Why would a Medieval Warm Period be proof that humans are not affecting global climate?

[patrice]

I get the point that some people are saying there are these larger super-super-super-ordinate cycles of warming, but I still don't understand why man's activities could not add to that momentum. Maybe there'd even be subsequent cooling cycles, but redistribution of thermal properties would continue would it not?

http://www.ncdc.noaa.gov/paleo/globalwarming/medieval.html

Is it wrong to think of a child's swing here, that each time it swings toward the warming party of its arc, it reaches apogee with NEW mass?

[hobbit709]

1. And it was followed by this.

http://en.wikipedia.org/wiki/Little_Ice_Age

[Deep13]

2. It isn't.

No one is disputing that climates can change naturally. No one disputes that climate fluctuates regionally from time to time. Global warming isn't about that. It's about the rapid, global rise in temperature that has happened since the industrial revolution and has been getting worse as time goes on.

[hobbit709]

3. Yep. and it can be traced to burning fossil fuel.

The increase in atmospheric CO2 is mostly C12.

[patrice]

4. It looks to me like this information does the opposite of what some people intend.

It means that, given the extremes of "natural" cycles, our activities are even MORE powerful than we thought.

[Deep13]

5. True, add GW to a naturally occuring temperature increase...

...and people start waterskiing at the north pole.

[customerserviceguy]

6. I think the point is

that natural cycles are inevitable, and that they exert a greater influence over global temperatures than anything that humans have done, or could do in the alternative to attempt to reverse them. Further, it would be silly to limit human activity if we're on the verge of going back to a cold part of the cycle, when technology will undoubtedly progress by the time we're getting back into the warm part of the cycle, and we will be better equipped to minimize our impact on the environment.

That's the argument that I've heard from some friends. Can't say I agree with them, but I have not been able to refute them effectively, either.

[patrice]

12. There's at least as much grounds for those predictions as there is

for saying that we are approaching a cycle in which "the chain on that swing breaks".

Yes, we've "been here before" and "it will swing back" to cooler again and then return to warmer again, but because we don't know all of the dynamics, we won't know whether the "chain" on that "swing" is going to break until after the fact.

[theophilus]

7. Was the ocean much more acidic during that period? Did CO2

cause the warming? I think getting rid of all the toxic crap from petroleum fires is enough justification to quit the petro teat even if it wasn't causing our current climate change. Peak oil and the rising prices will be economy killers, too. There are so many reasons to find safe alternatives. People will be monumentally, fatally, stupid if we miss this one. IMO.

[Jim__]

8. It's a false dilemma.

Either the climate changes naturally, or man causes it to change. But, that's not a legitimate either/or.

[The_Commonist]

9. It's proof because...

...a few slack-brained people want it to be proof.
Isn't that proof enough for you?

[NoNothing]

10. It's not proof humans aren't affecting the climate

But it does undermine the argument that significant warming trends can only be explained by human carbon emissions.

[FarCenter]

11. It supports the position that a small amount of added warming has no catastrophic effect

The Medieval Warm Period was formerly known as the Medieval Optimum, reflecting the opinion that conditions were more favorable to society in that period than during the later Little Ice Age.

Note also that the Holocene beginning about 14000 years ago is an abnormally warm period compared with the climate during most of the last 5 million years. The "normal" climate is several degrees colder than at present, which glaciation over much of Europe and North America.