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Sea Level Rise Pt. 2

Re: Sea Level Rise Pt. 2

Unread postby dissident » Wed 30 Oct 2019, 21:14:59

EnergyUnlimited wrote:Rockdoc & Kublikhan

Lets admit that we don't know how much warming we are likely to experience by the end of century.
It is probably between 3 and 10 *C.
Perhaps more likely 3 than 10 but still.
There are different models, different groups of scientists working on these models and different opinions.
Also unknown latent switches and obscure feedbacks.
So a lot can change in all these models.
Science has its limitations too and quality of scientific work is falling down during last 2-3 decades, so published results, even if constitute best guess we might have, need to be taken with a grain of salt.
Have red many entirely incompetent articles published in chemical journals so I do not expect situation to be very different elsewhere.
These aguments may go on ad nauseum so lets wait and see.
Even if we don't see it ourselves, our grandchildren surely will. Those of us who live for 10-30 years more may see some indications (or even spectacular catastrophies in places like India).
One way or another we are going to be dead by the end of this century, so entire exercise is very much like discussions of turkeys what they will eat on the Christmas.


I know these models and they are not as different as you believe. And for sure there is no disagreement between the scientists unless you are talking about the fringe like Richard "Linear" Lindzen. The variation between models shows you how are reasonable range of differences in the coding and parameter selection can produce a spread of results. The best approach is to take the average of this ensemble.

But the problem is that the current generation of models are not complete in terms of physical process resolution. Comparison between the model results in the last 20 years we see that they have been failing to fully capture the sensitivity of the atmosphere-ocean system to greenhouse gas induced warming. This flies in the face of all the denier BS about "climate alarmism". This issue does not make modeling a pointless activity and we have actually learned that there are missing aspects to known processes or unknown processes that have to be researched and implemented into the models. If the lunatic deniers had their way, we would have been sitting on our a**ses and been at the science level of the 1940s today.
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Re: Sea Level Rise Pt. 2

Unread postby rockdoc123 » Wed 30 Oct 2019, 22:29:31

Comparison between the model results in the last 20 years we see that they have been failing to fully capture the sensitivity of the atmosphere-ocean system to greenhouse gas induced warming. This flies in the face of all the denier BS about "climate alarmism".
 

If that were the case you would be seeing all measured temperatures higher than predicted from the range of coupled models used by IPCC in AR5 (CMIP 5) which is actually the opposite of what is recognized. Here is a plot that Curry updated from AR5 with data out to 2015 for her presentation to Senate (note that Gavin Schmidt and numerous others had the opportunity to comment on her presentation prior to it being made and she edited some material accordingly). Note that temperatures from Had Crut 4.3 along with uncertainties all plot at the bottom of the range of modeled predictions. The red hashered area is what the IPCC used as their lowered projections out to 2035 based on expert judgement of the authors who participated in that chapter reflecting on their concern that some of the models were too sensitive to anthropogenic forcing. Suggesting the authors of that chapter believed the models at that time (CMIP 5) were over-estimating projected temperatures, not under-estimating them.

Image

We are now at CMIP 6 and results are starting to trickle out with projected temperatures that are even hotter presumably as a result of increased sensitivity in the models. I suspect when those models are published the mismatch will probably be worse.
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Re: Sea Level Rise Pt. 2

Unread postby Plantagenet » Wed 30 Oct 2019, 23:53:45

New Climate Models run "hotter" then previous climate models and predict higher future temperatures

SCIENCE: new-climate-models-predict-warming-surge

Prior IPCC predictions were based on averages of numerous different climate models. But some models run "hotter" then others. It turns out that that models that predict lower amounts of global warming are usually very simple and don't include feedback effects from things like decreased ice cover in the Arctic Ocean. This explains why their predictions aren't very reliable.

The newest GCMs are more sophisticated and capture more natural processes. In addition, the newer models include some of the more significant feedback effects. The best new models are predicting we are in for higher temperatures then suggested by prior IPCC assessments.

Image

Cheers!
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Re: Sea Level Rise Pt. 2

Unread postby rockdoc123 » Thu 31 Oct 2019, 10:48:07

New Climate Models run "hotter" then previous climate models and predict higher future temperatures


interestingly enough if you look at the range of those predicted temperatures from CMIP 6 and compare them to the package of 5%-95% of all CMIP5 from IPCC AR5 they are almost exactly the same. Will have to wait for a number of papers to be published in order to ascertain how they arrived at their statistics but the one thing that is certain measured temperatures are still showing up at the bottom of the range.
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Re: Sea Level Rise Pt. 2

Unread postby Plantagenet » Thu 31 Oct 2019, 11:15:40

.... the one thing that is certain measured temperatures are still showing up at the bottom of the range.


There is another thing that is certain.....the rate of increase in temperature is accelerating.

The NOAA website states: "According to the NOAA 2018 Global Climate Summary, the combined land and ocean temperature has increased at an average rate of 0.07°C (0.13°F) per decade since 1880; however, the average rate of increase since 1981 (0.17°C / 0.31°F) is more than twice as great."

The fact that the rate of temperature increase is going up so much is significant because it is one of the main predictions of the GCM models. The observation that the rate of T increase now is more then twice what it was only a few decades is an important confirmation of the validity of GCM modeling, which predicts non-linear increases in T over the coming decades. And since GCM modeling predicts the rate of T increase will continue to accelerate as more and more greenhouse gas accumulates in the atmosphere, it is likely the rate of increase will double again in coming decades. This means observed temperatures will increase much more rapidly in the future then they have in the past and may ultimately match or even exceed the GCM predictions for coming decades.

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Re: Sea Level Rise Pt. 2

Unread postby rockdoc123 » Thu 31 Oct 2019, 12:36:00

The observation that the rate of T increase now is more then twice what it was only a few decades is an important confirmation of the validity of GCM modeling, which predicts non-linear increases in T over the coming decades.


Look at the IPCC plot. They lowered the model estimate range for the sake of forecasting as their expert groups believed the models were running too hot and that was with CMIP 5. There is no way based on plotting the actual data that you can argue otherwise unless you select a baseline other than what IPCC has traditionally used.
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Re: Sea Level Rise Pt. 2

Unread postby dissident » Thu 31 Oct 2019, 18:13:07

Plantagenet wrote:New Climate Models run "hotter" then previous climate models and predict higher future temperatures

SCIENCE: new-climate-models-predict-warming-surge

Prior IPCC predictions were based on averages of numerous different climate models. But some models run "hotter" then others. It turns out that that models that predict lower amounts of global warming are usually very simple and don't include feedback effects from things like decreased ice cover in the Arctic Ocean. This explains why their predictions aren't very reliable.

The newest GCMs are more sophisticated and capture more natural processes. In addition, the newer models include some of the more significant feedback effects. The best new models are predicting we are in for higher temperatures then suggested by prior IPCC assessments.

Image

Cheers!


Thanks for posting this. The IPCC was comparing apples and oranges if it was putting models with substantial differences in process implementation in the same ensemble. Doing such an ensemble is interesting to see how much of an effect leaving out some processes has. But then, reality does not leave any process that exists out. So a proper "forecast" ensemble of climate change would exclude all the models that are too simple. So these recent findings are in the "no sh*t Sherlock" category.
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