2010-11-25 04:00:30Basic rebuttal for 11: "CO2 lags temperature"
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
80.42.211.107

Here's my first attempt at this - as always, feedback welcome. 

 

Earth’s climate has varied widely over its history, from ice ages characterised by large ice sheets covering many land areas, to warm periods with no ice at the poles. Several factors have affected past climate change, including solar variability, volcanic activity and changes in the composition of the atmosphere. Data from Antarctic ice cores reveals an interesting story for the past 400,000 years. During this period, CO2 and temperatures are closely correlated, which means they rise and fall together. However, changes in CO2 follow changes in temperatures by about 600 to 1000 years, as illustrated in figure 1 below. This has led some to conclude that CO2 simply cannot be responsible for current global warming.

Figure 1: Vostok ice core records for carbon dioxide concentration and temperature change.

This statement does not tell the whole story. The initial changes in temperature during this period are explained by changes in the Earth’s orbit around the sun, which affects the amount of seasonal sunlight reaching the Earth’s surface. In the case of warming, the lag between temperature and CO2 is explained as follows: as ocean temperatures rise, oceans release CO2 into the atmosphere. In turn, this release amplifies the warming trend, leading to yet more CO2 being released. In other words, increasing CO2 levels become both the cause and effect of further warming. This positive feedback is necessary to trigger the shifts between glacials and interglacials as the effect of orbital changes is too weak to cause such variation. Additional positive feedbacks which play an important role in this process include other greenhouse gases, and changes in ice sheet cover and vegetation patterns.

The only conclusion that can be reached from the observed lag between CO2 and temperatures in the past 400,000 years is that CO2 did not initiate the shifts towards interglacials. To understand current climate change, scientists have looked at many factors, such as volcanic activity and solar variability, and concluded that CO2 and other greenhouse gases are the most likely factor driving current climate change. This conclusion is not based on the analysis of past climate change, though this provides key insights into the way climate responds to different forcings and adds weight to the several lines of evidence that strongly support the role of greenhouse gases in recent warming.

 

2010-11-26 11:17:49
Andy S

skucea@telus...
66.183.167.232

This is very good and clearly written. I have a few quibbles, though.

 "warm periods when life was able to thrive on land" I believe that life thrived on land even during the glacial periods, but not, of course in high latitudes.

I prefer "data reveal" rather than "data reveals" but that's a little pedantic, I admit. 

I don't disagree with the the ocean temperature-CO2 explanation but I think that some hint should be given that the exact mechanism of this linkage (ie chemical(solubility), biological (plankton, corals) and physical (ocean stratification)) is not clearly understood. A good discussion of this can be found in Box 6.2 of the IPCC chapter on Paleoclimate page 446. I don't think you need to get into the details, merely acknowledge that there is uncertainty as to mechanisms. (Page 449 also has a good FAQ article which covers the same ground as your rebuttal and which you may well have already seen).

" Without the release of CO2 (and other greenhouse gases), the shifts between glacials (ice ages) and interglacials would not be possible as the effect of orbital changes is too weak to cause such variation." I think this is too strong a statement. It's true that CO2 variations are essential to fully account for the magnitude of the temperature variation but  CO2 is not the only feedback (although they refer to them, confusingly, as forcings) and not even the largest one, according to Hansen et al.

 A final comment is that I don't understand what you mean by "internal variability" in the last paragraph. Also, I think that the last line downplays the importance of paleoclimatology a bit too much; the study of paleoclimate provides key insights into the way climate responds to different forcings and while it's true that the attribution of current climate change is not based on paleoclimate studies, these studies do lend considerable support to the current consensus viewpoint.


 

 

 

 

2010-11-27 20:57:05
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
80.42.215.235

Thanks for the feedback, Andy. I have to say although the topic itself is not too difficult, I found it difficult to write this as there are so many things that could be included. I finally settled on making it consistent with the intermediate version, but I can now see that a little more detail would be better - and removing that 'life was able to thrive on land' as it's shockingly bad.

And I get your point about data reveal vs data reveals - I'd looked it up and although data is plural to datum in Latin, in English, you can use data both as singular and plural. That's what major newspapers do, so what goes for the New York Times goes for me too ;)

2010-12-09 17:11:50Miscellaneous feedback
James Wight

jameswight@southernphone.com...
112.213.154.195

I suggest you change “warm periods when life was able to survive on land” to “warm periods with no ice at the poles.” Life has been able to survive on land since land-based life evolved 470 (?) million years ago.

 

Also, “past climates change” should be “past climate change”.

 

I also agree with Andy S about the final sentence.

 

Otherwise I think it is a good basic rebuttal.

2010-12-10 09:37:32
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
212.139.87.189
Thanks for the feedback, James. I've finally updated the post, hope it has clarified things.
2010-12-12 15:21:39No thumbs
James Wight

jameswight@southernphone.com...
112.213.154.195

I’d give you a thumbs-up, but John’s temporarily removed the thumbs for some programming reason!

2010-12-12 17:50:53
Glenn Tamblyn

glenn@thefoodgallery.com...
58.166.16.98

Anne-Marie

Sorry to jump in this late - work, slave driving etc grumble grumble...

I have a bit of a problem with "It tells us nothing about current warming. " and "This conclusion is not based on the analysis of past climate change" . Although the point of the rebuttal is essential to reject that CO2 should be/is the dominant/only/most immediate driver, these expressions opens the door to the 'CO2 is weak' argument which also gets used in relation to the ice cores. Climate Science does draw some support for past climate sensitivity etc from the ice core data. This seems a little too black & white.

Perhaps a rewording of this and also perhaps a pie chart showing the data from Hansen that Andy S put up plus the magnitude of the Milankovitch forcing. And just a small elaboration of "Without the release of CO2 as well as other greenhouse gases and other factors" to something like "Without the release of CO2 as well as other greenhouse gases and other factors such as changes in ice sheet cover and vegetation patterns"

This is close.

G

2010-12-19 09:33:36
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
80.42.220.101

Thanks Glenn. I've finally got round to editing my text - looking forward to the new year when hopefully things will calm down. It did seem like a good idea to make some of my presents at the time.

Let me know what you make of it.

Hope you all have a good festive break.

2010-12-19 09:48:53
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
80.42.220.101
And thanks James - still no thumbs up I see...
2010-12-19 17:58:03
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.248.18
I'd give you a thumbs up Anne-Marie, but that function is still inoperative.
2010-12-20 08:07:30
Andy S

skucea@telus...
66.183.190.176

Very good. Thumbs up from me.

Anne-Marie, you might want to change this phrase a bit:  as ocean temperatures rise, they release CO2 into the atmosphere

It's the "they" that I have a problem with, since it implies that it's the ocean temperatures that release the CO2 rather than the oceans themselves. After the comma you could instead write "the oceans release CO2..." or "CO2 is released..."  

Merry Christmas! 

2010-12-21 04:53:24
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
212.139.80.248

Well spotted Andy, thanks!

And Merry Christmas to you too.

2010-12-21 15:25:52Our thumbs are back!
James Wight

jameswight@southernphone.com...
112.213.166.150
Thumbs up.
2010-12-21 15:26:42And on behalf of Rob Painting
James Wight

jameswight@southernphone.com...
112.213.166.150
Another thumb
2010-12-21 15:27:04And of behalf of Andy S
James Wight

jameswight@southernphone.com...
112.213.166.150
A third thumb
2010-12-21 23:58:05
Glenn Tamblyn

glenn@thefoodgallery.com...
121.214.99.231
This is ready
2011-01-03 23:16:48This is languishing
James Wight

jameswight@southernphone.com...
112.213.166.150
And it's the most popular argument for which we still don't have a basic rebuttal.
2011-01-04 00:53:30
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
130.36.62.142
All in
2011-01-05 12:16:33Published
John Cook

john@skepticalscience...
60.231.58.57
Thanks for your patience, Anne-Marie, took a long time to bring this one home. :-)
2011-01-07 02:10:46
Anne-Marie Blackburn
Anne-Marie Blackburn
bioluminescence@hotmail.co...
212.139.85.64
No worries John. I should be apologising for not getting this one done more quickly. Things have calmed down a bit here so I'm hoping to be a bit more productive (once I've handed in my next assignment) :)