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
Phil does not think that the ocean surface water cools at night. Yes it does. Having swam in the sea both late afternoon and early morning in the tropics I can assure him that the water is cooler in the morning. Late afternoon the surface gets quite hot in the top meter below that it becomes quite cool.
Everything looses heat if the heat source is removed it is the rate of heat loss that varies between water and earth due to heat capacity and heat conduction through the surface material.
Eric Simpson says:
May 26, 2012 at 10:09 pm
My understanding of the alarmist CAGW ‘argument’ is that the water vapour feedback is positive. Hence, the amplification of the alleged CO2 effect. As you say, a zero effect, or even negative effect of water vapour, completely destroys any CAGW position. It is quite noticeable how this is never really explained by the warmista!
Most of the arguments presented in this paper seems reasonable to me. I would say that pro-CAGW critics could only ignore these results on the basis of the missing greenhouse forcing estimates for the geological past.
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf The IPCC’s best CO2 forcing estimate is 3.6-3.8 Watts per sq. meters per doubling – which includes a net positive feedpack parameter, λ = 0.8 K/(W/m2).
If I try to imagine an absurd world where water vapor acts as an amplifier in case of greenhouse forcing and as a dampener during increases in Total Solar Irradiance (TSI), even the large climate sensitivity estimates presented by the IPCC are not enough to explain away the Faint Sun Paradox. For a period of two billion years, we get a cumulative solar forcing of 40 W/m2. Geological records suggest relatively similar CO2 concentration during the Precambrian, with a best estimate of 6000 ppmv. If we assume a ‘pre-industrial’ level of 280ppmv and accept the IPCC numbers, we get an additional greenhouse forcing of 15.8-16.7 Watts per sq. meters. Large carbon dioxide concentrations can explain only 40-42 percent of the total discrepancy and if we admit that our Earth was (almost) completely unglaciated in 90 percent of her lifetime, the unexplained part becomes larger.
By assuming a zero feedback parameter the total CO2 forcing during a concentration increase of 280 ppmv to 6000 ppmv (which equals 4.4 doublings) is reduced to 4.1-4.5W/m2. It is almost a magnitude smaller than the total change in solar irradiance during the last 2 billion years.
Other naturally occuring greenhouse gases e.g. methane have extremely narrow IR absorbtion bands and we can only measure their atmospheric concetrations in parts per billions of volume: http://noconsensus.files.wordpress.com/2010/04/image71.gif
As far as global temperature records are failing to show steep increases in near surface average temperature, upper-troposphere specific humidity is decreasing according to radiosonde data and explaining the geological past seems impossible with the assumption of a net water vapor feedback I will remain a skeptic of the mainstream/IPCC version of global warming theory.
Could another interpretation be that in the wetter areas certain frequencies are saturated in water vapour so that less increase in feedback is possible, this coupled with more clouds could tip feedback negative? How does cloudiness change in the wet areas correlate with Crutem4?
We wrote this paper in 2002. Excerpt:
Computer models that predict catastrophic human-induced global warming have consistently failed to accurately reproduce past and present climate changes, so their predictions of future climate changes are highly suspect. These models incorrectly assume that increased CO2 concentration is a major driver of atmospheric warming, and also assume large positive feedbacks arising from increased CO2 concentration, for which there is no scientific evidence. Without these speculated positive feedbacks, even a doubling of CO2 concentration would lead to a theoretical warming of only approximately 1º C.
Full paper at http://www.apegga.org/Members/Publications/peggs/WEB11_02/kyoto_pt.htm
Applying Occam’s Razor:
There is a more succinct explanation, as provided by Stephen Wilde, May 26, 2012 at 11:42 pm
“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.”
I might delete the word “strongly” from Stephen’s post, but otherwise agree.
More Occam:
As I have said here before: :there is ample evidence that climate feedbacks are negative – if these feedbacks were strongly positive, life on Earth would be very different, if it existed at all.“
A quote from the postscript on Clive Best’s site: 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
Is this a joke from an editor of a respected peer-reviewed journal? Where are the recommendations on how it would be possible to get this paper accepted? We live in a strange world.
Maybe adding a statement like ‘Our results does not disprove that human activities are causing and will cause catastrophic changes in the global cimate system’ would have been enough to get it through the gatekeepers.
Over the eons the atmosphere very slowly seeps away into space (asteroid impacts may occasionally contribute). It is highly likely that atmospheric pressure was much higher in the past – and the relatively large size of flying dinosaurs and insects of the past would tend to back this up.
Even an increase of just 20% in atmospheric pressure would increase average global temperatures by up to 10 deg C. It is such a large effect that it can easily account for the higher temperatures on earth with the faint early sun. A thicker atmosphere also alters circulation of heat from tropics to pole – reducing the variation in temperature.
It is about time this study was done. I even mentioned it here at WUWT several years ago.That it took so long before being presented is an indication that it was probably thought of and carried out before this and roundly rejected by Pal-review.
I don’t wish to feed the troll, but I looked at the phrase he cut-and-pasted in:
“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“
And what do I see? That this paper by Clive Best Advances the science Apparently, Dr. Best has provided new information that extends the argument. I guess filthy, errr, phil c, cannot stand that.
Legatus says:
May 26, 2012 at 10:36 pm
First, has anyone bothered to study the effects of the change in the composition and especially the density of the atmosphere over time?
The density may be the key. A thicker atmosphere would be a very different atmosphere all other things being equal. It makes any comparison questionable from the start.
Urederra says:
May 27, 2012 at 2:14 am
The assumptions Dennis is talking about are about the composition of the early Earth atmosphere
He was referring to a model, so one could only assume he meant the solar model, as there are many models for the Earth’s atmosphere. I refer to my other post with a link to the current status of the faint solar paradox. The point is that the paradox is still with us. We cannot make the paradox go away by hand waving about ‘assumptions’.
I’m glad you presented this to a wider audience, Anthony, I personally find it very convincing.
The highest mean annual temperature anywhere on the planet is an equatorial low desert with less than 3 inches of annual rainfall. If water were a positive feedback then the place with the highest mean annual temperature would be a wet equatorial climate not a dry one. Quod erat demonstrandum.
Allan MacRae @ur momisugly May 27, 2012 at 3:39 am
if these feedbacks were strongly positive, life on Earth would be very different, if it existed at all
This cannot be emphasized enough. With positive feedback, any system will go to the extreme and stay there. Throughout its history, the Earth climate appears to have been remarkably stable, indicating negative feedbacks.
This, for me, is the fundamental lie of the Warmistas.
Interesting paper on feedbacks. I’ve always thought the positive feedback assumptions in GCMs is crazy talk. If in nature, positive feedbacks always more than offset negative feedbacks, the Earth would be similar to Venus, and life would never have evolved.
A few months back, I queried “Real” scientists as to whether they’d ever thought to run their GCMs many times, keeping all data the same, while varying their feedback assumption, from highly negative to highly positve, to see which virtual feedback level best matched the “actual” temperature record, as predicted by each particular model. To me, this seems like a great idea, a slam dunk, given the alleged criticality of anthropogenic CO2 forcings.
You could hear crickets chirping. Although I did get one response. RC regular Hank Roberts flattered me with an answer, informing me that supercomputer time is very expensive (I’ve worked as a software engineer for most of my professional life, so this was not a revelation to me).
Ergo, we can’t spend the relatively little money it would cost to run some computer models now, to see if CAGW is more likely, but we MUST demand the immediate and radical crippling all the western economies by restricting fossil fuel energy. Sometimes these people are just nuts in their imbalance.
John Marshall says:
May 27, 2012 at 2:41 am
“Phil does not think that the ocean surface water cools at night. Yes it does. Having swam in the sea both late afternoon and early morning in the tropics I can assure him that the water is cooler in the morning. Late afternoon the surface gets quite hot in the top meter below that it becomes quite cool.
Everything looses heat if the heat source is removed it is the rate of heat loss that varies between water and earth due to heat capacity and heat conduction through the surface material.”
John, the difference is that the oceans do warm in depths – the sunlight goes up to 200 m, even infrared goes about the first meter deep in the water. (btw, only the DLR from greenhouse goes only 6-8 microns deep – so stops at the surface layer).
When the oceans cool at the surface, it cools only the thin layer of the surface, not in depth. So this colder water will isolate the warmer water from below. It will of course mix, but this takes time. The water from below does not radiate – no IR transmition through water, only at the surface.
This makes oceans behave very differently then rocks which heat a lot at the surface and radiate much fater.
“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.”
This would work by the adiabatic cooling of moist thermals rising to a higher altitude, raising the height of the tropopause and reducing its temperature. The tropopause is highest and coldest over the tropics. The moisture in the stratosphere is controlled by the dew point of the tropopause and that is very low indeed, around -60°C depending on latitude. IR heating of the rising thermals by increased CO2 should cause an increase in altitude of the tropopause by slowing the condensation of water vapor.
Measurable results should be a drop in stratospheric humidity, a rise in the tropopause height (might be difficult to see a trend), a reduction in the tropopause temperature (easier), and an increase in the height of thunderstorms, especially over the tropics as in “The Thermostat Hypothesis.”
Maybe it’s time to add clivebest.com to the sidebar list of blogs?
Best’s analysis is compelling.
Additionally, you don’t even need negative feedback from clouds to limit temp rise from CO2 or any GHG. The weather is a water-vapor driven heat engine.
Consider the weather as a steam-locomotive with the wheel-action the work produced by the heat-engine, and the waste-heat out the stack as the resulting temperature. If you add more heat-input (fuel burned), say from GHGs or increased solar input, some of that added input will result in increased work output, along with some increased heat out the stack. The amounts depend on the efficiency of the engine.
If standard GHG theory says the bare CO2-doubling effect is ~1.2C, the actual rise will be LESS than that, as some of the added fuel input will go into increasing the work output (winds, convection, subsidence, etc). All of the increased fuel burned will NOT just go straight out the stack, as ~1.2C assumes.
IMO, ~1.2C from doubling CO2 is the maximum possible temp increase (w/no heat-engine effects). The actual will be less. If clouds cause negative feedback, the actual temp rise will be even less than that.
“Clive Best gives evidence for negative water feedback in Earth’s climate system using the faint sun paradox and CRUTEM4 data”
I think he made a monumental mistake.
CRUTEM4 data is from 1900 to 2012. Faint Sun is from at least 4 billion years ago (bya).
One cannot compare “current” climatic conditions with paleoclimatic conditions or draw any kind of trend between them as figure 1 tries to do. Certainly not from 4 bya.
Earth was so much more different then than now. We don’t even know how land distribution or ocean currents were in those epochs. How deep the oceans were or how geologically active the planet was. All these and other factors (greenhouse gas concentrations, no oxygen, no plants to name a few) contribute to other climatic conditions with probably other feedback conditions than current climate does with deep cold oceans.
Mickey Reno says:
May 27, 2012 at 6:36 am
RC regular Hank Roberts flattered me with an answer, informing me that supercomputer time is very expensive.
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There are more than a dozen major climate models that all run with the positive feedback assumption, and not a single model runs with a negative assumption. To have so many models running with the same assumption and not a single model testing the other possibilities is the real waste of money.
When the IPCC says the rise in temperature cannot be explained except as a consequence of CO2, what they are really saying is that it cannot be explained “except under the assumption of positive feedback”.
They haven’t looked at negative feedback and they can’t explain temperatures. From this it is reasonable to conclude that negative feedback may be the overlooked explanation.
Phil says:
May 26, 2012 at 9:50 pm
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It also should not be forgotten that in the early period of Earth’s formation, the earth spun significantly faster such that a day was only about 6.5 hours.
By the time oceans were forming a day may have been about 8 or so hours. Thus the diurnal range in the early period of Earth’s history is likely to be far less than it is seen to be now since the period of cooling was far shorter.
Just a though but it may be that the faster spin rate of the Earth offsets the effects of a faint sun.
This work appears to be a significant finding. One concern I would have is to ensure that the data is not simply modelling differences in latitude between wet and dry regions. Maybe adjust for grid size the way climate data is adjusted as a check.
It is possible the journal is trying to minimize the fallout that such a finding could have on its readership so perhaps the conclusion should be worded in such a way as to minimize the controversy by avoiding reference to GHG, but rather present the paper as “a possible solution” to the faint sun paradox.
The temperature anomaly data for the two samples are correctly weighted for grid sizes. It uses the same algorithm for area weighted averaging as that used by CRU. Also I am not really trying to explain the faint sun paradox as such. Rather I am drawing attention to the contradiction implicit in all models with built in positive feedback from water. The oceans would have long ago boiled away with any positive feedback. It is almost impossible to imagine another scenario where other possible effects (denser atmosphere, methane, geothermal, large tides etc.) conspired so perfectly as to exactly balance the amplifying effect of positive water feedback over the last 4 billion years.
RobL says:
May 27, 2012 at 4:27 am
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Some postulate that atmospjheric pressure was double during the time of the dinosaurs. There are many papers covering the pumping of blood in dinosaurs and flight of pterosaurs which conclude that atmospheric pressure must have been far higher back then.
We also need to remember that earth was so different 4 billion years ago. Good science tells us that land masses were fuzed and ocean currents were much different. The moon was significantly closer with huge tides that rushed into the super continent over long distances. Volcanic activity was most likely greater just to name a few. Does this analysis take any of this into account? My skepticism remains.