Related: A simple disproof of the runaway greenhouse theory and basis for climate alarm
Evidence for Negative Water Feedback
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-1favored 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 . 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.
The Faint Sun Paradox was first proposed by Carl Sagan  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 . 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 . Others have suggested that high cirrus clouds effectively warmed the Earth . 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.
All current IPCC models adopt net positive feedbacks for water vapor and clouds . A doubling of CO2 increases TOA radiative forcing by ~3.6 W/m2 causing a baseline surface temperature rise of about 1°C to restore global energy balance through increased outgoing Infrared . GCM models predict larger temperature rises ranging from 2-5°C due to these positive feedbacks. What do positive feedbacks imply for the Faint Sun Paradox? For a change in forcing DS, a feedback strength F, and G0 as the baseline response, the temperature rise DT is given by
DT = (DS +F.DT)G0
Black body radiation from the Earth’s surface is the primary negative feedback to any temperature rise DT.
DT =DS/(1/ G0 -F) 1/ G0 = 4?T3 = 3.75 W/m2K-1 T=288K
GCM model feedbacks F range from +1.6 to 2.5 with an average positive feedback of ~ 2.0 W/m2K-1 .
The sun has brightened 30% over the last 4 billion years and current average incident solar radiation is ~342 watts/m2. Assuming a slow linear increase of solar radiation with time yields a net forcing increase of 0.02 W/m2 every 1 million years. The temperature response to this forcing has been calculated for feedback values F=-2, 0, +2. This can be integrated backwards 4 billion years from current temperatures. The results are shown in Figure 1.
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 4?T3= 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..
The evidence is that global surface temperatures have changed rather little over the Earth’s history. It therefore seems likely that feedbacks were negative during the early lifetime of the Earth to avoid run away surface heating as the sun brightened. The continuous ~70% surface coverage of water on Earth has apparently stabilized global temperatures. A simple model of how this could work is described next, in analogy with Daisy World proposed by James Lovelock to justify Gaia theory .
remainder at CliveBest.com
Nice mathematical explanation of the thunderingly obvious.ReplyDelete
It's clear that a cognitive singularity has occurred in Climate Science, as it is replete with contrary-to-fact assertions and extrapolations. I blame positive feedback, in the forms of group think and financial exploitation success.
What meteorologists have known all along.ReplyDelete
Something that meteorologists have known all along.ReplyDelete
The observational fact that there has been no warming for 16 years supports the assertion that the planet resists forcing changes (negative feedback) rather than amplifies forcing changes (positive feedback).ReplyDelete
The warmists are running out of explanations and excuses to explain a plateau of no warming for 16 years.
Lindzin and Choi’s two papers both support the assertion that planetary cloud cover, for the planet as a whole (strongest negative feedback is in the tropics) increases or decreases to resist forcing changes.
On the Observational Determination of Climate Sensitivity and Its Implications
Richard S. Lindzen1 and Yong-Sang Choi2
….We again find that the outgoing radiation resulting from SST fluctuations exceeds the zerofeedback response thus implying negative feedback. In contrast to this, the calculated TOA outgoing radiation fluxes from 11 atmospheric models forced by the observed SST are less than the zerofeedback response, consistent with the positive feedbacks that characterize these models. ….
Rud Istvan says:ReplyDelete
September 13, 2013 at 4:46 pm
Throwing good money after bad is never wise.
All GCMs fail because the grid scale resolution you post (same image used in my book) is far too coarse to resolve things like tropical thunderstorm convection cells (which is why GCMs cannot resolve Lindzens adaptive iris, and therefore why CMIP5 still gets the water vapor feedback wrong, therefore why they still predict an equatorial troposphere hot spot when there isn’t one), or clouds.
This is inherent in the most powerful supercomputers, which are a couple of orders of magnitude not powerful enough to be able to adequately model these necessary phenomena on suitable small gridscales. Leaked AR5 WG1 SOD Chapter 7 (clouds) even said they may never be powerful enought to do so, before concluding that cloud feedback was significantly positive based on (and this is a direct quote) “unknown contributions by processes yet to be accounted for.”
IPCC cargo cult science.
So this formal appeal for GCM consolidation has very little real appeal. First rule of holes if you are in one and want out: stop digging.
the feedbacks are NEGATIVE by empirical evidence:ReplyDelete
Our JGR Paper on Feedbacks is Published
Then the next year he expands on it with another science paper, based on EMPIRICAL data:
Our Refutation of Dessler (2010) is Accepted for Publication
Since then there has been little support for the virtual reality modeled positive feedback idea.
Recent data from NASA shows decreasing H2O in the atmosphere, especially after 2008,
Ian W says:ReplyDelete
June 28, 2014 at 5:47 am
Geoff Sherrington says:
June 28, 2014 at 3:13 am
Colleagues here in Australia are working on a correlation between rainfall at a site and its maximum daily temperature. At sites so far examined in detail, the conclusion seems to be that “water cools”.
The correlation is not shown yet to be causation, but it is strong and large.
It is plausible that temperatures might need adjustment for rainfall before they are to be used for certain purposes. If it is not already catered for, one example of a need for rainfall-corrected data sets would be estimation of climate sensitivity. Another would be the calibration of tree ring proxies, which might be better done after removal of a known growth agent, namely rainfall, from the temperature data used for calibration.
Water as vapor and droplets raises the enthalpy of the air so a volume of air with increased enthalpy can carry more heat before rising in temperature. So the amount of heat in the atmosphere may remain constant as temperature varies with the amount of water. Temperature is the incorrect metric for measuring heat retention due to radiative gases.
Back again after a long hiatus. I found thisReplyDelete
excellent paper quickly. Nice piece of work.
I am thinking of setting up yet another AGW
blog on which I will put my own calculations
relating to global warming. If I do so, you
will surely be given a URL for it.
BTW, my climate sensitivity values
continue to be quite low. Currently:
CS : approx. = 0.5 deg.C