Showing from 200 to 11000 years ago, the subsequent graph is based on ice core data, readily visible in files hosted on the servers of the U.S. National Oceanic and Atmospheric Administration (NOAA):GISP 2 and EPICA Dome C:.



http://wattsupwiththat.com/2012/04/11/does-co2-correlate-with-temperature-histor...





Over the past few hundred thousand years of ice core data, a “medium” time scale in this sense, CO2 superficially appears to change in step with temperature if a graph is so zoomed out as to not show sub-millennial time scales well:




http://wattsupwiththat.com/2012/04/11/does-co2-correlate-with-temperature-histor...

A record of temperature and atmospheric CO2 over the past 400,000 years is preserved in the Vostok Ice Core and is shown in the figure on the right.

It can be seen that there have been a series of large fluctuations in temperature (the Ice Ages), accompanied by large changes in atmospheric CO2.

It is thought that these large temperature fluctuations are triggered by Milankovitch cycles - variations in the earth's orbit that change the amount of energy from the sun that reaches us.

However, on their own, these cycles are not enough to explain the changes in temperature.

The full explanation seems to be that the small change in temperature caused by the changing orbit are amplified by natural processes on earth. These cause CO2 to be released from the oceans and the biosphere, causing an increased greenhouse effect.

This is described more fully in this article from the New Scientist (see also Shackleton 2000). For more details on the timing of changes in CO2 and temperature, click on the figure.

http://www.brighton73.freeserve.co.uk/gw/paleo/paleoclimate.htm#100,000years





http://s155.n46.n171.n68.static.myhostcenter.com/WVFossils/Reference_Docs/Geocar...

Well sad Ajax. There seems to be a few useful idiots to the cause represented here, they'll distract and try to bog you down in nonsense circular arguments.

Stock in trade from the Al Gore school for obfuscation.

Rider wrote on Aug 7^th, 2013 at 1:54pm:

That first graph shows a δ18O graph against time for GISP2 in Greenland (Air temperatures at the summit of the Greenland Ice Sheet !), compared against an atmospheric CO2 from EPICA Dome C in Antarctica. Apart from the regional differences and the fact that the measurement was of local air temperatures, a δ18O measurement is less accurate that a Deuterium proxy, since the D proxy is measured on the ice, and the δ18O on the tiny air bubbles. Carrying out δ18O isotopic analysis on such a small sample increases the error level, not to mention the regional variation (geographically about as far as you can get). Watt's up with that?    Even Dodgy Dave Evans' trick of ignoring 85% of the ocean heat data is eclipsed by such blatant dodginess. He is not worthy.   

A total variation in CO2 of 20ppm over the range 260-280 ppm is likely to be associated with a temperature difference (Mean Global Surface) of about 0.1 degrees and that would be swamped by other forcings. In other words, nobody in their right minds would expect much of a correlation. It's another strawman.

It's like comparing apples with pears - in the case of Watts, deliberately.


On the second graph, you seem to have dropped the strawman for a moment.
Ajax wrote on Aug 7^th, 2013 at 10:22am:


Good. That's mainstream Climatology. You have accurately represented it.

As for the last Graph in the original post, the Atmospheric CO2 that appears to peak at 7000ppm in the Cambrian period is based on the Geocarb III model (Berner, 2004). Any modelling of Paleozoic CO2 is problematic and based on very sparse and unreliable data. There are two other studies commonly cited for this period, these being Rothman (2002) and Royer et al (2004).  For that peak at 7000ppm,  the other studies show CO2 concentrations much lower - around 500ppm.

It's a bit of a circular argument on your part to use these models anyway, because they all rely on atmospheric physics and generally accepted climate sensitivities.

Ironically the Royer et al poster is titled "CO2 as a primary driver of Phanerozoic climate"

By the way, life in the Cambrian period was totally different to life today. Most life existed in the oceans, and there were also primitive one celled organisms that lived under the earth.

So it's immaterial what the temperatures and CO2 levels were at that that time, because it was a totally different and hostile land environment. 

muso wrote on Aug 12^th, 2013 at 2:57pm:

Muso, I hope you don't think that question was directed at you. If I've caused any confusion or offence, I apologise.

muso wrote on Aug 12^th, 2013 at 2:57pm:


Well then as you can see all those graphs are the graphs that both sides use.

Any excuse to justify the AGW religion.

And your a scientist...???

Ajax wrote on Aug 13^th, 2013 at 7:19am:


The problem is not with the graphs, but the interpretation by Anthony Watts. Read the post carefully. 

Air temperatures at the summit of the Greenland Ice Sheet compared against data from Law Dome? I don't think so.

This may come as a revelation to you, but there are other forcings apart from CO2.

Let's say I was feeling hot, so I switched off my reverse cycle heating in the house, and the house continued to warm, would I be justified in saying that there is no correlation between the  heating and the temperature of the house?

It's similar to the argument you are making. OK, maybe I had the oven on. Maybe it was a hot day outside. There are other causes of that heating.

In the same way, looking at paleo temperatures and saying that there is no correlation between CO2 and temperature borders on ridiculous. You already stated that you knew that orbital variations were the main drivers of glaciations. Didn't you?

Who are you trying to kid? Yourself?