Can internal variability lead to a longterm energy imbalance?
...especially if the fluctuations average out to roughly zero over time? This seems to be the crux behind the "It's ocean cycles!" argument and the recent slew of Spencer papers.
2010-04-12T17:06:18Z
even if they didn't average out to zero?
2010-04-12T19:56:43Z
I can see how some ocean oscillations might lead to changes in the extent and location of clouds, thereby leading to short term energy imbalances, but these changes are oscillating about some mean, and show no upward secular trend that could explain multidecadal temperature changes.
MTRstudent2010-04-13T02:56:53Z
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I plan to do some more work on it, since I don't see that low sensitivity necessarily follows.
The crux of Spencer's point seems to be that if you try and estimate climate sensitivity from a small time period, then you will get wildly high estimates (although I can't see why you wouldn't also get wildly low estimates if you picked a different time period when the internal noise was in anti-phase)
Now, this might be true, I need to do more work on it. And in this case, it _could_ mean that estimates of climate sensitivity based on periods as long as 40, 50, 60... years are very sensitive to internal noise (ie a single measurement is likely worthless), but I don't see that all such measurements will be overestimates - some must be underestimates. Maybe recent ones are overestimates?
However, I don't see how this can explain all the palaeoclimate estimates of climate sensitivity in the 2-4.5C range unless for every time we've looked at, clouds have followed in lockstep with solar, volcanic, albedo and greenhouse forcing. If they aren't causally connected, then that seems very very unlikely.
I don't see how they could. Internal oscillations just move heat around between oceans and air. But that's not an energy imbalance - it's just moving the energy around. And since they're oscillations, sooner or later they move it back.
If you had say a weak negative cycle followed by a strong positive cycle, certainly it could cause the air to warm a few tenths of a degree overall. But this would also cause the oceans to cool. Obviously that's now what's happening right now, since both oceans and air are warming. http://www.skepticalscience.com/empirical-evidence-for-global-warming.htm
So I don't really understand how this argument can be physically viable.
I do see how they could. Internal oscillations move heat around between oceans and air. That is an energy imbalance - it's moving the energy around. And since they're oscillations, sooner or later they move it back.
If you had say a weak negative cycle followed by a strong positive cycle, certainly it could cause the air to warm a few tenths of a degree overall. But this would also cause the oceans to warm. Obviously that's not what's happening right now, since neither oceans or air are warming.
So I do really understand how this argument can be physically viable.
I have reported pseudo-Dana for impersonation. I hope others will as well, whatever their views.
If you say that land temperatures are being driven upwards by rising sea temperatures, you still have to explain why the sea temperatures themselves are rising.