High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)

[chubbs]

14 hours ago, blizzard1024 said:

CO2 has an absorption band in the IR between 13 and 17 microns with a peak at 15 microns. Water vapor has multiple bands in the IR in fact most of the emission spectra in the IR from the Earth resembles the H20 bands.  CO2 absorbs IR between -50c and -110C so it has little to no effect directly on the lower and middle troposphere. Also water vapor dominates the lower and middle troposphere and thins out dramatically in the upper troposphere. So CO2 does have the most influence in the upper troposphere where cold temperatures are affected. But how can a weak GHG dominate the entire choatic non-linear climate system? Water vapor and clouds are the primary GHGs.  CO2 theoretically leads to some warming in the upper troposphere which in theory would warm the lower troposphere and cool the stratosphere. But if H20 increases in the lower troposphere its emission cools the upper troposphere.  CO2 if all else remains equal leads to 1.2C of warming per doubling. But clouds, a negative water vapor feedback could easily drop the sensitivity to less than 1C.  The paleo records clearly show that CO2 is not the control knob on the climate system.  

A doubling of CO2 likely is less than 1C and possiblly even less. 

 

 

Not sure where you are getting your paleo (or other) info from. CO2 is a control knob and water magnifies the impact of CO2. Without CO2 there wouldn't be much water vapor in the atmosphere.

https://science.sciencemag.org/content/330/6002/356

[blizzard1024]

5 hours ago, chubbs said:

Not sure where you are getting your paleo (or other) info from. CO2 is a control knob and water magnifies the impact of CO2. Without CO2 there wouldn't be much water vapor in the atmosphere.

https://science.sciencemag.org/content/330/6002/356

 

Behind a paywall.  It doesn't make sense in the Paleo Records. I would like to see how they came up with this. If it has anything to do with climate modelling, its not credible. 

 

[blizzard1024]

20 hours ago, drstuess said:

So said chaotic and non-linear system is certain enough for you to say it isnt sensitive to CO2, but not enough for the best modeled and proposed answer to say it is?

Sent from my SM-G960U using Tapatalk
 

Best modeled?  what?  The whole theory of CAGW is based on trust in modelling the climate system. I distrust atmospheric models. They are often way wrong. The paleorecords disprove that CO2 is the primary control knob on the climate. It has some effect but not a dominate effect. Certainly not enough to destroy the Earth's ecosystems.  

[donsutherland1]

4 hours ago, blizzard1024 said:

Best modeled?  what?  The whole theory of CAGW is based on trust in modelling the climate system. I distrust atmospheric models. They are often way wrong. The paleorecords disprove that CO2 is the primary control knob on the climate. It has some effect but not a dominate effect. Certainly not enough to destroy the Earth's ecosystems.  

The scientific understanding of AGW is based on far more than models (which are also widely used in scientific fields). Some uncertainties exist, but the fundamental understanding (the reality of ongoing warming, the role anthropogenic greenhouse gas emissions have played in raising the atmospheric concentration of such gases, and that rising concentration’s being the principal driver of recent warming) is essentially settled in the climate science field. No credible alternative has been advanced, much less withstood robust scientific scrutiny.

Finally, the ongoing warming is indisputable. The NOAA observed in its July 2019 climate summary:

Last month was also the 43rd consecutive July and 415th consecutive month with above-average global temperatures.

In a relatively stable climate regime, the statistical probability of 415 consecutive months with warm anomalies is vanishingly small. Such streaks are almost certainly only possible during climate change, in this case toward a warmer state.

[bdgwx]

On 8/16/2019 at 5:21 PM, donsutherland1 said:

No credible alternative has been advanced, much less withstood robust scientific scrutiny.

^ This is the salient point. The consensus theory which includes ALL forcing agents in their appropriate proportions provides a reasonable match to ALL available observations. No other alternative theory especially those that selectively ignore or downplay forcing agents like GHGs even come remotely close to matching the consensus theory in terms of explanatory and predictive power. This is the scientific way...when faced with 2 or more choices you pick the simplest theory that best matches reality. 

If there is a GHG-less (or GHG-weak) alternative theory then it should be able to explain things like the PETM, other ETMx periods, Chicxulub event, amplitude of the glacial cycles, faint young Sun paradox, modern warming period, and much more at least equally as well and with at least as much evidence to support it. Nevermind that we would still need an explanation for how the consensus theory derived from 150+ years of experimentation, observations, and modern theory development spanning many disciplines of science was all wrong. Given the depth of evidence and the breadth across the many disciplines of science it would require an absolutely revolutionary advancement in the very core of scientific understanding itself to tear it all down. It is possible I suppose; just very unlikely. 

[bdgwx]

On 8/15/2019 at 3:54 PM, blizzard1024 said:

CO2 has an absorption band in the IR between 13 and 17 microns with a peak at 15 microns. Water vapor has multiple bands in the IR in fact most of the emission spectra in the IR from the Earth resembles the H20 bands.  CO2 absorbs IR between -50c and -110C so it has little to no effect directly on the lower and middle troposphere. Also water vapor dominates the lower and middle troposphere and thins out dramatically in the upper troposphere. So CO2 does have the most influence in the upper troposphere where cold temperatures are affected. But how can a weak GHG dominate the entire choatic non-linear climate system? Water vapor and clouds are the primary GHGs.  CO2 theoretically leads to some warming in the upper troposphere which in theory would warm the lower troposphere and cool the stratosphere. But if H20 increases in the lower troposphere its emission cools the upper troposphere.  CO2 if all else remains equal leads to 1.2C of warming per doubling. But clouds, a negative water vapor feedback could easily drop the sensitivity to less than 1C.  The paleo records clearly show that CO2 is not the control knob on the climate system.  

A doubling of CO2 likely is less than 1C and possiblly even less. 

 

 

< 1.0C for 2x CO2 is weak indeed. There is little evidence to support a doubling sensitivity this low especially for the modern era. Even Judith Curry's most recent estimate is still within the IPCC range of 1.5 to 4.5C at 1.66C for ECS and 1.33 for TCS. And since 1960 the surface had warmed by 0.9C with less than 50% of the CO2 forcing having occurred. And that's only the TCR as the planet still has a +0.6 W/m^2 or higher imbalance. We are well on our way to an observed > 2.0C sensitivity. Remember, uncertainty is a double edged sword. It's just as likely that we are underestimating the climate sensitivity as we are in overestimating it. In fact, the evidence suggests that the uncertainty on the high side is more than on the low side because of the under-studied (IMHO) tipping point feedbacks and because the low side is continually being constrained at higher values with each passing decade.  

By the way, I'm curious where the 1.2C figure came from? This is suspiciously close to that which can be computed from the Stefan-Boltzmann law using the canonical ΔF = 5.35 * ln(2) = 3.7 W/m^2 estimate for the radiative forcing and is often referred to as the no-feedback sensitivity.

 

[bdgwx]

On 8/16/2019 at 12:24 PM, blizzard1024 said:

Best modeled?  what?  The whole theory of CAGW is based on trust in modelling the climate system. I distrust atmospheric models. They are often way wrong. The paleorecords disprove that CO2 is the primary control knob on the climate. It has some effect but not a dominate effect. Certainly not enough to destroy the Earth's ecosystems.  

Assuming by "model" you mean a global circulation model or numerical weather prediction model then it's relevant to point out that they are just one among many tools, and a relatively recent one at that, for furthering our understanding of AGW and the climate system in general. AGW definitely isn't based on models of this type. In fact, the computers used to run them didn't even exist when AGW was first being developed. If your point was that they aren't perfect then I completely agree. If your point is that they aren't useful then I'll have to respectfully disagree. GCM/NWP models have proven to be a very useful tool in trying to better understand the climate. And the paleoclimate record is consistent with the modern understanding of how the climate system works and is even consistent with attempts at using computerized modeling to explain climate trends in the distant past.