Tuesday, September 8, 2015

Whatever happened to Dr. Mann's "hockey stick graph"? part 2

Dr. Mann's Hockey Stick times three dozen!

I came across this collection of over three dozen climate studies that examined Earth's climate history from various angles.  Interestingly these studies consistently produce a hockey stick shape graph reflection of what's happened here on Earth.  

The list was put together by Professor Jim Milks over at EnvironmentalForest.blogspot.    It underscores the substantive nature of the much maligned and misrepresented "Hockey Stick Graph" which actually first appeared in the iconic Keeling Curve, but was made infamous by the Republican/libertarian's malicious attack against the paleoclimate studies of Dr. Mann, et. al.  
{I informed Dr. Mann of posting this. He pointed out: thanks Peter,
yes—it’s a good site, and I have linked to some of their stuff before.
There is one slight error in the piece below (the Keeling Curve is definitely *not* the Hockey Stick!).
To which I responded: That's my layperson's sloppiness at work - From my perspective seems to me that our planet's skyrocketing CO2 levels over the past couple centuries looks frighteningly akin to a "hockey stick" shape.  But your point is taken.}

This PR campaign singled out Dr. Mann lead researcher of a large team of experts who's evidence these special interests simply refused to acknowledge.

Reality is that Dr. Mann's work isn't needed to make the point that we are really screwing up our planet's climate system, (the thing we and our society depend on for everything).  

With thanks to Dr. Milks' for his permission, I reprint his Hockey Stick Graph Collection:


Sunday, October 27, 2013
Enough hockey sticks for a team


One of the persistent denier myths is that the Hockey Stick (usually meaning Mann et al. 1999) has been discredited.  Not only is that myth false but Mann et al. (1999) has been validated through the publication of numerous hockey stick graphs since 1999.  Here is a brief list of the ones I know:

Crowley 2000: Used both his own and Mann et al. (1999)'s hockey sticks to examine the cause of temperature changes over the past 1,000 years.  Found that natural forcings could not explain twentieth century warming without the effect of greenhouse gases.

Huang, et al. 2000: Reconstructed global average temperatures since AD 1500 using temperature data from 616 boreholes from around the globe.
Bertrand et al. 2002: Reconstructed solar output, volcanic activity, land use changes, and greenhouse gas concentrations since AD 1000, then computed the expected temperature changes due to those forcings.  Compared the computed temperature changes with two independent temperature reconstructions.

Esper et al. 2002: Reconstructed Northern Hemisphere temperatures between AD 800 and AD 2000 using tree ring chronologies.

Cronin et al. 2003: Reconstructed temperatures between 200 BC and AD 2000 around Chesapeake Bay, USA, using sediment core records.

Pollack and Smerdon 2004: Reconstructed global average temperatures since AD 1500 using temperature data from 695 boreholes from around the globe.

Esper et al. 2005: Compared and averaged five independent reconstructions of Northern Hemisphere temperatures from AD 1000 to AD 2000.

Moberg et al. 2005: Combined tree ring proxies with glacial ice cores, stalagmite, and lake sediment proxies to reconstruct Northern Hemisphere temperatures from AD 1 to AD 2000.

Oerlemans 2005: Reconstructed global temperatures from AD 1500 to AD 2000 using 169 glacial ice proxies from around the globe.

Rutherford, et al. 2005: Compared two multi-proxy temperature reconstructions and tested the results of each reconstruction for sensitivity to type of statistics used, proxy characteristics, seasonal variation, and geographic location.  Concluded that the reconstructions were robust to various sources of error.

D'Arrigo et al. 2006: Reconstructed Northern Hemisphere temperatures between AD 700 and AD 2000 from multiple tree ring proxies using a new statistical technique called Regional Curve Standardization.  Concluded that their new technique was superior to the older technique used by previous reconstructions.

Osborn and Briffa 2006: Used 14 regional temperature reconstructions between AD 800 and AD 2000 to compare spatial extent of changes in Northern Hemisphere temperatures.  Found that twentieth century warming was more widespread than any other temperature change of the past 1,200 years.

Hegerl et al. 2007: Combined borehole temperatures and tree ring proxies to reconstruct Northern Hemisphere temperatures over the past 1,450 years.  Introduced a new calibration technique between proxy temperatures and instrumental temperatures.

Juckes et al. 2007: Combined multiple older reconstructions into a meta-analysis.  Also used existing proxies to calculate a new Northern Hemisphere temperature reconstruction.

Wahl and Ammann 2007: Used the tree ring proxies, glacial proxies, and borehole proxies used by Mann et al. (1998, 1999) to recalculate Northern Hemisphere temperatures since AD 800.  Refuted the McIntyre and McKitrick criticisms and showed that those criticisms were based on flawed statistical techniques.

Wilson, et al. 2007: Reconstructed Northern Hemisphere temperatures from AD 1750 to AD 2000 using tree ring proxies that did not show a divergence problem after AD 1960.

Mann et al. 2008:  Reconstructed global temperatures between AD 200 and AD 2000 using 1,209 independent proxies ranging from tree rings to boreholes to sediment cores to stalagmite cores to Greenland and Antarctic ice cores.

Kaufman, et al. 2009: Used tree rings, lake sediment cores, and glacial ice cores to reconstruct Arctic temperatures between 1 BC and 2000 AD.

von Storch et al. 2009: Tested three different temperature reconstruction techniques to show that the Composite plus Scaling method was better than the other two methods.

Frank et al. 2010: A brief history of proxy temperature reconstructions, as well as analysis of the main questions remaining in temperature reconstructions.

Kellerhals et al. 2010: Used ammonium concentration in a glacial ice core to reconstruct tropical South American temperatures over the past 1,600 years.

Ljungqvist 2010: Reconstructed extra-tropical Northern Hemisphere temperatures from AD 1 to AD 2000 using historical records, sediment cores, tree rings, and stalagmites.

Thibodeau et al. 2010: Reconstructed temperatures at the bottom of the Gulf of St. Lawrence since AD 1000 via sediment cores.

Tingley and Huybers 2010a2010b: Used a Bayesian approach to reconstruct North American temperatures.

Büntgen et al. 2011:  Used tree ring proxies to reconstruct Central European temperatures between 500 BC and AD 2000.

Kemp et al. 2011: Reconstructed sea levels off North Carolina, USA from 100 BC to AD 2000 using sediment cores.  They also showed that sea levels changed with global temperature for at least the past millennium.

Kinnard et al. 2011: Used multiple proxies to reconstruct late summer Arctic sea ice between AD 561 and AD 1995, using instrumental data to extend their record to AD 2000.

Martin-Chivelet et al. 2011: Reconstructed temperatures in the Iberian Peninsula from 2000 BC to AD 2000 using stalagmites.

Spielhagen et al. 2011: Reconstructed marine temperatures in the Fram Strait from 100 BC to AD 2000 using sediment cores.

Esper et al. 2012: Used tree ring proxies to reconstruct Northern Scandinavian temperatures 100 BC to AD 2000.  May have solved the post-AD 1960 tree ring divergence problem.

Ljungqvist et al. 2012: Used a network of 120 tree ring proxies, ice core proxies, pollen records, sediment cores, and historical documents to reconstruct Northern Hemisphere temperatures between AD 800 and AD 2000, with emphasis on proxies recording the Medieval Warm Period.

Melvin et al. 2012: Reanalyzed tree ring data for the Torneträsk region of northern Sweden.

Abram et al. 2013: Reconstructed snow melt records and temperatures in the Antarctic Peninsula since AD 1000 using ice core records.

Marcott, et al. 2013: Reconstructed global temperatures over the past 11,000 years using sediment cores.  Data ended at AD 1940.

PAGES 2k Consortium 2013: Used multiple proxies (tree rings, sediment cores, ice cores, stalagmites, pollen, etc) to reconstruct regional and global temperatures since AD 1.

Rohde et al. 2013: Used proxy and instrumental records to reconstruct global temperatures from AD 1753 to AD 2011.

The proper response to someone who asserts that the Hockey Stick has been falsified is to ask "Which one?"  As for what most of the temperature reconstructions show, the data from Marcott et al. (2013) combined with 30-year smoothed HadCRUT4 data is fairly representative:

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