Climate Models for the Layman

Climate Models for the Layman

Climate Models for the Layman is the title of Doctor Judith Curry’s latest paper.

Dr. Curry retired recently from the Georgia Institute of Technology, where she held the positions of Professor and Chair of the School of Earth and Atmospheric Sciences.

Her paper, Climate Models for the Layman, explains why global climate models (GCMs) are not suitable for making policy decisions.

Cover from Dr. Curry’s 2017 Paper

This article places a spot light on three details from her study that highlight fundamental flaws in GCMs. These flaws will be obvious to anyone who has received training in logic, or who is an engineer.

This article merely focuses on these three issues, while the full paper provides a comprehensive look at the shortcomings of GCMs.

Imprecise Data

The data used in the computer programs is not precise.

Everything is averaged. Therefore, if the data isn’t precise, the computer model will generate imprecise answers.

This goes back to what we all know as Garbage In, Garbage Out (GIGO).

As Dr. Curry points out, the surface of the earth is divided into cells, with each cell being between 60 to 120 miles in each horizontal direction, and around a half mile in thickness, i.e., altitude.

Envision a cell with New York City centered at the cell’s lower edge, with the Berkshire Mountains along its upper right edge and the Catskill Mountains along its left edge. New York City is situated in a maritime environment, while the mountains to its Northwest and Northeast are considerably colder and drier.

All the environmental conditions, temperatures etc. are averaged within this cell.

Envision another cell where San Francisco is at the center of the western edge of a cell.

San Francisco sits on the bay next to the ocean where temperatures are decidedly cool and moist, while thirty miles to the East, over the mountains bordering Berkely and San Leandro, the area is hot and semi-arid.

All the environmental conditions, such as temperature, would be averaged within this cell.

This is replicated around the world until every area is covered by a cell. Then the data, all of it averaged, none of it precise, is fed into a computer model.

Add to this, the fact that the computer codes used to simulate the physical world are frequently merely approximations of physical processes.

The answer generated by a Global Climate Model may not be garbage, but the answer isn’t factual and true-to-life either.

Unfortunately, we still do not have computers large enough to allow for more precise calculations using smaller cells that more accurately represent the real world.


The Oceans act as a heat sink and delay the effect of environmental changes. Their currents create a fluid, chaotic world.

The atmosphere is also chaotic, with wind and heat circulations, and events such as El Nino, and the Pacific and Atlantic Decadal and Multi Decadal Oscillations that are barely understood.

Yet the computers try to marry these two chaotic fluids together to predict how they will interact.

As Dr. Curry said in her paper, “Arguably the most fundamental challenge with GCMs lies in the coupling of two chaotic fluids: the ocean and the atmosphere.”

Computer Programs Not Validated

This gets back to what has been covered in previous articles. See, False Claims of Impending Disaster.

How can these computer models be used to predict climate 100 years from now when they haven’t been able to replicate or predict temperatures over the past 20 years? In short, these programs haven’t been validated.

Quoting from Dr. Curry’s paper, “So far in the 21st century, the GCMs are warming, on average, about a factor of 2 faster than the observed temperature increase.”


Dr. Curry in her paper, Climate Models for the Layman, delves more deeply into these and other factors that make the GCMs unsuitable for making policy decisions.

These three examples should be sufficient reason to conclude that laws and regulations shouldn’t be based on GCMs.

  • Imprecise Data
  • Chaos
  • Unvalidated Models

GCMs may be useful to explore “what-if” questions, and to identify areas of potentially useful research, but they should not be used to establish policy.

Policy decisions affect people’s lives.

The IPCC and the UNFCCC both rely on GCMs as they pursue regulations to cut CO2 emissions.



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