I put together a quick post on the new sea level hockey stick study:

Sea Level Hockey Stick

I'm wondering if I should nix the second figure to keep the focus on the first one.  But without the second figure it's a pretty short post.  Anyway, let me know if you have comments.  We want to get this one out while the iron is still hot, so quick feedback would be appreciated.

Wow, quite a timing! I have just exchanged e-mails with Martin Vermeer, one of the authors. They wanted me to check the Finnish version of their news release (as Martin works in a Finnish research institute). I did that and I also offered that I could recommend a blog post on it here too. Well, you have done it already so nevermind.

I'll read your piece later and make comments. There might be a possibility that I could squeeze a short interview out of him, if you have anything to ask.

Or better yet, I could give your text to him for comments. Is that ok?

I would suggest the key message from this paper is "since the 19th century, sea level has risen at an average rate of 2.1 mm/y, representing the steepest century-scale increase of the past two millennia.". Or in plainer terms, "recent sea level rise is the fastest over the last 2000 years" which is nicely emphasised in the graphic. So to emphasise this major point - get it up front and centre, the blog post could start like this (this is just a suggestion):

A paper recently published in the Proceedings of the National Academy of Sciences by Kemp et al. (2011) has assembled new sea level reconstructions for the past 2,100 years based on sediment from the US Atlantic coast. What they found was recent sea level rise is the fastest over the last 2000 years:

Figure 1: Sea level reconstruction by Kemp et al. (2011) using sediment from 10 salt marshes in North Carolina

Among the co-authors of this paper are some heavy hitters in climate research: Michael Mann, Martin Vermeer, and Stefan Rahmstorf.  The authors summarize their findings:

"Sea level was stable from at least BC 100 until AD 950. Sea level then increased for 400 y at a rate of 0.6 mm/y, followed by a further period of stable, or slightly falling, sea level that persisted until the late 19th century. Since then, sea level has risen at an average rate of 2.1 mm/y, representing the steepest century-scale increase of the past two millennia. This rate was initiated between AD 1865 and 1892. Using an extended semiempirical modeling approach, we show that these sea-level changes are consistent with global temperature for at least the past millennium."

In short, there was little change in their sea level reconstruction from 100 BC to 950 AD.  During the Medieval Warm Period and a bit beyond, sea level rose, as one would expect.  Into the Little Ice Age, sea level fell slightly, until just over a century ago, when sea level rise began to accelerate rapidly.

I noticed from the general chat section that you are trying to rush this out. I don't think there's much need for that as there are already articles out on this in Climate Progress and RealClimate for example.

Nice one! Could you add the link between North Carolina sea level rise and global sea level rise?

For North Carolina, we estimate
that the deviation in sea-level rise from the global mean due to
ocean circulation changes is between 0 and +5 cm. This estimate
was based on the IPCC AR4 model ensemble for a 21st century
global warming of ∼3 °C, in which sea level rises globally by 22–48 cm.

We take 5 cm. as an upper limit estimate as temperature
and sea-level variations over the last 2100 y were smaller
(Fig. 2A). The gravitational effect from continental ice sheet
melting on sea level along the Atlantic coast is negative and we
conclude that an upper limit is −5 cm for the largest sea-level
variations in North Carolina (SI Text).
IPCC AR4 (36) showed that local sea-level trends differed by
up to 2 mm/y from the global mean over AD 1955–2003, which
implies deviations of up to ±10 cm at some locations (but ±5 cm
along most coastlines) as the sum of forced and unforced effects.
This analysis suggests that our data can be expected to track
global mean sea level within about ±10 cm over the past two
millennia, within the uncertainty band shown for our analysis
(Fig. 2C).

"A paper recently published in the Proceedings of the National Academy of Sciences by Kemp et al. (2011) has assembled new sea level reconstructions for the past 2,100 years based on sediment from the US Atlantic coast."

I would include here a mention that they used microfossils of foraminifera instead of mentioning only sediment.

"In short, this sea level reconstruction is yet member of the ever-growing hockey team..."

Another member?

Dana, as well as Ari's amendments, perhaps this bit: 

"Looks remarkably like a certain piece of equipment from a certain cold weather sport, doesn't it?"

Should be a hyper-link to the Hockeystick post? I know most readers will grasp it immediately, however casual readers may not.

I knew the paper had only come out today (or yesterday) but obviously RC and CP are all over it. So not super urgent. Nevertheless, the earlier we get our post out, the more likely the graphic does get spread around more.

I still have great trouble predicting what makes a pic go viral. Dana's IEA graph went seriously viral. I've tried to replicate that success with other graphics, but really tough to put your finger on what makes a pic capture people's imagination (plus all the other factors like time of day, who tweets what when, etc that all add up to something spreading virally).

There's probably some optimum strategy - the best time of the week, the best time of the day, etc. Someone should figure that out, write up a formula for us to use :-)

So could you link the graphic to:

http://www.skepticalscience.com/graphics.php?g=22

Up to you but you're welcome to add a green box at the end saying there's a high rez version in the Climate Graphics section that others are free to use.

Perhaps replying to the skeptic meme too early nobbles it before it can built up a head of steam? The skeptics realize it aint' gonna fly so stop pushing the nonsense so hard. And perhaps the SkS graphic is almost unique?. The SkS sea level graph, although much clearer, has competition from those in the paper, whereas was there much competition, in terms of clarity, for Dana's graph? 

Just wonderin'.

Comments from Martin Vermeer:

- "Using sediment from 10 salt marshes" is not correct: data was used from two places, Tump Point and Sand Point.

- Additionally it might be good to show datapoints. Red curve and pink belt are just a "summary" of raw data using 9th degree polynomial fitting.

- Microfossils are a central issue so it would be good to describe their use, but the issue is rather complicated.

- Text doesn't mention the model research which was Stefan's and Martin's share of this research project. This was a semi-empirical equation that relates the Mann et al. 2008 temperature stick to this sea level stick.

with Rob Painting -- avoid the temptation to be smart-assy about a new hockey stick graph. They'll be plenty of opportunity to do that in the comment thread.

Just in case it helps, RealClimate has a post.

Fastest Sea-Level Rise in Two Millennia Linked to Increasing Global Temperatures

Okay I made a number of revisions as suggested.  I think the post is much improved.  John, what do you think about Vermeer's suggestion to add data points to the figure?

LOL, I can just picture John telling Vermeer "don't be such a scientist" :-)

Yeah, I agree with John. Remember the target audience and K.I.S.S.

Maybe it should be specified that it has been modified from the original fig. 2

I would still urge you to include a mention of microfossils of foraminifera.

Care to write up a little microfossil and foraminifera discussion that I can insert into the post, Ari?

We'll see if I have time (working in the office right now), but I just meant a tiny little mention, something like this: "...sea level reconstructions for the past 2,100 years based on microfossils of foraminifera found in sediment from the US Atlantic coast."

That should be fine.  I also linked to the write-up at RC for further explanation of the methodology.

Ari, are you in contact with Martin Vermeer?  If so, could you pass it along that Tiljander is back!, and in reference to the paper he co-authored.  You could point him to the conversation I'm having with Amac (the tiljander guy) at Amac's blog.  I'm not sure if he's interested, but he was at some point last year.

http://amac1.blogspot.com/2011/06/tiljander-data-series-appear-again-this.html

Grypo, the issue with Tiljander is simply that Mann et al. seem to have a wrong proxy number for Tiljander series. That number signs the reconstruction code that the series in question does not need to be inverted, when actually some Tiljander series would need to be inverted.

I'm in contact with Martin. We have a Finnish closed google group containing some bloggers, hobbyists, and climate scientists, including Martin. I can point out this to him, but I don't see AMac doing anything worthwhile there but just seems to wish a revival of this Tiljander issue, as it seems to be only one he/she cares about.

By the way, I have had a discussion with him/her as well. Behind the link you also find my take on the Tiljander issue.

Martin answered that he didn't check if they used the series that contained Tiljander series but he assumed they did. He said that according to Mann et al. (2008) the effect of problematic series is small so it doesn't really matter.

Please don't quote him on this, as I didn't ask if we can use his comments and I don't want to put him to a difficult position (as deniers sometimes react in an ugly manner to these things).

Thanks Ari,

I remember Martin was involved in a discussion last year and thought he might want to discuss it further.  I'm done with it as I can now see where the issues lie.  Amac and many other people won't let that go until Mann admits the mistake of using Tiljander data, shows why he used post 1720 data, and grovels for forgiveness.  They don't care that it doesn't matter in the results, even though Amac denies it in that thread, it's about Mann.   Although an explanation from Mann as to why he keeps using the series is not an unreasonable request IMO.  In a sense, "I use it because it doesn't matter" isn't a good explanation.  It leaves me in a tough spot to try and explain that the results don't effect the paper when the author allows skeptics to focus on the scientific behavior.

Amac says:

In my opinion, there's no explanation that starts out other than, "We erroneously employed the Tiljander data series as temperature proxies." This is a road that the authors decided not to travel in their Response to McIntyre's and McKitrick's Comment in PNAS. 

And they just keep doubling down, as far as I can tell.

My impression is that Mann is one of his own worst enemies.

That ceratinly could be the case, Neal.  At this point, I'm not sure there's anything that could be done.  He'll never get out their cross-hairs, but a little humility on his part (if there is cause for it) would help in getting past some of these issues for us trying to explain some big picture problems in relation to his work.  The fact that the sea level work is getting hijacked by Tiljander is absolutely atrocious.

The study has also been criticised on various blogs for using [edit] Tiljander lakebed sediment data series [edit]
I don’t claim to understand the objection but given that it has spread like wildfire on blogs I am surprised that no one has mentioned it here.

Is this objection valid?

[Response: No. Just more of the usual deception from dishonest mud-slingers. More on that in short order. -Mike]

 

It appears something is coming.  Amac is not going to like it, me thinks!