2011-06-21 05:48:25Last Interglacial Climate - Part TWO
Steve Brown

brownsg@gmail...
80.177.115.133

First draft of part two of the series is now up here.  Part 2 covers orbital forcing and CO2, with a couple of jg's illustrations put to good use.

Comments, criticisms and suggestions are greatly appreciated.  The forum peer review is extremely valuable and significantly improved part one.

Thanks, Steve

2011-06-21 15:07:16
Chris Colose

colose@wisc...
69.86.130.70

Hi Steve, this series is looking pretty good.  A few points:

Models have determined that much, if not all, this warming can be explained by increased insolation from orbital forcing as the Earth travels around the Sun and shifts its axial tilt in regular cycles.  However, it's likely that glacial-interglacial CO2 variations have strongly amplified warming via the greenhouse effect.

These two statements appear inconsistent.  I would consider re-wording, or at least making it clear that Milankovitch forcing is a pacemaker but other carbon feedbacks are required to get the full magnitude of climate change between glacial and interglacial cycles (as well as communicate a spatially heterogeneous forcing over the globe). 


I think it's also worth noting that the terms "Last Interglacial" and "Eemian" should not be used interchangeably, since the latter is a biotratigraphic representation of the Last Interglacial, and specifically in Europe (i.e., when a certain percentage of tree taxa is reached relative to the total pollen record), and so there's spatial and temporal variations for the onset of the Eemian in Europe.  Note also that the "Eemian" in Europe is the Sangamonian in North America, and there's also regional equivalents to the Eemian in various European regions, depending on intellectual and cultural heritage.

I think you should find a way to make your Figure 2 more appealing too, since it has a lot of detail and is a bit difficult to see.  You can also elaborate on greenhouse gas changes, such as methane concentrations, or convert these numbers into a radiative forcing.

2011-06-22 00:56:54Figure 2
jg
John Garrett
garrjohn@gmail...
108.23.2.2

I agree with Chris on Figure 2. Let me compose it differently for the 570 screen width limit and incorporate any other suggestions any of you make. One change be to use a pseudo-3d illustration of the orbit changes that may fit all three configurations in the same space (e.g within 570 pixels). (Or would you leave it as is?)

I'll be working on it.

jg

2011-06-22 02:31:50Know thy audience...
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

Steve,

Although your initial draft would be apprropriate for publication in a scientific journal, it is not appropriate for posting on SkS because it will be over the heads of most SkS readers.

During my professional career, I spent a good deal of time transforming drafts of technical reports generated by consultants into documents that the genearal public could comprehend, Drawing upon this experience, I am willing to help you transform you draft into a more digestable document.

PLMK if you would like me to provide you with a suggested rewrite of your draft?

Thanks.

John Hartz

2011-06-22 05:16:13
Steve Brown

brownsg@gmail...
80.177.115.133

@Chris - I'll certainly look at clarifying that snippet on the orbital and GHG forcings. 

WRT the interchanging between "Last Interglacial" and Eemian, I have tried to restrict use of "Eemian" to the context of W and N Europe in the posts, but I do recognise the potential for confusion so I'll take note.  Oddly though, when I did my extensive literature search last year there was surprisingly little published research that explicitly referenced the likes of Sangamonian, Ipswichian, Riss-Wurm etc.  The only keywords that tended to be assigned were "Eemian", "Last Interglacial" and "MIS 5e".  It seems that the lazy use of "Eemian" outside of it's strict definition has become more common.  I have documentary and video evidence of more than a couple very eminent climatologists who should know better being guilty of this ;-)

 

@jg - yes anything you can do for clarity is appreciated.  I was intending to do a link from the small image to a full-size one anyway, so it would be good to keep the drawing as informative as possible without sacrificing anything valuable to the pixel limit.  I was wondering if you could clearly highlight the Last Interglacial period on the Figure 1?

 

@Badgersouth - I would most certainly welcome suggestions for rewriting it.  What I've been conscious of is dumbing it down too much especially when there are a lot of rich resources already on SkS that explain forcings and Kroll-Milankovitch cycles etc. that regular readers may be familiar with.  Are there any known demographics on the typical SkS reader?

Many thanks all! Steve

2011-06-22 05:59:53
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve,

Yes. I have a version of Figure 1 on my home computer, so I'll revise it to highlight the Eemian.

Here is a visually more concrete orbit diagram to replace the same part in Figure 2 (note: I posted an earlier version here and deleted it):

Earth's orbit during last interglacial

2011-06-22 20:10:32simpler ending?
jyyh
Otto Lehikoinen
otanle@hotmail...
85.78.241.106

" it is not appropriate for posting on SkS because it will be over the heads of most SkS readers."

Conclusions chapter?

Northern hemisphere got more sun than now because the earth's orbit was such it was closest to the sun during the summer of the northern hemisphere. The opposite was true for the southern hemisphere, so the overall difference in temperatures was relatively small. The best records indicate the northern hemisphere was up to (degrees C) warmer than currently, and this would have melted the Greenland Ice Sheet more than during the current interglacial, This is one reason for scientists to be extra worried of the potential WAIS collapse. There are only few records from SH, and they indicate (what?) that the extra warmth the NH got spread somewhat even there.(is this correct?)...

2011-06-23 00:35:57Figure 1 question
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve, before I revamp figure 1, please know that I can do anything with that figure and you don't have to use it as is. For example, I can reduce the span so that it shows orbital changes over 100k, 200k or 400 k years instead of the 600k shown. A shorter span may make the cycles less intimidating to look at.

Standing by.

jg 

2011-06-23 01:50:14Suggested Revison #1: Green "Note" box needed
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

For starters, insert a green note box al la McManufactured Controversy with the following text (or some variation thereof):

NOTE:  This is the second article of a three-part series on what we can learn from the Last Interglacial time period. Understanding this period may provide clues on how the environment may respond to similar conditions in the future. In the first post, we described the conditions that exisited during the Last Interglacial. In this post, we we examine two of the key factors that caused the conditions described in the first post. In the third, and final, article we will explore what all this means for the future.

Note: Insert URL links to the first and thrd articles in the above text.

2011-06-23 02:54:38Suggest Revision #2: First paragarph
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

Note: Creating the green "Note" box recommendaed above obviates the need for most of the first paragraph of Steve's initial draft. Here's a suggested rewrite of the first paragraphs

Two of the the key factors in determining the conditions that existed during the Last Interglacial, also known as the Eemian in Europe, are:

1. changes in solar insolation, i.e., a measure of solar radiation energy received on a given surface area in a given time commonly expressed as average irradiance in watts per square meter (W/m2).

2. changes in the concentrations of greenhouse gasses in the atmosphere.

 

 

2011-06-23 06:05:31
Steve Brown

brownsg@gmail...
80.177.115.133

jg - With that new figure 2 you've done I think we can give the guts of the post more focus by providing an explanation for the illustration and removing some of the technical jargon in the current draft. WRT the figure 1, could you please shorten the timespan to 0 - 200 Ka.  That will include the penultimate glaciation through to the Holocene.  It would be helpful if you could integrate a similar glacial-interglacial highlighting as you did for the timeline in the first post. Thank you.

Badger - I've pleasantly surprised myself by working out how to do one of those green boxes.  I've also had a bash at integrating your suggestion for the first paragraph :-)  I'll start work on stripping out the techy jargon by the weekend.

To set expectations on the series (and put the heebiejeebies up everyone), I'm aiming to do 5 posts for this series:

part 3 - Ice sheet volume, sea level and albedo feedback

part 4 - role of thermohaline circulation on the LIG climate (ties in neatly with ice sheet melt) 

part 5 - summary post with discussion on the value of the LIG for predicting future impacts and a mention of the MIS 11 interglacial (400ka) which may be a better analogue for the Anthropocene

2011-06-23 06:11:48
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve: Here's the 200+ kya version. This version supercedes the illustration I posted in this comment earlier (I had a 400 kya timeline, but my timeline was marked incorrectly) .

jg

orbit parameters

 

 

2011-06-23 06:18:21
jg
John Garrett
garrjohn@gmail...
108.23.2.2

PS> I reversed the timeline from the original so that left is older and right newer (a feature I added to my graphing tool after an SKS reader requested it).

jg

2011-06-24 05:22:03Steve Brown
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

Either John Cook or Dana will have to explain how to create the "Green Box." I've never attempted to do so.

2011-06-24 05:43:43
Steve Brown

brownsg@gmail...
80.177.115.133

jg - that illustration is a work of genius.  I'll try to do it justice.  Thanks!

badger - I've managed to get a green box very similar to Dana's by inserting a 1 row x 1 col table and using a green background colour.  The table properties also allow you set a border.

2011-06-24 06:03:15Greenbox
BaerbelW

baerbel-for-350@email...
109.41.129.27

In order to get a greenbox you need to switch to HTML-editing and then start the relevant paragraph with the following code:

< p class="greenbox" > (just without the space after the < and infront of >).

Hope this helps!

For more tips and to copy the code check out Daniel's post: http://www.skepticalscience.com/thread.php?t=1587

2011-06-25 00:03:15graphic update
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve, just so you know, I'm working on the chart that shows rise of temperatures next to insolation values. I hope to have something later today.

 

jg

2011-06-25 05:54:38New Graph Compares Holocene and Eemian Orbital Forcing
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve,

Look at what you made me draw. I haven't added all of the annotations yet, but I wanted to share this graph as I think it tells so much. I reworked the old one because in the old one I compared today with the holocene peak. However, I thought that pairing was arbitrary. In this one. I sychonized the graphs based on the last time an equinox was at perihelion. When equinox is a perihelion (a situation Chris and I should explain in the Orbital Forcing series; or you might) the insolation graphs of north and south tend to cross. So rounding off at the nearest thousand (I retrieved orbital data in 1000s), I sychronized -134kya with -8kya and produced the graph below. Note that the full width graphs are Eemian and the cut off ones are Holocene. I'll add more labels later, but wanted to share what I had. I'm inviting criticism of my method.

jg

[update: Error. The labels on the graph below for present north and south insolation should be reversed, which calls to question my method. I'll update the figure and rethink the point at which I should synchronize the comparison between Eemian and Holocene. I think it should be at the previous crossing point for Holocene. Your thoughts?]

Orbital forcing comparing Eemian to Holocene

2011-06-26 02:03:16
Steve Brown

brownsg@gmail...
80.177.115.133

That insolation graph is very informative.  I can understand the reasoning behind synchronizing on the perihelion equinoxes, though we'll need to explain this in the figure description.  My only alternative suggestion would be to synchronize by centring on the Holocene and Eemian climatic optimums (5-8 ka & 125-127 ka).  That would demonstrate the relative differences in insolation from glacial termination, through peak warming and into cooling.  For annotations to the graph, I would suggest adding the Holocene years along the top x-axis and maybe making the Holocene lines dashed to differentiate them more from the Eemian ones.

2011-06-26 04:24:24
jg
John Garrett
garrjohn@gmail...
96.229.221.76
Steve Good suggestions. I will do what you suggest Jg
2011-06-28 05:41:47thumb
jyyh
Otto Lehikoinen
otanle@hotmail...
85.76.63.37

Yes, I was too hasty to suggest a provocative conclusion chapter... might the larger tilt of the axis be the reason for Atlantic water to have moved to the arctic? somewhat similar could possibly happen with the shifting storm tracks sometime in the future.

2011-06-28 06:10:52Illustration update
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve,

Here are four variations for the graph that bridges between the orbit diagram and the insolation values of Eemian and Holocene climatic optimums. (In the future, should I put these on my blog so as not to clutter up the conversation here?) These can be done as overlays: each diagram is the same as the previous but adds a new section. The last one is a variation of the third.

I plan to work on this some more this evening, so this posting is to get your feedback.

(Update: I cleaned up the last graphic)

jg

Orbit bracketing Eemian

orbit w forcing annotation

 

Eemian w/ holocene

 Eemian orbit, insolation w/ Holocene

 

2011-06-29 06:39:19
Steve Brown

brownsg@gmail...
80.177.115.133

Hi JG - These graphics are exceptionally good.  I think that the 3rd one is probably a bit too busy.  The last one is probably the one I'd pitch for having for the summary discussion in part 5 of the series.  I think the 2nd drawing would be ideal to add into the draft of part 2 that I'm close to finalising.

Unless John C is running out of disk space, I'd keep adding your graphics to the threads here so the others can comment or suggest alternate uses for them.

2011-06-29 06:54:12
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Just post a note here when you're ready to publish part 2, Steve.

2011-06-29 07:47:31
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Hi Steve. Will you want a version of these graphs with CO2 and temperatures too?

jg

2011-07-01 00:25:58
Steve Brown

brownsg@gmail...
80.177.115.133

Dana - I'm not planning to change anything further, so it's ready to go.  If Chris Colose is ready with his Milankovitch Cycles post, then it would be good for them to go out around the same time.  I'm now heading off for a few days camping by the seaside, so I won't be able to answer any questions until Tuesday.

JG - I think we're done for part 2.  I'll be starting on the draft for part 3 on sea-level and ice-melt next week.  I'm planning on using the Eemian&Ice drawing from your blog that has the representation of sea-level rise and ice-sheet melt contribution.  It would also be useful if you had the completed Eemian Sea drawing that you posted the other day.  Thanks again for your help! :-)

2011-07-01 01:52:36
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve,

I'll do a clean up of Eemian&Ice so it will fit nicely in the 570 wide limit and will finish the Eemian Sea.

Regarding the Milankovitch Cycles post, if Chris isn't releasing his soon, I could put together a few illustrations for a basic overview of tilt, eccentricity and precession. It could serve as the simple version on the topic and wouldn't take away from Chris's version, assuming he plans to release his later.

jg

2011-07-01 19:51:02
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.27.11

Steve - I reckon you need a concluding paragraph (in plain language) summing up the answer to the question you pose in the title of the post. 

2011-07-02 01:03:29Final sentence should be tweaked
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

The final sentence now reads,

We'll investigate in part 3 of this series on the Last Interglacial Climate....

Recommended rewrite:

This question will be answered in Part 3 of this series on the Last Interglacial Climate.

2011-07-02 04:20:59
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Steve - I've got you and Chris tentatively on the schedule for Wednesday Aussie time, Tuesday US/Euro time.  Lots of pending posts right now!  When it rains it pours, as they say.

2011-07-03 03:02:24Chris Cook
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

National Academy of Sciences, Committee on Abrupt Climate Change (2002). Abrupt Climate Change: Inevitable Surprises. Washington, DC: National Academy of Sciences (online here) includes the section, EEMIAN RAPID CLIMATE CHANGEi

I recommend that you read it prior to posting Part 2.

2011-07-06 05:57:28
Steve Brown

brownsg@gmail...
80.177.115.133

@Badger - I managed to get your tweak of the last sentence in, but didn't have a chance to look at a simple summary that Rob suggested before it was posted. 

I have read that "Abrupt Climate Change: Inevitable Surprises" book.  In fact, it was the main reference I used for my degree dissertation proposal. IIRC Richard Alley and Pielke Jr are two of the authors. 

2011-07-06 06:38:05
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

You can still edit the post if you'd like, Steve.

2011-07-06 08:24:38
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Great post, Steve. I was so proud of getting the illustrations to fit into the 570 limit, that I lost sight of the text quality, which is most noticeable on the 2nd illustration. Let me know if you'd like me to clean it up or have me post a larger version somewhere. Perhaps we can do a larger version of a summary to your series and post it as supplement to your last installment.

jg

2011-07-06 08:43:23
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.101.27

jg - you can upload a larger image via the Author Admin, click on the smaller image in the post and insert the link to the larger image. That way when the cursor rolls over the smaller image in the post, the clickable 'pointing hand' pops up allowing the reader to click on the larger version.

2011-07-06 08:51:24
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Such power! I'll give it a try.

thanks

--update: I take that back. Rob, I misunderstood. I see how to link to another graphic when I'm the author. I don't have author's access to Steve's post and I didn't mean to imply to others that I would edit someone's post without their permission.

2011-07-06 12:09:31
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Steve,

I tried a basic Milankovitch post here: Orbital Forcing.

I welcome your opinion.

jg

2011-07-06 12:57:16
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.250.27

jg - just FYI is all. Not suggesting you should tinker with someone else's post.

2011-07-06 13:13:03FYI
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

FYI:  If you see a post needing editing and the original author of the thread post is unavailable, just create a post detailing the corrections needed in the Author or the Blog post sections of the Forum and one of the Super Admin's (John's terminology) will see to it.

2011-07-07 06:08:46
Steve Brown

brownsg@gmail...
80.177.115.133

I'm loath to make any significant changes to the post now it's published - other than correcting errors.  However, I'm open to revising them in a few months if any hot papers appear that change or challenge anything.  My final post in the series will be a discussion and summary, so there is plenty of scope to expand on explanations and pull threads together.

jg - You never cease to amaze me.  I've only had a quick scan of your Milankovitch post and the quality of those graphics is stunning.  If you've not done so already, you should start a new thread in the forum for it to let everyone else see it.  I'll have a proper read through and get back to you with any comments tomorrow.

Also, if you do have larger copies of those graphics then I will do a mouse over link to them from the versions in the post.  Thanks!

2011-07-07 10:25:47
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Hi Steve,

I uploaded slightly larger versions of the graphics to these locations:

http://www.skepticalscience.com/pics/orbitParams_wUnits_lg.jpg

http://www.skepticalscience.com/pics/Orbit_130_125kya_lg.jpg

http://www.skepticalscience.com/pics/eemian_2_lg.jpg

I was mostly concerned that I had made the reference to Laskar et al in the 2nd illustration illegible.

thanks

2011-07-07 18:13:30
Steve Brown

brownsg@gmail...
91.220.25.25

Thanks jg, I've put links to the larger images on the post.

2011-07-12 06:26:55
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Steve,

I'll be travelling between July 16-24, so let me know when you think you'll do your next parts on the Eemian interglacial. I should be able to do any illustrations you need this week, but want to have a fresh conversation on what you'd like.

jg 

2011-07-13 06:16:24
Steve Brown

brownsg@gmail...
80.177.115.133

Hi jg,

For post 3 I'll be covering sea-level and ice-sheet melt, plus touching on Arctic sea ice area.  There are two graphics so far that I intend to use.  The first is the EemianAndIce illustration on your blog.  The 2nd is a sea-level chart from Hearty et al (2007), which is rather amateurish and could do with your magic brush - unfortunately the SkS genie is preventing me from uploading the image at the moment.

I would like a version of your EemianAndIce globe without the Holocene hemisphere.  It would be good to have the whole globe represent the Last Interglacial world with a representation of the size of the ice-sheets and showing the Eemian sea etc.

I've also found a past SkS post that discusses the Greenland Ice Sheet during the Last Interglacial, which I may link to.  I've got a first draft of the post nearly ready which I'll post up by the end of the week.

Thanks, Steve 

2011-07-13 07:30:25
jg
John Garrett
garrjohn@gmail...
108.23.2.2

Hi Steve,

Please email any graphic you'd like reworked to me at garrjohn@gmail.com 

I'd like to get the two illustrations done before I travel next week

jg

2011-07-14 13:18:03
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Steve,

(Its on the SKS site)

jg

2011-07-15 07:09:28
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Steve,

I've been creating a 3d model of the Earth. Here is my take on the Eemian peak. I've guessed at the glaciation. For sea level, followed low lying contours. You can see Scandavia as an island.

So, tell me what you'd like. I can annotate the globe, zoom in or whatever. jg

2011-07-15 13:17:18
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Steve, Here's some overview of the Eemian without a comparison to the Holocene (and corrected per Daniel's comment). Also, I split this into two illustrations.

 

2011-07-15 13:22:18
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Your title of the last graphic does not parse.

Or do I need another beer (as if I had to ask)?

2011-07-15 13:57:03
jg
John Garrett
garrjohn@gmail...
96.229.221.76
While your having another, parse me one too. Thx. Will fix in the morning.
2011-07-16 06:24:16
Steve Brown

brownsg@gmail...
80.177.115.133

duplicate deleted

2011-07-16 06:26:11
Steve Brown

brownsg@gmail...
80.177.115.133

jg - That MIS 5e sea-level chart is bang on the money!  Your Eemian globe illustrations have opened up some possibilities for the next post, so I'll need to spend a while mulling over what annotations they require.  I'll have a list for you for when you get back from your travels!  ;-) My first request would be for you to alter the shape of the Greenland ice sheet so it's similar to the shape of the GIS on this graphic from Otto-Bliesner et al (2006), which I'll be using.  It's worth presenting a consistent picture.  It would also be handy to have a caption for the Eemian Sea, so I can make the link back to the first post.

Cheers, Steve

 

2011-07-16 12:56:37
jg
John Garrett
garrjohn@gmail...
96.229.221.76

Steve, I look forward to addressing your wish list when I return.  I see illustration as a back and forth creative process, so I'm glad that you're taking advantage of this. Thanks for the greenland ice sheet reference and for the Hearty paper. I'm learning a lot.

jg

2011-07-16 13:39:23
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Umm, hate to nit-pik (but I'm grouchy because I'm out of beer), but shouldn't it be "Scandinavian Islands" vice "Scandanavian Islands"?

2011-07-16 13:41:06
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Umm, hate to nit-pik (but I'm grouchy because I'm out of beer), but shouldn't it be "Scandinavian Islands" vice "Scandanavian Islands"?

2011-07-16 13:42:58Oops
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Damn refresh bit me.

Please ignore the double-post.

Sigh...

2011-07-16 14:00:45
jg
John Garrett
garrjohn@gmail...
96.229.221.76
Thx Daniel. Please nitpick any illustration I draw. It flatters me to know that someone has looked at it long enough to catch something I missed.