Help with Understanding Global Warming Graph

[Nooj]

I'm debating with a global warming skeptic, and I'm pretty new at this. He's pulled http://www.clearlight.com/~mhieb/WVFossils/last_2000_yrs.html" graph showing the temperature from the last 2000 years and said that temperatures have previously risen faster and by greater numbers than the current anthropogenic warming. I'm not sure if this claim is true, so I was hoping someone could help me with this.

I was wondering if someone could also tell me if climate scientists usually use data sets from the Southern Hemisphere. I read that scientists use the North Hemisphere mean because there are larger sets of proxy data there (such as tree rings etc). Something doesn't quite feel right about the website.

 

[inol]

I can't comment on the data used there, but temperatures have risen faster and by greater numbers in the past.

You are right to be skeptical of the site though, at first glance is seems to only be presenting paleoclimate data, but here and there are sprinkles of text which seem to have a common theme of being anti-global warming. The contents of some of this text is incorrect or misleading, and there is enough of it to make me think the site has a hidden agenda.

 

[Mk]

Data from the Southern Hemisphere? What would be wrong with that as opposed to Northern? Andre I recall created an interesting graph showing a fairly flat line best fit line for data sets from the southern hemisphere, and a nice rise in the best fit line for data sets from the northern hemisphere.

What does "air data" mean? He didn't collect air from 2000 years ago and check it did he? if it were gas isotope ratio stats from the cores then "ice data" would be good enough, wouldn't it?