ventrilothree said:
Scientists cannot accurately determine the average global temperature for the past thousands of years, the fact is it's very difficult to determine the average global temperature nowadays sinnce thermometers are useless since they only measure a difference in temperature, you need satellites for anything reliable. Also look at the graph again, it goes quite a bit past 2000, notice how it levels out?
It's actually quite possible to figure out temperatures and CO2 levels for thousands of years with ice cores. I can't explain it, since I'm not a scientist, but you can.
It goes about one year past 2000. Yes, it levels in that, but there are fluctuations.
http://www.pbs.org/wgbh/warming/etc/graphs.html
Look at the second graph (temperature). It may only be a one degree warming, but in context, it is a lot. Something has happened.
http://www.whrc.org/resources/online_publications/warming_earth/scientific_evidence.htm
The top is confusing, but you can work it out if you want. Look at the temperature anomalies (small range of years, but still) and hottest months on record.
I wish I could copy this or put a link directly to it, but you'll have to search. A little more than halfway down the page, called "Temperatures over the last 1 million, 150 thousand, 16 thousand and 150 years".
http://math.ucr.edu/home/baez/temperature/temperature.html
(edit added the hyperlink)
In any case, we know that CO2 can cause warming and we know that temperatures have risen suddenly very recently. I shouldn't have gotten into this because most people can beat me for eloquence or even articulateness hands down. I'm just putting this out there for curious people. Let's get back to the original topic.