Are Local weather Feedbacks Strongly Non-Linear? – ?

By Bob Irvine

Is it doable that the Earth’s system is strongly buffered with robust constructive ice and mud feedbacks prevailing at colder temperatures, and robust detrimental convection/evaporation feedbacks prevailing in hotter instances?

Suggestions Issue (FF) is outlined as the overall temperature change at equilibrium for a given forcing divided by the calculated “no suggestions” temperature from that forcing.

The time period CO2 will probably be used right here to signify all of the non-compressing GHGs. (CO2, MH4, N2O, CFCs, HCFs and so forth.)


It’s definitely doable that robust constructive feedbacks can apply in a world the place H2O exists as a vapor within the environment, in addition to water and ice.

It can be crucial right here that we signify the alarmist place precisely and truthfully. Gavin Schmidt, director of GISS, and his predecessor James Hansen have pushed the alarmist narrative on the subject of local weather feedbacks.

Lacis, Schmidt et al. (2010) represents the alarmist narrative.

Pubs.GISS: Lacis et al. 2010: Atmospheric CO<sub>2</sub>: Principal management knob governing Earth’s temperature (

They base their paper on the next assumption which I settle for.

The distinction between the nominal international imply floor temperature (TS = 288 Ok) and the worldwide imply efficient temperature (TE = 255 Ok) is a standard measure of the terrestrial greenhouse impact (GT = TS – TE = 33 Ok). Assuming international power stability, TE can be the Planck Radiation equal of the 240 W/m2 of world imply photo voltaic radiation absorbed by Earth.

They then attribute virtually all of the GH impact (33C) to CO2 with the water vapor part as a suggestions solely.

Noncondensing greenhouse gases, which account for 25% of the overall terrestrial greenhouse impact, … present the steady temperature construction that sustains the present ranges of atmospheric water vapor and clouds through suggestions processes that account for the remaining 75% of the greenhouse impact.”

A Suggestions Issue of about 4 is implied by this 25% determine. They then take the following logical step and attribute practically all local weather change to CO2 with insignificant photo voltaic enter and inner variability being the one different contributors.

These research established way back that water vapor and CO2 are certainly the principal terrestrial GHGs. Now, additional consideration exhibits that CO2 is the one which controls local weather change.

To the political thoughts the proof of all that is fairly easy.

This misunderstanding is resolved by easy examination of the terrestrial greenhouse.

The concept of “CO2 because the local weather management knob” is then bolstered by eradicating all CO2 from the 1980 environment utilizing the local weather mannequin, GISS Mannequin E [G. A. Schmidt et al., J. Clim. 19, 153 (2006)]. The ensuing huge temperature drop after feedbacks is summarised beneath in Lacis, Schmidt, et al. 2010.

The scope of the local weather affect turns into obvious in simply 10 years. Through the first yr alone, international imply floor temperature falls by 4.6°C. After 50 years, the worldwide temperature stands at –21°C, a lower of 34.8°C. Atmospheric water vapor is at ~10% of the management local weather worth (22.6 to 2.2 mm). World cloud cowl will increase from its 58% management worth to greater than 75%, and the worldwide sea ice fraction goes from 4.6% to 46.7%, inflicting the planetary albedo of Earth to additionally enhance from ~29% to 41.8%. This has the impact of decreasing the absorbed photo voltaic power to additional exacerbate the worldwide cooling.

Some water vapor is then attributed to the solar (10%), are you able to consider, leaving an approximate suggestions issue for CO2 forcing of three.3. The official determine that has not modified to today.

Schmidt then implies that feedbacks to incremental temperature change in the course of the Final Glacial Maxima apply to the hotter interglacial world we inhabit at present.

   “…the final glacial interval is an effective instance of a giant forcing (~7 W/m2 from ice sheets, greenhouse gases, mud and vegetation) giving a big temperature response (~5 ºC) and implying a sensitivity of about 3ºC (with substantial error bars). Extra formally, you possibly can mix this estimate with others taken from the twentieth century, the response to volcanoes, the final millennium, distant sensing and so forth. to get fairly good constraints on what the quantity needs to be. This was completed by Annan and Hargreaves (2006), they usually give you, you guessed it, 3ºC.”

On this manner a story is established. CO2 is promoted because the management knob of the local weather with incremental adjustments in photo voltaic exercise lowered to insignificant.


The alarmist narrative is just too easy, and all of the local weather fashions are operating scorching. Consequently, all of the predictions based mostly on these fashions have failed (see Appendix “A”.). There are some areas of rapid concern with the Lacis, Schmidt 2010, strategy.

Of their modelled experiment sea ice fraction goes from 4.6% to 46.7% “inflicting the planetary albedo of Earth to additionally enhance from ~29% to 41.8%.”. 12.8% (41.8 – 29) of 340 w/m2 is an enormous ice suggestions of 43.5 w/m2 which dwarfs the 25 w/m2 for all of the non-condensing GHGs.

Within the trendy world, ice has retreated to the colder poles the place the suns angle is indirect. Ice feedbacks at present are an order of magnitude weaker than discovered within the mannequin experiment. If we take account of this, the suggestions issue have to be lowered considerably in a hotter world.

On the different excessive, a hotter world will drive higher convection, an enormous detrimental suggestions. Convection is allowed for within the fashions however is extraordinarily complicated. If the fashions have it unsuitable in any manner, suggestions issue may very well be considerably impacted. Definitely, this huge detrimental suggestions will probably be stronger in a hotter world.

Lacis, Schmidt 2010, particularly rule out any feedbacks which are distinctive to photo voltaic exercise. These might embrace, cosmic ray results, jet stream adjustments, and any variety of others. The oceans temperature profile is overwhelmingly pushed by photo voltaic forcing. Is it doable {that a} hotter ocean reacts extra vigorously to photo voltaic change than a colder ocean?

 As an illustration Determine 1 exhibits a doable relationship between CO2 and suggestions issue (FF). There are after all huge error bars concerned right here so this could solely be handled as “for dialogue solely”.

Determine 1. A doable comparability between CO2 focus and Suggestions Issue (FF). The low trendy suggestions issue displays my very own prejudices. The opposite two management factors are at zero CO2 ppm (Lacis 2010, discovered a FF of 4 at -21C international temps for zero CO2 taken from a 1980 environment), and at 100 ppm (Annan 2006, discovered a FF of two.7 at 9C international temps which might apply with 100 ppm CO2).



These exaggerated constructive feedbacks could not apply in a hotter interglacial and will have prompted all of the IPCCs forecasts to fail inside 10 years of their announcement. Their forecasts have constantly failed for the reason that first one was tried by James Hansen in 1988. See Determine 2 beneath. The latest of those is the anticipated temperature enhance within the Fourth Evaluation Report 2007. See Determine 9 beneath.

Determine 2. Hansen’s failed predictions from 1988. CO2 concentrations have really grown quicker than state of affairs “A”. The black and pink strains are the closely adjusted floor file (All the time including additional warming on common).

Present CO2 concentrations are growing at a charge just like the A1T and B2 eventualities within the 4AR IPCC report copied right here. I’ve used them for that reason.

These eventualities lead to between 750ppm and 800 ppm CO2 focus within the yr 2100. Learn the above hyperlink to get a way of the IPCCs processes and their place on future warming.

Determine 3, The IPCC forecast from 2007 in comparison with precise temperatures. The pink line is the Hadcrut4 temperature sequence.  It’s just like the NASA GISS sequence and has been adjusted many instances. The blue line is the extra correct Mid Troposphere Satellite tv for pc Temperature information. The yellow line is the NAS information from 1975. NAS was the precursor of NASA and was thought-about state-of-the-art in 1975.  The 2007 mannequin predictions (Gray Line) are already 0.7C hotter than the measured information in 2021.

  5-year averaged values of annual imply (1979-2015) international bulk (termed “midtropospheric” or “MT”) temperature as depicted by the common of 102 IPCC CMIP5 local weather fashions (pink), the common of three satellite tv for pc datasets (inexperienced – UAH, RSS, NOAA) and 4 balloon datasets (blue, NOAA, UKMet, RICH, RAOBCORE).

Determine 4. The graph introduced to the US Home Committee on Science, Area and Expertise by John Christy in 2016.  Based on the GHG idea, Mid-Tropospheric temperature rise is the fingerprint of GHG warming. It’s apparent that the fashions with their excessive feedbacks produce extra warming on this space than do our most correct temperature measure, the satellites.  The balloon information additionally agrees nicely with the satellites and is nicely beneath the fashions.

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