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drnickbone comments on Global warming is a better test of irrationality that theism - Less Wrong
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We need to think about what AGW actually "predicts".
In detail, it depends on how big climate sensitivity is, and also what time period we are looking at.
Remember that if small enough, the AGW impact will clearly be trivial compared to natural climate variations and weather. Also, even if the overall impact is big, the delta impact between two very close dates (AGW impact at 2012 minus AGW impact at 2011) is always going to be trivial compared to natural variations.
Qualitatively, over short enough time periods, the AGW signal will always be masked by the natural climate /weather noise; whereas over longer time periods, the signal will be evident as a statistically significant trend imposed on top of the noise.
Questions:
Do you disagree with this qualitative prediction, or do you really think that AGW predicts that every year should be hotter than the previous one (so each year is a record high)? Do you think it even predicts that every day should be hotter than the previous one (so each day is a record high)? Clearly if your mental model of AGW is "AGW predicts year on year increasing temperatures; we don't observe that, therefore AGW is falsified" then this is a rational deduction, but from false premises.
Would you like to make a bet on the average global temperature in the decade 2010-2019 versus average global temperature in the decade 2000-2009? If you really believe there is no global warming trend, you should be happy to take an even money bet on this decade being cooler than the last one. Fancy the bet? (Hint, you would have lost a similar bet made in any previous decade since the 70s).
If your answer to question 2 is "Ahh, I think I'd bet on warming after all, but I don't think it is anthropogenic" then you're acknowledging that the argument about year to year temperatures (less than decade averages) is basically irrelevant. So why raise it? If this were a political forum, and you were trying to score points in a debate, I'd understand it.... But this is Less Wrong.
If your answer to question 2 is "Climate scientists/meteorologists might end up reporting that each recent decade is hotter than the previous one, but I won't believe them because I think they're lying" then again you're acknowledging that an argument over year to tear temperatures is irrelevant (fictional/made-up evidence is irrelevant to choosing between hypotheses). So again, why raise it except for point-scoring?
It could be explained, that every year isn't hotter than the previous one. But how can you explain that 2011 was not hotter than a year a decade or more ago?
What are those natural factors which shadow a BIG change in the CO2 level over decade or so?
Could you explain the down-vote please? (My apologies if it wasn't you).
At the risk of another downvote, it seems your mental model of AGW is rather "AGW predicts that for each year y, the temperature T(y) in year y must exceed the temperature T(y-10) in year y-10; since we have observed a counter-example, AGW is falsified".
Is that correct? If so, could you cite a paper or presentation by climate scientists (or summary by IPCC etc) which makes such a prediction?
Here's a hypothesis to think about: Suppose the AGW trend (imposed on the climate noise) is +0.02 degrees per year, whereas the year to year fluctuation of temperature from natural causes (solar cycle, La Nina/El Niño, others) has a standard deviation of order 0.5 degrees. Then there will be a large number of individual years y which are cooler than year y-10. Do you agree or disagree?
In response to your own question, each of La Nina and a weak solar cyle would be easily big enough to overshadow a decade of AGW (sensitivity of 3 degrees to CO2 doubling implies about 0.2 degrees warming per decade at present).
Don't worry for downvotes. I downvote everything I disagree. How else would you know it? I am also frequently downvoted, and I find some pride in that.
But go back to the topic! You say it's possible that despite of the fact that T(y)<T(y-20), where CO2(y)>CO2(y-20) - the function still grows? Uhm ... I am not that certain. It is at least bumpy.
This I find particularly fishy. Half the amount of CO2 10 times! Then it will be less than 1ppm CO2 in the atmosphere. Do you expect 30 degrees cooling?
I doubt it.
But do half it 40 times. Some molecules of CO2 are still with us. Do you expect 120 degrees cooler outside?
Don't do that.
Let's say an object is tethered to a wall by a coil of metal. A displacement of 1 cm gives a 1 N restoring force and a displacement of 2 cm gives a 2 N restoring force. It's foolish to think the coil would give a 100000 N restoring force at 1 km; it would just break! So we can't treat the coil as a spring in the small displacement regime?
The elasticity of metals are all well known. You can get the data all over the internet.
Where can I get the same data about this "sensitivity of doubling" for various gasses and atmospheres? Also regarding to planet's star?
Suppose someone said that world population is increasing by one billion per decade. And then you said, that's impossible, because the population would have been negative in 1900... All that "argument" shows is that the trend in question couldn't be true across all time; it doesn't refute the contention that that is what's happening now. In the same way, what you just said only shows that doubling the CO2 can't lead to 3 degrees increase for all possible concentrations of CO2. It has no bearing on whether this is true for the range of concentrations that matter to us.
But in fact that is the expected result. "... the planet's effective temperature ... is about −18 °C, about 33°C below the actual surface temperature of about 14 °C. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect." CO2 is directly responsible for only about a third of this, water vapor does most of the job, but the water vapor is the dependent variable.
Reality is complicated because water vapor causes cooling (as clouds) as well as warming, and there is room to argue about how these effects vary, but the arguments you present aren't enough.