William M. Briggs, often contributor to PJM, has a post on his own blog about the Berkeley Earth Project’s BEST data, that was announced last week.  He’s kindly allowed us to reprint it here.

What BEST Means and What It Doesn’t

Temperature Changes

BEST has confirmed what everybody—and I mean everybody—already believed: that temperature changes. BEST has not—I repeat not; I repeat it in bold: not; I repeat it in italics: not—proved why the temperature has changed.

That is, BEST has not given any evidence that the temperatures changes because a particular theory of anthropogenic global warming is true. Nor has it proven that any AGW theory is false. BEST says nothing one way or another. As in nothing. As is not one thing. As in it remains mute. As in AGW is not confirmed nor discomfirmed by BEST. As in the debate is not over.

BEST believes that, over the past two centuries, the temperature went up in about two-thirds of all land-based stations. BEST also believes, and has so stated, that the temperature went down in about one-third of all land-based stations. As in decreased. As in became cooler. As in, it is no so that everywhere became hotter.

BEST has said nothing about temperature changes over most of the EARTH’s surface, which is to say, the oceans. As in BEST had nothing to say about most of the planet. And BEST has confined itself to a very brief period of time.

Uncertainty in BEST

Did you not know that BEST has not claimed absolute certainty in their results? It is true that many stories in the press have hinted at perfection, but these stories are the creation of reporters who are either (a) ignorant of math and meteorology, or (b) who desire certainty where none exists, because certainty is consonant with their political beliefs.

BEST provided point and uncertainty estimates of (an operationally defined) global average temperature. Most agree that the point estimate is “in there”, plus or minus, in the ballpark. BEST admits that its estimates may be refined, as in changed, as in moved to different numbers.

Even using BEST’s own estimates of uncertainty, we are only confident of change over the past century or so. As in even BEST themselves say they are far less certain what happened before about 1900.

BEST’s estimates of uncertainty are too narrow. That is, BEST is too sure of themselves. By how much they are uncertain, there is disagreement. There is strong evidence that their certainty is off by at least a factor of two.

That is, BEST should at least double its uncertainty, which means we should have even less confidence in what happened in the past. Which means we are still unsure—we may always be unsure—exactly what the temperature was prior to about 1940. We may be sure what it was at a few individual land stations, but we will probably remain unsure what the temperature was averaged over all land surfaces. This is likely a case of scientific tough luck. If only our ancestors had thought to measure temperature most assiduously, we wouldn’t be in this boat.

Peer Review

BEST has not been peer-reviewed. And incidentally, peer-review is the weakest filter of truth science has.

Let’s repeat that. BEST announced its results via press conference, press release, and blog. Just in the way that we always hear is shocking, anathema, horrifying, suspicious, wrong, worthy of being denounced, and so forth.

Peers (like your author) have released critiques of BEST in the same way that BEST announced their own results.

It is a fallacy, and a stupid one, to say that because a peer has not reviewed a claim (according to the procedure laid down by some editor), or that because a claim has not appeared in the pages of some journal, then that claim is therefore false or cannot be believed.

If this were not a fallacy, then the comments you are now making in support of (or in the criticism of) BEST are also false, because your comments have not been reviewed by scientist peers.


It is again a fallacy, and an asinine one, to claim that those who make up BEST, or those who criticize it, have this or that “agenda”, or “history”, or this or that political or religious or philosophical belief, and that because of these antecedents the claims of BEST are therefore true (or false).

Again, if it were not a fallacy, then the comments you are not making are subject to the same failing.

Every argument must be judged on its own merits.

(See also my “Watch Out for Science Reporting” piece“, Briggs’ technical review on the BEST release [warning: there is math], Doug Keenan’s similar critique [more math], Willis Eschenbach’s critique [here too], Anthony Watts’ initial response, and Judith Curry’s original discussion on the release..)