No offense, but I think they’re overpaying you. Seriously, most of the points you raise here are not particularly impressive arguments. Oh well, one by one:
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By the way, I have no doubt that the average tempreature of the earth is greater than 100 years ago.
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So far so good, then.
[QUOTE=Ají de Gallina]
- I disagree with “AGW therefore whatever seems nice”, mainly because it means more hunger and poverty than it is supposed to solve. As planet-wide problems go, AGW is incredibly much smaller and less importat than to access to clean water.
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A. You’re right that “AGW therefore My Own Pet Policy Preferences” is not a valid line of reasoning. That’s true for any other environmental/social/political problem as well as AGW.
B. Arguments that AGW-amelioration policies are automatically going to be more damaging to humans than the effects of AGW itself are very suspect, especially when phrased so generally. Yeah, we shouldn’t immediately abandon all modern economic activity for the sake of reducing our carbon footprint, but neither should we be too credulous about anti-AGW fearmongering claiming, e.g., that any emissions reductions policies are tantamount to abandoning all modern economic activity.
C. AGW is not a separate issue from other environmental or economic challenges, including access to clean water. Changes in glacier melt, sea level rise, and regional climate patterns are directly linked to water accessibility.
[QUOTE=Ají de Gallina]
- The central case is based on ignorance, in that what its proponents say is that “we don’t know what could cause the warming trends except CO2”. Surprisingly, a very similar trend happened early in the 20th century.
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No, the central case is not based on “we don’t know what could cause the warming trends except CO2”. It’s based on the combination of the following facts:
a) we understand how increasing CO2 physically causes warming,
b) we understand the long-term correlation between CO2 levels and temperature in past eras,
c) we know that CO2 levels have been drastically increasing due to human activity,
d) and also we have found no other physical mechanism to account for the observed warming besides anthropogenic CO2 increases.
That’s not an argument based on ignorance, any more than it’s basing the theory of gravitation on ignorance to acknowledge that we haven’t found any physical mechanism besides gravity that can explain our observations of falling objects and orbiting bodies.
[QUOTE=Ají de Gallina]
- The importance of CO2 in regulating temperature simply doesn’t work backwards. If you try to get to 4°C by 2100 you need a sensitivity that would not “predict” recent past temperatures.
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I’m not quite sure what you’re saying here, and I’m not quite sure that you understand what you’re saying either. As both GIGObuster and Sam Stone have pointed out, current AGW climate models predict recent past temperatures quite well.
Starting with the basics: Climate sensitivity is usually defined as the change in average global temperature (in degrees centigrade) resulting from a doubling of the atmospheric CO2 concentration. The IPCC Fourth Assessment Report estimates climate sensitivity at somewhere between 2 to 4.5 degrees C, most probably around 3 degrees.
The IPCC currently predicts the increase in global mean temperature to fall somewhere between about 1.5 and 6 degrees C by 2100.
[QUOTE=Ají de Gallina]
- The error bars are gigantic compared to what is measured.
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What specific measurements are you talking about?
[QUOTE=Ají de Gallina]
- The ammount of fidgeting wih the raw data is astonishing. Of course all raw data needs adjustments, but almost all of the recent temperature increase (at least the numbers) seems to come from the adjustments. I’m not implying foul play, but simply that it is interesting.
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What specific data are you talking about?
[QUOTE=Ají de Gallina]
- It is assumed that warmer means bad.
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No, it’s deduced from the specific changes to global climate associated with a significantly warmer atmosphere that significant warming will have some bad consequences. There will definitely be some positive changes as a result of rising global temperature as well, but they are predicted to be less significant and more local.
The warnings about negative consequences of AGW are based on predictions of specific bad things based on specific climate models, not on some unfounded “assumption” that warming in general is automatically bad.