Hockey Stick Resources

Perhaps there's nothing in climate science subjected to more conspiratorial and defamatory thinking than the hockey stick. Before 1998 and the publication of the Mann, Bradley, Hughes "hockey stick" reconstruction (MBH98), scientists were severely limited in understanding global or even hemispheric temperature variability prior to about 1880. Scientists had access to individual proxies, like those from ice cores in Greenland and Antarctica, and they had some long-term reconstructions focusing on local areas, like Central England. But scientists also knew that, even over time scales of hundreds to thousands of years, temperature proxies at individual locations were not reliable indicators of global temperature variability. With the publication of MBH98 (and MBH99 the following year), scientists for the first time had hard evidence that global warming following the Industrial Revolution was truly exceptional, and natural variability simply wasn't producing the kinds of swings in global temperatures that we are currently experiencing.

In the quarter decade following the publication of MBH98, the networks of proxies that scientists have been able to access has grown, both in geographic and temporal resolution, and scientists have been able to reconstruct global temperatures for the last 2000 years with enough confidence to confirm that warming in recent decades has been truly exceptional. And investigations into earlier periods of the Holocene have shown that both the amount of warming and rate of warming have not been matched in the last 100,000 years.

Shortly after the publication of MBH98 (and especially after its inclusion in the following IPCC's third assessment report, or TAR), opposition to the "hockey stick" began to take aim at Mann, his co-authors and the TAR. This opposition appears to have been motivated almost entirely by political ideology. In several posts, I attempt to document the how the controversy unfolded, and I do this under several headings:

Has the Hockey Stick Been Disproven?
In this series I cover the accusations by Stephen McIntyre and Ross McKitrick (M&M) published in several papers, comments, and Climate Audit blogposts. Much of this took place before 2007.

Part 1 - Here I cover M&M's initial criticism of MBH98/99, much of which turned out to be due to M&M failing to make their spreadsheet correctly. The paper was published to support the political agenda of Energy & Environment. as the journal's editor admitted.

Part 2 - Here I cover the continued criticism from M&M, much of which turned out to be due to M&M censoring the proxy data. A paper by Wahl and Ammann essentially vindicated the MBH papers. 

Part 3 - Here I cover what turned out to be a political interference campaign, where several prominent Republicans attempted to attack the academic freedoms of MBH without any substantial criticism of the scientific papers replicating the MBH hockey stick.

Was There a Nature Trick to Hide the Decline?
In this series I cover attempts to revitalize criticism of the hockey stick following the hack of CRU emails. These attacks generally depend on misreading the language of the emails and have nothing to do with the validity of the peer-reviewed literature on the hockey stick.

Part 1 - Here I cover the misreading of an email in which Phil Jones explained how he constructed a graph that was submitted to a WMO report. While Jones wasn't transparent about where the proxy data ended and where the instrumental data began in each time series, most of the controversy that came out of this email depends on a misreading of what the email actually says.

Part 2 - Here I covers attacks by M&M attempting to manufacture controversy between Mann, Briffa and others as they were preparing their graph for the TAR. It turns out that M&M had to insert words in to the emails that were never written in order to make it appear like the controversy he wanted was in the emails.

Part 3 - Here I cover the continuing saga of M&M refusing to give up on their debunked talking points some 25 years after the publication of MBH98

Proposed Alternatives to the Hockey Stick
This isn't a series, but in several posts I describe what many contrarians propose as alternatives to the Hockey Stick. Long-story short, to date there is not one reconstruction of global or hemispheric temperatures in the peer-reviewed literature that doesn't show a hockey stick shape. Not a single one.

Loehle - Loehle 2007 published a reconstruction that essentially attempted to construct a reconstruction with no tree ring proxies. The initial attempt was flawed and republished as Loehle 2008. Despite having low resolution and poor geographic coverage, it's just a wavier-looking hockey stick.

Schönwiese - There's a graph often attributed to Schönwiese that is reported to be an alternative to the hockey stick, except contrarians don't seem to be able to agree on what they want the graph to be. It turns out that if you track down the original, it supports the hockey stick.

Alley - R.B. Alley published a reconstruction of temperatures in Central Greenland that is sometimes used by contrarians as an alternative to the hockey stick. However, they neglect to inform you that the graph is of local temperatures, not global, that the time series, ends in 1855, and that R.B. Alley himself says that this misuse of his paper is "stupid."

Other Matters
Here are some other posts dealing with other matters related to the hockey stick.

Mann v Ball - Here I summarize the evidence surrounding the Mann v Ball case that was dismissed after a partial settlement with FCPP in which FCPP admitted to publishing untrue and disparaging statements about Mann.