AK, I replied above: accidentally misplaced it in this nested loop.
Dave
Comment on A War Against Fire by physicistdave
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Comment on A War Against Fire by Peter Lang
Judith,
Agreed that the top policy relevant climate science goal should be realistic clarification of the ‘very likely’ top to ECS. Agree that 3.5C is about right. I suspect that once the climate models start using more realistic aerosol forcing, they will be retuned (or will be wildly too warm relative to observations) and the high values of ECS will disappear.
I suggest you and the climate scientists are far too fixated on ECS. What does it matter what ECS is if the damage function is negligible or net beneficial with increasing temperature and CO2 concentration?
It is the damage function that is most uncertain and where the attention needs to be focused.
The modellers also need to focus on abrupt climate change and probabilities of when it will happen and which direction the change will be.
We also need a much better projections of how much CO2 can be produced this century and is likely to be.
Climate Scientists have been focused on ECS for over 25 years and not paying enough attention to the other key inputs needed for policy analysis and for the economic models.
I hope you might be able to enlighten your colleagues through the course of 2016.
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Comment on A War Against Fire by physicistdave
David Springer wrote to me:
ECS can be zero. TCS can’t be zero.
Well, it depends on the time scale you insist upon for ECS: over a long enough time scale, the oceans absorb the CO2, eventually it all precipitates out, and life returns to normal.
But, I suspect that time scale is much longer than the scale most people are interested in.
As long as a lot of extra CO2 remains in the atmosphere, it will have a warming effect: it is simple frosh physics.
Perhaps negative feedbacks will reduce that warming effect (though it will still be positive) and quite possibly it will be swamped by natural variations — natural variations in the climate system, changes in the solar constant, etc. Judith knows much more about this than I, and she seems to think those are real possibilities. But, the anthropogenic CO2 will have a net warming effect while it remains in the atmosphere.
Again, frosh physics.
Dave
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Comment on Week in review – science edition by Peter Lang
“it appears that the Paris agreement will turn out to be phenomenally expensive but ultimately futile in altering the course of the 21st century climate“
Yes. i agree. It is likely to be extremely expensive and make not an iota of difference to the climate.
It is estimate the world is spending $1.5 trillion per year on the “climate industry”. There is no evidence that this expenditure will make the slightest difference to the climate. The majority of it is being spent on consultants and the second highest on useless policies such as support for renewable energy (a complete waste of money and having zero measurable effect on the climate and never likely to).
Then there is the $100 billion per year the US President (Obama) committed the developing world to pay to corrupt and incompetent regimes in developing countries.
What a bloody disaster.
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Comment on A War Against Fire by physicistdave
matthewrmarler wrote:
That is not true. As I outlined, an ECS (of global temporally averaged mean temperature) can be 0 if increased temperature produces increased cloud cover which subsequently reduces insolation at the surface.
Matt, the problem is that if the increased clouds completely eliminate the warming effect, you will no longer have an increased temperature to produce the clouds! And, then you no longer have the clouds to mitigate the warming at all.
Partial reduction of warming from clouds? Maybe. Complete elimination of warming by clouds? No, that is self-contradictory.
Dave
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Comment on A War Against Fire by physicistdave
matthewrmarler wrote:
Starting from where we are now: Increased CO2 could produce warming which produces increased cloud cover which produces reduced surface insolation which reduces temperature which reduces cloud cover which produces warming, etc. The net effect of increased CO2 could be an increase in the oscillation between relatively high and relatively low values without any change in global mean temperature.
Matt, anyone who knows any systems theory, and certainly anyone who knows anything about the physics of the weather, knows that that sort of thing will indeed happen: indeed, that is weather!
But, can you come up with a plausible quantitative model in which the effect of this is to give no warming at all? In all seriousness, if you can, I think you will add something important to the climate debate.
Dave
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Comment on A War Against Fire by Peter Lang
Jim D,
Hansen believed the planet’s ocean’s would boil off and Earth would develop an atmosphere like Venus. (He did his PhD on Venus and it deeply affected his beliefs and still does).
We now know this is BS. It seems most rational, informed people now realise that warming is not catastrophic or dangerous. There seems GHG emissions may deliver benefits that exceed damages throughout this century.
I suggest we’ve made enormous progress in understanding that GHG emissions are not dangerous or catastrophic .. and we have a long way to go yet. This is the area of climate science that is crying outr for better, unbiased, objective research.
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Comment on A War Against Fire by David Springer
ECS can be zero. TCS can’t be zero.
Mosher might understand an analogy.
Consider an aircraft. Can it maintain straight and level flight without pilot input despite dynamically changing center of gravity such as passengers moving around? Sure. It’s called positive longitudinal stability.
https://en.wikipedia.org/wiki/Longitudinal_static_stability#Longitudinal_stability
Another analogy, from electronics this time, is a common component called a constant current source. It delivers a constant, unchanging current despite a changing load.
https://en.wikipedia.org/wiki/Current_source
In the first changing CO2 is analogous to changing center of gravity and in the second CO2 is analogous to changing load. Temperature is pitch and current respectively. Feedback that keeps pitch or current constant is TCS and the constant output is ECS. It’s not rocket science but it is something that all engineers understand. Load balancing is done everywhere from bridges to aircraft to electric power supplies. You’re not an engineer and that’s the problem. You might understand after it is explained to you but someone has to explain it first. You can’t get there on your own recognizance.
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Comment on A War Against Fire by physicistdave
Lucas Nicolato Pereira wrote:
The bottom line is: even if the whole AGW thing is real, and the most catastrophic scenario predicted by the IPCC reports are true, and even if we managed to zero emissions, we would still be extremely vulnerable to any random event that produced a small climate forcing, because a catastrophic scenario is only possible if the Earth’s climate is an intrinsically unstable system.
Lucas, I am a physicist who has also done engineering. I had similar thoughts when I first started looking into this. Part of the answer is that a modest positive feedback will not produce a catastrophe but can produce amplification of the initial signal.
The other part of the answer (I owe thanks to my fellow physicist John Baez for pointing this out) is that Stefan-Boltzmann is non-linear (the fourth power) and, for larger positive feedbacks that would otherwise be catastrophic, the Stefan-Boltzmann non-linearity has an effect, roughly speaking, of the “rails” that limit the effects of positive feedback in actual electronic systems.
What I have just said is, of course, just giving a qualitative sense of what is happening: you really have to go through and do good numerical calculations.
And, my own experience with years of computer modeling confirms what you say on that issue: there are too many ways to fit a complex computer model to data incorrectly — they need to show they can make correct predictions, and they have failed to do that thus far.
Dave
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Comment on A War Against Fire by captdallas2 0.8 +/- 0.3
physicist dave, “But, can you come up with a plausible quantitative model in which the effect of this is to give no warming at all? In all seriousness, if you can, I think you will add something important to the climate debate.”
At the point where climate shifts into a new ice age you could make a case for negative sensitivity, but the real driving force would be albedo. In reality, sensitivity to CO2 would just be overwhelmed by other forcings and not technically feedbacks to CO2. I guess the important thing added to the debate is that sensitivity to CO2 is not linear and using a linear definition isn’t very useful :)
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Comment on Week in review – science edition by David Wojick
I like your Financial Post op-ed, Judy. Just show them the data. FP readers are used to analyzing data (and spotting scams). Back in the days of Kyoto I did about 14 op-eds for FP. They are good people.
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Comment on Week in review – science edition by captdallas2 0.8 +/- 0.3
MattStat, I love digging out old real climate posts :)
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Comment on A War Against Fire by David Springer
Wars are politics not science, babbleboy. But then again consider NYQUIST!
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Comment on A War Against Fire by David Springer
ulric – I note you qualify solar irradiance with “heating effect”. H2O does have a deep absorption band at the low frequency end of the near infrared but I’d not considered it as having any great effect due to the overall low percentage of solar energy in the near infrared. HOWEVER, you qualify it and now that I think about it a lot of the power in visible light from the sun is reflected not absorbed and frequencies above visible are absorbed mostly in the stratosphere without any surface heating.
What’s your source for the 49% number?
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Comment on A War Against Fire by JCH
Saying they have failed is not reasonable. Other than that, you appear to be reasonable. Models that predicted cooling during the current period were wrong; models that predicted natural variation would stave off AGW for a brief time before warming resumed (pale blue)… they’re still in the hunt. Look outside. We just experienced the hottest month in the the entire record, and January looks to be off just as serious a start:
Also, demanding models have to demonstrate predictive skill may, given the complexity of the system, may be unreasonable:
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Comment on A War Against Fire by captdallas2 0.8 +/- 0.3
JCH, “Saying they have failed is not reasonable.”
Nope, it is pretty reasonable to say they have failed. Of course confidently saying that requires a bit more than throwing up a “global” anomaly comparison. The real physics, mainly thermo and fluid dynamics require absolute temperature or energy by region and hemisphere to sort out how useful the models may be. “Average” temperature and temperature anomaly are just about meaningless.
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Comment on A War Against Fire by franktoo
Matthewrmarler: I appreciate any corrections, even though I dealt with this over simplification in a second comment.
An instantaneous doubling of CO2 produces a 3.7 W/m2 imbalance at the TOA. We could imagine an instantaneous change in albedo/clouds that would negate that 3.7 W/m2 imbalance*. However, if the change in clouds is a feedback driven by a change in planetary temperature, climate sensitivity will not be zero: If it takes 0.1 K of warming for clouds to block 3.7 W/m2 of incoming SWR, then ECS will be about 0.1 K/doubling. That would be a -37 W/m2/K cloud feedback** that would dominate all of the other feedbacks (about +2 W/m2 for WV, -1 W/m2 for LR, +0.3 W/m2 for surface albedo).
*An instantaneous change in clouds that reduces incoming SWR by 3.7 W/m2 without a change in temperature probably should be thought of as internal/unforced variability.
** It is hard to imagine ice ages, if cloud feedback can be anywhere near this large. The existence of ice-ages – assuming we understand their cause – is one of the better reasons for believing that negative cloud feedback can’t dominate the other feedbacks. A -5 K change in GMST and a -37 W/m2/K cloud feedback is a +185 W/m2 increase in incoming SWR. Clouds only reflect about 100 W/m2 of incoming SWR.
Simple physics makes it easy to prove that ECS can’t be near zero.
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Comment on A War Against Fire by AK
@physicistdave...<blockquote>If feedback is a myth, why do you cite a guy who takes it seriously?</blockquote>Because his statement makes the point I wanted. When people speak of “<i>feedback</i>” in terms of <b>global</b> heat budgets, they could be using the term as a loose metaphor (a myth), or they could actually be using a mental model where "averages" and global "temperatures" are somehow real inputs to what's going on.
Based on what I've heard and read of him, Lindzen is the former, although he's said some things that IMO are wrong. (Especially in his 1997(?) PNAS discussion.)<blockquote>But, still, it really does seem to make sense to talk about global climate and what affects it, and that requires us to at least try to think about things like feedbacks.</blockquote>That's fine, as long as you don't start thinking your <b>descriptive metaphors</b> are valid models of reality.
To be precise, “<i>global average temperature</i>” doesn't have any influence on total planetary radiative heat loss. Thus “<i>control theory</i>” doesn't apply, and claims that the overall effect of “<i>greenhouse warming</i>” <b>can't</b> be zero or negative can't be justified on the basis of it.
I could go into greater detail, but usually when I do people just skip it with tl:dr.
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Comment on A War Against Fire by David Springer
Ulric – I found a 40% quote from a research group at MIT developing transparent photovoltaic panels that generate electricity from the near IR portion of sunlight.
Actually the transparent PV cells are really interesting. Efficiently done means windows and skylights could be dual-purposed as solar cells. Also since current PV uses visible light this may greatly increase PV efficiency since a traditional visible light cell could lie underneath the NIR cell given the NIR cell transmits most or all the visible light.
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Comment on A War Against Fire by David Springer
http://news.mit.edu/2012/infrared-photovoltaic-0621
Ulric – I found a 40% quote from a research group at MIT developing transparent photovoltaic panels that generate electricity from the near IR portion of sunlight.
Actually the transparent PV cells are really interesting. Efficiently done means windows and skylights could be dual-purposed as solar cells. Also since current PV uses visible light this may greatly increase PV efficiency since a traditional visible light cell could lie underneath the NIR cell given the NIR cell transmits most or all the visible light.
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