).

Jonas at 02:53 AM on 13 July 2015

2015 SkS Weekly News Roundup: End of the Series

I want to tell my gratitude for all the work you did: it was one of the most important items for me here, apart for the other important ones :-) .. Since I do not use facebook, I am also very thankful for your links.

Sks in general does a grat job in providing us small and big non climate scientist multiplicators with information so we can contain the spread of misinformation.

Moderator Response:

[JH] You're welcome. I'm adding some new sections to the Weekly Digest to take-up some of the slack. Other new resources may also be added to the SkS website. Stay tuned.

dcpetterson at 02:19 AM on 13 July 2015

2015 SkS Weekly News Roundup: End of the Series

Thank you for all the valuable work you do, and all the long hours it requires.

Moderator Response:

[JH] You're welcome.

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