Monday, January 1, 2018

Climate Models - Pruitt look at Red team deceptions

Republicans never acknowledge that climate models are among the most formidable and exacting challenges scientists undertake.  Then to make matters worse Republicans are consistently misrepresenting not only how climate models are used, but also doing their best to characterize them as failures, when they most certainly are not failures!

For the details on the General Circulation Model success story I’m going to hand it over to Coby Beck with the introduction to his November 20, 2006 Grist article.  After that I list significant models that have been correct.  Which is followed by links to and exerts from various informative articles.

Factcheck: Climate models have not ‘exaggerated’ global warming
Zeke Hausfather  September 21, 2017
Climate models are accurately predicting ocean and global warming
John Abraham, July 27, 2016
Climate models are even more accurate than you thought
Dana Nuccitelli, July 31,2015
The model scientist who fixed the greenhouse effect
Andy Extance - November 23, 2013
Fighting for useful climate models
Andy Extance - November 30, 2013
Why trust climate models?   It’s a matter of simple science
Scott K. Johnson - Sept 5 2013

‘Climate models are unproven’  –  Actually, GCM’s have many confirmed successes under their belts
By Coby Beck on Nov 20, 2006

In 1988, James Hansen of NASA GISS fame predicted [PDF] that temperature would climb over the next 12 years, with a possible brief episode of cooling in the event of a large volcanic eruption. He made this prediction in a landmark paper and before a Senate hearing, which marked the official “coming out” to the general public of anthropogenic global warming. 

Twelve years later, he was proven remarkably correct, requiring adjustment only for the timing difference between the simulated future volcanic eruption and the actual eruption of Mount Pinatubo.

And let’s face it, every year of increasing global mean temperature is one more year of success for the climate models. The acceleration of the rise is also playing out as predicted, though to be fair, decades will need to pass before such confirmation is inarguable.

Putting global surface temperatures aside, there are some other significant model predictions made and confirmed:

 •  models predict that surface warming should be accompanied by cooling of the stratosphere, and this has indeed been observed;

 •  models have long predicted warming of the lower, mid, and upper troposphere, even while satellite readings seemed to disagree — but it turns out the satellite analysis was full of errors and on correction, this warming has been observed;

 •  models predict warming of ocean surface waters, as is now observed;

 •  models predict an energy imbalance between incoming sunlight and outgoing infrared radiation, which has been detected;

 •  models predict sharp and short-lived cooling of a few tenths of a degree in the event of large volcanic eruptions, and Mount Pinatubo confirmed this;

 •  models predict an amplification of warming trends in the Arctic region, and this is indeed happening;

 •  and finally, to get back to where we started, models predict continuing and accelerating warming of the surface, and so far they are correct. …


Key studies/models that have withstood the test of time:

1959 - “Carbon Dioxide and Climate”

An article from our July 1959 issue examined climate change: “A current theory postulates that carbon dioxide regulates the temperature of the earth. This raises an interesting question: How do Man’s activities influence the climate of the future?” … During the past century a new geological force has begun to exert its effect upon the carbon dioxide equilibrium of the earth [see graphs on page 43]. By burning fossil fuels man dumps approximately six billion tons of carbon dioxide into the atmosphere each year. His agricultural activities release two billion tons more. ...

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1967 - “Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity”

The First Climate Model Turns 50, And Predicted Global Warming Almost Perfectly
Ethan Siegel, March 15, 2017,

Modeling the Earth’s climate is one of the most daunting, complicated tasks out there. If only we were more like the Moon, things would be easy. The Moon has no atmosphere, no oceans, no icecaps, no seasons, and no complicated flora and fauna to get in the way of simple radiative physics.

No wonder it’s so challenging to model! In fact, if you google “climate models wrong”, eight of the first ten results showcase failure.

But headlines are never as reliable as going to the scientific source itself, and the ultimate source, in this case, is the first accurate climate model ever: by Syukuro Manabe and Richard T. Wetherald. 50 years after their groundbreaking 1967 paper, the science can be robustly evaluated, and they got almost everything exactly right.

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1972 - “Man-made carbon dioxide and the “greenhouse” effect”
A remarkably accurate global warming prediction, made in 1972
Dana Nuccitelli, March 19, 2014, UK Guardian

A paper published in Nature in 1972 accurately predicted the next 30 years of global warming

John Stanley (J.S.) Sawyer was a British meteorologist born in 1916. He was elected a Fellow of the Royal Society in 1962, and was also a Fellow of the Meteorological Society and the organization’s president from 1963 to 1965.

A paper authored by Sawyer and published in the journal Nature in 1972 reveals how much climate scientists knew about the fundamental workings of the global climate over 40 years ago. For example, Sawyer predicted how much average global surface temperatures would warm by the year 2000.

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1975 - “Climate Change: Are We on the Brink of a Pronounced Global Warming?”

Wallace Broecker was among the first climate scientists to use simple climate models to predict future global temperature changes.

Broecker anticipated the actual increase in CO2 very closely, predicting 373 ppm in 2000 and 403 ppm in 2010 (actual values were 369 and 390 ppm, respectively). Broecker also used an equilibrium climate sensitivity of 3°C for doubled CO2; however, his model’s transient climate sensitivity worked out to be 2.4°C for doubled CO2.  …

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1981 - “Climate Impact of Increasing Atmospheric Carbon Dioxide”

A paper published in the journal Science in August 1981 made several projections regarding future climate change and anthropogenic global warming based on manmade CO2 emissions.  As it turns out, the authors’  projections have proven to be rather accurate — and their future is now our present. …

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2015 - First direct observation of carbon dioxide’s increasing greenhouse effect
February 25, 2015

The influence of atmospheric CO2 on the balance between incoming energy from the Sun and outgoing heat from the Earth (also called the planet’s energy balance) is well established. But this effect has not been experimentally confirmed outside the laboratory until now.  The research is reported Wednesday, Feb. 25, in the advance online publication of the journal Nature.

The results agree with theoretical predictions of the greenhouse effect due to human activity.  The research also provides further confirmation that the calculations used in today’s climate models are on track when it comes to representing the impact of CO2.

Various articles providing deeper insights:

Prof John Mitchell: How a 1967 study greatly influenced climate change science

Yesterday, Carbon Brief published the results of our survey of climate scientists asking them to name the most influential studies of all time. The clear winner was a paper published in 1967 written by Syukuro Manabe and Richard. T. Wetherald.

Today, we published an interview with Manabe. Here, Prof John Mitchell, the Met Office Hadley Centre’s chief scientist from 2002 to 2008, explains why the paper has proved to be so significant.

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Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity

Geophysical Fluid Dynamics Laboratory, ESSA, Washington, D.C.
Published online May 1, 1967

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Factcheck: Climate models have not ‘exaggerated’ global warming

ZEKE HAUSFATHER  September 21, 2017

A new study published in the Nature Geosciences journal this week by largely UK-based climate scientists has led to claims in the media that climate models are “wrong” and have significantly overestimated the observed warming of the planet.
Here Carbon Brief shows why such claims are a misrepresentation of the paper’s main results. In reality, the results obtained from the type of model-observation comparisons performed in the paper depend greatly on the dataset and model outputs used by the authors.
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The model scientist who fixed the greenhouse effect
November 23, 2013 — Andy Extance

In 1963, using one of the world’s first transistor-based supercomputers, Syukuro Manabe was supposed to be simulating how Earth’s atmosphere behaves in more detail than ever before. Instead, the young US Weather Bureau scientist felt the frustration, far more common today, of a crashed system. But resolving that problem would lead ‘Suki’ Manabe to produce the first computerised greenhouse effect simulations, and lay the foundations for some of today’s most widely used climate models.

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Fighting for useful climate models
November 30, 2013 - Andy Extance

“When Princeton University’s Syukuro Manabe first studied global warming with general circulation models (GCMs), few other researchers approved. It was the 1970s, computing power was scarce, and the GCMs had grown out of mathematical weather forecasting to become the most complex models available. “Most people thought that it was premature to use a GCM,” ‘Suki’ Manabe told interviewer Paul Edwards in 1998. But over following decades Suki would exploit GCMs widely to examine climate changes ancient and modern, helping make them the vital research tool they are today.

In the 1970s, the world’s weather and climate scientists were building international research links, meeting up to share the latest knowledge and plan their next experiments. Suki’s computer modelling work at Princeton’s Geophysical Fluid Dynamics Laboratory (GFDL) had made his mark on this community, including two notably big steps. He had used dramatically simplified GCMs to simulate the greenhouse effect for the first time, and developed the first such models linking the atmosphere and ocean. And when pioneering climate research organiser Bert Bolin invited Suki to a meeting in Stockholm, Sweden, in 1974, he had already brought these successes together.

Suki and his GFDL teammate Richard Weatherald had worked out how to push their global warming study onto whole world-scale ocean-coupled GCMs. They could now consider geographical differences and indirect effects, for example those due to changes of the distribution of snow and sea ice. …”

Further reading:
Andy Extance previously wrote about the following pivotal climate scientists who came before Suki Manabe, or were around at the same time: Svante ArrheniusMilutin MilankovićGuy Callendar part IGuy Callendar part IIHans Suess, Willi DansgaardDave Keeling part IDave Keeling part II, Wally Broecker part I, Wally Broecker part II, Bert Bolin part I, Bert Bolin Part II


Climate Modeling 101 - 
By the National Academy of Sciences, 2012

A model is defined as "a schematic description of a system, theory, or phenomenon that accounts for its known or inferred properties and may be used for further studies of its characteristics." (American Heritage Dictionary)


Why trust climate models? 
It’s a matter of simple science

How climate scientists test, test again, and use their simulation tools.

by Scott K. Johnson - Sept 5 2013 - ARS TECHNICA.COM

It starts out:

¶1 " Talk to someone who rejects the conclusions of climate science and you’ll likely hear some variation of the following: “That’s all based on models, and you can make a model say anything you want.” Often, they'll suggest the models don't even have a solid foundation of data to work with—garbage in, garbage out, as the old programming adage goes. But how many of us (anywhere on the opinion spectrum) really know enough about what goes into a climate model to judge what comes out?

¶2  Climate models are used to generate projections showing the consequences of various courses of action, so they are relevant to discussions about public policy. Of course, being relevant to public policy also makes a thing vulnerable to the indiscriminate cannons on the foul battlefield of politics.

¶3  Skepticism is certainly not an unreasonable response when first exposed to the concept of a climate model. But skepticism means examining the evidence before making up one’s mind. If anyone has scrutinized the workings of climate models, it’s climate scientists—and they are confident that, just as in other fields, their models are useful scientific tools.”

It’s a model, just not the fierce kind (¶4-¶13)

Touches on equations, comparing them with earth observations, explaining how various components of the climate present challenge and how dealing with those challenges helps explore the complexities of climate.  Andrew Weaver, a researcher at the University of Victoria, described the model evaluation process in three general phases.

Coding the climate (¶14-¶22)
{Get's into questions of verification and validation of climate models, and Steve Easterbrook's review of climate modeling groups and what he found.}

Firing up the wayback machine (¶23-26)
{Looking at the work of Bette Otto-Bliesner at the National Center for Atmospheric Research on their Community Earth System Model, researching past climate.  Taking model simulations one step further by mimicking the creation of proxy records such as ocean sediments and comparing that with actual depositions.}

Setting the bar (¶27-¶30)
{Then, on to Gavin Schmidt a climate researcher at the NASA Goddard Institue for Space Studies, who evaluates climate models and studies issues with comparisons between models and observations, "Improving the model means better simulating physical processes"}

Why so cirrus? (¶31-¶35)
{Next up is Tony Del Genio, also from at the NASA Goddard Institute for Space Studies who studies complex cloud modeling.  Looking for weakness, and improving next-generation versions: "We then run the model with the new process in it and we look for two things: whether the process as we have portrayed it behaves the way it does in the real world and whether or not it makes some aspect of the model's climate more realistic. We do this by comparison to observations, either field experiment, satellite, or surface remote sensing observations, or by comparing to fine-scale models that simulate individual cloud systems." }

Ice, on the rocks (¶36-¶41)
{Finishing with Richard Alley the well know Penn State glaciologist who's an expert on ice cores and modeling ancient climate discussing his work.}

Community service (¶42-¶47)
{Comparing climate models with each other, the “model intercomparison projects,” including ones focused on atmospheric models, paleoclimate simulations, or geoengineering research. Explains what the Coupled Model Intercomparison Project (CMIP) is about.}

No crystal ball—but no magic 8 ball, either (¶48-¶53)
¶49  "But climate scientists know models are just scientific tools—nothing more. In studying the practices of climate modeling groups, Steve Easterbrook saw this firsthand.  He said. "The models are perfectly suited for this. They get the basic physical processes right but often throw up surprises in the complex interactions between different parts of the Earth system. It is in these areas where the scientific knowledge is weakest. So the models help guide the scientific process.


Climate models are accurately predicting ocean and global warming
A new study from my colleagues and I vindicates climate models, which are accurately predicting the rate of ocean heat accumulation

John Abraham, July 27, 2016

Two incorrect but nevertheless consistent denial arguments are that the Earth isn’t warming and that climate models are inaccurate. A new study, published by Kevin Trenberth, Lijing Cheng, and others (I was also an author) answers these questions. …

The study was just published in the journal Ocean Sciences; a draft of it is available here. In this study, we did a few new things. 
First, we presented a new estimate of ocean heating throughout its full depth (most studies only consider the top portion of the ocean). 
Second, we used a new technique to learn about ocean temperature changes in areas where there are very few measurements. 
Finally, we used a large group of computer models to predict warming rates, and we found excellent agreement between the predictions and the measurements. …

… What about the next question – how did the models do? Amazingly well. From 1970 through 2005, the models on average showed a warming of 0.41 Watts per square meter and from 1992-2005 the models gave 0.77 Watts per meter squared. This means that since 1992, the models have been within 3 % of the measurements. …


Climate models are even more accurate than you thought
The difference between modeled and observed global surface temperature changes is 38% smaller than previously thought

Dana Nuccitelli, July 31,2015

… As the 2014 IPCC report showed, observed global surface temperature changes have been within the range of climate model simulations.

Now a new study shows that the models were even more accurate than previously thought.

There’s a common myth that models are unreliable, often based on apples-to-oranges comparisons, like looking at satellite estimates of temperatures higher in the atmosphere versus modeled surface air temperatures. Or, some contrarians like John Christy will only consider the temperature high in the atmosphere, where satellite estimates are less reliable, and where people don’t live.

This new study has shown that when we do an apples-to-apples comparison, climate models have done a good job projecting the observed temperatures where humans live.

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