@Tarquin ftlb and @JC_
"In the middle ages the vast majority of people believed with all their hearts that the world was flat and you could fall off the edge if you travelled far enough."
No they didn't. Seriously. This myth was bruited about during the 1800s and has long since been discredited: the ancient Greeks already knew the Earth wasn't flat. There is absolutely no evidence whatsoever that anyone in the Middle Ages believed the Earth was flat. The evidence that it isn't is easy to find: just go stand on the coastline and look out to sea. See those ships rising over the horizon as they approach port? That. See how the cliffs and mountains of your home port drop slowly below the horizon as you head out to sea? Again, that.
That there are people in this thread arguing on both sides who appear to have fallen for this myth hook, line and sinker makes me suspect the quality and level of debate here.
Even so, I don't understand this fixation on "the scientific consensus". It's a blatant Appeal to Authority. Unfortunately, this "authority" has variously supported Pholgiston, Aether, Miasma and other equally discredited theories—London's Victorian sewage system was constructed because of a firm belief in the Miasma theory. It was successful despite its original design intentions, not because of them. And it took the better part of a generation for "the scientific consensus" (for which, read "the scientific establishment") to accept Plate Tectonics.
Granted, the establishment isn't always wrong, but it's clearly not always right either. And, when they are wrong, they can clearly be spectacularly wrong on a staggering scale, so what the establishment happens to believe at any one point in time is an utter irrelevance. They are no more an indicator of truth than my brother's pet cat.
Finally, a scientist doesn't simply accept the status quo as dictated from on high. A scientist works to disprove a hypothesis. Only by doing so will we chip away the unwanted lies to reveal nature's truths. When large groups of powerful vested interests in the status quo insist on supporting one hypothesis over another, that process becomes much, much harder as funding becomes more difficult to find.
This is wrong. It is not how science is supposed to work and is why I take a very cynical view of the "Anthropogenic Climate Change" camp's politics and media exposure. The science in this field is clearly being deliberately skewed in favour of supporting a preferred political stance. And that is unacceptable. It is bad science.
There is no way in hell that Climate Science can be considered old enough and mature enough to be able to have such a consensus in place already. We have barely a century's worth of solid, reliable temperature readings (and even that's a stretch), whereas the Earth's climate has an age measured in millions of years. Our evidence for global temperatures beyond the 1800s is fragmentary at best. Most of it is conjecture at best. We can measure tree rings, we can measure ice cores, we can look at core samples taken from various geographical locations, but these are just the equivalent of archaeological test pits: we're only getting a tiny, tiny glimpse of the full picture at each site. We have no idea of the full context of each sample.
(This is a problem which plagues archeologists too. Anyone who's ever watched a few seasons of "Time Team" soon realises that there's an awful lot of guesswork and conjecture going on. The evidence often throws up surprises that can completely change the context of a site.)
Anyway, the point is that I'm just not satisfied that the science is there yet. This article points out some context-changing evidence. Granted, it might just be that the MWP only affected northern Europe and a few other unusually specific sites, but this new evidence suggests that it may well have been a global event. (Yes, there are some qualifiers in the original paper, but note my points above about the stifling effects of an "establishment" view. There are political repercussions involved here too.)