No, I'm not talking about you. You're not perfect. I'm not either. We still matter though. We matter because we're humans, and humans don't need to be perfect to matter. Only data does. Or at least, that's what BEST says.
In a recent post at Judith Curry's site, BEST members Robert Rohde, Zeke Hausfather and Steve Mosher finally got around to responding to the point I've made about their work for the last six months. You may remember me saying:
But here’s the thing. BEST is supposed to be the best temperature record. It has a website encouraging people to look at data on as fine a scale as individual cities. WHY?! If BEST can’t come close to getting things right for the state of Illinois, why should anyone care at what it says about the city of Springfield, Illinois?
At what scale does BEST stop giving imaginary results and start getting a right answer? It doesn’t at the city level. It doesn’t at the state level. What about at the regional level? Could it get temperatures right for something like, say, Southeast United States? Nope.
We can’t pick areas much larger than that. The Southeast United States is about half the size of Australia. It’s about a third the size of Europe. If BEST can’t get it right, how could it get Australia or Europe right? And that’s ignoring the fact the Southeast United States has far more temperature stations (per area) than either of those!
I get almost everybody seems to agree BEST gets things right at the global scale, but couldn’t we all agree there’s a problem if BEST can’t come close to the right answer when looking at entire continents?
The BEST team has finally responded to this concern. At Judith's site, they wrote:
One other feature of the approach that requires some comment is the tendency of the approach to produce a smoother field than gridded approaches. In a gridded approach such as Hadley CRU, the world in carved up into discrete grids. Stations within the grid are then averaged. This produces artifacts along gridlines. In contrast, the Berkeley approach has a smoother field.
If we knew the true field perfectly, we could decide whether or not our field was too smooth or not. But without that reference we can only note that it lacks the edges of gridded approaches and tends to have a smoother field.
This struck me as incredibly strange, so I said:
This is simply untrue. We don’t need to know “the true field perfectly” to decide whether or not the resolution of a temperature record is too coarse. We don’t need to know “the true field perfectly” to compare the spatial resolution of BEST’s results to that of other groups’ results and judge which are more useful.
We can do far more than “note [BEST] lacks the edge of gridded approaches and tends to have a smoother field.” This post tries to hand-wave away the issue, but We can specify how much smoother BEST’s temperature field is and make judgements about whether or not it’s a bad thing. In fact, we should.
Nobody from BEST offered a reason to believe I was wrong, but a commenter defended their statement by saying:
No you can’t. All you can show without knowing the true field perfectly is that one smoother is more or less smooth than another (or no smooth at all.)
Which sums up what I have to say is one of the silliest ideas I've ever heard. The global temperature record is effectively created by smoothing the planet's temperatures so much there is only one value for the entire planet. Imagine if BEST had published a data set showing temperatures for every part of the planet, but those temperatures were all identical. That'd be pretty silly, right?
Not according to BEST. According to BEST, we can't tell if that'd be silly or not. After all, we don't have perfect information about the planet's temperatures. That means we can't say results which show Antartica warming at the same rate as the equator are worse than results which show there is a significant difference between the regions.
Imagine if we applied this argument to anything else. Does the 50lb bag of dog food I bought from the store weigh more than the 20lb bag I didn't buy? I don't know. I can't measure their weight exactly.
Does a car go faster if you push the gas pedal down more? I don't know. I don't have perfect information about the car's speed.
Is the planet warming? I don't know. I don't have perfect information about the planet's temperatures.
Requiring perfect information to draw any conclusions at all is beyond silly. We'll never have perfect information about things. BEST's standards require us never draw any conclusions about which results are better than which.
Of course, BEST doesn't actually use that standard. It just wants its critics to use it. After all, if you set impossible standards for any criticism of your work, you never have to listen to any criticism of your work!