Image talk:Vostok-ice-core-petit.png

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Contents 1 comment 2 Time 3 temperature change? 4 Good Graph 5 Volcanic influence

[edit] comment

Here is my first interpretation.

1. The rise of the dust level kicks the planet out of the ice age by acting as a blanket and possibly absorber of solar radiation. It in turn reradiates the heat energy to the planet. 2. Dust levels fall as ice retreats and trees etc. begin to capture the dust 3. CO2 levels rise and continue the heat retention process started by the dust. Possibly the CO2 increase is due to melting ice releasing the gas captured earlier. 4. Temperatures continue to rise. 5. Continued growth of trees etc begins to pull out the released CO2 (removing the blanket). 6. Melting of the ice caps in the North Pole introduce much fresh water to the Atlantic and shut down the gulf stream. 7. Shutting down the Gulf Stream cools the Northern Hemisphere. 8. Increase glacial formation in the Northern Hemisphere traps additional CO2. 9. CO2 levels drop, Solar reflection becomes stronger, and Radiational cooling is stronger without the dust or CO2 blanket. 10. Temps continue to fall and the planets ice caps grow large enough acting as condensers to pull the moisture from the areas of the planet where it can still be evaporated (unfrozen regions). 11. As the planet dries the equatorial regions become sources of dust and the cycle repeats again.

C. Frelier 06/09/06

[edit] Time

I dont understand the graph. shouldnt time be on the base/horizontal axis? The current baseline of co2 ppmv 1x100-5 does make sense there, but, if the time is on the left then its showing there are different c02 levels happening at once. If you know what this graph is really showing, please provide clear explanation.

Time is on the base axis. 1x10^5 means 100,000 years ago. The present is on the very left of the graph.

Wouldn't it make more sense to have the present on the right? It is normal to see time go from left to right and it's also normal to have point zero (the present) at the point where one axis intersects the other (so on the right, because the other values are negative). Or is this a standard in some field? And if so, why? DirkvdM 20:10, 9 December 2005 (UTC)

I can't tell you why, but it is common in geology and paleoclimatology to place the present day on the left and have postive numbers denote past times running towards the right. Dragons flight 04:25, 12 December 2005 (UTC)

I can confirm that this is indeed standard practice in paleoceanography. But Petit's timescale is not unequivocal (cf Shackleton, Science 2000 and the new EPICA timescale, although NB these are different timescales, Shackleton's primarily orbital and the other relying largely on ice-thinning models.) --Orbitalforam 14:53, 25 May 2006 (UTC)

[edit] temperature change?

The temperature is preceded by a 'delta', which would mean that each point on the graph is a temperature change. Shouldn't that be just temperature? In which case each point on the graph gives the temperature and the graph thus shows the change. DirkvdM 20:05, 9 December 2005 (UTC)

Vostok is normally a very cold place (-55C ?). The plot shows temperatures with respect to the modern annual average for Vostok and hence it is a change in temperature relative to today. Dragons flight 04:25, 12 December 2005 (UTC)

I would think that this would be better expressed as "relative temperature," not "change in temperature." --- Stephen Goldmeier | Profile | Talk | (._.) | 17:55, 29 April 2007 (UTC)

[edit] Good Graph

The graph shows a clear relationship between CO2 and temperature. The dust appears to show some correlation but not anything as definite. What I also found interesting is that the CO2 was on the up well before fosil fuels came into the picture.

Jimsun 02 Oct 2006

The graph doesn't show the most recent CO2 rise, which at 380 ppm would be off the scale... William M. Connolley 19:02, 2 October 2006 (UTC)

The graph doesn't show that there are spots where the samples are 6000 years apart. How can you be certain that there weren't CO2 and temp spikes in those gaps? We know it's possible for CO2 to rise by 100ppm in 200 years. It would be interesting to see what scientists could determine about our current climate from ice cores 200k years from now. Is it possible that when CO2 and temp goes up above a certain level that it can't be captured by the ice? Is it possible that the extreme pressures that the ice is under could cause gases to leak? What is the certainty that gases in ice cores are exactly the same as the day they were captured and how has this been proven? Jimberg98 15:18, 14 March 2007 (UTC)

[edit] Volcanic influence

Surely the rise in dust can be attributed to volcanic eruptions, most probably of the flood basalt kind. This initially triggered further cooling but then, as previously mentioned, the dust acted as a radiation blanket to heat the earth up. It is known that there was a major flood basalt eruption on the Russian Steppes around 250 million years ago which triggered temperature rise and the Permian extinction and this is replicated by the graph. Flood basalt eruptions can continue for tens of thousands fo years so they also release CO2 leading to a greenhouse effect.

The dust is not usually ascribed to volcanoes, but to increased aridity and wind speeds. It would be unlikely for volcanoes to be in sync with the icea age periods William M. Connolley 13:18, 28 November 2006 (UTC)

Oyboe 05:01, 14 August 2007 (UTC)==Correlation==

There is such a strong correlation that surely one must be causing the other. I'd guess that temperature drives carbon dioxide. Have any scientists proposed this theory? --Uncle Ed 18:05, 5 December 2006 (UTC)

They are generally regarded as having feedback. You can't see it at this scale, but on some parts of the cycle T leads CO2. Which is no great surprise: the current theory would be orbital focing leading to small T change leading to CO2 feedback leading to larger T change William M. Connolley 18:16, 5 December 2006 (UTC)

There could be another explanation on a broader scale. Rotting vegetation create CO2 and Methane. Vostok graph show that after a temperature peak, a slow decline in temperature occurs. Other graphs show that this occurs together with the build up of glaciers and ice shelves, thus reducing the ocean levels causing receeding shorelines towards the basins. Landmasses increase, but so does the ice coverage. Vegetation remains more or less stable having more or less the same land area to grow on. Sediments on continetal shelves should eventually show whether they once were covered with woodlands if this scenarion holds water. By and by the very massing of ice and snow have profound effects on weather patterns, high pressure positions, rainfall and low pressure throughs. Colder climate means a dry atmosphere without much greenhouse effect, and the large increase of landmasses becomes deserts, hot in summer and cold in winter. Vegetation rots and dust flies, but as this happens, the summer desert sun starts to pump up seasonal temperatures while rotting vegetation increases CO2 and Methane levels. At one time or the other, the weather patterns flip over again and a dramatic melt down of the ice begins. This explanation does not require a lot of outside influences. The requirement is almost only an inherent imbalance in cause/effect reaction time in the atmosphere relative to that of oceans and glaciers. I have speculated on this scenario for some time, but have not found any discussions around it, although I am sure that there has to be a scientist somewhere that could comment Oyboe