European medieval warm period

Slide 4 introduces this discussion

Little Ice Age and Mediaeval Warm Period

• In the 14th C Europe plunged into the Little Ice Age

Followed by 2 graphs. A graph of the temperature from 1000 to 2000 in Europe taken from the documentary (though an IPCC graph) and a graph of global reconstructed temperatures from 0 to 2000. The Europe graph shows the medieval warm period as warmer than now. The reconstructed global graph has the temperature from several models but showing current temperatures as warmer than the medieval period. By plotting several models with no smoothing it is harder to see the trends except for the last few years which shows the hockey stick graph in black.

My concern here is that Merchant dismisses documented evidence (records from Europe (not necessarily thermometer readings) for the last several hundred years) in favour of a reconstruction of a global temperature. Now I don't expect there to be records from Africa. But documented data is usually better than data constructed from theory. That Merchant doesn't give this to them is very interesting as this is strong evidence against the modern theory. But then perhaps that is why he doesn't.

The previous slide (3) said

Climate has always changed

• Proposition: climate has changed naturally (a true statement)
• Inferences we are meant to draw:
• Recent climate change is natural (because previous changes have been)
• Climate change is not a problem (because it is natural)
• The correct inferences:
• Recent climate change might have (a) natural origin(s)

He is right that natural doesn't equal good, and that natural then doesn't equal natural now. But the point of the medieval warm period data is not that humans can't have any effect in the world, it is just that variation is not a new phenomenon. Therefore if you are going to blame humans for variation in weather when variation has been going on a very long time, you need very good evidence that this is the case. And given that scientists in the 20th century told us that there is global cooling, then warming, then cooling and then warming—I'm starting to get very suspicious.

This is an example of making the program imply more than it does. And even if this segment of the Great Global Warming Swindle is saying that humans cannot have an effect; his refutation solely says that they can, not that they have.