Normally, I don’t bother to discuss paleoclimatological reconstructions. The reason: most try, some through questionable methods, to illustrate that the recent warming is unusual and could only be explained by the increased emissions of manmade greenhouse gases. And that’s the same claim being made for the instrument temperature record by proponents of the hypothesis of human-induced global warming. But as I’ve been illustrating and discussing for 4 years, ocean heat content data and satellite-era sea surface temperature indicate Mother Nature is responsible for the warming of the global oceans, see here [42MB], so I don’t find claims of unprecedented, human-induced global warming to be realistic. However, I noticed something that’s very obvious in an illustration from a recent paper that’s getting some press, and I wanted to make it easier to see, for those who’ve overlooked it.
There have been numerous discussions about the Kaufman et al (2013) paper “Continental-scale temperature variability during the past two millennia”, also known as the PAGES (PAst Global changES) reconstruction. ClimateAudit has been reporting on it for a number of days. See Steve McIntyre’s posts here, here and especially here. WattsUpWithThat has discussed the paper here and here. SkepticalScience responded to the paper as could be expected here. RealClimate’s post includes an interesting illustration, which drew my attention to the paper. It’s a modified version of Figure 2 from Kaufman et al (2013). I’ve included the original version from the paper as my Figure 1. The source of the illustration is here.
Figure 1
The illustration presents their color-coded temperature anomaly reconstruction as 30-year mean temperature anomalies for the individual regions, which are further identified in the map (Figure 1) from the Kaufman et al (2013). Clearly, there has been, as the title of the paper states, “Continental-scale temperature variability during the past two millenia”. In some of the regions, recent temperatures are warmer than they have been in the past, but in others, the recent temperatures have been exceeded in the past or are comparable. Here, let me make it easier to see.
I’ve modified Figure 2 from Kaufman et al (2013) to show only the regions where recent temperatures are warmest in my Figure 2. Those 3 regions include only the Arctic, Asia and Australasia. In my Figure 3, I’ve modified their illustration to show the regions where recent temperatures are cooler than or comparable to past temperatures. Those 4 regions are Europe, North America, South America and Antarctica.
Figure 2
####
Figure 3
Something else also stands out in the 3 regions where current temperatures are warmest, my Figure 2. Only one of the reconstructions extends back the full 2000 years. Would Asia and Australasia have warmer temperatures than those we’ve experienced recently if their reconstructions could be extended farther back in time? Dunno.
CLOSING
Clearly, the claims of unprecedented recent temperatures are not supported by the regional reconstructions. Four of the seven regions presented by Kaufman et al (2013) clearly show that recent temperatures are comparable to past temperatures or they have been exceeded in the past. This can also be seen in the individual graphs presented in Steve McIntyre’s post here. Now, hasn’t this been one of the arguments by climate skeptics since the hockey stick was introduced—that the hockey-stick appearance is a regional phenomenon? That regional reconstructions show current temperatures have been exceeded in the past in many parts of the globe?
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Another straw man Bob, where the mainstream media reports on paleoclimatic reconstructions at all it tends to be hemispheric and global rather than regional.
You’ve already stated that, through choice, you are not well informed in this topic and that’s fair enough, but it would behoove you to learn more before chucking out scurrilous insinuations.
Kevin MacDonald appears to be completely uninformed. The issue is over global warming, not ‘hemispheric’, or ‘regional’ warming.
Global warming is being disregarded and ignored, because it stopped a decade and a half ago. Warmists lost the argument, as judged by the ultimate Authority: planet earth.
Bob Tisdale:
I’m more familiar with the notion of regional difference as applied to the MWP (and LIA), usually voiced by mainstreamers when ‘skeptics’ posit that the MWP was a global phenomenon. The chart Tsidale point to here indicates that previous periods of warm and cold were regionally distinct, including for the MWP.
But we know from the instrumental record that every region of the globe has been warming for the past 40 years or so, which would appear to be ‘unprecedented’, at least in terms of the proxy data analysed in this comprehensive study.
It should be noted that some of the continental reconstructions come a bit short of AD 2000.
Arctic 1 – 2000
Europe 1 – 2003
Asia 800 – 1989
North America 480 – 1974
South America 857 – 1995
Australasia 1001 – 2001
Antarctica 167–2005
http://www.nature.com/ngeo/journal/vaop/ncurrent/fig_tab/ngeo1797_T1.html
So one should add a bit more warmth to the end of Asia and North America.
Well, we have the Arctic, Europe and Antarctica back to AD167, and North America back to AD480. That’s a lot to compare, and, at least as far as this study shows, there is quite distinct variability between regions at the same time, as well as centennial trends that go in the opposite direction. This suggests we should not expect uniform temperature reconstructions bewteen regions.
Claims of recent temperatures being likely unprecedented are about global average temperatures, not regional. Rebuttals of the claim should get the claim right to begin with.
FTR, I do not consider the question of regionality/homogeneity of the MWP and LIA to have been decisively answered. Comprehensive reconstruction efforts like these get us closer to underdstanding the past, and should be lauded. But we don’t need comments like this in the discussion;
That’s not science, that is politics. It’s a group smear, unprovable, and should be against the comments policy for guest writers.
Kevin MacDonald appears to be completely uninformed. The issue is over global warming, not ‘hemispheric’, or ‘regional’ warming.
db, I don’t think you understood what Kevin wrote. Bob was confused about the connection between regional and global, and Kevin pointed this out. Regional-global confusion is a recurring theme of this thread.
Indeed, and elsewhere, too. For a long time people claimed that temps were hotter in 1934, mistaking the US temp record for global. It takes more effort to clear up inaccuracies than it does to propagate them.
I find it curious that Antarctica looks to have been in a warm trend, at least up to 200-300 years before present.
Anomalies? Curiouser and curiouser; makes one wonder how that particular paleo data was verified and how the whole region suffered such anomalies.
Correct me if I’m wrong, but didn’t the BEST project show that a significant number of regions of the globe have actually got a cooling trend? Not a majority, obviously, but enough to be noticeable. The figure of 30% comes to mind, but I could be misremembering.
@ur momisugly Bob Tisdale / April 23, 2013 at 7:22 am
Antarctica: maybe we can conclude that slow ‘coolers’ are slow ‘warmers’?
my point was to demonstrate that in this important matter in the discussion and the division you made, you missed the issue of seas and oceans;
the SH is mostly water (and ice); all that water behaves differently, you could have taken that in account;
Kaufmann et all did adress this matter in the chapter “Twentieth-centure reconstructed temperature” of their article;
Fredd and barry:
I am replying to your posts at April 23, 2013 at 7:10 pm and April 23, 2013 at 8:55 pm, respectively.
Clearly, you have completely misunderstood the issue.
This misunderstanding is endorsed by barry in his post which supports the post by Fredd which says
Firstly, at first I thought Kevin MacDonald was “completely uninformed” but his responses to me convince me he was being disingenuous.
The issue of ‘global vs regional’ was specifically addressed in my post to him at April 23, 2013 at 11:34 am
http://wattsupwiththat.com/2013/04/23/a-quick-comment-about-the-pages-continental-temperature-reconstructions/#comment-1285118
The three of you have studiously evaded that issue.
To save others needing to use the link I copy my explanation to here.
Please explain why you think the finding of Kaufman et al (2013) does not have low confidence when most of the regions it assessed disconfirm its global conclusion.
Richard
Kevin MacDonald says: “You’ve already stated that, through choice, you are not well informed in this topic and that’s fair enough, but it would behoove you to learn more before chucking out scurrilous insinuations.”
When I wrote the comment you replied to, the paper that came to mind was Gergis et al 2012, which was a hockey-stick reconstruction of Australian temperatures, not global or hemispheric. It received pre-publication promotion at alarmist websites and by the MSM–and was later withdrawn. (I also believe the Gergis et al data was incorporated into Kaufman et al 2013, so it’s relevant.) It might behoove you, Kevin MacDonald, to consider Gergis et al before making accusations of “scurrilous insinuations”. Additionally, I’m sure I could find other regional hockey-stick reconstructions discussed by the media and alarmists. While I don’t study paleoclimatology, I’m not immune to headlines.
Darrell Kaufman states on RealClimate blog 21st apr that “During the last 30-year period in the reconstructions (1971-2000 CE), the average reconstructed temperature among all of the regions was likely higher than anytime in at least ~1400 years.” Without access to the paper from my current location, I raised a question on the blog after having looked in the supplementary information:
8 Jens Raunsø Jensen says:
22 Apr 2013 at 5:31 AM
Dr Kaufman: According to the Fig S1 in the supplementary information on the Pages website referred to above, the Pages 2K reconstructed temperature consistently overestimate global temperature in more recent decades by say 0.1 C. How has this been taken into account when concluding that “.. the average reconstructed temperature among all of the regions was likely higher than anytime in at least ~1400 years.” ? (sorry, but I can not read the paper from my current location).
As there was no answer to my question, I restated the question today, which after a few hours of moderation disappeared from the blog:
1. Jens Raunsø Jensen says:
Your comment is awaiting moderation.
24 Apr 2013 at 2:29 AM
I posed a question to Dr Kaufman 2 days ago (#8). If Dr Kaufman is out of reach, perhaps one of the many reaearch team members could answer my question. Given the significant overestimation of global temperature in recent decades by the reconstructed temperatures, documented in the supplementary material, it may not be surprising that the reconstructed temperatures during the recent 30 year period may be found to be at the higher end of the reconstructed temperature curve. Do you still consider it a “likely” reality, that temperatures during “1971-2000″ was higher than at any time > 1400, or could this be an artifact associated with a bias in the temperature reconstruction?
Can anybody here comment on the substance of my question, which apparently 78 authors or the staff at RC have no time or inclimation to address?
thanks, jens
Jens Raunsø Jensen:
At April 24, 2013 at 4:36 am you ask
Yes, I do.
You have made a good find.
I respectfully suggest that you rephrase it as a statement then submit it to Nature Geoscience. Ensure your submission and all responses are recorded by e.g. copying it to WUWT. The rephrasing could be similar to this
Sirs:
I write to draw attention to an unexplained matter which seems to require and addendum or corrigendum to the paper
Ahmed M, et al., ‘Continental-scale temperature variability during the past two millennia’, Nature Geoscience, 21 April 2013.
According to the Fig S1 in the supplementary information on the Pages website, the reconstructed temperature consistently overestimate global temperature in more recent decades by about 0.1 C. The paper and supplementary information do not state how has this been taken into account when concluding that “.. the average reconstructed temperature among all of the regions was likely higher than anytime in at least ~1400 years.”
regards
& etc.
And I also suggest that you make your submission soon or somebody may take the credit for your observation and forestall it.
Richard