What are the implications of this new temperature reconstruction?

Question

A new study has come out examining temperatures over the past 2000 years. They find that the Earth has been in a modest cooling trend since at least the Roman times. Other significant conclusions:

"We found that previous estimates of historical temperatures during the Roman era and the Middle Ages were too low,"

"Our results suggest that the large-scale climate reconstruction shown by the Intergovernmental Panel on Climate Change (IPCC) likely underestimate this long-term cooling trend over the past few millennia."
Press release: http://www.uni-mainz.de/eng/15491.php

The graph itself does not look like a hockey stick at all: http://www.uni-mainz.de/eng/bilder_presse/09_geo_tree_ring_northern_europe_climate.jpg

They also mention: "Such findings are also significant with regard to climate policy, as they will influence the way today's climate changes are seen in context of historical warm periods."

Note: This study used tree rings for proxy data and I have been skeptical of their use for temperature reconstructions. As well, the main author Dr. Jan Esper has been uncooperative in the past regarding the release of data, especially to Steve McIntyre. I would expect that McIntyre would audit this study just like he did Mann's and report any problems. So I'll wait to see if the results turn out to be robust but for now let's speculate that it may indeed by accurate.

Answer 1

Why post it if you don't trust proxy data, an old claim of deniers (unless of course you are using to try and make one of you own points)

This is hardly new info the long term proxy data for the entire Holocene shows gradual cooling starting ~8000 years ago with a few bumps along the way due to natural changes.



Can I also suggest (although I think I am wasting my time) that you reread the title of the paper especially this part "Climate in northern Europe" then check a globe of the world, this is globally speaking a small region and one that has local phenomenon like the North Atlantic Current warming the region, what that current has done over the last 2000 years is not fully known or understood, so using data from just this single region is not that good a guide to global conditions.

The paper states they used trees from just one small region (Finland) a point I'm sure the Jim's and Twitchie and yourself would be jumping all over if one of us had posted this paper.

Why not use such proxy data from a number of regions (Canada for instance) to give at least a second reference point.



At the risk of repeating Big G's answer "Will you ever give up the BS,"

You may want to call this throwing daggers, I calling pointing out the abundantly obvious.

As a number have tried (in vain it seems) to point out to deniers like yourself over a considerable period of time just getting a paper published is not in itself proof, it is one scientist (or small group of scientists) putting forward an idea, many paper are published in many fields of science and come to nothing as they are based on an idea that doesn't hold up. Cold Fusion is a prime example, but AGW is now 30 years (at least) in the literature it is not one paper or even just a few papers it is thousands of papers that have built on and increased our understanding of the atmosphere and climate. This is of course why denier try to discredit peer review, because they know they have little in their array of absurd theories that can even get past the hurdle of that first publication, never mind stand up to the follow up papers that have to date easily torn denier nonsense to bits.

That you also attempt to suggest "scientific discussion" when you are part of group that still try to use absurd arguments like "it's volcanoes" or "it's the Sun" is truly laughable.

Answer 2

It suggests that natural variation has played a more important role in climate change in the recent past than what alarmists care to admit



Hey, GasByAssFire reads Watts. There is hope for him yet.

Answer 3

Once again, the "experts" are only looking at a very small portion of the Earth to "declare" what happened over the whole Earth. This is very unscientific. Then again, over the past 35 years "scientific research" has become a lot more political and a lot less scientific.

Answer 4

Yet another fascinating coincidence, you and anthony watts must be brothers from another mother to think alike frequently. I mean, he already asked this question on his blog two days ago. It is purely a coincidence I know, there is no chance you read it first on his blog. You were just browsing new scientist and came up with the exact points that he did:



"I’m sure Steve McIntyre will give this paper a thorough examination for the same sorts of issues we’ve seen before in MBH98. Hopefully he won’t have to beg for years to get the data for replication like he did with Mann."

http://wattsupwiththat.com/2012/07/09/this-is-what-global-cooling-really-looks-like/

Answer 5

""The graph itself does not look like a hockey stick at all""



That's because tree proxies can only be correlated with growing season (i.e. summer) temperatures. The hockey stick graph is in regards to to global temperatures. The hockey stick used multiple proxies to create the reconstruction.



So, what are the implications of this? Not sure, but showing that summers have gotten increasingly cooler until recently kind of supports what many here have said; that before the anthropogenic forgings came into play the globe was in a cooling phase.





EDIT - BTW, the irony of your new found faith in climate science and scientists isn't lost, regardless of your attempt to rationalize it away.

Answer 6

Will you ever give up the BS,



Climate change of course looked at the past, but we are concerned with the 1880s when many places began keeping weather records.



I believe you know full well that climate scientists have studied both the average global temp since the late 70s and earlier, correlating the rise in temp with rising CO2 levels and hence climate change.



You deniers just keep grasping at straws.

Answer 7

It sounds like David is ready to scrap tree ring proxies. The problem with that line of thinking is that alarmism is absolutely dependent on tree ring proxies. In fact it is dependent on an exaggeration and distortion of tree ring proxies. I don't mind. Let's throw all tree ring proxies into their proper perspective. They really aren't that reliable which is why this one is so great. It really demonstrates what a house of cards alarmists rely on. I got a feeling that this one is really going to stick in the craw of alarmists but maybe like the previous answerers they can just poo poo it away. I would very much like to see McIntyre audit it and I know he would do a great job and he wouldn't treat it with kid gloves.