Climate variability

[Ariel]

Hello everyone,

I'm a first-year PhD student in Agricultural and Resource Economics at
the University of Maryland.
I'm wondering if someone in the forum could point me to research about
any predicted changes in climate variability for the US or any other
country or region.

By climate variability I mean a change in the shape of the
"probabilistic distribution" of temperature and rainfall, i.e. a
change in the variance (extreme weather events on BOTH sides of the
distribution become more frequent... the "tails" are fatter).

I have the impression is that a lot of the focus of climate research
is in the "shift" of the distribution (answering the question: how
warmer or dryer or wetter is it going to be ON AVERAGE in location A
on average?).

Any help would be greatly appreciated!!

AOB

[David B. Benson]

On Apr 5, 8:30 am, Ariel <ariel...@gmail.com> wrote:
> Hello everyone,
> ...

I haven't seen any but the most primitive regional climate
predictions, but haven't looked much except for Patagonia. Maybe
there are some useful key words you can use to track down what you
want from this article:

Farming in a Warmer World, to the left. Click on it:

http://www.nytimes.com/2008/04/17/business/worldbusiness/17warm.html?pagewanted=1

Also, IPCC AR4 WG1 may have something regarding projected
precipitation patterns.

[Ariel]

Thank you, I will look into it.
AOB

On Apr 6, 8:01 pm, "David B. Benson" <dben...@eecs.wsu.edu> wrote:
> On Apr 5, 8:30 am, Ariel <ariel...@gmail.com> wrote:
>
> > Hello everyone,
> > ...
>
> I haven't seen any but the most primitive regional climate
> predictions, but haven't looked much except for Patagonia.  Maybe
> there are some useful key words you can use to track down what you
> want from this article:
>
> Farming in a Warmer World, to the left.  Click on it:
>

> http://www.nytimes.com/2008/04/17/business/worldbusiness/17warm.html?...

[David B. Benson]

On Apr 9, 10:32 am, Ariel <ariel...@gmail.com> wrote:
> Thank you, I will look into it.

Here are some other links which might be helpful:

Regional Water & Ag changes in U.S.

http://www.nytimes.com/2008/05/28/science/earth/28climate.html?_r=1&oref=slogin

Ag in 2030 (FAO)

http://www.fao.org/docrep/005/Y4252E/y4252e00.HTM

http://topics.nytimes.com/top/news/business/series/the_food_chain/index.html

[crandles]

Constraints on future changes in climate and the hydrologic cycle
Myles R. Allen* & William J. Ingram†
http://www.climateprediction.net/science/pubs/nature_insight_120902.pdf

"Changes in precipitation extremes
Long-term mean precipitation is a useful summary indicator of the
intensity of the hydrologic cycle, but details of the distribution of
precipitation over time, including the peak intensity of precipitation
events and duration of prolonged droughts, are likely to be the most
important issues in determining impacts of precipitation changes9.
Although global-mean precipitation is primarily constrained by the
energy budget, the heaviest rainfall events are likely to occur when
effectively all the moisture in a volume of air is precipitated out,
suggesting that the intensity of these events will increase with the
availability of moisture7 (that is, significantly faster than the
global mean). Thus we might expect the uppermost quantiles of the
rainfall distribution to increase by about 6.5% per kelvin (ref. 44)
if the ambient flows change (most likely at higher latitudes). In the
tropics, where the flows leading to precipitation are themselves
driven largely
by the latent heat released by precipitation, larger increases still
might occur7. In particular, the maximum thermodynamically possible
rainfall and winds in hurricanes are predicted to increase rapidly
with warming56.
The red and purple curves in Fig. 4 show the magnitude of daily
precipitation as a function of percentile of the precipitation
distribution in one AOGCM under climate change and control conditions,
respectively. The green curve (and right-hand axis) shows the ratio
between them. At the highest end of the distribution (all tropical
cases), it appears to be converging to about a 25% increase, which is
indeed slightly more than we would expect from the Clausius–Clapeyron
relationship.
Because such increases are more than double the increase in
global-mean precipitation (that is, the change summed over all
percentiles, which is constrained by the energy budget, not by the
Clausius–Clapeyron relation), there must be decreases lower down the
distribution. Indeed, the increase at the heaviest rain events is
large enough that the energy constraint on the total implies that only
on one day in ten does precipitation increase (the control and
perturbed distributions cross around the 90th percentile in Fig. 4).
It would be interesting to know how other models compare — if this
were be another emergent constraint generic over all models in regions
of interest, then we could use forecast temperature changes to
constrain extreme as well as mean precipitation. Given the
acknowledged difficulties in relying on model simulations of extreme
events and in observing changes in extremes directly57, this could be
a
powerful result. In particular, this convergence to a particular
fractional increase, possibly related to the Clausius–Clapeyron limit,
could even improve as we move to the highest percentiles, which are
generally the least tractable under more direct approaches."

There is probably better papers to quote than that.

When I did quote that before, this exchange which followed seemed
quite odd:

>[You should be aware that the claims of more weather extremes are often over-hyped; our weather will change somewhat, with the climate, and hence become more unexpected; but there is no great evidence for it becoming more variable -W]

Regarding temperature extremes and wind extremes, I have seen nothing
to disagree with what you are saying. However with rainfall, I thought
there was agreement that warmer atmosphere holds more water and due to
some constraint (energy budget?) it was fairly clear that the heavy
downpours are going to get heavier. Have I got that wrong, is this
highly contested?

[I agree; and so does WJI, given the paper you've quoted above. But
there is another way of looking at it: most stuff is approx normal,
but rainfall isn't. If you look at extremes of its log distribution,
which is approx normal, you may find its changes revert to what
everything else does, ie the distribution just shifts -W]

W Being William Connolley and the exchange at
http://scienceblogs.com/stoat/2009/01/arctic_sea_ice_retreat_when_wi.php
My thoughts shouldn't be counted as meaning anything.