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Christopher Majka wrote:
> Hi Dave,
>
> On 10-Jun-08, at 8:02 PM, David & Alison Webster wrote:
>
>> Figure 1a shows without doubt that temperature, CO2 & CH4 are
>> related but--- temperature starts to increase BEFORE CO2 & CH4
>> start to increase. There may subsequently be positive feedback, but
>> at least initially, higher temperatures are driving CO2 & CH4
>> increase not the converse.
>>
>> I suppose one could call this 'tceffe esuohneerg a' but it would
>> be awfully difficult to pronounce.
>
>
>
> You must have preternaturally acute vision to be able resolve this
> from Figure 1a. :-> I'm looking at it at the moment and, as you point
> out, does show a clear historical relationship of temperature, CO2,
> and CH4 but the graph, which represents 800,000 years, is only 3.75"
> wide on my screen. At that level of resolution, these graphs, set one
> over the other, look absolutely co-incident to me. I tried printing
> this out and running a vertical rule over it, but I don't see how one
> could possibly discern whether temperature, carbon dioxide, or
> methane are increasing before or after one another at this
> resolution. :->
Hi Chris, June 10, 2008
A larger scale graph would make it more evident but-- I printed it
and drew fine vertical lines to join the ticks at 600, 400 and 200
thousand YBP. Looking at major abrupt increases in temperature and the
center as opposed to either edge of ink lines (some lines are wide, some
narrow)--
1) Temperature starts to rise 4 mm left of the 400 line, CO2 starts 3 mm
left [note 1mm~ 8700 years],
2) Temperature starts to rise 6.5 mm right of the 400 line, CO2 starts
7.2 right [lag of ~ 6000],
3) Temperature starts to rise 6mm left of the 200 line, CO2 starts 5 mm
[lag of ~8700 yrs],
4) Temperature starts to rise 3.4 left of the 200 line, CO2 starts 2.8
mm [lag of 5200],
5) Temperature starts to rise 1.3 right of 600, CO2 starts 1.2 [advance
of ~900],
6) Temperature starts to rise 7 right of 200, CO2 starts 7.2 [lag of 1700],
7) Temperature starts to rise 1.7 left of 0, CO2 starts 1.4 [lag of ~2600].
Based on these 7 points the average lag [as represented in this graph]
of CO2 behind temperature is about 4500 years. What really matters of
course is the data behind the graph and the date resolution of these
data. But this figure reminds me a lot of one that we discussed several
years ago; don't have time to locate it now.
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