Ljungqvist 2010's "Hockey Stick" Paper

About 15 years ago a paper was published[1] that included a proxy reconstruction of extratropical Northern Hemisphere temperatures for the last 2000 years. The graph included in the paper sometimes gets adapted by contrarians to give the impression that the Medieval Warm Period was warmer than today. Here's one example:

The claim is then made that this is evidence or proof that Mann's hockey stick was a fraud, and scientists like Mann were actively trying to erase the Medieval Warm Period. Of course there are a few problems with this conclusion, beginning with the fact that it appears these people haven't even read the abstract of Ljungqvist's paper:

Our temperature reconstruction agrees well with the reconstructions by Moberg et al. (2005) and Mann et al. (2008) with regard to the amplitude of the variability as well as the timing of warm and cold periods, except for the period c. ad 300–800, despite significant differences in both data coverage and methodology.

Rather than proving Mann was a fraud who erased the Medieval Warm Period, this paper actually replicates both Moberg et al 2005 and Mann et al 2008 with differing methodology. Here's the graph published in the paper.

This shows that the last decade or so before the publication of this paper was warmer than the warmest years of the Medieval Warm Period. And Ljungqvist actually says this in the paper:
Decadal mean temperatures seem to have reached or exceeded the 1961–1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself.
The data table with Ljungqvist 2010 records that the decade from 1010-1019 had a mean value of 0.063 C. The proxy value for 1990-1999 had a mean value 0.055 C. The two values are statistically identical, so the proxy evidence does not prove that the 1990s were warmer than the 1010s, though the instrumental record does show temperatures were warmer during the 1990s than during 1010-1019. 
However, GMST has been increasing at a rate of 0.2 C/decade since 1970, and the NH has been warming faster than the SH, so the decade that was a statistical tie with the warmest decade of the MWP has been surpassed by the decades that followed. NH temperatures are now much warmer than the warmest decade of the MWP. There's now no question that the 21st century is warmer than the warmest decade of the MWP.


Reference:

[1] Ljungqvist, F. C. (2010). A new reconstruction of temperature variability in the extra‐tropical northern hemisphere during the last two millennia. Geografiska Annaler: Series A, Physical Geography, 92(3), 339–351. https://doi.org/10.1111/j.1468-0459.2010.00399.x


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