A favorite from Rod Stewart:
If I listened long enough to you,
I’d find a way to believe that it’s all true.
Knowing that you lied, straight-faced, while I cried,
Still I’d look to find a reason to believe.
I don’t know. AGW theory has some good prima facie arguments:
- Temperatures have increased dramatically since 1900 given that 1 decree Celsius over the long haul is significant.
- Temperature is well correlated to atmospheric CO2.
- We are adding more CO2 than ever (a no brainer given our industrialization and population growth). There is debate from many sources as to what percentage of greenhouse effect is due to us, but even if the percentage is small it represents a net imbalance to the carbon ‘budget’.
- Arctic and antarctic ice have declined dramatically in the decade after 1990.
Now comes the trouble. The AGW claim is that it is getting warmer, CO2 and other GHG gasses we are adding to the atmosphere at a record rate are the drivers, causing an imbalance and forcing us into an upward temperature spiral. The proof however, depends on computer models that add up all the known inputs to the climate system, and show that their calculation for CO2 provides the incremental value. The ‘forcing’ diagram sums up what factors affect the planets input vs. output of heat received from the sun. All energy received goes back out (an equilibrium), but greenhouse effect means we hold it longer and stay warmer – like a extra blanket.
Note the right hand column in the forcing diagram. LOSU means level of scientific understanding. The IPCC is telling us how much they think they know about each factor (assuming they have all factors accounted for) – in some cases they are admitting they have considerable uncertainty.
That’s the detective story. Its getting warmer, so we add up what we know and assign the balance to CO2 emissions. Why? Because (to us) it is the most obvious thing that has changed recently and we think we can correlate it to the rise in temperature using Global Climate Models (GCM). Also, we have pretty solid science that shows CO2 in the atmosphere will reflect energy waves (heat) back, thus serving as that extra blanket to make us warmer.
Now, quite a few scientists have put out theories to account for other factors that may affect the climate more. They have been less than warmly received by the scientists whose work is funneling into the central AGW consensus and the IPCC reporting that has gained wide acceptance by the media and governments. In a rather one-dimensional reaction (so far), much of the impetus is to reduce CO2 emission so as halt the upward temperature spiral.
But this post is strictly about the fundamental uncertainty of such a garguantuan calculation. Here are the problems I am learning about:
- The temperature record is not as simple and well anchored as one might wish. There are indications that the record is incestuous and less robust than advertised (not the legions of scientists working blind from each other and coming up with the same result that are alluded to by the spokespeople)
- Temperature correlation to CO2 does not necessarity mean CO2 increase causes temperature increase. This seems counterintuitive since we know that CO2 adds to the greenhouse effect, but here is a good discussion. Also, there are apparently upper limits to greenhouse on the paleo-scale.
- Even though we are increasing the C02 ppm, there is uncertainty as to the magnitude of the effect. My understanding of climate sensitivity is weak, and my math is too rusty to fully follow this, but I think that it comes down to:
a. How many feedbacks to forcings (reactions to inputs) are positive (amplifying temperature).
b. How many are negative (causing additional cooling effects in response to the effects of heat input).
One theoritical example is the Iris effect which is still being investigated.
My take away at present is that the science must improve and hopefully will do so more rapidly now that Climate-Gate and Copenhagen are juxtaposed.
- The rapid ice melt is tougher to explain, but there are some alternative explanations being considered like soot, currents, or wind pattern shifts carrying warmer air. Again that pesky correlation vs. causation.
While I wanted to believe, I expected the climate scientists to do due diligence. The global climate models (GCM) which were touted as giving us ‘robust’ results are starting to look very suspicious to me. Most reasonable people on either side will agree they bungled (a very instructive read) the Medieval Warming Period with the Hockey Stick, so we could very well be returning to the top of the next hill with very little CO2 boost.
Or not, but the problem is that we don’t know and the scientists we trusted are at minimum guilty of arrogant overreach, or at worst incompetence and, in some individual cases, fraud.