Climate Parallax

Why different views of the surface temperature record should always be regarded as a good thing.

Parallax: Channel 4 title sequence (Source: http://www.tvwhirl.co.uk)

Parallax – noun: the apparent change in the position of an object due to a change in the position of the observer.

(Famously used by UK Channel 4 in a series of animations of their title sequences where landscape features line up at a certain point to form “4”).

Zeke Hausfather’s recent post Agreeing at the Blackboard begins:

My personal pet peeve in the climate debate is how much time is wasted on arguments that are largely spurious, while more substantive and interesting subjects receive short shrift. While I’m sure a number of folks will disagree with me on what is spurious vs. substantive, I think it would be useful to outline which parts of the debate I feel are relatively certain, are somewhat uncertain, and quite uncertain.

I found myself agreeing mostly with Jeff Id’s post about it,  but much of that is gut feeling.  There are a couple of Zeke’s statements where my opinion is based on having looked in detail at data. In Zeke’s category What I think is likely he says:

Land and ocean temperature measurements over the past century are largely accurate at a global level, though there are some regions that have limited data, especially toward the earlier part of the century. That said, factors like UHI, instrument change, siting issue, and other data quality issues could potentially change the global trend modestly.

For the first sentence, well, no, I can’t agree. Why? Because of what he says in the second; I have seen enough of the data and the adjustments to think that these ‘factors’ could reduce the calculated warming dramatically. But then it might not; either way I can’t assign it to ‘likely’.

In the past year countless hours have been spent perfecting reproductions of the GISS and CRU global average anomalies (e.g. this post at WUWT). There has been some sterling work done by Zeke, Ron Broberg, Nick Stokes, Steven Mosher and others.  It is reassuring in a way and I applaud them for it.  Each analysis has taken very similar data processed it using small variations in the input data and methods but with the same approach – that of averaging it with spatial weightings to account for changes in the number and location of the thermometers.  Their analysis is equivalent to looking at the data from one angle, a single viewpoint.  It is one where slight variations in data produce an almost identical graph.  What we need to do is take a few more steps sideways, away from the CRU/GISS ‘line of sight’.

A look at the data itself – measuring it, poking it, prodding it and generally chopping it into little bits and examining it, shows inconsistencies, omissions and errors.  Looking from different angles generally shows up ‘stuff’.  I don’t know if this will matter but at least looking at it with ‘fresh eyes’ has to be a good thing.

Anthony Watts’ today mentions a new approach – the Berkeley Earth Surface Temperature project (BEST).  He expresses confidence in their methods and says:

But as the famous saying goes, “there’s more than one way to skin a cat”. Different methods yield different results. In science, sometimes methods are tried, published, and then discarded when superior methods become known and accepted. I think, based on what I’ve seen, that BEST has a superior method. Of course that is just my opinion, with all of it’s baggage; it remains to be seen how the rest of the scientific community will react when they publish.

WM Briggs, also discussing BEST, makes a very good point about the treatment of uncertainty in predictive vs parameter based statistics. In a linked post which I have now read several times (Global Average Temperature: An Exceedingly Brief Introduction To Bayesian Predictive Inference)  there is quite an insight into the traps and pitfalls that analysis of climate data has fallen into (and I gained more insight with each reading).

We all await the BEST output with interest, not least because the GISS, NCDC and CRU analyses are so closely related that one can only worry about the fitness of their offspring. New blood is needed – new ideas and a lack of groupthink.  If it is possible to ‘walk around’ the data and, seeing it from all angles, still come to the conclusion that the warming is something to worry about and that man-made “CO2 did it” then so be it.  I remain to be convinced.

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6 Responses to Climate Parallax

  1. KevinUK says:

    Verity,

    Another well written thread. I love the idea of climate parallax i.e the fact that it is possible to see quite a different view of a object depending on what viewpoint you observe it from. The Channel 4 adverts are an excellent example of this.

    I haven’t had a chance to read the W M Briggs article you’ve link to but will do this morning. I’ve always been in favour of ‘keeping it simple’ and so have never been a fan of Bayesian statistics (http://en.wikipedia.org/wiki/Bayesian_inference). IMO if the trend is not clear (preferably pretty obvious) then no amount of the application of different statistical methods (otherwise known as torturing the data until it submits) is going to make much difference. It’s always best in such circumstances IMO to just admit that ‘we just don’t know’.

    Now to BEST. I’m afraid my expectations for this project are not great. Having said that I agree that it won’t do any harm for a different more independent to team to provide a different ‘viewpoint’ on the historic data.

    In this respect, I hope that they are at least going back to the original measurements and not relying on the NCDC GHCN raw dataset (as NCDC, GISS and CRU do). I also hope they are (thanks to Anthony) improving the station meta-data i.e. fully allowing for TOBS, equipment and/or station location changes, land use changes/population growth/UHI etc.

    I also hope that the net output from the project will be some form of web site which provides full access to the dataset (not just to max/min/mean data but the FULL raw daily station temperature data), complete with derived trend charts/maps etc. Please God – no delusional colour coded 2D ‘contour’ anomally charts!!

    I sincerely hope that BEST doesn’t turn out to be yet another re-hash of the same old data with the same/slightly tweaked methods as we’ve seen from analysts like Zeke Hausfather, Ron Broberg, Nick Stokes and Steve Mosher. And if they do release any code, please let it NOT be written in Python (the new academic Fortran)!!

  2. Pascvaks says:

    “Where we stand” has so much to do with where we’ve been, how we’ve grown –based on what we’ve seen, heard, smelled, felt, and ‘tasted’– and what we’ve thought up to that instant when we come to stop and gaze in a specific direction. And, isn’t it a strange fact of life, that we can eventually come to be standing next to another and not see (etc) what that person does simply because we cannot occupy the same space in time? Ahhhhh… that’s the beauty of it all!!! We are all sooooo different.

    Now life is a perplexing little affair. That which we tend to agree upon is either so VERY BIG that we cannot really know the truth of it. Or so very small that we really care nothing about it and agreement is just another way of saying “I don’t care!” It’s the mighty middle that makes the muddle.

    Life is really too short to solve all our differences so we really shouldn’t try. Instinctively each of us know this little fact of life and act accordingly. We ‘turn off’ to the noise we do not wish to hear and focus only upon the music we do. Each of us really do only hear what we want to hear, see what we want to see, and think what we want to think, and sometimes –if we’re lucky– eat, taste, smell, and feel too. Life’s a beach (or a city) (or a forest) (or..). And it really is short.

    It’s a mistake to think that everyone can agree about anything. We don’t have the time, or inclination.

    • Verity Jones says:

      Well, philosopher of the day 😉

      [updated – BTW I was in a hurry when I was writing this and far from meaning to be facetious, I genuinely do enjoy your comments!]

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