{"id":299194,"date":"2024-01-31T17:58:08","date_gmt":"2024-01-31T16:58:08","guid":{"rendered":"https:\/\/climatescience.press\/?p=299194"},"modified":"2024-01-31T17:58:11","modified_gmt":"2024-01-31T16:58:11","slug":"long-term-climate-sensitivity-after-all-feedback-has-acted","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=299194","title":{"rendered":"Long Term Climate Sensitivity After All Feedback Has Acted"},"content":{"rendered":"\n
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From Watts Up With That?<\/a><\/p>\n\n\n\n

By Bob Irvine<\/p>\n\n\n\n

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The world\u2019s climate is an immensely complex and chaotic system. Climate forcings have different efficacies depending on whereabouts on the planet they act. Massive convective forces and energy transport mitigate any warming but are nearly impossible to quantify. Even our global temperature series are unreliable. And then there is clouds!<\/p>\n\n\n\n

The problems encountered by scientists trying to put a number on Equilibrium Climate Sensitivity (ECS) for CO2x2 are almost insurmountable because of this complexity and estimates, consequently, vary greatly.<\/p>\n\n\n\n

The Non-Condensing Green House Gasses (NCGHG) include CO2, CH4, N2O, CFC11, and CFC12. CO2 dominates the forcing from these gasses until 1850 and was responsible for 83% of their forcing at that time. It is a reasonable assumption to say that, prior to 1850 the average climate sensitivity to all the NCGHGs combined was very close to CO2 sensitivity both historically and in 1850.<\/p>\n\n\n\n

If all NCGHGs were removed from the system, the sun would still be beating into the tropical and temperate oceans creating large amounts of water vapour and clouds. The only way this can change is by expanding Earth\u2019s orbit or turning down the sun\u2019s intensity.<\/p>\n\n\n\n

The world will always have a strong GHG Effect while the sun continues to shine and that feedback to change for all concentrations of NCGHGs, including close to zero, will always be acting in a world with an existing strong GHG component. For this reason, feedback is likely to be relatively linear.<\/p>\n\n\n\n

This essay will attempt to find an estimate for Equilibrium Climate Sensitivity (ECS) based on two methods of estimating the Global Mean Surface Temperature (GMST) after all NCGHGs have been artificially removed. Both these estimates include an unknown figure for System Gain Factor (SGF). We solve for the two equations and get a System Gain Factor of about 1.09. This implies a long term ECS for CO2x2 of about1.3K (1.09 x 1.2 = 1.3K)<\/p>\n\n\n\n

I\u2019d like first to get a definition out of the way. Reference Temperature (RT) is defined here as the base temperature attributed to a forcing before any atmospheric or ocean feedback has been applied. For example, the Reference Temperature for CO2x2 is agreed at 1.2C (Hansen \u201984).<\/p>\n\n\n\n

Another definition is also needed at this point. The System Gain Factor (SGF) is defined here as the Equilibrium Temperature divided by the Reference Temperature (RT). For example, the IPCC central SGF of CO2x2 is their likely ECS of 3.0K divided by the Reference Temperature (RT) of 1.2K. (3.0\/1.2 = 2.5). The IPCC\u2019s likely System Gain Factor (SGF) for CO2 is 2.5.<\/p>\n\n\n\n

In 1850 the global temperature was 287.5K (NASA) and the total Reference Temperature for all the NCGHGs combined was 7.9K (IPCC). This is not contested.<\/p>\n\n\n\n

The approximate total GH Effect (GHE) in 1850 was 32.5K and is derive by subtracting the global emission temperature (255K, IPCC) from the surface temperature (287.5K, NASA) at that time. Of that 32.5K, 7.9K is directly attributed to and is the reference temperature for all the NCGHGs as mentioned, the rest (24.6K) being made up almost totally by the contribution from water vapour (WV) and clouds.<\/p>\n\n\n\n

The IPCC position is that over half this 24.6K WV and Cloud GHE is a direct result and is feedback to the NCGHG\u2019s 7.9K direct contribution or reference temperature. I intend to show that this position is not correct and calculate a much better estimate.<\/p>\n\n\n\n

METHOD<\/p>\n\n\n\n

The unknown factor here is the SGF for any reference temperature from any cause. This I will designate as \u201cA\u201d.<\/p>\n\n\n\n

Other figures used are.<\/p>\n\n\n\n