Week 9: Random problems in climate
Combined list of areas in climate (doc)
Thanks everybody for sending ideas. These are fairly narrow of climate
study, but still substantial enough that the right questions to ask are
note obvious. For this Wednesday, let's go through the exercise of
trying to find good questions, where good questions means interesting,
and are likely to lead to significant understanding.
Pick any 4 out of the list. Pair up and brainstorm.
As an example of what we would like, here is my ill though-out take on
one of the problems (fairly, but not completely randomly picked). I
have probably also gotten a little carried away compared to what we
expect. Feel free to get carried away!
One question/area was: How has solar variability contributed to
large-scale (continental,hemispheric, global) climate variations during
My subquestion based on this area:
Can we identify the places and mechanisms where we can clearly
understand how atmospheric and ocean dynamics have played a significant
role in affecting the climate (i.e. over and above the local energy
balance changes), and can we reconcile that answer with the geologic
Take an energy balance model, calibrated for today, and force it with
Milankovitch insolation variations of the last 10 thousand years. Take
a suite of coupled GCMs and do the same thing (would have to be ).
Compare them. How are the GCMs different from the EBM? In what regions
and seasons do all the GCMs disagree with the EBM in the same way (i.e.
the difference has the same sign)? On the other hand, where and when do
they not agree? For something where all the GCMs differ from the EBM in
the same direction, it probably points to the role of atmospheric and
ocean dynamics as explaining the difference. Moreover the model
agreement means we can be fairly confident of the sign of the changes.
Diagnose and understand the differences (i.e., talk to David). Find
suitable paleorecords (talk to Eric, Julian, and Sandy).
Why does it feel like a good question?
I am certain that some regions like the monsoons/maritime climates, we
are going to have confident, consistent answers from the GCMs, and it
will be progress to have nailed them down systematically. That is, we
know we can answer some part of the problem.
It would also be very valuable to identify areas of violent
disagreement between models. It points to aspects of the climate are i)
highly variable ii) hard to predict (unknowable?), and iii) might be
best tackled by simply describing what happened using the best data
possible. That is, the surprises along the way are likely to be
Why it is interesting (from Julian Sachs) - the magnitude of Holocene
solar variability changes in W/m2 are much larger seasonally and
latitudinally than the W/m2 from doubling of CO2 (albeit
shortwave vs longave). In many ways, if done carefully we can look for
analogues of specific possible changes for the future, or at least put
them in much better context..
Note the whole exercise could be done from the perspective of the range
of variability in GMC output. Without a compelling reason, it is
awfully hard to reject a GCM scenario as being impossible. The range of
GCMs therefore provide a not-silly first guess at bounding the answer
of the problem. Where inter-GCM agreement is high, it suggests a good
question, where agreement is low, it hints at a bad question (if your
goal is to understand reality).
Problems with this approach:
1. What to do with the ocean?
2. It's probably all about the clouds anyway.
3. I'm not a climate modeler. Who's counting?
Here's the list: