A Quick look at the Assumptions being made in the GCMs

From the grid size of 100 - 250Km to the vertical spacing of 1Km, but as valuable as a key assumption the vertical spacing in the ocean of 100m are all significant in that earth wants to be chaotic on smaller scales and without that precision the question becomes how can the GCM output be considered accurate?

As significant are the assumptions of causes of climate.    The inputs of solar irradiance is assumed constant.   The main cause of climate change is assumed to be CO2.   The diagram at right is an indication of how the IPCC treats water vapor as a slave to the conditions of warming caused by CO2 absorption of OLR. 


The interface and exchange with the ocean are assumed overly simple.   The time increments are also long by many processes on earth. 


All of these constraints are to alleviate the compute requirements which are significant. 


From Tim Ball

In these GCMs, the CO2 concentration is not just a forcing, a boundary condition to which the GCM reacts, but exclusively so. In the GCMs, no part of the CO2 concentration is a “feedback”, a consequence of other variables. The GCMs appear to have no provision for the respiration of CO2 by the oceans.  They neither account for the uptake of CO2 in the cold waters, nor the exhaust of CO2 from the warmed and CO2–saturated waters, nor the circulation by which the oceans scrub CO2 from the air. Because the GCMs have been split into loosely–coupled atmospheric models and primitive ocean models, they have no mechanism by which to reproduce the temperature dependency of CO2 on water temperature evident in the Vostok data.

GCMs have a long history. They contain solid, well-developed sub-models from physics. These are the bricks in the GCM structure. Unfortunately, the mortar won’t set. The operators have adjusted and tuned many of the physical relationships to reproduce a preconceived, desired climate scenario. There is no mechanism left in the models by which to change CO2 from a forcing to a feedback.


Ball Book - Chapter 7 Part 2

Ball excerpt:

The IPCC produced the SPM for policymakers. Cleverly and cynically they disclosed the limitations of their work in the Physical Science Report of Working Group I. This means nobody can say they didn’t acknowledge the limitations. One of the most serious is the lack of data and the way it is created. In the 2007 IPCC AR4, Chapter 8 Advances in Modeling they say:

Despite the many improvements, numerous issues remain. Many of the important processes that determine a model’s response to changes in radiative forcing are not resolved by the model’s grid. Instead, sub-grid scales are used to parametrize the unresolved processes, such as cloud formation and the mixing due to oceanic eddies. It continues to be the case that multi-model ensemble simulations generally provide more robust information than runs of any single model. Table 8.1[ 123] summarizes the formulations of each of the AOGCMs used in this report.[ 124]


At the Reading conference Shukla reported: The current generation high-end computers for climate research have a capability of about 50 teraflops, which makes it possible to integrate a typical climate model with about 100 km horizontal resolution for 20 years in one day.[ 130] So at 50 trillion floating point calculations per second they only study 20 years of record per day. Worse, each run using identical input yields different results so they average several runs. This is with a grossly simplified model with a grid so large that each covers very different climate regions. Shukla challenges:

We must be able to run climate models at the same resolution as weather prediction models, which may have horizontal resolutions of 3- 5 km within the next 5 years. This will require computers with peak capability of about 100 petaflops.


Global climate models are composites of individual models for each component of the atmosphere and assume the smaller model output is real data and they know how it interacts with all other model inputs. Even that is a problem as Koster et al. explain:

The soil moisture state simulated by a land surface model is a highly model-dependent quantity, meaning that the direct transfer of one model’s soil moisture into another can lead to a fundamental, and potentially detrimental, inconsistency.

The NASA statement identifies another limitation of the IPCC model when they refer to “the exchange of water and heat energy between the land surface and the atmosphere.”


The IPCC take the average results of some 22 computers and average them to produce an ensemble result. As Robert Brown, physicist at Duke University notes: First— and this is a point that is stunningly ignored— there are a lot of different models out there, all supposedly built on top of physics, and yet no two of them give anywhere near


Section for a video or follow-on comment

We should revisit occasionally what the proper role of government is.   As the constitution was a good sense of direction, we need a core set of principles to add in order to deal with the future.


So many want to engineer society, remove risk, assist certain groups, rather than let individuals thrive and raise communities.  Why?


Is Democracy where we all "get it good and hard" or is it the best means to a free society?


Should we roll with the special interests, or make the government achieve its proper role, what is that role, and how to do this?


When do deficits and governments become too large?


Government is becoming more elitist while trying to sell corrections to problems it created, what makes this possible?


Could include a pic

This could also be inserted into the field above, or erased


Currently as a society, we are having a most difficult time discussing political issues.  What is driving this?   And why a rebirth in political culture would be a good thing.


Market Economy

Are "markets" dead as some would conjecture? Or is free enterprise what got us here?


Economic Theories

At the heart of economics there are several possible economic schools of thought, the essence of these schools of thought and how they relate to our lives.


Add Comments


Powered by Disqus