Punx0r said:
I'm far from qualified to tell you what the ice core does and does not mean (the conclusions of the people who compiled it would be a good place to start) but I'll offer the following comments based on a bit of background knowledge combined with critical thinking.
1) No dispute there
2) Correct: the changes in the chart occur over a (by human standards) very long period of time. The current changes in CO2 level and temperature are far more rapid, which is the problem. It would be hard to even represent on that graph as the time axis is so compressed. The current changes are, unlike all those previous peaks and valleys on the chart, not explainable by any known natural phenomena (volcanic activity, solar output, astronomical effects), so the chance of it being "normal" are extremely small.
3) The 12°C variation is actually the peak-to-peak, not the average (which is much smaller). Regardless, 12 degrees is a lot of range, but again, these changes are normally quite slow, and readily explained by natural phenomena. Life has a chance to adapt. ~100 years (and ~1C) in climate timescale is, by comparison, the blink of an eye. Also note the trend in variation is normally downwards (ice ages) whereas we're now heading for a more unusual "hot house Earth" type scenario, all at a time when natural cycles ought (by past experience) be pushing global temperatures downward.
I'm also far from qualified, but i've decoded some other scientific mysteries in the past, so getting at the truth in multiple realms of science is something i consider fun.
1) Not a surprise !
2) Well, actually we've had extreme swings in co2 from natural phenomena such as volcanoes. We have good reason to suspect that volcanic eruptions and asteroid impacts are responsible for a ~90% species dieoff, and we find either large amounts of dust in the ice, large amounts of co2, etc during these periods.
3) Okay, i used the wrong term, but you got what i meant.
But your 'hothouse earth' scenario has already happened many times. I'm just saying that it's not new, and the geological record says so.
Here is another dataset which shows very large variations over short time spans, since i cannot find a really high resolution long plot of the vostok ice core data.
So we can see that the earth before industrial times has a rather unstable climate and a variance of 2.5 degrees in global temperature can happen over a 100-200 year timespan.
So 1.1 degrees C rise over ~100 years is actually mild compared to what natural phenomena can dole out.
Short term data ( which you will see AGW alarmists use constantly ) can readily be used to deceive people who are otherwise ignorant. My science nerd specialty is in diet as a form of medicine and also regenerative medicine. In the diet field, i see short term data used VERY OFTEN as a means to deceive the public. Here's a quick example..
On a low carb diet, the adaptation phase can last all the way up to a month. During this month, blood markers will actually be worse, because the body is still learning how to operate on a completely different source of fuel. After this month, blood markers will gradually get MUCH better than the baseline diet ( AKA Standard American Diet ), to the point where many doctors are shocked at things like massive improvements in A1C, blood glucose, and even cholesterol markers, considering that the patient is eating a diet based on saturated fat and cholesterol :lol:
Every single study that shows that a low carb diet is bad either uses invalid methodology ( not actually testing a low carb diet ), or short term data ( 1-2 weeks, where the subject is still undergoing massive systemic changes; even mitochondrial function is undergoing huge changes at this point. )
So that being said, i have noticed over the years that AGW alarmists uniformly use short term data; scrubbing the reference point of what the earth naturally does. This is a huge red flag for me.
So here's where i hand you a bone.
One thing we do know is that ice cores are pretty good at revealing co2 . Here is the most recent ice core data i could find.
So we know that co2 relates to temperature and humans are emitting a shit ton of co2.
The thing i still question, is how much of an impact we are making. I suspect we are making less of an impact than is suggested, and future nightmare scenarios are a bit overblown. Many short term predictions from science have been completely wrong, and we still do not have a solid model for climate; just a bunch of various ones that range from pessimistic to optimistic. But really, if we had a very good understanding of all of this, there would only be one standard model.
The whole 'temperature lags carbon by 100 years' idea does not match up to ice core data. in fact, sometimes co2 will rise and temperature will not. So i don't know about that whole lag idea, which seems to be what the AGW alarmist case rests on today.
But how i see things is not a good reason to continue burning fossil fuels, of course.
So if deforestation and burning of fossil fuel don't result in increase of CO2, what does ? 
