Wednesday, December 28, 2011


From: Tim Johns <>
To: "Folland, Chris" <>
Subject: Re: FW: Temperatures in 2009
Date: Mon, 05 Jan 2009 09:34:49 +0000
Cc: "Smith, Doug" <>,, Tim Johns <>

Dear Chris, cc: Doug

Mike McCracken makes a fair point. I am no expert on the observational
uncertainties in tropospheric SO2 emissions over the recent past, but it
is certainly the case that the SRES A1B scenario (for instance) as seen
by different integrated assessment models shows a range of
possibilities. In fact this has been an issue for us in the ENSEMBLES
project, since we have been running models with a new
mitigation/stabilization scenario "E1" (that has large emissions
reductions relative to an A1B baseline, generated using the IMAGE IAM)
and comparing it with A1B (the AR4 marker version, generated by a
different IAM). The latter has a possibly unrealistic secondary SO2
emissions peak in the early 21st C - not present in the IMAGE E1
scenario, which has a steady decline in SO2 emissions from 2000. The A1B
scenario as generated with IMAGE also show a decline rather than the
secondary emissions peak, but I can't say for sure which is most likely
to be "realistic".

The impact of the two alternative SO2 emissions trajectories is quite
marked though in terms of global temperature response in the first few
decades of the 21st C (at least in our HadGEM2-AO simulations,
reflecting actual aerosol forcings in that model plus some divergence in
GHG forcing). Ironically, the E1-IMAGE scenario runs, although much
cooler in the long term of course, are considerably warmer than A1B-AR4
for several decades! Also - relevant to your statement - A1B-AR4 runs
show potential for a distinct lack of warming in the early 21st C, which
I'm sure skeptics would love to see replicated in the real world... (See
the attached plot for illustration but please don't circulate this any
further as these are results in progress, not yet shared with other
ENSEMBLES partners let alone published). We think the different short
term warming responses are largely attributable to the different SO2
emissions trajectories.

So far we've run two realisations of both the E1-IMAGE and A1B-AR4
scenarios with HadGEM2-AO, and other partners in ENSEMBLES are doing
similar runs using other GCMs. Results will start to be analysed in a
multi-model way in the next few months. CMIP5 (AR5) prescribes similar
kinds of experiments, but the implementation details might well be
different from ENSEMBLES experiments wrt scenarios and their SO2
emissions trajectories (I haven't studied the CMIP5 experiment fine
print to that extent).


On Sat, 2009-01-03 at 21:31 +0000, Folland, Chris wrote:
> Tim and Doug
> Please see McCrackens email.
> We are now using the average of 4 AR4 scenarios you gave us for GHG + aerosol. What is the situation likely to be for AR5 forcing, particularly anthropogenic aerosols. Are there any new estimates yet? Pareticularly, will there be a revision in time for the 2010 forecast? We do in the meantime have an explanation for the interannual variability of the last decade. However this fits well only when an underlying net GHG+aerosol warming of 0.15C per decade is fitted in the statistical models. In a sense the methods we use would automatically fit to a reduced net warming rate so Mike McCracken can be told that. In other words the method creates it own transient climate sensitivity for recent warming. But the forcing rate underlying the method nevertheless perhaps sits a bit uncomfortably with the absolute forcing figures we are using from AR4. However having said this, interestingly, the statistics and DePreSys are in remarkable harmony about the temperature of 2009.
> Any guidance welcome
> Chris
> Prof. Chris Folland
> Research Fellow, Seasonal to Decadal Forecasting (from 2 June 2008)
> Met Office Hadley Centre, Fitzroy Rd, Exeter, Devon EX1 3PB United Kingdom
> Email:
> Tel: +44 (0)1647 432978
> Fax: (in UK) 0870 900 5050
> (International) +44 (0)113 336 1072)
> <>
> Fellow of the Met Office
> Hon. Professor of School of Environmental Sciences, University of East Anglia
> -----Original Message-----
> From: Mike MacCracken []
> Sent: 03 January 2009 16:44
> To: Phil Jones; Folland, Chris
> Cc: John Holdren; Rosina Bierbaum
> Subject: Temperatures in 2009
> Dear Phil and Chris--
> Your prediction for 2009 is very interesting (see note below for notice that went around to email list for a lot of US Congressional staff)--and I would expect the analysis you have done is correct. But, I have one nagging question, and that is how much SO2/sulfate is being generated by the rising emissions from China and India (I know that at least some plants are using desulfurization--but that antidotes are not an inventory). I worry that what the western nations did in the mid 20th century is going to be what the eastern nations do in the next few decades--go to tall stacks so that, for the near-term, "dilution is the solution to pollution". While I understand there are efforts to get much better inventories of CO2 emissions from these nations, when I asked a US EPA representative if their efforts were going to also inventory SO2 emissions (amount and height of emission), I was told they were not. So, it seems, the scientific uncertainty generated by not having good data from the mid-20th century is going to be repeated in the early 21st century (satellites may help on optical depth, but it would really help to know what is being emitted).
> That there is a large potential for a cooling influence is sort of evident in the IPCC figure about the present sulfate distribution--most is right over China, for example, suggesting that the emissions are near the surface--something also that is, so to speak, 'clear' from the very poor visibility and air quality in China and India. So, the quick, fast, cheap fix is to put the SO2 out through tall stacks. The cooling potential also seems quite large as the plume would go out over the ocean with its low albedo--and right where a lot of water vapor is evaporated, so maybe one pulls down the water vapor feedback a little and this amplifies the sulfate cooling influence.
> Now, I am not at all sure that having more tropospheric sulfate would be a bad idea as it would limit warming--I even have started suggesting that the least expensive and quickest geoengineering approach to limit global warming would be to enhance the sulfate loading--or at the very least we need to maintain the current sulfate cooling offset while we reduce CO2 emissions (and presumably therefore, SO2 emissions, unless we manage things) or we will get an extra bump of warming. Sure, a bit more acid deposition, but it is not harmful over the ocean (so we only/mainly emit for trajectories heading out over the ocean) and the impacts of deposition may well be less that for global warming (will be a tough comparison, but likely worth looking at). Indeed, rather than go to stratospheric sulfate injections, I am leaning toward tropospheric, but only during periods when trajectories are heading over ocean and material won't get rained out for 10 days or so.
> Would be an interesting issue to do research on--see what could be done.
> In any case, if the sulfate hypothesis is right, then your prediction of warming might end up being wrong. I think we have been too readily explaining the slow changes over past decade as a result of variability--that explanation is wearing thin. I would just suggest, as a backup to your prediction, that you also do some checking on the sulfate issue, just so you might have a quantified explanation in case the prediction is wrong. Otherwise, the Skeptics will be all over us--the world is really cooling, the models are no good, etc. And all this just as the US is about ready to get serious on the issue.
> We all, and you all in particular, need to be prepared.
> Best, Mike MacCracken
> Researchers Say 2009 to Be One of Warmest Years on Record
> On December 30, climate scientists from the UK Met Office and the University of East Anglia projected 2009 will be one of the top five warmest years on record. Average global temperatures for 2009 are predicted to be 0.4�C above the 1961-1990 average of 14 � C. A multiyear forecast using a Met Office climate model indicates a �rapid return of global temperature to the long-term warming trend,� with an increasing probability of record temperatures after 2009. �The fact that 2009, like 2008, will not break records does not mean that global warming has gone away . . . . What matters is the underlying rate of warming,� said Dr. Phil Jones, the director of climate research at the University of East Anglia. The presence of La Nina during the last year partially masked this underlying rate. �Phenomena such as El Nino and La Nina have a significant influence on global surface temperature,� said Dr. Chris Folland of the Met Office Hadley Center.
> �Further warming to record levels is likely once a moderate El Nino develops.� The transition from a La Nina effect to an El Nino one is expected late next year.
> For additional information see:
> older-than-in-Iceland.html
Tim Johns Manager Global Coupled Modelling
Met Office Hadley Centre
FitzRoy Rd Exeter Devon EX1 3PB United Kingdom
Tel: +44 (0)1392 886901 Fax: +44 (0)1392 885681

Please note I work part time, normally Monday-Tuesday Thursday-Friday

Met Office climate change predictions can now be viewed on Google Earth

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