CO2 and Temperature Correlation in Past Climate Reconstructions

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Discussion Overview

The discussion revolves around the correlation between CO2 levels and temperature in historical climate reconstructions, particularly focusing on data from the past 1000 to 1500 AD. Participants explore the implications of various studies and data sources, including ice core and plant stomata data, and their reliability in assessing the role of CO2 in climate change.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants highlight that both CO2 and temperature exhibited independent variations, suggesting that CO2 concentration may not solely control temperature.
  • Others argue that CO2 forcing should not be overlooked, especially during the period between 1000 to 1500 AD, and that different data sources yield varying conclusions about the significance of CO2.
  • There is a discussion about the reliability of ice core data versus plant stomata data for measuring historical CO2 levels, with some suggesting that ice core data may underestimate CO2 fluctuations.
  • Concerns are raised about the interpretation of data, including the potential issues with gas age and ice age differences in ice core samples.
  • Participants express uncertainty about the impact of CO2 in an open-ended climate system, with references to historical climate conditions and potential cataclysmic events.
  • Some contributions emphasize the importance of confronting different data sets to draw personal observations rather than relying solely on authors' opinions.

Areas of Agreement / Disagreement

Participants do not reach a consensus; multiple competing views remain regarding the role of CO2 in historical climate change and the reliability of different data sources.

Contextual Notes

Limitations include unresolved questions about the reliability of various data sources, the assumptions underlying the interpretations of CO2 forcing, and the complexities of the carbon cycle.

Andre
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Last year saw several publications about the climate of the past. I call to the stand, http://www.pnas.org/content/early/2008/09/02/0805721105.full.pdf+html about a reconstruction of the global temperatures in the last 2000 years and http://www.pnas.org/content/105/41/15815.full.pdf+html about a CO2 reconstruction based on stomata variation, reacting on CO2 levels in the period 1000-1500 AD.

This is how they correlate:

2505ybt.jpg


Who would want to conclude that the CO2 concentration controls the temperature?
 
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Ah reality wrong, assumptions right.

Not the point. The point is that there was independent variation both in CO2 and temperature. Mind that the enormous dynamic flux of CO2 between atmosphere and with the ocean dwarfs everything else. Some changes there in flows could have a big impact on that balance.

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/earth_system/carbon_cycle_NASA.jpg
 
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Andre;

Read the van Hoof paper carefully!.

Their conclusion is that if anything the role of CO2 forcing should not be ignored during the period between 1000 to 1500.

CO2 fluctuations from the Antarctica ice cores (in particular Law Dome) are not as great as they are when measured from plant stomata. However, when global CO2 forcing are calculated using the plant data, then the forcing is on the same order of magnitude as that from Solar. However, if we use the ice core data, then CO2 forcing is insignificant.

Examine Figure 1 E carefully and answer this question:

Should we use the red or blue line for CO2 forcing?

Is ice core data more reliable than plant stomatal for measuring historic CO2 levels?
 
It's not about the opinion of the writers; it's the data that they produce; and the data that others produce and the confrontation of one data set with another. Then you can make your own observations.

Ice core data are also subject to some problems, like the gas age - ice age difference, to open firn-ice above 80 meters works as a low bypass filter, smooting out higher frequency variations.

Red and blue line, according to the publication, are the high/low sensitivity borders.
 
Examine Figure 1 E carefully and answer this question:

Should we use the red or blue line for CO2 forcing?
 
Xnn said:
answer this question:

Red herring You are not to toss me around :mad: in an attempt to divert from the main problem. Things don't add up.

You can answer the question yourself.
 
Andre said:
Things don't add up.


A straw man argument about the role of CO2 in global warming.


Read the Van Hoff paper.
 
I think you're right Andre; there is no way of knowing whether CO2 levels contribute to warming in an open ended system as ours. If it is warming; it's about time since in the not too distant past it seems we had a homogenous temperate climate. Everywhere from the Antartic to Siberia has tropical vegetation buried in its permafrost. Something cataclysmic happened and perhaps only now are we beginning to see recovery.
 
Andre:
"Not the point. The point is that there was independent variation both in CO2 and temperature. Mind that the enormous dynamic flux of CO2 between atmosphere and with the ocean dwarfs everything else. Some changes there in flows could have a big impact on that balance."

Thank you for bringing this up. I saw the logic and I am glad that I am not the only one.
 
  • #10
Could have, might have, could maybe possibly have an impact. An enormous one by chance these variations are symptomatic indicators of the same.
 
  • #11
Andre said:
It's not about the opinion of the writers; it's the data that they produce; and the data that others produce and the confrontation of one data set with another. Then you can make your own observations.
And how do propose we make our own observations? Are we supposed to eyeball Fourier transforms and correlation coefficients?
 

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