If Lindzen looks only at short-term feedbacks and ignores long-term feedbacks, what would ...?

Question

... his results look like?

A recent, paper by Lindzen & Choi, "On the determination of climate feedbacks from ERBE data" -- "has proven with hard data that Global Warming is a myth" (claims one denier), or "shows the “global warming” scare is over" (according to another denier) -- because the result of the paper is a climate sensitivity of 0.5° C for a doubling of CO2.
 (http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf)

In doing their study, L&C focused on nine episodes of rapidly warming or cooling sea surface temperatures (SSTs), each of which lasted from 6 to 18 months, and compared them to the outgoing longwave radiation (OLR) observed by satellite during those periods. 

In other words, their study, by design, is capable of detecting short-term climate feedbacks only, and is incapable of detecting long-term climate feedbacks.

According to Lindzen himself, "simple calculations as well as GCM results suggest response times on the order of decades for positive feedbacks and years or less for negative feedbacks."

So if Lindzen includes short-term negative feedbacks and excludes longer term positive feedbacks, will his climate senstivity result be higher or lower than the actual honest-to-god climate sensitivity?

Dana1981 · Accepted Answer

Ah, I was wondering how Lindzen had found such a low value for climate sensitivity, which is inconsistent with paleoclimate data.
http://www.ecohuddle.com/wiki/climate-sensitivity

Short-term sensitivity doesn't tell us much at all.  Oceans take time to warm, ice takes time to melt, it takes time to release methane from melting permafrost and warming peat bogs, etc. etc.  In fact for this reason, Hansen found that long-term (centuries) climate sensitivity is more like 6°C for a doubling of CO2, whereas more medium-term (decades) sensitivity is 3°C.
http://www.grist.org/article/another-must-read-from-hansen

As for short-term (months to years) sensitivity, as Spencer states, "climate modelers have not yet demonstrated that there is any short-term behavior in their models which is also a good predictor of how much global warming those models project for our future."

I don't really see any particular value to calculating the climate sensitivity on such short timescales.  It certainly doesn't tell us much at all about long-term climate change.

As for jim's comment that short-term and long-term sensitivity are the same, that's a completely nonsensical statement.  That's like saying if permafrost doesn't melt if the planet warms 0.5°C, then it will never melt.

Ottawa Mike · Answer

I will agree with you that skeptics claiming "the global warming myth is over" using this paper is the equivalent to saying "the science is settled" by AGW proponents,  Actually, what the paper says is that the science is not settled.

JimZ · Answer

You are really grasping at straws.  Short term feedbacks are longterm feedbacks or should I say long term feedbacks are a series of short term feedbacks.  If the sensitivity is 0.5 degrees, then there is very little harm that come from our CO2 emissions, short term, long term, whatever term, period.

If Lindzen looks only at short-term feedbacks and ignores long-term feedbacks, what would ...?

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