GeologyRocksThe Really Inconvenient Truth
The really inconvenient truth about CO2 levels and global warming is that the temperature change occurs about 800 years before the change in CO2 levels. The simple interpretation of this is that CO2 levels are an effect, not the cause of climate change.
The Real Climate website examines this here.
The reason has to do with the fact that the warmings take about 5000 years to be complete. The lag is only 800 years. All that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.
The 4200 years of warming make up about 5/6 of the total warming. So CO2 could have caused the last 5/6 of the warming, but could not have caused the first 1/6 of the warming.
So basically they can't explain one six of the data but we'll ignore that be cause CO2 'could' amplify what is going on the rest of the time.
Let me try an analogy (bare with me on this one) ...
I support a middle ranking football club. They start the season with mid-table hopes and average crowds. They start putting together a few wins and their position in the league rises. More people start going to watch. About Christmas they start losing more than winning. The attendances are maintained for a week or two because it might just be a blip, but as the team continues to slide down the table attendances fall.
Now, there is a clear correlation between league position and attendance over the season with a lag of a couple of weeks between change in position and crowd size. League position is clearly the cause and attendance clearly the effect. But with climate change we a being asked to believe that crowd attendance is the cause of league position! Don't worry about buying new players, just get more people to watch!! It may be that a large crowd when your team is doing well or a small crowd when they are doing poorly may prolong their peak or slump but to say that they are driving the system is nonsense.
The really inconvenient truth is that there has to be something else driving the system.
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hypocentre wrote: The
Wed, 03/14/2007 - 16:48The really inconvenient truth about CO2 levels and global warming is that the temperature change occurs about 800 years before the change in CO2 levels.
[snip]Â
The really inconvenient truth is that there has to be something else driving the system.
Don't agree with you there. Let's take a step back. We know CO2 is a greenhouse gas. We know that humans have been pumping lots of the stuff out (100 times more per year than volcanoes do, for instance). If we model the Earth and temperature (including things like solar activity) we come to the conclusion that humans are having a large effect:
http://www.grida.no/climate/ipcc_tar/wg1/figspm-4.htm
So what about this 800 year thing? Few issues about that. Firstly there is a 200 year error on that. 25%. Not big, but not nothing either. Secondly, ice cores are depth dependant, not time. There needs to be a conversion, which is the main source of error.Again nto a big thing, it has presumably been done correctly. But this is my logic on this is:
If we assume the model is wrong, this means that our knowledge on the system is wrong and our knowledge of anthropogenic CO2 is also wrong. This is unlikely: we have good agreement with observations here. If the lag does mean that we are wrong about CO2 then we have no explaination what-so-ever. It would mean our knowledge on climate changes is all wrong; despite the fact out models (i.e. the embodiment of our knowledge) are good: they can predict reality! In that case the time lag remains unexplained (and I agree that it is unexplained), but this lag does not mean the model and all the other evidence that points to a CO2 cause is wrong. It is, for the moment, unexplained. I therefore diagree with the last statement: there does not have to be anything else driving the system.
Does any of that rambling make sense?Â
Geologists are gneiss!!
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but ...
Wed, 03/14/2007 - 22:55But the lag means there can be no causal effect - not just that we can't explain it at the minute - there has to be something else - even the climate expert on Newsnight the other night brought in to support the orthodoxy suggested it was orbital forcing.
(OK, I am partially playing devil's advocate here - the key may well be that the degree to which CO2 assists once the thing gets going - the 'sing when your winning' factor in my analogy - but it still can't be 'the cause')
Analogy update: My football club tried the CO2 orthodoxy approach - instead of bringing in new loan signings it reduced ticket prices last night to increase the crowd. We lost and are heading for relegation. I rest my case
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I am probably being stupid
Thu, 03/15/2007 - 08:49I am probably being stupid here, but i thought of all green house gasses CO2 was one of the weakest ones. Methane is a worse one, and water vapour is worse again (i think). How much CO2 do we pump into the atmosphere in comparison with water vapour and methane? I unfortunatly dont have access to the proper journals on GW, but in the media they seem to ignore most of the other green house gasses. Is there other work that tries to combine all the gasses, sunspots, etc?
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however...
Thu, 03/15/2007 - 09:30But the lag means there can be no causal effect
Incorrect, I'm afraid. This is a complex (in the true, mathematical sense of the word) system, with many non-linear feedbacks (both positive and negative). CO2 is known to effect temperature and temperature is know to effect CO2. This can be shown from observations, lab studies, computer simulations, etc. With such systems, it's very difficult to tease apart the underlaying causes (which was the focus of my PhD, but with carbonates, not CO2). You have to take the whole body of evidence and attempt to do so, but it is not easy.
(OK, I am partially playing devil's advocate here - the key may well be that the degree to which CO2 assists once the thing gets goin
Devils advocate is fun. You get to use this icon --->
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Long life is the key...
Thu, 03/15/2007 - 09:32I am probably being stupid here, but i thought of all green house gasses CO2 was one of the weakest ones. Methane is a worse one, and water vapour is worse again (i think). How much CO2 do we pump into the atmosphere in comparison with water vapour and methane? I unfortunatly dont have access to the proper journals on GW, but in the media they seem to ignore most of the other green house gasses. Is there other work that tries to combine all the gasses, sunspots, etc?
Very sensible question actually! The answer lies with longevity of the greenhouse gas. CO2 has by far the longest residence time in the atmosphere. Methane and water vapour are "better" greenhouse gases, but they rapdily dissipate.
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...
Thu, 03/15/2007 - 21:33Its been good to get some debate going - it's been a bit quiet around here lately. Just trying to drive up traffic, honest
I was trying to be 'clever' with my use of the word 'causal' (in the filter sense) rather that 'cause'. I'm not denying that CO2 doesn't affect climate, but in the past climate record I still don't believe is causal (s.s.).
What C4 did leave off their graphs (a touch naughtily) is the last 20 years where CO2 shoots up dramatically as does the temperature .
However, comparison with the geologic record is interesting.
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Shame that the graph is on
Fri, 03/16/2007 - 08:42Shame that the graph is on wiki! Is there one on any other website? Whilst wiki is good, for this it would be good to see a site that does the research itself!
When i watched that the C4 prog, they mentioned that GW would affect the higher levels of the atmosphere more than the lower ones. I wondered, if all the CO2 is made at low level, even though it will rise, would it increase the temperature at the bottom of the atmosphere more than normal? A second layer of green house gasses lower down?
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References
Fri, 03/16/2007 - 09:13Shame that the graph is on wiki! Is there one on any other website? Whilst wiki is good, for this it would be good to see a site that does the research itself!
The graph came from GlobalWarmingArt
There are references under the image
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I found this the other day.
Fri, 03/16/2007 - 14:18I found this the other day. quite interesting i thought! Shows a good correlation between CO2 and temp. could be taken several ways. 1) we pump out and CO2 so increase temp. or Temp is increasing anyway, with CO2 so we cant do alot about it!
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Here we go again
Sat, 03/17/2007 - 10:37This is the whole argument we have been discussing!
The temperature curve is ahead of the CO2 curve by about 800 years give or take - notice that the peaks in blue occur slightly earlier that the peaks in red.
My argument in this thread has been that since CO2 lags behind temperature then CO2 is the effect and temperature is the cause.
Time to go round the argument one more time?
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I posted that not because of
Mon, 03/19/2007 - 13:35I posted that not because of any apparent lag, but because it is a re-occuring event. Can we do anything about it? It looks like it is going to happen anyway, with or without human input.
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Speed!
Mon, 03/19/2007 - 16:04Yes, it is going to occur again: it's part of a natural cycle.
However, looking at the temperature graph we have a 10° change in temperature occurring over about 10,000 years: 1 degree per 1000 years. Or 0.1 degree per centaury.
Climate models put the current change at around 1-3° in the next centaury - an order of magnitude faster. That's the problem; it's quicker and probably of bigger magnitude than the natural cycles that are observed in those curves above.
Remember that it's not the planet that's in danger: it's us (and any other animals we might take with us
)
Geologists are gneiss!!