Amazing as it Seem, We still have to shoot down the "Medieval Warming" Crock

The so called Medieval Warming Period is an article of faith among deniers.

I’ve had deniers write to me to say that this is the single most convincing piece of “skeptic evidence”.

But what does the “Supreme Court of Science” say?  Here’s a piece you can pass around to friends who need the best information in a nutshell. 


The math is too hard.

What I mean by that is that this video points to the hockey stick and that brings us back to basic criticism of graph making. The critics will charge that 1, the graph shape has more to do methods employed than with the actual data and 2, most of the data comes from temp proxies in nature which are pretty dodgy and naturally allow for a lot of private interpretation.

So with that slippery starting point, you have to ask yourself if you really want to dig into the math that has resulted in the graph. For most of us the answer is no because we aren’t statisticians and even if we are, how much can we really trust the raw data?

A graph is basically a way for the reader to avoid math and trust the mathematician and his sources, but theres a problem with that:

Graph makers of all stripes are more and more seen to have a prior agenda.

So for those reasons, I think all these graphs are losing meaning with most ordinary people.

Did you actually watch the video?

FYI, if you had watched the video, you would realise that the hockey-stick is not the only evidence that undermines the denialists’ favourite Mediaeval Warm Period. It’s not a single graph, it’s a whole bunch of hockey-sticks that say much the same thing.

Not only that, but a whole swathe of the best science available overwhelmingly confirms that the MWP wasn’t as warm as now and there still isn’t proof that the MWP was anything but local. For example, the fact that the Greenland Ice Sheet is at least 400,000 years old and that easily spans the MWP. So, combining the GIS with the permafrost, Greenland could hardly have been verdant and lush even at the peak of the MWP.

The recent anomalous warming, is for various reasons disputed by those with an anti-science agenda. AGW deniers latch onto key parts of the science for reasons political, ideological, or pay-cheque concerns that requires them to undermine the science.

Why do deniers so often claim that the most recent world class science is somehow suspect and unreliable. Claiming that earlier measurements were somehow much more reliable? Could it be that they cannot resist cherry-picking and twisting the science to suit their agenda?

Awkward questions to ask
Even if the MWP were shown to be a global event [it hasn’t]:

  • How might this negate the radiative physics of greenhouse gases?
  • How might this prove that the current warming is not anthropogenic?

It can’t!

But at least RickJames has done his bit of denial for today and thrown up a smoke-screen of FUD.

I did watch the video and I didn’t defend the notion of a mwp. My skepticism is that some california tree rings and some ice cores from here and there can really give us a super accurate picture of the global past spanning 2000 years - HA! don’t forget to examine the chicken entrails as well!

… and I can’t tell the difference between the National Academy of Science and the Oregon Institute of Science and Medicine, so I am going to throw up my hands.” Okay, RickJames didn’t actually say the second part, but he might as well have. Of course the math is hard. We wouldn’t laud the best scientists in the world if they weren’t capable of the odd tricky calculation. It’s also difficult to give an accurate weather report from 900 AD. That’s why those scientists have searched for evidence in many different places and from many different sources. And they have come up with a whole bunch of graphs - based on rigorously tested statistical methodology - all of which agree that the temperature is currently higher than at any time in 1,000 years and maybe any time in 2,000. If you doubt that the math has been rigorously tested, run on over to Climate Audit and see if Steve McIntyre has found a single flaw(perceived or otherwise) in any graph other than the original Mann hockey stick. (I’ll save you the trip: NO he hasn’t.) So, RickJames can remain delusional if he insists. But it seems to me that when the math is hard, you look to good mathematicians (not to oil industry analysts) to help you out. And if you do, the answer is unanimous and clear: the MWP is BS.

what happened with the ” original Mann hockey stick” graph?

=”The so called Medieval Warming Period is an article of faith among deniers.”= - Peter Sinclair

Hmmm. And the MWP used to be an article of faith among climate scientists. Funny how a concensus can change.

And regarding the Hockey Stick, the NAS gave, at best, a tepid endorsement of it. As for many of the other reconstructions supposedly agreeing with Mann’s work, it is important to note that almost all of them use many of the same proxies as Mann’s study does.