date: 22 Jun 2007 18:32:42 -0400 from: Gavin Schmidt subject: Re: Wengen section to: Phil Jones It would indeed be nice if they would do something constructive like write an actual paper, but it's extremely unlikely that they'll bother. As we've discussed before, this isn't really about the science - it's more of a way to shift the topic of conversation away from physics and on to perfidious scientists, totalitarian bureaucracies and freedom of speech. Those subjects resonate with a lot of people who are looking for reasons not to want to trust the IPCC. Keenan is extremely unpleasant - much more so than McIntyre. Ask Pascal Yiou the next time you see him! There is unfortunately no good way to deal with this micro-parsing - but don't let anything you do allow them to shift the focus onto 'hiding' data etc. regards, gavin On Thu, 2007-06-21 at 03:58, Phil Jones wrote: > Gavin, > So you do look at CA occasionally! Yes nice emails > welcomed all the time. CRU gets a number of emails each > week from interested amateurs (the public). I'm much more > careful how I reply to these. > I won't be replying to CA. McIntyre's email wasn't too bad. > The really awful one with threats came from Douglas Keenan. > The only issue I can see they are complaining about is that > we said we used 84 sites (42 rural and 42 urban) and that > we chose those with the fewest site changes. They have found > site histories for some of them and there are site moves! They > have yet to look at the temperature data that I sent them! So > their claim is nothing about the analysis in the paper! > They don't seem to realise that when you spend ages doing all > the site adjustments they only make differences locally. At > large scales they tend to cancel each other out. In > Brohan et al. (2006) Figure 4 you can see a histogram of > adjustments - the average of which is close to zero! > Adjusting is useful as it improves the continuity of spatial > patterns. > The real issues are the biases like urbanization, buckets > and the exposure issues from pre-Stevenson screen days. > Jim will have realized this ages ago, as I did around the > mid-1980s. > > If only they would write a paper, then I'd know what to deal > with. I reckon they are trying this new tack now (blogs, > personal attacks and maybe complaints to our employers) > as they realize they can't write papers (the MM ones re MBH > were poor), and they see their new approach as being more > productive for them. > > So more nice emails every now and then. > > Cheers > Phil > > > At 17:21 20/06/2007, you wrote: > >yeah, I've been noticing... Well, just let me know if I can do anything > >- even if it's just sending the occasionally nice email! > > > >Gavin > > > > > >On Wed, 2007-06-20 at 05:59, Phil Jones wrote: > > > Gavin, > > > Thanks. Yours was the nicest email I got overnight. > > > Cheers > > > Phil > > > > > > > > > At 20:02 19/06/2007, you wrote: > > > >Refs for my section - note that the first Goosse reference should be > > > >Goosse et al 2006, and the second was in error and shouldn't be there > > > >any way. > > > > > > > > > > > >Gavin > > > > > > > > > > > > > > > >References > > > > > > > >Collins, W. D., et al., Radiative forcing by well-mixed greenhouse > > > >gases: Estimates from climate models in the Intergovernmental > > > > Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), J. > > > >Geophys. Res, 111, 2006. > > > > > > > >Dickinson, R., Solar variability and the lower atmosphere, Bull. Amer. > > > >Meteor. Soc., pp. 1240­1248., 1975. > > > > > > > >Gerber, S., F. Joos, P. P. Bruegger, T. F. Stocker, M. E. Mann, and S. > > > >Sitch, Constraining temperature variations over the last > > > > millennium by comparing simulated and observed atmospheric CO2, Clim. > > > >Dyn., 20, 281­299, 2003. > > > > > > > >Goosse, H., O. Arzel, J. Luterbacher, M. E. Mann, H. Renssen, N. > > > >Riedwyl, A. Timmermann, E. Xoplaki, and H. Wanner, The origin > > > > of the European "Medieval Warm Period", Climate of the Past, 2, > > > >99­113, 2006. > > > > > > > >Haigh, J. D., The impact of solar variability on climate, Science, 272, > > > >981­984, 1996. > > > > > > > >Houghton, J. T., Y. Ding, D. J. Griggs, M. Nouger, P. J. van der Linden, > > > >X. Dai, K. Maskell, and C. A. Johnson, Climate Change > > > > 2001: The scientific basis, Cambridge Univ. Press, New York, 2001. > > > > > > > >Lean, J., Evolution of the sun's spectral irradiance since the Maunder > > > >Minimum, Geophys. Res. Lett., 27, 2425­2428, 2000. > > > > > > > >LeGrande, A. N., G. A. Schmidt, D. T. Shindell, C. Field, R. L. Miller, > > > >D. Koch, G. Faluvegi, and G. Hoffmann, Consistent simulations > > > > of multiple proxy responses to an abrupt climate change event, Proc. > > > >Natl. Acad. Sci., 103, 837­842, 2006. > > > > > > > >Oman, L., A. Robock, G. Stenchikov, G. A. Schmidt, and R. Ruedy, > > > >Climatic response to high-latitude volcanic eruptions, J. Geophys. > > > > Res., 110, 2005. > > > > > > > >Ruddiman, W. F., The anthropogenic greenhouse era began thousands of > > > >years ago, Clim. Change, 61, 261­293, 2003. > > > > > > > >Shindell, D. T., G. A. Schmidt, R. L. Miller, and D. Rind, Northern > > > >hemisphere winter climate response to greenhouse gas, ozone, > > > > solar and volcanic forcing, J. Geophys. Res., 106, 7193­7210, 2001. > > > > > > > >Shindell, D. T., G. Faluvegi, R. L. Miller, G. A. Schmidt, J. E. Hansen, > > > >and S. Sun, Solar and anthropogenic forcing of tropical > > > > hydrology, Geophys. Res. Lett., 33, 2006. > > > > > > > > > > > > > > > >On Tue, 2007-05-29 at 05:55, Phil Jones wrote: > > > > > Gavin, > > > > > Thanks for this. I'll incorporate this into a revised draft > > > > > later this week > > > > > and then send around. Gene has sent me something as well. > > > > > Can you send the refs if you have them? > > > > > > > > > > Thorsten will likely send a reminder around as he's being > > > > > pressurized by Larry from EPRI. > > > > > > > > > > Cheers > > > > > Phil > > > > > > > > > > > > > > > At 09:51 28/05/2007, you wrote: > > > > > > > > > > >Hi Phil, sorry for the long delay. But here is a first draft of the > > > > > >forcings and models section I was supposed to take the lead on. > > > > > >Hopefully, we can merge that with whatever Caspar has. > > > > > > > > > > > >Thanks > > > > > > > > > > > >Gavin > > > > > > > > > > > >================ > > > > > > > > > > > >4 Forcing (GS/CA/EZ) 4-5pp > > > > > > > > > > > >Histories (CA) > > > > > >How models see the forcings, especially wrt aerosols/ozone and > > > > > >increasing model complexities (GS) > > > > > > > > > > > >An important reason for improving > > climate reconstructions of the past few > > > > > >millenia is that these reconstructions can help us both evaluate > > > > > >climate model responses and sharpen our understanding of important > > > > > >mechanisms and feedbacks. Therefore, a parallel task to improving > > > > > >climate reconstructions is to assess and independently constrain > > > > > >forcings on the climate system over that period. > > > > > > > > > > > >Forcings can generically be described as external effects on a > > > > > >specific system. Responses within that system that also themselves > > > > > >have an impact on its internal state are described as feeebacks. For > > > > > >the atmosphere, sea surface temperature changes could > > > > > >therefore be considered a forcing, but in a coupled ocean-atmosphere > > > > > >model they could be a feedback to another external factor or be > > > > > >intrinsic to the coupled system. Thus > > the distinction between forcings and > > > > > >feedbacks is not defined a priori, but is a function of the scope of > > > > > >the modelled system. This becomes especially important when dealing > > > > > >with the bio-geo-chemical processes in climate that effect the > > > > > >trace gas concentrations (CO2 and CH4) or > > > > aerosols. For example, if a model > > > > > >contains a carbon cycle, than the CO2 variations as a function of > > > > > >climate will be a feedback, but for a simpler physical model, CO2 is > > > > > >often imposed directly as a forcing from observations, regardless of > > > > > >whether in the real world it was a feedback to another change, or a > > > > > >result of human industrial activity. > > > > > > > > > > > >It is useful to consider the pre-industrial period (pre-1850 or so) > > > > > >seperately from the more recent past, since the human influence on > > > > > >many aspects of atmospheric composition has increased dramatically in > > > > > >the 20th Century. In particular, aerosol and land use changes are > > > > > >poorly constrained prior to the late 20th Century and have large > > > > > >uncertainties. Note however, there may > > conceivably be a role for human > > > > > >activities even prior to the 19th Century due to early argiculatural > > > > > >activity (Ruddiman, 2003; Goosse et al, 2005). > > > > > > > > > > > >In pre-industrial periods, forcings can be usefully separated into > > > > > >purely external changes (variations of solar activity, volcanic > > > > > >eruptions, orbital variation), and those which are intrinsic to the > > > > > >Earth system (greenhouse gases, aerosols, vegetation etc.). Those > > > > > >changes in Earth system elements will occur predominantly as feedbacks > > > > > >to other changes (whether externally forced or simply as a function of > > > > > >internal climate 'noise'). In the more recent past, the human role in > > > > > >affecting atmospheric composition (trace gases and aerosols) and land > > > > > >use have dominated over natural processes and so these changes can, to > > > > > >large extent, be considered external forcings as well. > > > > > > > > > > > >Traditionally, the 'system' that is most usually implied when talking > > > > > >about forcings and feedbacks are the 'fast' components atmosphere-land > > > > > >surface-upper ocean system that, not coincidentally, corresponds to > > > > > >the physics contained within atmospheric > > > > general circulation models (AGCMs) > > > > > >coupled to a slab ocean. What is not > > > > included (and therefore considered as a > > > > > >forcing according to our previous definition) are 'slow' changes in > > > > > >vegetation, ice sheets or the carbon cycle. In the real world these > > > > > >features will change as a function of other climate changes, and in > > > > > >fact may do so on relatively 'fast' (i..e multi-decadal) > > > > > >timescales. Our choice then of the appropriate 'climate system' is > > > > > >thus slightly arbitrary and does not give a complete picture of the > > > > > >long term sensitivity of the real climate. > > > > > > > > > > > >These distinctions become important because the records available for > > > > > >atmospheric composition do not record the distinction between feedback > > > > > >or forcing, they simply give, for instance, the history of CO2 and > > > > > >CH4. Depending on the modelled system, those records will either be a > > > > > >modelling input, or a modelling target. > > > > > > > > > > > >While there are good records for some factors (particularly the well > > > > > >mixed greenhouse gases such as CO2 and CH4), records for others are > > > > > >either hopelessly incomplete (dust, vegetation) due to poor spatial or > > > > > >temporal resolution or non-existant (e.g. ozone). Thus estimates of > > > > > >the magnitude of these forcings can only be made using a model-based > > > > > >approach. This can be done using GCMs that include more Earth system > > > > > >components (interactive aerosols, chemistry, dynamic vegetation, > > > > > >carbon cycles etc.), but these models are still very much a work in > > > > > >progress and have not been used extensively for paleo-climatic > > > > > >purposes. Some initial attempts have been made for select feedbacks > > > > > >and forcings (Gerber et al, 2003; Goosse et al 2006) but a > > > > > >comprehensive assessment over the millennia prior to the > > > > > >pre-industrial does not yet exist. > > > > > > > > > > > >Even for those forcings for which good records exist, there is a > > > > > >question of they are represented within the models. This is not so > > > > > >much of an issue for the well-mixed greenhouse gases (CO2, N2O, CH4) > > > > > >since there is a sophisticated literature and history of including > > > > > >them within models (IPCC, 2001) though some aspects, such as minor > > > > > >short-wave absorption effects for CH4 and N2O are still not > > > > > >universally included > > > > > >(Collins et al, 2006). However, solar effects have been treated in > > > > > >quite varied ways. > > > > > > > > > > > >The most straightforward way of including solar irradiance effects on > > > > > >climate is to change the solar 'constant' (preferably described as > > > > > >total solar irradiance - TSI). However, observations show that solar > > > > > >variability is highly dependent on wavelength with UV bands having > > > > > >about 10 times as much amplitude of change than TSI over a solar cycle > > > > > >(Lean, 2000). Thus including this spectral variation for all solar > > > > > >changes allows for a slightly different behaviour (larger > > > > > >solar-induced changes in the stratosphere where the UV is mostly > > > > > >absorbed for instance). Additionally, the changes in UV affect ozone > > > > > >production in both the stratosphere and troposphere, and this > > > > > >mechanism has been shown to affect both the total radiative forcing > > > > > >and dynamical responses (Haigh 1996, Shindell et al 2001; > > > > > >2006). Within a chemistry climate model this effect would potentially > > > > > >modify the radiative impact of the > > original solar forcing, but could also > > > > > >be included as an additional (parameterised) forcing in standard GCMs. > > > > > > > > > > > >There is also a potential effect from the indirect effect of solar > > > > > >magnetic variability on the sheilding of cosmic rays, which have been > > > > > >theorised to affect the production of cloud condensation nuclei > > > > > >(Dickinson, 1975). However, there have been no quantitative > > > > > >calculations of the magnitude of this effect (which would require a > > > > > >full study of the relevant aerosol and cloud microphysics), and so its > > > > > >impact on climate is not (yet) been included. > > > > > > > > > > > >Large volcanic eruptions produce significant amounts of sulpher > > > > > >dioxide (SO2). If this is injected into the tropical stratosphere > > > > > >during a particularly explosive eruption, the resulting sulphate can > > > > > >persist in the atmosphere for a number of years (e.g. Pinatubo in > > > > > >1991). Less explosive, but more persistent eruptions (e.g. Laki in > > > > > >1789??) can still affect climate though in a more regional way and for > > > > > >a shorter term (Oman et al, 2005). These aerosols have both a > > > > > >shortwave (reflective) and longwave (absorbing) impact on the > > > > > >radiation and their local impact on stratospheric heating can have > > > > > >important dynamical effects. It is therefore better to include the > > > > > >aerosol absorber directly in the radiative transfer code. However, in > > > > > >less sophisticated models, the impact of the aerosols has been > > > > > >parameterised as the equivalent decrease in TSI. For extreme eruptions > > > > > >it has been hypothesised that sulphate production might saturate the > > > > > >oxidative capacity of the stratosphere leaving significant amounts of > > > > > >residual SO2. This gas is a greenhouse gas and would have an opposite > > > > > >effect to the cooling aerosols. This effect however has not yet been > > > > > >quantified. > > > > > > > > > > > >Land cover changes have occured both due to deliberate modification by > > > > > >humans (deforestation, imposed fire regimes, arguculture) as well as a > > > > > >feedback to climate change (the desertification of the Sahara ca. 5500 > > > > > >yrs ago). Changing vegetation in a standard model affects the seasonal > > > > > >cycle of albedo, the surface roughness, the impact of snow, > > > > > >evapotranspiration (through different rooting depths) etc. However, > > > > > >modelling of the yearly cycle of crops, or incorporating the effects > > > > > >of large scale irrigation are still very much a work in > > > > > >progress. > > > > > > > > > > > >Aerosol changes over the last few milllenia are very poorly > > > > > >constrained (if at all). These might have arisen from climatically > > > > > >or human driven changes in dust emissions, ocean biology feedbacks > > > > > >on circulation change, or climate impacts on the emission volatile > > > > > >organics from plants (which also have an impact on ozone > > > > > >chemistry). Some work on modelling a subset of those effects has > > > > > >been done for the last glacial maximum or the 8.2 kyr event > > > > > >(LeGrande et al, 2006), but there have been no quantitative > > > > > >estimates for the late Holocene (prior to the industrial period). > > > > > > > > > > > >Due to the relative expense of doing millennial simulations with > > > > > >state-of-the-art GCMs, exisiting simulations have generally done the > > > > > >minimum required to include relevant solar, GHG and volcanic > > > > > >forcings. Progress can be expected relatively soon on more > > > > > >sophisticated treatments of those forcings and the first > > > > > >quantitative estimates of additional effects. > > > > > > > > > > > >============= > > > > > > > > > > > > > > > > > >*--------------------------------------------------------------------* > > > > > >| Gavin Schmidt NASA/Goddard Institute for Space Studies | > > > > > >| 2880 Broadway | > > > > > >| Tel: (212) 678 5627 New York, NY 10025 | > > > > > >| | > > > > > >| gschmidt@giss.nasa.gov http://www.giss.nasa.gov/~gavin | > > > > > >*--------------------------------------------------------------------* > > > > > > > > > > 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.jones@uea.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.jones@uea.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.jones@uea.ac.uk > NR4 7TJ > UK > ---------------------------------------------------------------------------- > >