Scientists say that the historical record must be wrong, and that they have scientific evidence - tree ring data - that demonstrates absolutely, positively that it was much colder in the Middle Ages than the chroniclers of the time said.
There's a very interesting set of discussions going on now about the use of photographs to push the theory of AGW. The most notorious, of course, is the photo that Science Magazine published of a polar bear on a tiny ice flow, accompanying a letter from 255 members of the National Academy of Sciences saying it's really, really a crisis, mkay?
It was a Photoshop.
A lot of the debate was "It's just a picture, who cares?" More sophisticated was "You need more competent PR flacks" to hype the science - you know, ignore or downplay the margin of error, to overemphasize the worst possible - although vanishingly unlikely - case, and to find scary images that are less obviously faked.
You're still left with those stupid medieval chroniclers, writing about scientifically impossible events, and those stupid historians, writing books about what the stupid, unscientific chroniclers said.
Case in point: sea levels. The UN's Intergovernmental Panel on Climate Change (IPCC) writes in their Fourth Assessment Report (AR4) says that the science is clear that sea levels are rising fast and that large portions of the globe will be flooded out. ZOMG, unprecedented Thermageddon!
Except not so fast. This is all about us burning fossil fuels, right? If this sort of thing has been normal throughout history, that sort of kills the whole "unprecedented" thing, and that sort of kills the whole we-have-to-impoverish-the-world-by-giving-up-fossil-fuels thing. So what can we learn from history about sea levels? As it turns out, a lot.
Edward Longshanks was King of England in the thirteenth century (note to Climate Scientists: this is a documented fact. Srlsy!). Anyone who's seen Mel Gibson's Braveheart knows him as the Bad Guy who was trying to conquer Scotland and take away their Freeeeeeedom!
Which he did, crushing the Scots and carrying off to Westminster Abbey the Stone of Destiny (otherwise known as the Stone of Scone, but pronounced Stone of Scoon).
But Edward had first crushed the Welsh, and he did it by building a bunch of castles to dominate the Welsh landscape. Castles like Harlech.
Now take a look at this picture for a minute: you have a Castle built on a hill. Behind the castle - at the foot of the hill - is a wide plain sloping down to the sea. What's wrong with this picture? Remember, you're trying to conquer the Welsh, a feisty and unruly group, who keep raising armies to attack you. What's to stop their army from besieging the castle and starving it into submission? Stupid medieval castle builders, picking such a bad site!
Except not so fast. The chroniclers tell us that the castle was resupplied by sea. They're quite clear about this, about how ships used to sail right up to the foot of the cliff, and dock there. In other words, the sea level was higher in the Fourteenth Century than it is today. Strangely, this corroborates other historical records like the Domesday Book, which describes a large number of vineyards in England around 1090 AD. ZOMG, Medieval Thermageddon!
And so if Science Magazine can serve up a Photoshop, so can I. Here's Harlech Castle, circa 1350 AD:
Image modified by Borepatch, using The Gimp
The difference between the modification used by Science and the one that I made here, is that mine is actually backed up by the data. After all, the number of polar bears is increasing - they're not endangered at all. The sea did come right up to the foot of Harlech Castle's cliff. You might call mine "Fake But Accurate", as opposed to Science, who gave us "Fake But Inaccurate".
And so, the issue is not getting a higher caliber of PR Flack to torture the data to scare us with Thermageddon Just So stories. They need to stop disappearing data that falsifies their AGW theory of sudden and unprecedented warming.
The current computer models don't predict a Medieval Warm Period, nor do they predict the Little Ice Age that followed. But don't worry, say the Scientists, the current predictions are accurate. Srlsy. Trust us.
And listen to the PR Flacks. Unprecedented! Sudden! Thermageddon! On Noes - what, don't you love cute little polar bear cubs? You Denier scum. Get offa my lawn.
And this is precisely the heart of the problem: it's not at all clear that what's happening today is historically unprecedented. It's obvious that the Medieval Warm Period was warm, and it could not have been caused by all those dang coal fired power plants. In other words, we know from historical observation that the climate is variable, within the bounds of what is happening today.
So tell me again why we need to impoverish our children, and all of the Third World, by giving up fossil fuels. Come on Scientists - dazzle me.
Via Watts Up With That, who has a ton more, including data.