Sunday, November 25, 2012

Has there been "Little change in global drought over the past 60 years"? - info links

I'm a regular visitor at the Climate Change board over at  A recent post has inspired me to compile the following collection of links to recent articles since they examine a recent paper that "obfuscationists" are trumpeting as more proof that global warming is nothing to be concerned about.

The paper being:
"Little change in global drought over the past 60 years"
Nature 491, 435–438 (15 November 2012) doi:10.1038/nature11575

So while denialists continue using every diversion in their drive to disregard the seriousness of our warming planet.  I believe we need to refocus on The Real Story.     

That is, the effort of working toward better understanding the physical dynamics of this one and only planet we inhabit.

More specifically our global heat distribution engine.

After all, science is a learning process and learning tends to be one lesson after another.

There are a handful of serious blogs looking at this.  Good places to continue the learning process.  For instance Nielsen-Gammon gives a nice thousand word description of the basic situation:

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"Counting Drought" by John Nielsen-Gammon 
Wednesday, November 21, 2012  
The paper is called “Little Change in Global Drought Over the Past 60 Years”(Nature, doi:10.1038/nature11575), and it’s by a team led by Justin Sheffield,a research scientist at Princeton University.  When carefully parsed, the paper makes two arguments.  
First, it argues that previous analyses of increasing drought used a drought index that is artificially biased toward increasing drought in a warming climate.Second, it argues that when an appropriate drought index is used, one finds “little change” in drought.{...}...The trend in the old PDSI is twice the trend in the new PDSI, and the average area in drought is 25% of the globe with the old PDSI and only 15% of the globe with the new PDSI.So far, things seem straightforward.  But there’s the minor matter of two earlier studies that looked at the difference between old and new PDSI and, contrary to Sheffield et al., concluded that there was little practical difference. . .there's more

Then, there is this...
Tree rings and Drought IndicesKevin Anchukaitis ~  
. . .  Sheffield et al. note that the bias they identify arises from ‘a simplified model of potential evaporation [Thornthwaite model] that responds only to changes in temperature’. Indeed, this is something that scientists in the drought community have been aware of — For example, Aiguo Dai published a paper last year in the Journal of Geophysical Research in which he noted that {link}

Trenberth has a few things to add...
By Joe Romm on Nov 20, 2012 ~ A “drought” in good science  
Kevin Trenberth:"The new paper recently published in Nature by Sheffield et al “Little change in global drought over the past 60 years” [Nature 491 15 Nov 2012 435-440] has done some impressive work. . . "

Here's another good one...
Drought area changed little over recent decades15 Nov 2012, Freya Roberts  
What's changed?The Intergovernmental Panel on Climate Change (IPCC) concluded in its Fourth Assessment Report, published in 2007, that "Globally, the area affected by drought has likely increased since the 1970s". In its 2012 Special Report on Extreme Events (SREX), the IPCC was more cautious about past trends, concluding "there are large uncertainties regarding global-scale trends in drought".{and some say the IPCC is extreme and bias... nonsense !}{...}Newer models include more of these factors, giving a more accurate picture of drought. . .{...} 
Does this affect future predictions of drought?The finding that some models may have overestimated past drought is unlikely to affect predictions about future droughts. That's because working out how climate change might affect drought in the future is done using different - climate - models. These climate models are more sophisticated and operate in a different way than the simple models this study looked at to analyse past drought. . .
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ also has a good round up


The thing that frustrated me the worst is how well the denialist camp manages to get everyone to focus on minute details.  
All intended to keep us from learning to appreciate what we do know.  
Our weather is the product of our planet's climate.   
GHGs are a central component of that global heat distribution engine.  
GHGs ARE sequestering more heat. 
Anthropogenic global warming will manifest itself in many ways, 
many of which we don't fully understand.  

But, the fact that we don't fully understand every aspect has nothing to do with the fact of the warming.  
How long will it take us to stop arguing about the scientific consensus and get on with the real work?

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The AGW consensus is NOT formed by scientists.
The AGW consensus IS compelled by the evidence.
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One Directional Skepticism Equals Denial


Dan Pangburn said...

Paraphrasing Richard Feynman: Regardless of how many experts believe it or how many organizations concur, if it doesn’t agree with observation, it’s wrong.

The Intergovernmental Panel on Climate Change (IPCC), some politicians and many others stubbornly continue to proclaim that increased atmospheric carbon dioxide was the primary cause of global warming.

Measurements demonstrate that they are wrong.

The atmospheric carbon dioxide level has now increased since 2001 by 23.2 ppmv (an amount equal to 25.9% of the increase that took place from 1800 to 2001) (1800, 281.6 ppmv; 2001, 371.13 ppmv; October, 2012, 394.32 ppmv).

The average global temperature trend since 2001 is flat.

That is the observation. No amount of spin can rationalize that the temperature increase to 2001 was caused by a CO2 increase of 89.5 ppmv but that 23.2 ppmv additional CO2 increase had no effect on the average global temperature trend after 2001.

Without human caused global warming there can be no human caused climate change.

Analyses that can be reached at the link (highlighted in red) given at include an equation based on rational physics that, without considering any influence from CO2 whatsoever and using only one independent variable, has calculated average global temperatures since they have been accurately measured world wide (about 1895) with an accuracy of 88% (R2 = 0.88, correlation coefficient = 0.938). Including the influence of CO2 (a second independent variable) increased the accuracy to 88.5%.

Peter said...
This comment has been removed by the author.
Peter said...

Regarding Dan's comment, there's too much to answer here so I've put together a more detailed post dedicated to examining Dan's conjectures.

Please see: