date: Thu, 16 Apr 2009 17:13:36 +0100 from: Thomas Crowley subject: Re: trends for n. land (summer) vs globe to: Phil Jones

Phil its hard to believe the nh land record is off - so the 1.5 C warming is still significant - and the global temp. record is being cited a zillion times - so as long as I keep it at that level, I don't understand why there should be a problem - especially if I cut out or minimize any discussion about offsets in the latter part of the record - doesn't that seem a little worthwhile, given the fixation on global temps. rather than land temps? tom > > Tom, > I wouldn't bother posting this on Real Climate. > Cheers > Phil > > > At 21:15 15/04/2009, you wrote: >> Quoting Phil Jones : >> >> >> I don't want to be posting something on RealClimate.org that is going >> to create confusion rather than clarification. >> >> should I just not submit the piece after all? >> >> tom >> >> >>> >>> John, >>> Another possible issue is the 61-90 ship based SST normals >>> for the SH oceans in the range 40-60S. I presume you're working on >>> improving these for the next version. >>> >>> Cheers >>> Phil >>> >>> >>> At 12:10 15/04/2009, John Kennedy wrote: >>>> The ARGO data don't go into SST analyses at the moment. They do make >>>> measurements at depths that overlap with the deeper ship-based >>>> measurements, so there's no reason why they couldn't be included in >>>> the >>>> future or used as an independent validation of the SST data once >>>> the QC >>>> issues are sorted out. >>>> >>>> Drifting buoys measure SSTs about 0.15C cooler than ships (with some >>>> geographic variation) probably due to predominantly warm biases in the >>>> ship data. They are included in SST analyses - more than 85% of all >>>> SST >>>> observations now come from buoys - and have probably led to a slight >>>> underestimate in the rate of warming since the late 1970s when they >>>> were >>>> first introduced. >>>> >>>> John >>>> >>>> On Fri, 2009-04-10 at 22:29 +0100, Simon Tett wrote: >>>>> I don't think ARGO goes into the SST dataset though there are a >>>>> lot more >>>>> buoys in it. When I was at the Hadley Centre we wondered if buoys >>>>> were >>>>> causing a slight cooling trend. [John Kennedy CCed might have some >>>>> more >>>>> thoughts on that.] >>>>> >>>>> Simon >>>>> >>>>> Susan.Solomon@noaa.gov wrote: >>>>> > Tom >>>>> > The fact that land could be shown to be warming more than ocean >>>>> was a >>>>> > major conclusion of the AR4. >>>>> > >>>>> > It's good to see the update to 2008. Quite striking. >>>>> > >>>>> > I hate to say this, but I wonder if some of the recent behavior is >>>>> > spurious - the Argo floats just don't seem very consistent with >>>>> earlier >>>>> > records not only for surface temperature but also for sea level (ie >>>>> > subsurface). What do you think? >>>>> > Susan >>>>> > >>>>> > >>>>> > ----- Original Message ----- >>>>> > From: Thomas Crowley >>>>> > Date: Friday, April 10, 2009 6:10 am >>>>> > Subject: trends for n. land (summer) vs globe >>>>> > >>>>> >> Hi, >>>>> >> >>>>> >> I am in the process of producing a new, long (733-1960) paleo >>>>> >> reconstruction at annual resolution for purposes of better >>>>> >> validation >>>>> >> against models. since tree rings are most sensitive to summer >>>>> half- >>>>> >> year >>>>> >> temperatures, and trees usually grow on land, I am calibrating >>>>> >> against >>>>> >> 30-90N summer (land), using HadCRU data updated through 2008, >>>>> >> kindly >>>>> >> provided by Phil. >>>>> >> >>>>> >> some interesting items jump out from just comparing (attached) the >>>>> >> instrumental reconstructions for 30-90N land, summer vs global >>>>> >> temps >>>>> >> (anomalies based on 1960-1990 mean for each data set): >>>>> >> >>>>> >> 1) the n summer land changes are almost twice as large (1.5 vs. >>>>> >> 0.8°C) >>>>> >> as the global - this is not surprising because we know that land >>>>> >> heats >>>>> >> up faster than ocean, but the magnitude is quite striking. >>>>> >> >>>>> >> 2) since most people still live on land, this means the human >>>>> >> impact >>>>> >> factor has been twice as large as normally assumed for close to 3 >>>>> >> billion people >>>>> >> >>>>> >> 3) the divergence between northern land and global temps seems to >>>>> >> be >>>>> >> increasing - both record show the recent decrease in temperatures, >>>>> >> but >>>>> >> on land it only started last year (2008) >>>>> >> >>>>> >> 4) seven large volcanic eruptions can easily be identified in the >>>>> >> northern land record - this again makes sense from an energy >>>>> >> balance >>>>> >> viewpoint, as summer temperatures are more driven by >>>>> thermodynamics >>>>> >> than >>>>> >> dynamics, so the signal is more easily detectable, especially >>>>> given >>>>> >> the >>>>> >> added impact of maximized reflection of insolation due to high sun >>>>> >> angle. >>>>> >> 5) this suggests that northern hemisphere land (summer) might be >>>>> >> the >>>>> >> most logical data set to look at for detection of volcanic >>>>> signals. >>>>> >> as >>>>> >> I have nearly finalized the new paleo reconstruction of volcanos, >>>>> >> it >>>>> >> might be interesting to re-apply detection and attribution to the >>>>> >> new, >>>>> >> longer, and (hopefully improved) data sets. >>>>> >> >>>>> >> fyi, Tom >>>>> >> >>>>> >> -- >>>>> >> The University of Edinburgh is a charitable body, registered in >>>>> >> Scotland, with registration number SC005336. >>>>> >> >>>>> >> >>>>> > >>>> -- >>>> John Kennedy Climate Monitoring and Research Scientist >>>> Met Office Hadley Centre FitzRoy Road Exeter EX1 3PB >>>> Tel: +44 (0)1392 885105 Fax: +44 (0)1392 885681 >>>> E-mail: john.kennedy@metoffice.gov.uk http://www.metoffice.gov.uk >>>> Global climate data sets are available from http://www.hadobs.org >>> >>> 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 >>> ---------------------------------------------------------------------------- >>> >> >> >> >> -- >> The University of Edinburgh is a charitable body, registered in >> Scotland, with registration number SC005336. >> > > 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 > ---------------------------------------------------------------------------- > > -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.