Here is an interesting exchange at the House Energy and Commerce Subcommittee hearings about the provenance of the hockey stick diagram in An Inconvenient Truth. Thanks to the reader who spotted this.
Rep Stearns took aim at the apparent use of Mann’s Hockey Stick in Inconvenient Truth (the methodology of which had been severely criticized by Wegman and North in the hearings), only to be assured that the diagram in Inconvenient Truth was based on Thompson’s ice core data. The congressmen cover some of the same debate being covered here and at Tamino’s. To rebut Stearns, Rep Schakowsky stepped in and stated that “[AIT] says “But as Dr. Thompson’s thermometer show,” and so it is not based on Dr. Mann. This is a different source which our staff had confirmed with Al Gore.”
Here’s a more complete excerpt of the exchange:
MR. STEARNS. Thank you. It talked about the hockey stick
hokum and it goes on to talk a little bit about Mr. Mann and
we all talked about it all morning but it says in 2001 the
IPCC replaced the first graph with a second in its third
report on climate change and since then this graph has cropped
up all over the place. In fact, I think it is in Vice
President Gore’s movie and I believe it is in his book,
“Inconvenient Truth.” On page 65 he has got the source as
the IPCC and then a little bit above it he talks about the
hockey stick, a graphic image representing the research of
climate scientist Michael Mann and his colleagues. So I
would just say to my colleagues and Ms. Schakowsky to that it
is important that if a graph suddenly becomes a significant
graph in all these publications and shows up everywhere and
is used in debate to make argument, I think it is important
for all of us to look at this graph and I think that is all
Dr. Wegman is doing is to say we are looking at this graph
and as it turns out in this book, “An Inconvenient Truth” by
Vice President Gore that he is using a graph as I understand
it that has been established this morning that the
methodology and the statistical analysis of it is incorrect
MS. SCHAKOWSKY. No, that is not–will the gentleman yield
for a second?
MR. STEARNS. Well, let me ask–
MS. SCHAKOWSKY. Just for one second.
MR. WALDEN. Just regular order.
MR. STEARNS. I will be glad to do that. Let me just ask
Dr. Wegman, if I have in his book the reference to the
hockey stick and I have reference to the IPCC, then we have
here a graph that you in fact are disputing because of its
methodology and the statistics. Would that be a fair
DR. WEGMAN. Well, I would like to be careful in that
MR. STEARNS. Sure. I know. Do you want me to bring the
book down and have the staff bring the book to you?
DR. WEGMAN. I have one.
MR. STEARNS. Oh, you have it
MS. SCHAKOWSKY. Would the gentleman yield–
MR. STUPAK. Would the gentleman yield on that point
MR. STEARNS. Well, let me just finish with my question
here because what I am trying to understand is, you have
a graph that suddenly goes everywhere and we have
established today that the methodology for Dr. Mann’s graph
is questionable, so the question is, if it shows up
everywhere, shouldn’t the American people understand that
some of the reference here in the book, the methodology is
in question? That is all I am asking.
MR. STUPAK. Would the gentleman yield on that point?
MR. STEARNS. Well, let me ask–
MR. STUPAK. Because if you are going to ask the
MR. WALDEN. Regular order, please. It is the gentleman’s
MR. STEARNS. I am not asking the question to you. I am
asking it to Dr. Wegman, so I think, Mr. Chairman, I would
like to have the question asked to him and not to my fellow
DR. WEGMAN. Let me be precise on the statement. There is
some ambiguity in this book because it talks about ice
cores and as I understand it, this particular–
MR. STEARNS. This is on page 65.
DR. WEGMAN. This particular picture–
MR. STEARNS. Yeah, that is right, the same one.
DR. WEGMAN. –was based on ice core studies–
MR. STEARNS. But it says below, it says source, IPCC, at
the very little, small little note there.
DR. WEGMAN. Right.
MR. STEARNS. Okay.
DR. WEGMAN. Higher on the same page in the text it talks
about Mann but I believe if one is going to be precise,
this is a piece of study based on ice cores, not on the
MR. STEARNS. So we just don’t know, and I think that is
accurate. I am glad you pointed that out so that the reader
or anybody looking at this would not necessarily say that the
source of the IPCC is indeed Dr. Mann’s hockey stick–
MS. SCHAKOWSKY. Would the gentleman yield for just a minute?
MR. STEARNS. No, I am just asking Dr. Wegman–
MS. SCHAKOWSKY. Please, I can read from–I am looking at the
MR. STEARNS. You folks had your time. I am just–
MR. WALDEN. Regular order.
MR. STEARNS. When I complete my thing. So the question is,
he says IPCC here and he has got this graph that looks like a
hockey stick, you are saying that you cannot correlate that to
mean that it is Dr. Mann’s graph? That is what you are saying?
DR. WEGMAN. I believe that is true.
MR. STEARNS. Okay. All right. Yes, I will be glad to yield
to Ms. Schakowsky.
MS. SCHAKOWSKY. Thank you. I just want to read to you from
that same–it says “But as Dr. Thompson’s thermometer show,”
and so it is not based on Dr. Mann. This is a different source
which our staff had confirmed with Al Gore. I just want to
MR. STEARNS. I respect that.
MS. SCHAKOWSKY. –that point. I know, but your question wanted
to reinforce the notion that this was based on this false or
inaccurate Dr. Mann study–
MR. STEARNS. Well, I think–
MS. SCHAKOWSKY. –-and it is not.
MR. STEARNS. Okay.
DR. WEGMAN. And I responded that it was not.
MS. SCHAKOWSKY. No, I–
MR. STEARNS. Go ahead. You respond to that.
DR. WEGMAN. I responded exactly the same way you just did.
MR. STEARNS. And I think that is important to realize because
it is showing up not just here but it is showing everywhere
and so it is not precise that that is Dr. Mann’s graph here,
and that is what you have confirmed.