Friday, March 6, 2015

This is what a scientist sounds like - Dr.Dessler's video shorts

Here are five short videos by Atmospheric scientist Dr. Andrew Dessler explaining various aspects of climate sensitivity including a look at Lindzen and Spencer's failed cloud feedback study.  I think these videos are fine examples of a real scientist in action explaining the facts.  Tell me you don't notice a huge difference between Dr. Dessler's approach to his topic and the weird handwaving and innuendo laced approach of folks like Dr. Singer or my man Steele.  
(I put together the notes so any mistakes in them are mine alone.)

Summary of Dessler GRL 2011
Is the climate sensitivity less than 2°C?
Stratospheric water vapor feedback
Climate sensitivity calculations, Kummer and Dessler, GRL, 2014
Decision making under uncertainty


Uploaded on Sep 5, 2011 | dessler2 | 3:45 minutes

"Cloud variations and the Earth's energy budget"
published in Geophysical Review Letters

Dessler examines Lindzen and Spencer's suggestioin that it's clouds causing warming and that human influence warming.

Earth's energy balance equation
Energy deposited by clouds
Energy deposited by the ocean

Lindzen, Spencer argue cloud "deposits" are high
1:30  "What they didn't do though was use data to actually evaluate the magnitude of these terms (deposits) directly, and that's what I've done in my paper using measurements made over the last decade.

repeat "Lindzen and Spencer "assumed" their values and many problems in their paper flow from the incorrect values that they assumed."

Clouds turn out to make a minor contribution.  (0.5W/m2 clouds vs 10W/m2)

2:45  Closer look at other Lindzen, Spencer evidence, "lag between time series" plot suggesting climate models are doing a poor job.

In my paper I reproduce the plot and show how it is constructed with a set of models and particular set of observations that maximize disagreement.
And that a fuller comparison of all models and all data provide quite a different view.

* No merit to the suggestions that clouds cause climate change
* No merit to the claims that climate models as a group are "wrong"
* No evidence that revisions to mainstream climate science are required

A copy of the paper is available here: (if that link doesn't work, try:


Published on Aug 4, 2013 | dessler2 | 6:39 minutes

My analysis of why I think it's unlikely that climate sensitivity is below 2°C


Amplification from feedbacks
Quantifying the water vapor and other feedback
Cloud feedback - there is no evidence for negative cloud feedback
bottom up approach (bottom line) climate feedback >2°C
5:15  Problem with estimates based on twentieth century temperatures


Published on Oct 2, 2013 | dessler2 | 3:42 minutes

A short summary of the Dessler et al. PNAS paper, Stratospheric water vapor feedback, 2013


Anatomy of our atmosphere
Humidity of the Troposphere increasing -
Stratospheric water vapor feedback
If a warming climate causes and increase in the humidity of the stratosphere
Water vapor is greenhouse gas this would warm the stratospheric 
and add additional warming to the climate system
{or as I like to call it our Global Heat Distribution Engine, cc}

Testing their hypothesis using data from the Microwave Limb Sounder collecting monthly anomalies over the last eight years from the tropical lower stratosphere.
Found evidence that "A warmer climate increased the stratospheric water vapor" of our planet, confirming the hypothesis. 

2:20  "We then analyzed a chemistry climate model from NASA Goddard and found that it had a similar water vapor feedback in it which was encouraging."

2:45 look at  "change in stratospheric H2O over the 21st century in the GEOSCCM"

3:00  "Stratospheric Water Vapor feedback"
* our best estimate is that this feedback is responsible for 5-10% of the climate warming from addition of greenhouse gases
* this is operating in present climate models, but is it simulated correctly?
* this feedback is an important part of our climate system


Published on May 13, 2014 | dessler2 | 4:26 minutes

"The impact of forcing efficacy on the equilibrium climate sensitivity"
Geophysical Research Letters, 2014

Equilibrium Climate Sensitivity (ECS)
ECS = warming after CO2 is doubled and the system runs to steady state

How to calculate ECS:
     climate models
     paleoclimate records
     interannual variations
     20th century observational record    (<2° hmmm)
~ ~ ~
importance of "forcing efficacy"
Dessler explains error...
Forcing "efficacy can resolve the differences between various ECS estimates
20th century ECS is 6°F (3°C), in good agreement with the IPCC's canonical range

They find no evidence to support the very low value sensitivity that some are arguing for.


Published on Aug 11, 2013 | dessler2 | 6:13 minutes

"Should we listen to the 97% or the 3%"

Well for starters, it should be obvious ...
*if 97% of the experts agree on something, that's probably correct
- Earth is warming
- Humans are very likely responsible for most of the recent warming
- Future warming may be severe
*That doesn't mean it IS correct

Let's investigate some decision making under uncertainty and see how we handle uncertainty in other venues.

* Considering our legal system, "guilty beyond a reasonable doubt"
* Cheney's 1% doctrine 
* Mechanics and the plane you are about to take-off in

4:00 Normative Choice.  Our choices:
* We must be certain that climate change is going to be catastrophic before we take action to head off climate change???
*If there's even a small chance of catastrophic harm occurring, we must act now as if it were a certainty??? (Cheney standard)

Evaluating potential errors

We are dealing with irreversible changes


No comments: