Quote:
Originally Posted by Shiraz
the Vostok ice core data point to the real nature of the problem - the CO2 level in the past ~1/2 million years has bounced about in the region between about 180 and 300ppm.
Not any more - we have now pushed it past 400ppm and it is still rising rapidly. This is uncharted territory and we are running an uncontrolled experiment with our only life support system. Modified graph shows where we are now.
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The thing that talks to me about this graph is that CO2 and temperature are linked in this data (IMO). Whether temperature is the 'horse' or the 'cart' can be argued - however (from the data presented) they are linked IMO. The other thing that pops out for me is that the transition to warmer levels from the ice-ages has a fast rise-time, while the drift into ice-ages is a slower decline with a looser linking between CO2 and temperature.
But the part that really gets my attention is that the onset of ice-ages seems to be held off by a lagging high CO2 level. If you compare the fall of temperature in the last ice-age to previous ones you can see that there is a correlation between continuing high CO2 levels and a slower decline in temperature. The graph suggests that the current warm period should be in decline about now, but temperatures seems to be bobbing along. The difference is that now human activity has sent CO2 upwards independent of previous drivers - if CO2 was the 'cart' it has now broken free from the 'horse'. The consequences of that are unknown. It would unwise not to be concerned. My uneducated guess is that it just possible that AGW will be somewhat mitigated by the next cooling period and consequently the argument about AGW will run on for decades. On the upside it might give the human race time to adapt to a low emission future.