Thursday, October 27, 2011

Dr. Ben Santer explaining climate science to Anthony Watts

Unauthorized notes of Dr. Ben Santer’s October 21, 2011 Chico State talk to Anthony Watts and friends.

Anthony Watts' blog posted a personal video of a talk given to him by Dr. Santer.  The WUWT comments section is dismaying in its predictable knee jerk denial that sidesteps much of what Santer was explaining.  It's like folks simply believe they can ignore anything he has to say because he's been labeled a 'bad guy' by a bunch of smooth PR guys with an axe to grind.

But, before I take the time to review some of the comments from over at WUWT to Santer's talk I believe it is appropriate to share highlights from the talk.  To that end I have transcribed large portions of the talk. 
I have also transcribed Ben Santer's full answers to the Question/Answer session after the talk in the next thread.

{brackets indicate my comments}

I've striven to double check and correct errors, but imagine I've missed some.  
Remaining errors will be corrected as I find them, or as they are pointed out to me.

Posted at Watts Up With That?

Dr. Ben Santer speaks on climate modeling, and everything else
Posted on October 21, 2011 by Anthony Watts

"Today is a day I got not one thing done for myself due to the Berkeley Earth Surface Temperature release sucking all the oxygen out of the climate debate with their pre-peer review release shenanigans. Tonight was no different, as I spent it watching Dr. Ben Santer give a presentation at Chico State University. I had a front row seat. . ."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Dr. Ben Santer’s October 21, 2011 Chico State

0:20 - {intro and satellite image of global water vapor on day Katrina made landfall.}
“It’s not just a pretty picture.  It illustrates that since the late 1970s we have had the ability to monitor global scale changes to the climate from space...”

1:00 - “Jim mentioned the IPCC, I’m sure many of you know of that organization.  They were set up in the late 1980s to advise the nations of the world what we know and what we don’t know about the nature and causes of climate change.  Like the impacts of climate change on many things we care about.  And possible mitigation and adaptation strategies.
They’ve issued four reports the most recent one being 2007.

“I was lead author of chapter 8 of the Second Assessment Report.  A chapter that dealt with cause and effect relationships within the climate system.”

1:45 - “After years of work the we came to this conclusion: “The balance of evidence suggests a discernible human influence on global climate.”  I spent roughly two years of my scientific career defending that conclusion and the process by which it was reached.”

2:15 -  “Extraordinary claims do require extraordinary proof... that (IPCC) claim back then in 1995 was extraordinary.  We were not saying eureka, there’s water in the bath tube, we understand everything.  But, we were saying look at the totality of the scientific evidence most of it points in that direction.

“Subsequently,  other groups of scientists in 2001 and 2007 came to much stronger statements regarding the reality of the human effect on climate.  They actually tried to quantify the size of that human fingerprint and again most recently the bottom line statement was: “Most of the observed increase in globally averaged temperatures since the mid twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”  Very likely having a specific probabilistic meaning greater than 90% probability of occurrence.  So one of my jobs here tonight is to give you some sense of the scientific underpinning for these conclusions.”

3:50 -  “
First of all I’ll will tell you a little bit about the drivers of climate change, both natural and human, the things that can cause changes in the climate system...”

{an outline for the talk}
* Natural and human influences on climate
* Observed climate change
* Studying cause and effect relationships in the climate system
* Evaluating climate models
* Can we reduce uncertainties in projections of future climate change
* Debunking myths about climate change
* Conclusions”

4:15 - “... climate models.  How good are they?; How do we compare them with observations? How do we use them to do climate fingerprinting to try and unlock cause and effect relationships.”

4:40 - “... I also want to tell you that there is still a lot of uncertainty in our science particularly with regard to projections out to the end of the twenty-first century.  How large are the changes in the temperature and sea-level and precipitation going to be, what is their seasonal and regional distribution, these are critically important questions.  And yet, the uncertainties in these projections out to twenty-one hundred are very large.  Are there clever ways that we might shrink those projection uncertainties?”

5:30 - “I’ve spent a lot of my career trying to address myths about climate change and to do the science necessary to address the criticism.”

5:50 - “One take home message is that climate change is not an either or proposition. It is not either all natural or all human.  The climate changes that we have experienced over the last one hundred fifty years is due to some combination of natural influences and human influences.
The natural influences include things like changes in the suns energy output.  The Sun is a variable star, we have measured, as I will show you later it energy output ...” {some details}

6:50 - “In addition to purely natural changes in the sun, there are changes in the amount ofvolcanic dust in the atmosphere ...” {Mount Pinatubo eruption, some details}

7:40 - “Then there are things that are completely unrelated to changes in the sun and changes in the amount of volcanic dust in the atmosphere and we know and love many of them here in California El Ninos, La Ninas, things like Pacific Decadal Oscillation.  These are internal modes of oscillation of the climate system.  Think of a bell, when you ring it, it rings in preferred ways depending on the composition of the bell, shape, size of the bell.  The climate system likes to ring in certain preferred ways.  El Nino, La Nina is one way in which the climate system oscillates. ...  {El Nino details}  This is all natural.”

8:55 - “In addition to these purely natural drivers of climate change, there are things that we have done to the climate system.  We know that, beyond a shadow of a doubt. ...” {GHG details}

9:50 - “From my perspective the debate in our field has not been: have human activities changed the chemistry of Earth’s atmosphere.  We know they have.  The debate has always been how much climate change will that human caused change in atmospheric chemistry lead to?”

10:10 - “In addition to changing the levels of GHG in the atmosphere, we’ve also changed the composition of and loadings of aerosol particles. ...  {aerosols some details}  ... locally and even regionally these aerosols can have profound effects on climate.”

11:15 - “Additionally humans have transformed the surface of the land...”  {example & albedo effect described}

11:40 - “So the challenge is: How do we separate the natural drivers of climate change and their impacts on climate from these human influences on climate.”

12:00 - “OK, let’s step back and look at observations of climate change.  Much discussion about  observations, the credibility, the quality.  And of course much of that discussion has focused on the integrity and reliability of surface temperature records.

“There are now four groups around the world that have taken on the difficult job of trying to assimilate information from many, many different sources. ... {some details} ... and spliced together some coherent picture of global scale changes in our planet.
National Climatic Data Center
Goddard Institute of Space Studies
UK Metoffice, Hadley Center
Berkeley Earth Surface Temperature project
{all pretty much agree}

13:15 - “Overall an increase of roughly 1.3°F over the past hundred thirty years of so, with a lot wiggles a lot of noise.  And we’ll get back to these concepts of signal and noise later.”
{many have criticized surface measurements...}

13:45 - “... so what we do in science is we look at independent measurements.  These are independent satellite measurements of the temperature of the lower atmosphere.  Roughly the lowest five miles of the atmosphere, these have been primarily made by two groups.  One group at the University of Alabama and one group at Remote Sensing Systems in Santa Rosa, California.”

14:05 - “For a long time the Alabama group {UAH} actually estimated that there was global scale cooling of the lower atmosphere.  It turned out that they had made a sign error in accounting for the effects of satellite orbital drift on the sampling of Earth’s daily temperature cycle.”

14:25 - “Now however the two groups really produce very similar estimates of global scale temperature change, and the warming during the full 32, 33 year period of the satellite record, is roughly 1°F.  Again these measurements are complete separate of the surface thermometer measurements we saw in the previous panel.”

14:45 - “ there other corroborative evidence to support these surface temperature measurements and the satellite based measurements of temperature change of the lowest five miles of the atmosphere? 
The answer is yes.”

15:10 - “People have looked at not only atmospheric temperature measurements,..
They’ve looked at Sea Level measurements,  they’ve looked at surface humidity,
they’ve looked at the total amount of water vapor in the atmosphere, they’ve looked at the heat content of the upper 300 or 700 hundred meters of the ocean, temperatures over ocean and over land, people have used multiple observational methods for this.  The bottom line is that they are going all going up...”

16:05 - “Things going down, Glaciers, Sea-Ice ...”

16:10 - “the bottom line here is that there is internal and physical consistency to the changes that we see in many different aspects of climate system.  This is not a house of cards built on one observational data-set alone.”

16:30 - “... how do we put it all together?...  How do we study cause and effect relationships...”

16:45 - “This is a very famous figure from the 4th IPCC Assessment Report ... it’s an observational estimate of surface temperature changes of the planet...”

17:10 - “... and it shows this complex behavior...”

17:20 - {Thought Experiments a la Einstein... modeling is the exercise of necessary thought experiments and learning from the lessons try offer... }

17:45 - {a synthesis of two dozen of the worlds leading models...} “... from over a dozen of institutes from around the world...”
{examining purely natural drivers}

18:05 - “I like to call this the Undisturbed Earth Experiment, essentially you are trying to simulate how might the climate of the planet have evolved in the absence of any human intervention?  ...” {detailing some complexities}

18:35 - “But the bottom line is that the undisturbed Earth experiments can’t capture the rapid warming that we have observed over second half the twentieth century.  Now when you run the same models not only with natural factors but also with human caused changes in greenhouse gases, aerosols, stratospheric ozone depletion you get this red envelope here {referring to the Hegerl et al. graph.}

19:10 - “There is some similarity between the model solution and
when you include natural and human factors and observations.  Now this isn’t compelling statistical evidence by any stretch of the imagination.  The global mean temperature can change for many different reasons.  It’s a sort of necessary Consistency Test.”

19:20 - “But it’s pretty weak evidence, so can we go further?  We can.”

19:35 - “Back in the 1970s  Claus Hasselman the director of the Max Planck Institute for Meteorology in Hamburg, recognize that the problem of trying to identify some human caused climate change signal embedded in noise of natural climate variability was a signal to noise problem and that one could borrow technics that were standard in electrical engineering to try and do that separation of the signal from the noise.

“What he recognized was you gotta look at patterns.  If you are just looking at global mean information alone there’s not a lot of specificity there, but if you’re looking at the complex geographical patterns of climate change.  Or if you take slices through the Earth’s atmosphere you have much better hope of being able to discriminate between different things that cause climate change and that’s what you see here ...”

21:00 - {examining National Center for Atmospheric Research simulations, no observations yet}
“... slices through the atmosphere, from the north pole to the south pole, and from the surface right up to about 20 miles, right up into the stratosphere.  And in each case this model was run with changes in one thing only, according to our best understanding of how that factor actually changed over the twentieth century.  So here this model was run only with changes in carbon dioxide; methane; nitrous-oxide; clouroflorocarbons over the twentieth century.

“Here the same model was run only with changes sulfate aerosol particles...
here the model was run only with stratospheric ozone changes...
here it was done with only volcanic dust over the past twentieth century...
and here only with natural changes in the sun’s natural energy output...”
{last experimental model was run with all five natural factors simultaneously.}

22:00 -  “. . . Key point: their different . . . focus on two {factors}

22:15 - {when you increase atmospheric CO2, you increase atmospheric heat retention. . .}

22:45 - “People always say that computer models are not falsifiable, that they don’t make projections that you can actually compare with observations and falsify a model.

“That’s not true.
  Back in the 1960s when Manabe
, Hansen, Washington were doing this work, we really didn’t have the observational data to determine what was happening, particularly in the stratosphere.  Satellite measurements kicked-in in the the late 70s, weather balloon measurements were sparse back in the 1960s.  These guys could have been wrong, but as I’ll show later they were not.  This is what they observed warming of lower atmosphere and cooling of the upper atmosphere.”

23:25 - “Now the fingerprint of changes in the sun’s energy output, as you slice through the atmosphere is completely different...”
{examining atmosphere cross sections}

25:20 - “The sun does not explain everything...”  {a look at the data. . .}

26:00 - “So the sun explains everything hypothesis does not fit the available observations...”

26:30 - {look beyond temperature... a valid criticism}
“... if there really is some human caused climate signal working in observations you should see it in many different aspects of the climate system.  Not just in surface temperature, not just in atmospheric temperature.  Go look beyond temperature and that was valid criticism.”

26:50 - “... and the community responded by doing this kind of pattern comparison between simulation output and observations for many different things.
total amount of water vapor in the atmosphere;
for surface pressure patterns;
for rainfall patterns;
for the vertical structure of ocean warming;
continental scale runoff”

“Now the number of different climate variables for which work has been performed is probably several dozen.”

27:30 - “... and in each case the bottom-line message is “natural causes alone can’t explain the observed changes that we’ve seen in many independently monitored variables.”

27:45 - {finger-printing and climate models}

28:00 - “Some have claimed these models are garbage, garbage in, garbage out: “You folks never compare them with observations!  You never scrutinize them!  That’s not true, as I hope to convince you.”

“The group that I work with at Livermore is called: “Program for model climate diagnosis and comparison”

“We are not climate model developers, back in the late eighties the Department of Energy decided that it was useful to separate the endeavor of developing computer models for the climate system from the job of evaluating them.  Comparing them with observations. 

“Our job is to evaluate all the world’s climate models.  To compare them with observations in a variety of different ways.
{gives details}

29:35 - “My own interest is in confronting models with observations over the satellite era, the past thirty plus years or so, and over the full instrumental temperature record...”

30:00 - {confronting models with ice age conditions... orbital parameters... ocean circulation}

30:40 - “... diagnose models by running them in weather forecast mode... taking climate model and actual make weather forecasts hours, days into the future, you can immediately confront the model with high quality observations, and you can quickly see errors that set up and learn something about the causes of those errors...”

31:15 - “... two examples of climate evaluation studies... performance portrait... comparing each model (the two dozen that were used for the IPCC 4th Assessment Report) with observations...”

33:25 - “One of the curious things is that when you take the results from this collection of nearly two dozen models and average them, and compare the model average with observation, the model average actually out performs any of the individual models.  (wisdom of the masses)”

34:30 - “Back in 2007 my colleagues and I published a paper in the Proceedings of National Academy of Sciences where we claimed to have identified some human caused climate change signal in satellite measurements of water vapor change...  In doing that climate-fingerprint work we used all of these models... that I showed you previously.

35:00 - “we were criticized, quite rightly I think: well some of these models are better than others...  you should identify the top ten models and then repeat your 2007 analysis and see whether you can still identify a human effect on climate...”

35:35 - “so we revisited this in 2009 in a followup paper and what we did was we looked at 70 different measures of model performance. We just looked two things, we looked at water vapor, and we looked at ocean surface temperature.  And we looked at how well these two dozen models simulated observed average water vapor and average sea surface temperatures and how well they captured more difficult things...”

38:00 - “... What this tells you is that even for a relatively simple case, where you’re only looking at two things, not a whole slew of variables, only water vapor, only ocean surface temperatures, it’s very difficult to identify the best models.  Model errors are complex, their complex in geography, their complex in time, it’s not easy to answer the question which is the best.

“What we did answer was: Did it matter for what we did?  Did it matter for our claim to have detected a human influence on water vapor and the answer was no.  We did the fingerprint analysis 144 different ways, using different combinations of top ten and bottom ten models and it didn’t make a difference...”

38:50 - “In each case we could identify some human influence on water vapor.  Why?  Because the physics governing water vapor changes is very simple.  You get the largest increases of water vapor over the warmest area of the ocean.  And increases in water vapor were everywhere over the globe.

“But, the natural variability pattern for water vapor didn’t look anything like the signal.  Which is why model quality for that particular problem didn’t matter.  And I think that’s the stage where we’re at.  When you do this kind of carbon fingerprinting work you have a responsibility to see whether your conclusions depend on which models you select, which statistical methods you use,  and to really look at this question of the robustness of the results.  We did and in this case it didn’t matter.”

39:40 - “But this is clearly an important question...”

40:05 - “Is there some scientifically credible way of reducing those projection uncertainties in projection, can we shrink them? ...”

42:10 - {drivers of uncertainties are uncertainties in feedbacks and their amplifications.}

42:40 - “Four primary feedbacks: one is associated with clouds and their behavior. . .
 a feedback associated with water vapor. . .
feedback associated with snow. . .
sea ice. . .”

43:00 - {snow feedback, Hall and Xu GRL 2006,}
{snow feedback, albedo effect}

43:42 - “What Alex Hall did was he looked at these roughly two dozen models which I already discussed.  And first of all he looked at the seasonal cycle.  He looked at April to May temperature changes in the Northern Hemisphere and he looked April to May snow cover changes which he could get at from satellites.  And then in the models he looked at the relationship between twenty-first century changes in temperature and snow cover.  He found this beautiful linear relationship...”

45:20 - Very quickly here I want to tackle one particular myth... This claim... that there has been no warming since 1998...

{Professor Will Happer - “Climate Science in the Political Arena”
Testimony before the US House of Rep. Select Committee on Energy and Independence and Global Warming, May 20, 2010.}
{looking at the data, signal and noise, trend period end-points - RSS data}

46:00 - "I feel it is important in the case of all these kinds of issues is to do the science, see whether the claim has validity or not...”

47:00 - {looking RSSs temperature data, comparing ten year & twenty year smoothed data trends...}

49:00 - {testing Professor Happer’s model}
{taking a closer look at the temp data from 1979 to end of 2010}

50:45 - “So, Professor Happer was wrong.  Models clearly can replicate observed temperatures changes over the post 1998 period.

51:00 - “a ten year (temperature) chunk, selected to start at a high point and end at a low point, does not constitute evidence for absence of human effect on climate...”

51:30 - “In each case the story is internally and physically consistent, natural causes alone can’t explain observed changes that we’ve seen and monitored independently in many different aspects of the climate system.”

51:45 - “People criticize climate models and say they are not useful for this kind of purpose, you never confront them with observations, that’s not true.  I’ve given you a couple examples of how our community routinely evaluates models over a variety of different innovative ways.

“But, there’s still important uncertainties. For me one of the key uncertainties is the projections of future climate change.  Shrinking those projection uncertainties, finding those transfer functions that might, just might, enable us to relate present day observable to the behavior feedbacks and to these large uncertainties in projects of future climate change.”

“So there are plenty of interesting problems for all you students in this room...”

52:35 - "There’s been a lot of discussion about trust and accountability in climate science.  I’d like to make two comments about that. 

"First of all, some folks have argued that climate modeling is some shadowy back room endeavor where people don’t share simulation output.  It’s done in the darkness, not in full public scrutiny.   That’s not true, the simulation output that I showed you here today is currently used by 4,500 scientists around the world.  It is extremely available to anyone, you can upload it without charge, you can do research with it.  We routinely share not only simulation output and observation data, we also share analysis software, visualization software.

"There’s something called the Earth System Grid which our community uses to facilitate this sharing of information.  Basically now modeling groups make their simulation output available to the whole world to look at."

53:45 - “I’m sure you all heard about ClimateGate, I was personally effected by that.  Some of my emails were in the roughly thousand emails that were illegally purloined from the University of East Anglia...”

54:00 - “ClimateGate does not call into question the IPCC and National Academy of Sciences conclusions that the Earth is warming and that humans are a major contributor to that warming.  There have been now I believe six investigations, the allegations have been shown to be baseless.  These are good men and women who have spent much of their scientific careers devoted to the difficult job of trying to understand the nature and caused of climate change.  They deserve our thanks in my opinion.”

54:30 - “Unfortunately some of our, even some of our elected representatives use words like scam, hoax, and conspiracy to describe everything that I’ve presented to you today.  That does all of us a disservice.  I firmly believe that in order to take wise decisions on what to do about climate change, we need the best available scientific information.  Not misinformation, not disinformation, not wishful thinking.

"My job as I see it is to do the best science I can and also to try and explain that science in plan English.  What we did, what we learned, what it means.

"We can’t afford to embrace ignorance.”

55:15 - “just finally, I’m a climber, I’ve spent a lot of my life in high alpine environments around the world.  In addition to the scientific imperative to understand the nature and causes of climate change and likely outcomes.

"I also believe there is a moral and ethical imperative.  Over my life-time I’ve seen important changes in some of the regions that I’ve climbed in...  These are fragile places and I’m concerned that future generations will not experience these places in the same way that I have."

Questions and Answers follow
to be continued...



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