Excerpts from Evidence for Negative Water Feedback
by Clive Best
Abstract: Positive linear climate feedback for combined water effects is shown to be incompatible with the Faint Sun Paradox. In particular, feedback values of ~2.0 W/m2K-1 favored by current GCM models lead to non physical results at solar radiation levels present one billion years ago. A simple model is described whereby Earth like planets with large liquid water surfaces can self-regulate temperature for small changes in incident solar radiation. The model assumes that reflective cloud cover increases while normalized greenhouse effects decrease as the sun brightens. Net water feedback of the model is strongly negative. Direct evidence for negative water feedback is found in CRUTEM4 station data by comparing temperature anomalies for arid regions (deserts and polar regions) with those for humid regions (mainly saturated tropics). All 5600 weather stations were classified according to the Köppen-Geiger climatology [9]. Two separate temperature anomaly series from 1900 to 2011 were calculated for each region. A clear difference in temperature response is observed. Assuming the difference is due to atmospheric water content, a water feedback value of -1.5 +/- 0.8 W/m2K-1 can be derived.
I. INTRODUCTION
The Faint Sun Paradox was first proposed by Carl Sagan [1] who pointed out that the geological evidence that liquid oceans existed on Earth 4 billion years ago appears incompatible with a solar output 30% dimmer than today.
The sun is a main sequence star whose output is known to increase slowly with age. The total change in solar radiation over this long period turns out to be huge ~ 87 W/m2. It has been argued that an enhanced greenhouse effect due to very high CO2 and/or CH4 concentrations could resolve this paradox [2]. However, recent geological evidence does not support CO2 as being responsible but instead the authors propose a greater ocean surface leading lower albedo as a likely solution [3]. Others have suggested that high cirrus clouds effectively warmed the Earth [4]. Although the atmosphere must have been very different before photosynthesis began, the presence of large liquid oceans still implies that clouds and water vapor played a similar role in the Earth’s energy balance then, as they do today.
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Figure 1: Past temperatures extrapolating backwards from today (T=288ºK) assuming different linear feedback values.
It is apparent that a simple linear positive feedback of +2 leads to unphysical results. The basic problem is that if the temperature falls sufficiently so that 4σT3= F then a singularity occurs ~1.5 billion years ago. Instead a negative feedback value of -2 W/m2K-1 is more compatible both with current temperatures and with the Faint Sun Paradox..
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IV. CRUTEM4 ANALYSIS
Water vapor feedback in recent climate data have been investigated by studying differences between regions with very low atmospheric water vapor (Deserts and Polar) and those regions with very large water vapor content (Tropical Wet regions). The latest CRUTEM4 data [8] consisting of 5500 individual station data covering global land areas has been studied. Each station was classified by indexing its geographic location against the Köppen-Geiger climate classification [9].
“ARID” stations are defined as those with precipitation values ‘W’ or with climate ‘E’ in [9]. These are situated either in deserts or in polar areas having the lowest atmospheric water column on Earth [10]. “WET” stations are defined as those within fully humid Tropical areas – Climate ‘A’ and precipitation ‘f’ in [9]. These are situated in tropical rain forests or year-round humid climates having the highest atmospheric water column on Earth [10]. Global anomalies have been calculated for both stations ARID and WET stations independently using the same algorithm as used for CRUTEM4. The results are shown in Figure 4.
Figure 4: Temperature anomalies for ARID(DRY) stations in red and WET stations in blue. The smooth curves are FFT smoothed curves. The black dashed curve is an FFT smooth to the full CRUTEM4 global temperature anomalies.
There is a clear trend in the data that ARID stations warm faster and cool faster than WET stations. They respond stronger to changes in external forcing. The WET humid stations respond less than both the ARID stations and the global average.
Climate change is complex and global so it is reasonable to assume that both anthropogenic and natural forcing are reflected in the temperature anomaly data. For a given forcing DS the consequent change in temperature anomaly is gDT where g is a gain factor. The period between 1900 and 2005 is used to measure the temperature rise for each region DT1 and DT2 as given in Table 1. DS is assumed to be global in extent.
Table 1 : Temperature changes for ARID and WET regions and their ratio. Errors on DT are derived from differences between the FFT smooth and a linear fit.
| Period | DT1(DRY) | DT2(WET) | DT1/DT2 |
| 1900-2005 | 1.1 +/-0.1 ºK | 0.8+/- 0.1 ºK | 1.4 +/- 0.2 |
Heat inertia effects due to nearby oceans may cause tropical climates to react slower than desert regions, but not over such long periods. If positive feedbacks from increased water evaporation lead to enhance warming then this should be apparent in the tropics, and this is not observed. In fact the opposite is the case implying a negative feedback. Under the assumption that net water feedback F is present only for the WET stations (taking F=0 for ARID stations) then F can be measured from the data:
DT1/DT2 = 1 – G0F , where DT1 = G0DS and DT2 = G0 (DS+FDT2)
For G0-1 = 3.75W/m2K gives Water Feedback F = – 1.5 +/- 0.8 W/m2K-1
This is compatible with the value needed to resolve the Faint Sun Paradox. As has been pointed out by Lindzen [11] and others, much of the Earth’s heat is transported bodily through evaporation and convection to the upper atmosphere where IR opacity is low and can then escape to space. Therefore water feedback effects depend mostly on the water vapor content of the upper atmosphere. Increased evaporation, convection and consequent rain out could then result in lower humidity in the upper atmosphere. This is a possible mechanism for negative feedbacks in the tropics. Such effects would be largely absent in ARID areas, which have no local sources of evaporation.
Read the entire analysis here, it is well worth your time, well written, and easy to comprehend.
h/t to Scott Gates
I don’t want to be picky, but it would appear that the paper disregards atmospheric enthalpy. There is a considerable difference between the heat required to increase the temperature of a volume of dry (ARID) air and a volume of humid/saturated (WET) air. If this is true this is a major flaw in the paper.
The paper should be assessing the heat content in kilojoules. Temperature alone is meaningless and the incorrect metric for heat content.
(see http://www.engineeringtoolbox.com/enthalpy-moist-air-d_683.html )
The above paper was submitted to Geophysics Research Letters on April 25th. The editor later rejected it on the grounds that “the work appears to represent an incremental advance in our understanding of a problem that has already received attention in the peer-reviewed literature, and extends its conclusions beyond what is supported by the research methods and results“
Phil Clarke says:
May 26, 2012 at 6:45 pm
“,,, a problem that has already received attention in the peer-reviewed literature, and extends its conclusions beyond what is supported by the research methods and results“
Can’t have that, can we?
This is most interesting. I have never fully understood the attractiveness of the the Faint Earth Hypothesis as it is nothing but a model that is based on assumptions, if I remember my Astronomy from all those years ago. This work is filled with assumptions too. That is fine as long as we all remember we are dealing with models based more on assumptions then observations.
“the work appears to represent an incremental advance in our understanding of a problem that has already received attention in the peer-reviewed literature, and extends its conclusions beyond what is supported by the research methods and results“
So the only papers worth publishing are those which support the zeitgeist of the time? And who said science was independant of the social context in which it operates.
Dennis Nikols, P. Geo says:
May 26, 2012 at 7:41 pm
as it is nothing but a model that is based on assumptions
Our understanding of stellar evolution is very good and not just ‘based on assumptions’. We observe stars in all phases of their evolution, so have a direct check on the theory.
The point of the paper is the incompatibility of the Faint Sun and positive water feedback hypotheses. It results in strong paradox.
This is supposed to be news. I do believe I have been saying water feedback is negative (more water vapor, less solar energy absorbed by the earth); almost since we had that faint sun . Heating of the atmosphere is peanuts compared to cooling of the non gaseous part of the earth.
….and along comes Phil Clarke to demonstrate his complete inability to discuss the science in any meaningful manner. Instead he casts aspersions on the paper by noting that it was rejected by some journal. Please Phil, all kinds of good science has been rejected in the past by journals. Turned out that the journals were wrong, and frequently too. But the real problem here is you insisting on cluttering up one thread after another with comments intended to misdirect the reader from the science itself. Being incapable of discussing the science yourself, you have no other tools at your disposal, and so use tactics that are hallmark of trolls.
Phil Clarke says:
May 26, 2012 at 6:45 pm
The above paper was submitted to Geophysics Research Letters on April 25th. The editor later rejected it on the grounds that “the work appears to represent an incremental advance in our understanding of a problem that has already received attention in the peer-reviewed literature, and extends its conclusions beyond what is supported by the research methods and results“
==========================
Thank you for informing us as to the very prompt rejection of this paper. The editor at GRL is really on the ball. Rejection of a submitted paper in less than 30 days. A reference to peer review. By the gang for ‘the cause’? Seems like ‘the peers’ have rubber stamps in hand and reject is the default stamp if it questions previous pal reviews. The approved stamp must be for pal review only.
Thank you again for letting us know pal review still exists. The paper will get a fair vetting here @ur momisugly WUWT. If not the paper, the concept certainly will.
The oceans feature no diurnal variability, they have enormous heat capacity. This mere fact is ignored even today as the oceans cover 78% of the Earth’s surface hence 78% of the surface does not cool at night..
James Hansen ignored this and claimed that the Earth’s surface temperature should reside at -18C which truly is BS when accounting for the Oceans.
Oceans conduct heat to the atmosphere which for the most part is non-emitting so after a few month lag is accounted for atmospheric temps are driven via SSTs once the heat variations are able to traverse the globe/become mixed.
The faint Sun paradox isn’t really much of a paradox when you account for the Ocean’s heat capacity and reduced evaporation rates with the weaker solar output. The solar winds were also much more vigorous.
Solar irradience varies by over 100W/m^2 between the solstices every year, the effect on cloud cover is one thing but topography is important as the highest Earth surface temperatures by far occur during the minimum insolation (NH Summer).
We weight radiation too high and neglect the thermal inertia present in our climate system.
So…. forget Phil, let’s actually talk some science!
As Ian W points out, it takes a lot more energy to heat humid air than to heat dry air. Agreed. The issue is far more complicated than just measuring temperature. But then dry air also cools a lot faster than does humid air. And, since the theory is that water vapour traps LW emanating from the earth surface, one would expect that if the water vapour feedback were significant, it would show up in the temperature trend regardless. Unless itz effects are so insignificant that they are overwhelmed by enthalpy…. in which case, what the heck are we worried about?
While we’re on the topic, has anyone actually studied the total amount of water vapour in the atmosphere over time? Not certain how one would even measure such a thing, but if there was a way to measure it, my guess is that it hasn’t changed appreciably over time. If there’s no extra water vapour due to the extra 1 degree or so temp rise of the last 100+ years, then… there’s no feedback loop to discuss!
There is a huge amount of scientific disagreement and ambiguity about the nature of CO2’s supposed greenhouse effect. But one thing is for sure, if water vapor is a negative feedback, AGW theory has a major problem.
Yet, regardless of whether water vapor is a negative or positive feedback, CO2 is a trace gas, constituting just a minuscule 1 in 2500 parts of the atmosphere. In previous ages there has been as much 18 times the level of CO2, to 7000 ppm, with no discernible effect on the climate. It’s almost common sense to reason that the ultra-trace gas CO2’s effect doesn’t amount to a hill of beans. As the MIT professor Richard Lindzen puts it: “Claims… that man’s activity have contributed to warming are trivially true but essentially meaningless.” Piers Corbyn, in a comment, takes it further: “Observational evidence gives the possibility that the net effect of CO2 increases on World temperatures may not be ‘only trivial’ but in fact miniscule, zero, or even negative due to errors in some of the science some claim or – I would suggest – hitherto not understood feed-back and competing processes…” There is no empirical evidence that CO2 effects climate scale temperatures: http://www.youtube.com/watch?feature=player_embedded&v=WK_WyvfcJyg
By a strange coincidence, only a few minutes ago I was perusing a paper by Carl Brehmer that I found through Postma’s site, Principia Scientific (by way of James Sexton’s blog), that has marked similarities to this paper in that it looks at latitudinally paired humid and arid locales and compares temperature records looking for feedback signals (also negative, as it turns out):
http://myweb.cableone.net/carlallen/Greenhouse_Effect_Research/Water%20Feedback_files/Is%20Water%20Vapor%20Feedback%20Positive%20or%20Negative.pdf
When I popped over here to see WUWT’s take on Postma, I found this post. Kinda eerie.
REPLY: I ignore anything published by the “slayers” in their fake journal “Principia Scientific”. It isn’t worth anyone’s time – Anthony
The faint young sun paradox is lessened by the theory of high ancient obliquity (viz. G.E. Williams at Google Scholar), which causes hot-water summers at the poles, preventing permanent freezing. Annual high temperatures would be why life seems to have a high-temperature origin. At high obliqities, equatorial continents can become glaciated, misinterpreted as a Snowball Earth.
About a billion years ago, Earth’s obiquity lowered to a critical 54 deg, when the poles are no longer the hottest. Modern obliquites were attained about half a billion years ago, via core-mantle coupling. If Earth’s obliquity had stayed high, it’s hard to imagine life ever flourishing on land.
“”””” davidmhoffer says:
May 26, 2012 at 9:57 pm
So…. forget Phil, let’s actually talk some science! “””””
Best be cautious David; not all Phils are created equal !!
First, has anyone bothered to study the effects of the change in the composition and especially the density of the atmosphere over time? I ask this because today, science has become compartmentalized, no scientist bothers to learn about any branch outside of their own, increasingly narrow specialty. Thus, they don’t seem to know the recently learned fact that the atmosphere is being slowly stripped away by the solar wind (helped by the moons tidal effects) and at a far faster rate than previously believed. This means that as we go back in time, the atmosphere gets progressively thicker. That will effect any greenhouse effect from anything, and will also effect evaporation and how much water vapor the atmosphere can hold and in what form it will take as clouds. So, how would an atmosphere say 5 times thicker than today (and it was probably more dense than that) effect evaporation, the amount of water vapor the atmosphere can hold, clouds, the type and altitude of clouds, the amount of UV radiation at the surface, and many other things? We should not only find out what effect the different composition of the atmosphere back then had (lots of methane etc), but the effect of that at a much higher density.
Second, are we saying that there was a much greater surface area to the ocean back then? We know that when the earth first formed, and was hot, it would be fairly smooth, and after it starts to cool, the crust will start to wrinkle. When it was smooth, the ocean could cover the entire earth, when it wrinkles, dry land will hump up out of it. Are we then to conclude that the crust continued to wrinkle slowly over billions of years, with higher land and deeper and thus smaller in surface area oceans as time went on, and if so, for how long, when did the oceans and land attain the proportions compared to each other that they have today?
Until we know the answers to these questions, how are we to know how much effect water vapor has in an unknown earth with an unknown atmosphere? And why do “scientists” always insist that things were, back then, exactly like they are today? They need to look outside their own little specialty. They need to get out more.
Liquid oceans for 4 billion years despite huge volcanic outbreaks, asteroid strikes, changed atmospheric density and composition and a substantial change in the output of the sun.
The only solution is a strongly negative water cycle response to ANY disruption to the system.
That said, it doesn’t have to be water. Any material capable of a phase change involving latent energy exchanges will do the job such as Methane on some of the outer planetary moons and CO2 itself on Mars where it seasonally gets deposited at the Martian poles as a solid then evaporates in the Martian polar spring.
Interstellar Bill says
“At high obliqities, equatorial continents can become glaciated, misinterpreted as a Snowball Earth.”
“Snowball Earth”/low latitude glaciation only occurred in a brief interval about 700 million years ago. The 3 billion years before that were remarkably free of glaciations at any latitude.
@Ian W Yes you are correct about enthalpy differences. However here we are comparing annual average temperature anomalies for land areas only covering 120 years. Nearly all solar radiation is absorbed by the surface which cools be emitting IR. Greenhouse gasses reduce outgoing IR to space leading to increased surface temperatures to restore overall energy balance. Water is a strong greenhouse gas but has it also has other effects – lapse rate, clouds etc. It is to be determined experimentally if the net feedback is positive or negative.
@Phil Clarke The conclusions of the paper may be correct or they may be false, but a negative feedback is NOT an incremental advance over a positive feedback. I therefore welcome all critical arguments, and stand willing to be corrected if in error.
There is clearly much to discover about the Earth’s early atmosphere, volcanic activity, meteor impacts etc. However, It is remarkable that for over 80% of the Earth’s history geology proves that the surface has been mostly covered in liquid water. That must say something profound.
REVIEWS OF GEOPHYSICS, VOL. 50, RG2006, 29 PP., 2012
doi:10.1029/2011RG000375
The faint young Sun problem
Georg Feulner
Earth System Analysis, Potsdam Institute for Climate Impact Research, Potsdam, Germany
For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem.” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25% lower than today. This would result in a completely frozen world over the first 2 billion years in the history of our planet if all other parameters controlling Earth’s climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane, or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geochemical constraints on the composition of Earth’s early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely.
The assumptions Dennis is talking about are about the composition of the early Earth atmosphere and about the impact of those components on the themperature of the early Earth. The initial explanation was that the “greenhouse effect” of gases such as CO2, and mainly CH4 and ammonia kept Earth above freezing point. They were assumptions because there was not evidence of big amounts of ammonia in the early Earth atmosphere. Later it was found that ammonia couldn’t be the explanation because is photochemically unstable and renders N2 and H2. .
Other possible explanations are also based on similar assumptions.
Of course.
Let’s not forget that according to this study the earth has had much more water in the early days:
http://sciencenordic.com/earth-has-lost-quarter-its-water
Very interesting! But one thing that immediately struck me, is that the most arid areas of the world are the artic and Antarctic deserts, so I wonder if the crutem4 analysis could simply be explained by cyclical climate in the Arctic. If I were a reviewer, I think I would have asked for a discussion of how the wet/arid difference appears in different latitude bands.