Radiation Transfer Calculations and Assessment of Global Warming by CO2

This is very challenging material, but some of our more math-minded DP'ers should find it interesting.

Radiation Transfer Calculations and Assessment of Global Warming ...

https://www.hindawi.com/archive/2017/9251034/


by H Harde - ‎2017 - ‎Cited by 1 - ‎Related articles
Volume 2017 (2017), Article ID 9251034, 30 pages ... Although in all these fields of climate sciences great progress has been achieved over the last decades and our ... [10]; Ziskin & Shaviv [11]; Scafetta & Willson [12]; Usoskin et al. [13]; Zhao ...

. . . . Altogether, we see that the positive feedbacks, originating from clouds, water vapor, and albedo, are partially compensated or in the case of a moderate cloud feedback are even overcompensated by lapse rate and evaporation feedback. Particularly clouds have two stronger opposing effects on the energy balance, which can neutralize each other or can even have an overall attenuating impact on the ECS, dependent on the mechanisms responsible for cloud changes. From these studies we conclude that all constraints can best be explained by a cloud feedback mechanism, which is dominated by the solar influence, while thermally induced contributions only should have minor influence.

Our investigations further indicate that a CO2 climate sensitivity larger than 1°C seems quite improbable, whereas a value of 0.6–0.8°C, depending on the considered solar anomaly, fits well with all observations of a changing solar constant, the cloud cover, and global temperature. A climate sensitivity as specified in AR5 (1.5–4.5°C) would only be possible when any solar influence could completely be excluded and the negative feedbacks further be attenuated.

Maybe the most important message of this investigation is that on the basis of well retraceable physical interrelations there exist several stronger arguments for the inclusion of some effects, which obviously were not considered in the IPCC reports and which can significantly attenuate the influence of CO2 on global warming. The discrepancies primarily go back to an overall negative feedback we find in our calculation, and to the inclusion of solar effects.

[h=4]Abstract[/h]
We present detailed line-by-line radiation transfer calculations, which were performed under different atmospheric conditions for the most important greenhouse gases water vapor, carbon dioxide, methane, and ozone. Particularly cloud effects, surface temperature variations, and humidity changes as well as molecular lineshape effects are investigated to examine their specific influence on some basic climatologic parameters like the radiative forcing, the long wave absorptivity, and back-radiation as a function of an increasing CO2concentration in the atmosphere. These calculations are used to assess the CO2 global warming by means of an advanced two-layer climate model and to disclose some larger discrepancies in calculating the climate sensitivity. Including solar and cloud effects as well as all relevant feedback processes our simulations give an equilibrium climate sensitivity of

= 0.7°C (temperature increase at doubled CO2) and a solar sensitivity of

= 0.17°C (at 0.1% increase of the total solar irradiance). Then CO2 contributes 40% and the Sun 60% to global warming over the last century.

Jack Hays said:

This is very challenging material, but some of our more math-minded DP'ers should find it interesting.

Radiation Transfer Calculations and Assessment of Global Warming ...

https://www.hindawi.com/archive/2017/9251034/


by H Harde - ‎2017 - ‎Cited by 1 - ‎Related articles
Volume 2017 (2017), Article ID 9251034, 30 pages ... Although in all these fields of climate sciences great progress has been achieved over the last decades and our ... [10]; Ziskin & Shaviv [11]; Scafetta & Willson [12]; Usoskin et al. [13]; Zhao ...

[FONT=&]. . . . Altogether, we see that the positive feedbacks, originating from clouds, water vapor, and albedo, are partially compensated or in the case of a moderate cloud feedback are even overcompensated by lapse rate and evaporation feedback. Particularly clouds have two stronger opposing effects on the energy balance, which can neutralize each other or can even have an overall attenuating impact on the ECS, dependent on the mechanisms responsible for cloud changes. From these studies we conclude that all constraints can best be explained by a cloud feedback mechanism, which is dominated by the solar influence, while thermally induced contributions only should have minor influence.

[/FONT][FONT=&]Our investigations further indicate that a CO2 climate sensitivity larger than 1°C seems quite improbable, whereas a value of 0.6–0.8°C, depending on the considered solar anomaly, fits well with all observations of a changing solar constant, the cloud cover, and global temperature. A climate sensitivity as specified in AR5 (1.5–4.5°C) would only be possible when any solar influence could completely be excluded and the negative feedbacks further be attenuated.

[/FONT][FONT=&]Maybe the most important message of this investigation is that on the basis of well retraceable physical interrelations there exist several stronger arguments for the inclusion of some effects, which obviously were not considered in the IPCC reports and which can significantly attenuate the influence of CO2 on global warming. The discrepancies primarily go back to an overall negative feedback we find in our calculation, and to the inclusion of solar effects.[/FONT]

Click to expand...

Oh, that's a nice one.

Thanx.

There is new sensitivity study in Nature Geoscience that slightly downgrades the TCS of CO2, but they still use the 3.7 W/m^2 per doubling in their calculations.

Beyond equilibrium climate sensitivity

Here is one of the figures... at least if it isn't paywalled to you all...

Nir Shaviv had a similar insight years ago.

• Carbon Dioxide or Solar Forcing?

[FONT=&quot]. . . So why is this link important for global warming? As previously mentioned, solar activity has been increasing over the 20[/FONT][FONT=&quot]th[/FONT][FONT=&quot] century. This can be seen in fig. 5. Thus, we expect warming from the reduced flux of cosmic rays. Moreover, since the cosmic ray flux actually had a small increase between the 1940's and 1970's (as can be seen in the ion chamber data in fig. 6), this mechanism also naturally explains the global temperature decrease which took place during the same period. [/FONT]

[FONT=&quot]Using historic variations in climate and the cosmic ray flux, one can actually [/FONT]quantify empirically[FONT=&quot] the relation between cosmic ray flux variations and global temperature change, and estimate the solar contribution to the 20[/FONT][FONT=&quot]th[/FONT][FONT=&quot] century warming. This contribution comes out to be 0.5±0.2°C out of the observed 0.6±0.2°C global warming (Shaviv, 2005).[/FONT][FONT=&quot]Fig. 5: Solar activity over the past several centuries can be reconstructed using different proxies. These reconstructions demonstrate that 20th century activity is unparalleled over the past 600 years (previously high solar activity took place around 1000 years ago, and 8000 yrs ago). Specifically, we see sunspots and 10Be. The latter is formed in the atmosphere by ~1GeV cosmic rays, which are modulated by the solar wind (stronger solar wind → less galactic cosmic rays → less 10Be production). Note that both proxies do not capture the decrease in the high energy cosmic rays that took place since the 1970's, but which the ion chamber data does (see fig. 6). (image source: Wikipedia)
[/FONT]

[h=1]Paper: Influence of solar cycles on climate change during the Maunder Minimum[/h]Both observational and proxy records of climate change often show quasi periodic variations similar to solar activity cycles over a wide range of time scales. However, the detailed mechanism and the extent of the influence of solar activity on climate change have not been clearly understood. Although the exact role of each of solar parameters…

September 29, 2014 in Cosmic rays, Solar.

[h=3]Indirect Effects of the Sun on Earth's Climate | Watts Up With That?[/h]https://wattsupwiththat.com/2017/06/10/indirect-effects-of-the-sun-of-earths-climate/

Jun 10, 2017 - At this point, the clean-shaven Henrik Svensmark, as a kind of protest, decided not to shave ..... “Edward B Hanley June 10, 2017 at 6:53 pm

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[h=1]The Effects of the Bray Climate and Solar Cycle[/h]By Andy May Javier has posted three new essays on the Bray climate and solar cycle on Judith Curry’s web site. Part A is here, part B is here and Part C is here. In these posts, he lays out the evidence, in some detail, for the climate cycle and the associated solar cycle. Here…

August 8, 2017 in Climate News, Paleoclimatology.

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