Guest essay by Roger A. Pielke Sr.
Main Points
1. The difference in ocean heat content at two different time periods provides the global average radiative imbalance over that time [within the uncertainty of the ocean heat measurements]
2. This global average radiative imbalance is equal to the sum of the global average radiative forcings and the global average radiative feedbacks.
3. The global average radiative forcing change since 1750 is presented in the 2013 IPCC WG1 Figure SPM.5 as 2.29 [1.13 -3.33] Watts per meter squared.
4. The global average radiative imbalance is given in the 2013 IPCC report as 0.59 Watts per meter squared for 1971-2010 while for 1993-2010 it is 0.71 Watts per meter squared.
5. Thus, assuming that a large fraction of the global average radiative forcing change since 1750 is still occurring, the global average radiative feedbacks are significantly less than the global average forcings; i.e. a negative feedback.
6. Such a negative feedback is expected (since the surface temperature, and thus the loss of long wave radiation to space would increase).
7. However, the water vapor and cloud radiative feedback must also be part of the feedback. This water vapor feedback is a key claim in terms of amplifying warming due to the addition of CO2 and other human inputs of greenhouse gases. The IPCC claims that the net cloud radiative feedback is also positive.
8. The IPCC failed to report on the global average radiative feedbacks of water vapor and clouds in terms in Watts per meter squared, and how they fit into the magnitude of the diagnosed global average radiative imbalance.
9. The reason is likely that they would to avoid discussing that in recent years; at least, there has been no significant addition of water vapor into the atmosphere. Indeed, this water vapor feedback, along with any other feedbacks must be ALL accommodated within the magnitude of the global average radiative imbalance that is diagnosed from the ocean heating data!
It certainly appears that, even using the 2013 IPCC WG1 assessment estimates, that the vapor amplification of global warming is not, as least yet, occurring.
I explain and elaborate on these issues below.
Introduction
As I wrote above, the 2013 WG1 IPCC assessment of the magnitude of the radiative forcings on the climate system persists in missing discussing a key fundamental issue, namely the estimated magnitudes of
· the global annual average radiative imbalance,
· the global annual average radiative forcing
· the global annual average radiative feedbacks
and how these quantities are related to each other.
Section 1 The Fundamental Budget Equation
The relationship between the annual global average radiative forcings, radiative feedbacks and radiative imbalance can be expressed by this budget equation
Radiative Imbalance = Radiative Forcing + Radiative Feedbacks
where the units are in Joules per time period [and can be expressed as Watts per area].
The fundamental difference with this approach and that presented in papers such as Stephens et al (2012) – see http://bobtisdale.files.wordpress.com/2013/10/05-figure-1-from-stephens-et-al-2013.png
is that instead of computing the radiative imbalance as a residual as a result of large positive and negative values in the radiative flux budget with its large uncertainty as shown by Stephens et al, this metric is a robust constraint on the analysis of the radiative fluxes.
As Bob Tisdale reports, the Stephens et al value of the global average radiative imbalance [which Stephens et al calls the “surface imbalance”] is 0.70 Watts per meter squared, but with the large uncertainty of 17 Watts per meter squared!
The Stephens et al paper is
Stephens et al, 2012: An update on Earth’s energy balance in light of the latest global observations. Nature Geoscience 5, 691–696 (2012) doi:10.1038/ngeo158 http://www.nature.com/ngeo/journal/v5/n10/abs/ngeo1580.html [as an aside, that paper, unfortunately, makes the typical IPCC type mistake in stating that the
“Climate change is governed by changes to the global energy balance.”
Changes in the climate system on any time scale is much more than just any changes in the global energy budget as we discuss, for example, in
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union. http://pielkeclimatesci.files.wordpress.com/2009/12/r-354.pdf
Section 2 The Radiative Imbalance
With respect to the Radiative Imbalance, as I proposed in my paper
Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331- 335.
http://pielkeclimatesci.files.wordpress.com/2009/10/r-247.pdf
the radiative imbalance can be estimated based on the changes in the ocean heat content. As written in
Levitus, S., et al. (2012), World ocean heat content and thermosteric sea level change (0-2000), 1955-2010, Geophys. Res. Lett.,doi:10.1029/2012GL051106
“The world ocean accounts for approximately 90% of the warming of the earth system that has occurred since 1955”
Jim Hansen had provided his value of the heating rate in a communication to me in 2005 http://pielkeclimatesci.files.wordpress.com/2009/09/1116592hansen.pdf]
as
The Willis et al. measured heat storage of 0.62 W/m2 refers to the decadal mean for the upper 750 m of the ocean. Our simulated 1993-2003 heat storage rate was 0.6 W/m2 in the upper 750 m of the ocean. The decadal mean planetary energy imbalance, 0.75 W/m2 , includes heat storage in the deeper ocean and energy used to melt ice and warm the air and land. 0.85 W/m2 is the imbalance at the end of the decade.”
More recent information, with respect to the Radiative Imbalance is reported in
Levitus, S., et al. (2012), World ocean heat content and thermosteric sea level change (0-2000), 1955-2010, Geophys. Res. Lett.,doi:10.1029/2012GL051106
“The heat content of the world ocean for the 0-2000 m layer increased by 24.0×1022 J corresponding to a rate of 0.39 Wm-2 (per unit area of the world ocean)…. This warming rate corresponds to a rate of 0.27 Wm-2 per unit area of earth’s surface.”
The IPCC WG1 Chapter 3 [http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter03.pdf]
writes
“It is virtually certain that Earth has gained substantial energy from 1971–2010 — the estimated increase in energy inventory between 1971 and 2010 is 274 [196 to 351] ZJ (1 ZJ = 1021 J), with a rate of 213 TW from a linear fit to the annual values over that time period (Box 3.1, Figure 1). Ocean warming dominates the total energy change inventory, accounting for roughly 93% on average from 1971–2010. Melting ice (including Arctic sea ice, ice sheets, and glaciers) accounts for 3% of the total, and warming of the continents 3%. Warming of the atmosphere makes up the remaining 1%. The 1971–2010 estimated rate of oceanic energy gain is 199 TW from a linear fit to data over that time period, implying a mean heat flux of 0.55 W m–2 across the global ocean surface area. Earth’s net estimated energy increase from 1993–2010 is 163 [127 to 201] ZJ with a trend estimate of 275 TW. The ocean portion of the trend for 1993–2010 is 257 TW, equivalent to a mean heat flux into the ocean of 0.71 W m–2.”
Using the 93% dominance of the ocean in this heating, then from the 2013 IPCC report
· 1971-2010 the total earth surface heating rate is 0.59 Watts per meter squared
· 1993-2010 it is 0.71 Watts per meter squared.
Of course, there is the question as to whether the Levitus et al 2012 calculation below 700 meters before 2005 is even robust. The 2013 IPCC WG1 Chapter 3 report writes [highlight added] – http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter03.pdf
“Below 700 m data coverage is too sparse to produce annual global ocean heat content estimates prior to about 2005, but from 2005–2010 and 0–1500 m the global ocean is warming (von Schuckmann and Le Traon, 2011). Five-year running mean estimates yield a 700–2000 m global ocean heat content trend from 1957 to 2009 (Figure 3.2b) that is about 30% of that for 0–2000 m over the length of the record (Levitus et al., 2012). Ocean heat uptake from 700–2000 m continues unabated since 2003 (Figure 3.2b); as a result, ocean heat content from 0–2000 m shows less slowing after 2003 than does 0–700 m heat content (Levitus et al., 2012). “
Remarkably, the IPCC report persists in making claims regarding deeper ocean heating before 2005. But that is a subject for another time.
Section 3 The Radiative Forcing
Using even the largest value [the 0.85 W/me value for the Radiative Imbalance from Jim Hansen], however, it is still significantly less than the total anthropogenic change in radiative forcing since 1750 reported by the IPCC.
In Figure SPM.5 in the 2013 IPCC WG, they report that the total anthropogenic change in radiative forcing since 1750 is
2.29 [1.13 -3.33] Watts per meter squared.
They write that
“The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750.”
and
“The total anthropogenic RF for 2011 relative to 1750 is 2.29 [1.13 to 3.33] W m−2 (see Figure SPM.5), and it has increased more rapidly since 1970 than during prior decades.”
Unfortunately, the IPCC did not provide an estimate of the CURRENT “total anthropogenic RF”.
Some of this forcing would have been accommodated with warming of the climate system since 1750. When I served on the NRC (2005) assessment [http://www.nap.edu/openbook/0309095069/html/], one of my colleagues on the Committee (V. Ramanthan), when I asked him this question, he said that perhaps 20% of the CO2 radiative forcing was already equilibrated to. In any case, the CURRENT forcing must be somewhat less, but not probably by more than 20% or so.
Regardless, unless the IPCC estimates of the Radiative Forcing are too positive, this means that the
Radiative Imbalance < Radiative Forcing.
4. Radiative Feedbacks
However, while the warming of the climate system is a negative radiative feedback, and thus we should expect this part to be a negative feedback [since a surface temperature results in an increase of the outgoing long wave radiation to space], added water vapor, if it is there, would be a positive radiative feedback.
In my book
Cotton, W.R. and R.A. Pielke Sr., 2007: Human impacts on weather and climate, Cambridge University Press, 330 pp
in Section 8.2.8 we reported on an analysis of the water vapor feedback by Norm Woods using column assessments for three selected vertical soundings. Norm showed that the positive significant radiative forcing from even modest (e.g. 5% increase is atmospheric water vapor) is significant. [See also http://pielkeclimatesci.wordpress.com/2006/05/05/co2h2o/].
Norm Woods’s further analysis can be read on this posts
http://pielkeclimatesci.wordpress.com/2007/08/24/further-analysis-of-radiatve-forcing-by-norm-woods/
Among the conclusions for the representative soundings Norm used are
“with the tropical sounding ….adding 5% more water vapor, results in a 3.88 Watts per meter squared increase in the downwelling longwave flux. In contrast, due to the much lower atmospheric concentrations of water vapor in the subarctic winter sounding, the change from a zero concentration to its current value results in an increase of 116.46 Watts per meter squared, while adding 5% to the current value results in a 0.70 Watts per meter squared increase.”
and
“The effect of even small increases in water vapor content of the atmosphere in the tropics has a much larger effect on the downwelling fluxes, than does a significant increase of the CO2 concentrations.”
However, there appears to be no long trend in atmospheric water vapor! This can be seen in the latest analysis we have;
Vonder Haar, T. H., J. L. Bytheway, and J. M. Forsythe (2012), Weather and climate analyses using improved global water vapor observations, Geophys. Res. Lett., 39, L15802, doi:10.1029/2012GL052094. [http://onlinelibrary.wiley.com/doi/10.1029/2012GL052094/abstract]
Although they write in the paper
“at this time, we can neither prove nor disprove a robust trend in the global water vapor data.”
just the difficulty in showing a positive trend suggests a very muted water vapor feedback at most.
The figure from their paper with respect to this analysis is shown below
The 2013 IPCC WG1 SPM report states with respect to the radiative feedbacks that
“The net feedback from the combined effect of changes in water vapour, and differences between atmospheric and surface warming is extremely likely positive and therefore amplifies changes in climate. The net radiative feedback due to all cloud types combined is likely positive. Uncertainty in the sign and magnitude of the cloud feedback is due primarily to continuing uncertainty in the impact of warming on low clouds.” [http://www.climatechange2013.org/images/uploads/WGIAR5SPM_Approved27Sep2013.pdf]
They also write, in contrast to what is seen in the Vonderhaar et al 2012 paper,
“Anthropogenic influences have contributed to observed increases in atmospheric moisture content in the atmosphere (medium confidence)”
This report also write that
“The rate and magnitude of global climate change is determined by radiative forcing, climate feedbacks and the storage of energy by the climate system.”
Of course the report also fails to distinguish “global climate change” [which is much more than just the global average radiative forcings and feedbacks; a mistake also made in Stephens et al 2012].
The IPCC WG1 report discuss the reduced heating and Radiative Forcing in recent years as follows
“The observed reduction in surface warming trend over the period 1998–2012 as compared to the period 1951–2012, is due in roughly equal measure to a reduced trend in radiative forcing and a cooling contribution from internal variability, which includes a possible redistribution of heat within the ocean (medium confidence). The reduced trend in radiative forcing is primarily due to volcanic eruptions and the timing of the downward phase of the 11-year solar cycle. However, there is low confidence in quantifying the role of changes in radiative forcing in causing the reduced warming trend. There is medium confidence that internal decadal variability causes to a substantial degree the difference between observations and the simulations; the latter are not expected to reproduce the timing of internal variability. There may also be a contribution from forcing inadequacies and, in some models, an overestimate of the response to increasing greenhouse gas and other anthropogenic forcing (dominated by the effects of aerosols)…”
Nowhere in this discussion, except implicitly in the mention of internal variability, is the role of the radiative feedbacks including the role of water vapor and clouds presented.
5. The IPCC Failure
The IPCC report has failed to report on the implications of the real world radiative imbalance being significantly smaller than the radiative forcing. This means not only that the net radiative feedbacks must be negative, but they failed to document the magnitude in Watts per meter squared of the contributions to positive feedbacks from surface warming, and from atmospheric water vapor and clouds.
These must be smaller than what the IPCC models are producing.
One clear conclusion from their failure is that the climate system has larger variations in the Radiative Imbalance, Forcing and Feedbacks than is predicted by the model and accepted in the 2013 IPCC assessment report. Judy Curry David Douglass, Roy Spencer, Bob Tisdale, Anastasios Tsonis, Marcia Wyatt and others have been pioneers in advocating this perspective, and the failure in the SPM of the 2013 IPCC WG1 report to discuss this issue is a major failing of the assessment.
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Genghis.
I think we are saying the same thing.
Expansion converts kinetic to potential and so cools the air.
The lower density then allows energy to flow through faster to retain ToA balance.
What happens is that GHGs slow down the energy throughput, expansion then occurs to reduce density and accelerate energy throughput again by an equal and opposite amount.
Meanwhile the ‘surplus’ held by the GHGs has gone to potential energy which does not affect temperature.
It is all made possible because the ‘specific’ part of Rspecific varies according to molecular characteristics other than mass.
The gravitational field stays constant but the behaviour of a molecule within it is not determined solely by its mass.
Since Rspecific is on the opposite side of the relevant Gas Law equation to V one can vary both in parallel without affecting balance.
PV = mRspecificT
Effectively, one can increase V without increasing T, m or P.
Climatology has missed that critical point by focusing on radiative physics instead of the mechanical processes involved.
In radiative physics one MUST increase T in order to increase V.
The radiative flux is a consequence of the mechanical process, merely a side effect.
Although I have been making the general point for years it is only now that I have identified the error being made by others.
The Gas Law equation relating to non Ideal Gases has been incorrectly applied.
Rspecific is a variable but it has been treated as a constant like R in the Ideal Gas Law.
We are not dealing with Ideal Gases.
My proposition fits Roger’s findings does it not ?
It also allows a cascade of other conclusions which I am now exploring.
Nice summary Dr. Pielke Sr., nice summary, and we do appreciate your clear thoughts and considerations.
Perhaps I should offer bit more detail on the effect of changes in atmospheric volume and density on energy transmission through an atmosphere.
Apply a rather absurd example and consider Earth’s current atmosphere expanded out all around the Earth as far as, say, the border of the solar system.
The thermal effect of the delay between arrival time and departure time for energy coming in at the top of such an atmosphere would be spread across the entire distance with only an infinitesimal portion of the effect observable from any given position so the temperature of the atmosphere at any given point of observation between surface and top of atmosphere will be very low. Hardly above the temperature of space.
Then consider Earth’s current atmosphere compacted to 1 millimetre above the surface.
In that case all the thermal effect of the delay between arrival time and departure would be focused within that distance and an observer would see a very hot layer of gas enveloping the planet.
What determines the difference is the relative distributions of kinetic and potential energy.
In the first example nearly all the energy in the atmosphere is potential energy.
In the second example it is nearly all kinetic energy.
In both cases the atmosphere contains exactly the same amount of total energy.
It is that ability of an atmosphere to switch between kinetic and potential energy when expanding or contracting that makes it possible for adjustments to be made when molecular characteristics other than mass seek to destabilise the top of atmosphere energy balance.
That is why the variable nature of the term Rspecific is essential to the formation of atmospheres in the first place and their retention thereafter.
Bill Illis – You have presented an effective figure and summary. We need to make sure the IPCc and other assessments are confronted with this issue. Roger Sr.
lurker, passing through laughing – The expansion from heating of the atmosphere does, of course, occur. However, the heat added in Joules is still present. It is just redistributed.
Alan Watt, Climate Denialist Level 7 – thanks for catching the typos
#9 should be
“9. The LIKELY reason that they avoid discussing IS that in recent years there has been no significant addition of water vapor into the atmosphere.”
The correct way to express the flux, as you noted is W/m2. or Wm-2
Thank you for alerting us to these typos.
Roger Sr.
Stephen Wilde,
How about a counter example? Not that I think we are disagreeing.
The effective source of energy is coming from the surface of the earth because the atmosphere is largely transparent to short wave radiation. The average surface temperature of the ocean is 22˚C. The GHG’s are primarily responsible for creating the temperature gradient (or lapse rate) which starts at 15˚C (at head height) and goes down from there at an environmental lapse rate of 6.5˚C/km.
If you take away all of the greenhouse gases the atmosphere becomes isothermal and 5˚C (and the oceans surface temperature will fall too.) By the way, an atmosphere in equilibrium is isothermal. An atmosphere without water vapor (just GHG’s) will have a higher surface temperature (higher than 22˚C) and a lapse rate of 9.8˚C/km. but if we add water vapor that can lower the lapse rate all the way down to 5˚C/km and lower the surface temperature down to apx. 10˚C.
But here is the thing, the TOTAL ENERGY in the atmosphere stays the same whether it is isothermal at 5˚C, or if it has a lapse rate of 9.8˚C, or if it has a lapse rate or 5˚C.
The only thing that changes is the temperature gradient and the volume of the atmosphere. There can’t be a radiative imbalance on average. Of course the system is not in equilibrium and there is a constant net outflow and net inflow of radiation as the earth rotates.
This is all basic, meteorology 101, that the warmistas never learned.
Genghis.
You can’t have an isothermal atmosphere because the lapse rate set by the pressure gradient prevents it.
I covered those points in my article:
http://www.newclimatemodel.com/how-the-gas-laws-as-applied-to-non-ideal-gases-prevent-the-radiative-capabilities-of-gases-from-contributing-to-the-greenhouse-effect/
Total energy in an isothermal atmosphere would be much higher.
“There is no net loss of energy as one goes up through an atmosphere because a molecule at the surface has the same total energy as a molecule at the top of an atmosphere. At the surface it carries 100% kinetic energy and at the boundary of space it is almost 100% potential energy. The potential energy never quite gets to 100% because space is not at absolute zero.
That brings up a bizarre proposition from the concept of an isothermal atmosphere. The energy content would be skewed towards the top with the molecules at the boundary of space containing both a full load of kinetic energy AND a similar amount of potential energy whereas those at the bottom would have kinetic energy only.
That would result in indefinite expansion at the top of such an atmosphere and it would be lost to space. The gravitational field would not be able to constrain such energetic molecules high up.
So, in fact a radiatively inert atmosphere will still have a convective circulation, there will still be an energy exchange cycling adiabatically between surface and atmosphere, the entire mass of the atmosphere will be involved and the surface will be warmer than the temperature predicted by the S-B equation.
All that will be achieved without greenhouse gases.”
As regards the oceans the amount of kinetic energy that they can hold is set by surface atmospheric pressure because that sets the amount of energy required to achieve evaporation. See here:
http://www.newclimatemodel.com/the-setting-and-maintaining-of-earths-equilibrium-temperature/
Genghis says:
October 21, 2013 at 5:07 pm
Stephen Wilde, “The increase in average heights then reduces average atmospheric density and allows more energy out to space faster to negate their thermal effects. ”
Actually, the increase in average height (volume) is from the kinetic energy doing work (expanding the atmosphere) and hence causes lower temperatures. Just look at the temperature (and height) of a hurricane. The expanded gas radiates less IR than the condensed gas because it is colder. Also moist air contains more energy than an equivalent volume and temperature of dry air.
—–
If the height of the atmosphere changes, doesn’t the area that radiates energy into space change also?
Surface area of a sphere = 4*pi*radius2 i.e. as the r increases the surface area gets larger or the radiator gets bigger and that affects the rate of energy transfer…
***
Leonard Weinstein says:
October 21, 2013 at 10:39 am
This means the added long term effect of return of the deep ocean heat to the surface and increased heat transfer would not be to return the huge amount of energy put into and stored by the ocean, but rather could only have a maximum temperature increase effect of 0.37 C from the deep stored energy, and in fact would be less than that. Since the deeper ocean takes an average of many hundreds to thousands of years to cycle to the surface, the actual long term effect would be even far less than this. Only near surface heating (0 to 700 m or so) significantly matters, and this interchange of energy with the surface is much more rapid. In other words, deep ocean energy storage is not a significant factor in global warming, either on the short or long time scale.
***
Exactly. The deep water (below 700m) is a black-hole for heat, given its huge mass, cold temperature, thermal isolation, and constant replenishment by ice-melting.
“The decadal mean planetary energy imbalance, 0.75 W/m2 , includes heat storage in the deeper ocean and energy used to melt ice and warm the air and land. 0.85 W/m2 is the imbalance at the end of the decade.”
Some stupid questions:
a) Presumably re melting ice (or warming of air/earth) you are referring to net differences. The ice melts and refreezes every year.
2) The vapor pressure of water (at atmospheric pressure) is dependent basically on temperature. First, one couldn’t expect a big change with even + 0.5C change in 60 years. e.g. at 15.0C it is 1.71 kPa and at 15.5 (rough global temp) it is 1.76 kPa.
3) Can we use this relation above as a proxy measure of the earth’s temperature trends. Vonderhaar et al’s figure “Global Monthly Average TPW Time Series” for water vapor shows, strikingly, the rise in temp through the 1980s to the peak in 1998 and the flattening to 2005 and dropping thereafter. They either disengenuously or obliviously say:
“at this time, we can neither prove nor disprove a robust trend in the global water vapor data.”
not noting the the remarkable fit to temperature trends.
“Vonderhaar et al’s figure “Global Monthly Average TPW Time Series” for water vapor shows, strikingly, the rise in temp through the 1980s to the peak in 1998 and the flattening to 2005 and dropping thereafter”
Yes, I noticed that but it is a small variation showing how the water cycle speeds up and slows down with a bit of a time lag as the circulation changes catch up with the temperature trend in a negative system response.
The feature that is conspicuously missing is any sort of correlation with CO2 amounts.
So I agree that the speed of the water cycle as discerned in that data can be used as a proxy for temperature trends.
Likewise one can use global reflectivity from the Earthshine project or the average latitudinal position of the ITCZ or the degree of zonality / meridionality of the global jet streams.
Stephen Wilde,
I read your article and here is where I think you are in error. In an Isothermal atmosphere the
pressure declines as the volume increases, while the temperature stays the same. The equation can also be written P = nRT/V.
The temperature gradient (lapse rate) comes from the thermalization of the energy from the GHG’s. Conduction and convection in the atmosphere are adiabatic, i.e. the warm gases don’t warm the surrounding gases as much as they expand and rise.
I can think of two things to help your visualization, first look at the IR images of a hurricane the top of the hurricane is extremely cold much colder than the surrounding air for the altitude, as much as -120˚C if I recall.
Second visualize a very tall container filled with air at a constant temperature (a normal situation) the pressure will be higher in the bottom of the container than than at the top of the container. Pressure only increases temperature when a gas is being compressed, after a gas is compressed it radiates the heat away. That is the principle behind refrigeration.
Ghengis.
You are using the Ideal Gas Law equation where R is a universal constant.
My article clearly explains why that is not appropriate for a non Ideal Gas atmosphere. One must use Rspecific.
You have either not read it or not absorbed it.
How would ‘thermalisation of the energy from GHGs’ cause a lapse rate ?
An isothermal atmosphere has no lapse rate.
The lapse rate is caused by the decline of pressure with height and that happens whether GHGs are present or not.
Pressure is a result of mass and density. Constant irradiation of a greater density produces a higher temperature than constant irradiation of a lower density because there is more mass present per unit of volume to absorb the irradiation.
The surface temperature is not caused by pressure. It is caused by greater density which happens to be a consequence of greater pressure.
An atmosphere can only achieve the temperature necessary to keep the gases off the surface AND match energy out with energy in.
If anything other than more mass, more gravity or more insolation adds ‘extra’ energy over and above what is needed then ALL of it goes to increasing atmospheric height and the extra height creates more PE at the expense of KE so that T does not change.
I see no way out for AGW theory once one realises that Rspecific is variable for every gas and every mixture of gases.
good discussion
Stephen,
If you take a metal bar and heat one end with a blow torch, that will create a temperature gradient in the metal bar. It has nothing to do with pressure, It has everything to do with the energy flux through the metal. When the blow torch is turned off the metal bar will equalize in temperature and become isothermal.
Greenhouse gases create a similar effect in the atmosphere. The GHS’s absorb and thermalize the LW radiation from the surface. That creates the temperature gradient or lapse rate in the atmosphere. An atmosphere without GHG’s has a very limited mechanism for creating the lapse rate because warm rising air is adiabatic it does not warm the surrounding air.
Here is another thought experiment for you. Take an aerosol can at room temperature, put it in a sealed box at room temperature and release the pressurized gas. Does the temperature of the air in the box change?
I will answer the question, the temperature of the air in the aerosol container will go down and the temperature of the air in the container will go up, The only thing I know for sure is that the energy content in the box will stay the same. I didn’t provide enough detail in the question to answer the temperature question. Which is kind of the problem with this whole Global change nonsense.
Let me use your example to specifically answer your question.
Stephen Wilde, “Pressure is a result of mass and density. Constant irradiation of a greater density produces a higher temperature than constant irradiation of a lower density because there is more mass present per unit of volume to absorb the irradiation.”
Without GHG’s present in the atmosphere, the atmosphere would be transparent to to the long wave irradiation. This is how GHG’s warm the surface and the atmosphere and create a lapse rate.
Genghis says:
October 22, 2013 at 11:10 am
“….
Greenhouse gases create a similar effect in the atmosphere. The GHS’s absorb and thermalize the LW radiation from the surface. That creates the temperature gradient or lapse rate in the atmosphere. An atmosphere without GHG’s has a very limited mechanism for creating the lapse rate because warm rising air is adiabatic it does not warm the surrounding air…..”
So are you saying that a planet with an atmosphere w/o GHGs would only cool through convection theN?
Box of Rocks, “So are you saying that a planet with an atmosphere w/o GHGs would only cool through convection theN?”
No, the atmosphere will cool through long wave radiation. everything radiates.. What I am saying is that the surface would be cooler without greenhouse gases.
Genghis –
Help me with heat transfer.
There are how many different ways an object cools?
I think that the role of increasing evapotranspiration is underestimated in most models and would be interested in comments from others.
This is based on several items. The vegetative health of our planet has been benefiting greatly from increasing CO2. This has been shown by many studies. Most crops have also benefited and modern technology applications have resulted in crops like corn, being planted in much tighter rows. This means many more plants/acre and a corresponding increase in the amount of evapotranspiration.
The fact that it is multiplied by many tens of millions of acres in the Midwest Cornbelt over numerous states, creates a micro climate during the growing season that in my experience/opinion has resulted in dew points often 5 degrees higher than they were 30 years ago with most other variables held constant. This is well documented by several studies.
Along with these higher dew points and all things being equal, the lifting condensation levels are lower which means more clouds and maybe more importantly, more low clouds, which are much more likely to exist after several hours of heating, after which they would clearly be a negative radiative feedback.
The most obvious example of this is the Midwestern US Cornbelt during the growing season. This area may only represent a small % of the total planet but this observation implies that other countries, like Brazil, Argentina or China, with their expanding and more concentrated crop densities are experiencing similar effects.
Taking this one step further, on a larger scale but maybe not as powerful locally is the greening of our planets biosphere and likelihood of additional evavapotranspiration contributions that lead to an increase in, especially low clouds that have a negative radiative feedback.
Box of Rocks, “Help me with heat transfer.
There are how many different ways an object cools?”
Basically conduction, convection and radiation, but ultimately the only way the atmosphere can cool is by radiation to space. I don’t think that is your real question though, help me out here : )
I think your real question is how does the atmosphere warm and the answer to that is primarily via GHG’s thermalizing LW radiation and through convection and release of latent heat of water vapor condensing.
Temperature is almost a red herring, figure out the energy flux first. Cool moist air contains more energy than warm dry air, even though the temperature is lower.
Mike Maguire says:
“I think that the role of increasing evapotranspiration is underestimated in most models and would be interested in comments from others.”
Bingo we have a winner! Water vapor from any source lowers the lapse rate which directly lowers the surface temperature.
It is not of how or why but of what degree.
I just can not wrap my brain around the idea that a gas that constitutes less than 0.5% of the atmosphere can absorb and release enough energy to warm the remaining 99.5% of the atmosphere.
So how does that magical gas work to warm it’s surroundings when in fact it self is cooling along with the surrounding environment?
Box of Rocks says:
“It is not of how or why but of what degree.
So how does that magical gas work to warm it’s surroundings when in fact it self is cooling along with the surrounding environment?”
Think of a microwave oven. If you put a hollow ceramic sphere in a microwave and turn it on it won’t heat up. Squirt some water into the sphere, seal it up tight, turn on the microwave and run! Hasn’t everyone done this?
That is how the ‘magical’ gas works. The atmosphere without GHG’s is very hard to heat up.
The concentration of GHG’s primarily affects the ‘rate’ of heating. A higher concentration of GHG’s will warm the atmosphere faster.
Genghis:
“…
Think of a microwave oven. If you put a hollow ceramic sphere in a microwave and turn it on it won’t heat up. Squirt some water into the sphere, seal it up tight, turn on the microwave and run! Hasn’t everyone done this?…
”
So you are saying that the water after is is vaporized and turned into steam is responsible for warming the ceramic sphere?
So how can something that is less than 1% of a control volume release enough energy (at the right wavelength) to impart enough energy in the remaining 99% to either maintains it temperature or in fact increase it.
Remember – Heat capacity, or thermal capacity, is the measurable physical quantity that specifies the amount of heat energy required to change the temperature of an object or body by a given amount. …. the specific heat of water is 1 BTU/(F°·lb).
So if we have a control volume of 1 foot square … How much energy will it loose to it’s surrounding if it cools one degree F?
So, Ghengis, what you are saying is that minute amount of CO2 in that 1 square foot can convert enough radiation from one wavelength to another to prevent the CV from cooling, right?