Thursday, May 24, 2012

4660.txt

date: Fri Oct 17 16:59:05 2008
from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: RE: global temperatures
to: "Bob Eagle" <bobatXYZxyzagle.co.uk>

Bob,
Water vapour content is rising - see the attached. This is Figure 3.21 from
the IPCC WG1 Report from 2007.
The second paper shows that surface specific humidity is also going up around
the world since the 1970s. This sort of data are not so readily available before
this date. Also the paper shows that RH is not going up. Specific humidity is
going up because temperatures are and RH is staying roughly the same. Climate
models have always said - even for simulations of the last Ice Age and
the 22cnd century, that RH remains roughly the same. This is one of the first
papers to show this observationally - albeit for only ~30 years, but this is all
the data we have. Why all this happens is due to the Claussius-Clapeyron
relationship.
On your theoretical reasons: these have nothing to do with relationships
between CO2 and temperature. The confidence comes from simple physics.
More CO2 means higher temperature, it has nothing to with how well models
correlate with historic data. Also, if you look at many scenarios of future temperature
change,
the emissions scenario makes very little difference until 2040. This means
that what we do now will have hardly any effect on temperature increases until 2040.
The next 30 or so years are predetermined. There will be variability from year to year,
but the level for the 2040s is essentially independent of the emissions scenario.
This is why the sooner we start doing something about CO2 levels the sooner our
children we see some effect.
Cheers
Phil
At 14:29 16/10/2008, you wrote:

Many thanks Phil.
One can find all sorts of comments through googling and most of them are not
worth reading - but on occasion one picks up a site which does make
interesting points. One such is
[1]http://www.climate4you.com/ClimateReflections.htm#20080927:%20Reflections%20
on%20the%20correlation%20between%20global%20temperature%20and%20atmospheric%
20CO2
You are possibly familiar with it.
There are good theoretical reasons for CO2 to be a greenhouse gas but there
are limits to the warming that it will provide. It has been assumed that a
warmer troposphere will be a wetter one and therefore that the impact of CO2
will be re-inforced by water vapour. Yet the water content of the
troposphere appears not to be rising. The above site shows that the warming
that did occur from about 1974 to about 1998 seems to have ceased.
Therefore there is a question about the direction that will be taken in the
future - yes the warming trend may be re-established, perhaps as a
consequence of further increases in CO2 levels, but the picture is far from
certain.
There are theoretical reasons why CO2 levels in excess of some figure -
perhaps around present levels - will provide the maximum heating effect in
the absence of indirect influences. Therefore further increases in CO2 will
not in themselves create extra warming. Over the past 9 years it appears
that warming has ceased. The experts appear to be confident that the
warming trend will become re-established - on what is that confidence based?
Is it simply through the brilliant models which correlate so well with the
historical data?
Best
Bob
-----Original Message-----
From: Phil Jones [[2]mailto:p.jones@uea.ac.uk]
Sent: 13 October 2008 15:38
To: Bob Eagle
Subject: RE: global temperatures
Bob,
You're wrong on a few points here. The 1997/98 El Nino generated the
greatest response in global surface temperatures compared to any
other in the 20th century - because it was the biggest El Nino event.
The 0.2 deg C per decade T increase is what has happened over the
last 2 decades and is what is predicted to happen over the next 2-3
decades.
The rate does increase for future decades.
CO2 is higher now than it has been for the last 800,000 years
and probably for the last few millennia since the start of the
Quaternary Era.
When you talk about CO2 levels falling and temperatures rising, it is
important to have temperatures measured around the world. You can't
assume what the global T was from Greenland or the Antarctic ice cores.
On glacial timescales they vary out of phase with one another.
We use trees where they respond to temperature - it is a simple as that.
If we core some trees and they don't respond to temperature we
don't use them.
They are still in datasets though, as they may be usful for something else
or
someone else.
Cheers
Phil
At 21:24 09/10/2008, you wrote:
>Many thanks for this speedy response!
>
>Looking at the 1998 El Nino event it seems to have generated a greater
>temperature anomaly than earlier ones - but probably not to a significant
>extent. I note the estimate of 0.2 deg C per decade - that is lower than
>the IPCC 4 median estimate isn't it? The records suggest that during the
>course of the last few million years CO2 levels have been much greater than
>they are now - maybe an order of magnitude greater. Yet the earth cooled
>and then CO2 levels fell. Are these observations entirely consistent with
>the current mathematical models? CO2 of itself will have an effect which
is
>asymptotic to neutral - do we have an estimate for the level at which this
>occurs?
>
>Many thanks for the explanation about tree ring width. We use only
>northerly or high sites for temperature proxies - is it the case that some
>analysts reject most of these data? Could you direct me to a plot which
>shows all the data from the best sites by any chance?
>
>All the best
>
>Bob
>
>
>-----Original Message-----
>From: Phil Jones [[3]mailto:p.jones@uea.ac.uk]
>Sent: 07 October 2008 10:51
>To: bobatXYZxyzagle.co.uk
>Subject: FW: global temperatures
>
>
> > Bob,
>
> Brief answers. Global temperatures vary a lot from year to year.
Much
> of this is due to El Nino and La Nina events. The last major El Nino
> occurred in 1997/1998 and that was why 98 was so warm. We are just
> finishing a major La Nina event and this has cooled the world.
> Greenhouse gases warm the world at about 0.2 deg C per decade at the
> moment. This is 0.02 deg C per year, nmuch smaller than the swings of
> 0.1 deg C between years due El Nino and La Nina.
> I also do know how trees grow. They respond to temperature and
>moisture.
> They have regions where they grow, so we choose sites in Europe in the
> north of their zone or high up where moisture is less of a limiting
factor
> and temperature effects dominate. If we're trying to do precipitation
then
> it is the opposite - more south and lowland. So we isolate the effects
by
> taking samples from the extremes of their distribution.
> All this is done by standard tree-ring techniques called response
>function
> analysis which the skeptic web sites don't seem to know about.
>
> Cheers
> Phil
>
>
>
> >-----Original Message-----
> >From: Bob Eagle [[4]mailto:bob@greagle.co.uk]
> >Sent: Monday, October 06, 2008 5:48 PM
> >To: Sheppard Sylv Miss (SCI)
> >Subject: global temperatures
> >
> >
> >I wonder if you could help.
> >
> >I note that the temperature plot for the period from 1850 to the present
> >day shows that the highest temperature occurred in 1998. Since that
> >year temperatures appear to have been falling. Yet CO2 levels and those
> >of other greenhouse gases have continued to rise. Is this in any way
> >odd?
> >
> >I believe you have developed an equation relating temperature at a
> >particular site with tree ring width. Clearly tree growth is not
> >linearly related to temperature - whilst growth may cease at low
> >temperatures it will also cease at high temperatures too. Furthermore
> >growth is affected by other factors such as moisture availability,
> >disease, changes in sunlight and changes in soil fertility. How do you
> >isolate these confounding factors when estimating temperature by
> >measuring tree-ring width?
> >
> >With best wishes
> >
> >Bob
>
>Prof. Phil Jones
>Climatic Research Unit Telephone +44 (0) 1603 592090
>School of Environmental Sciences Fax +44 (0) 1603 507784
>University of East Anglia
>Norwich Email p.jonesatXYZxyz.ac.uk
>NR4 7TJ
>UK
>---------------------------------------------------------------------------
-
Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jonesatXYZxyz.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------

Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jonesatXYZxyz.ac.uk
NR4 7TJ
UK
----------------------------------------------------------------------------

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