2012-03-06 13:55:01neglected new rebuttal?
Sarah Green

I put this one up in the basic thread some time ago, complete with a nice picture by John G. It seems to be languishing there, though.


2012-03-06 16:27:11
Dana Nuccitelli

I'd suggest noting that humans are now relatively sedentary - we've built cities and large agricultural farms based upon local climates.  Our ancestors were hunter gatherers and such who could move around to adjust to changing climates.

I'd also suggest deleting the 'digging way back in time' paragraph.  I don't think it really adds anything to the myth rebuttal, and shorter is better, especially for the basics.

I'm not really sure how the 'geologic record' paragraph is relevant either.  The myth is specific to human experiences.  I'd kill that one too.

2012-03-06 17:24:26
Andy S

I've got a post under construction that argues we're on track to recreate the atmosphere and, perhaps , the climate, of the Eocene, maybe 1000 ppm CO2 if we follow the A1FI case. And by 2100. Apart from the disappearance of ice caps and the disastrous extinction event and the impossibility of our current agriculture, there is the issue of whether we'd be able to even live outdoors in a climate like that. The question Sarah raises about whether we could even survive in that kind of hothouse is therefore not a vain exercise in speculation, since there's a good chance that we are headed there. So, I'm inclined to leave those sections in, but I agree with Dana that they may distract us from the main point (that the fluctuations we have survived as a species were cold phases and that our agriculture has only known the benign and stable Holocene). Is there a quote from someone who actually tried to start this myth?
2012-03-06 21:09:33
John Cook

When you say "we have never experienced a hotter global climate than now", should you clarify that to "civilized humanity has never..." as humans did experience warmer global temps in the Eemian?

Has global temp never been warmer throughout the entire Holocene? Is that a rock solid statement to make?

2012-03-06 21:45:11
Glenn Tamblyn



As an important meme, or if you like a counter-meme to the denialists, it is perhaps worth highlighting the difference bewteen what humans have endured/survived - a lot, and what modern 'civilised' humans have endured/survived - 2 / 10ths of F@ck-All.

If we want to go back to our cave-man ancestor's lives we can endure a lot. But if piped water is our definition of endurance our limits are way lower.

As for languishing, time to unlanguish it - gee that has a sensual ring to i!


2012-03-07 14:59:35
Sarah Green

Thanks all.

Andy: I first thought about writing this when Rick Perry said last fall:

"Yes, our climates change. They've been changing ever since the earth was formed."

quoted  here at sks: http://www.skepticalscience.com/skepticquotes.php?s=106

The sks rebuttal to that quote is about forcing. But some people are not interested in why the climate changed. They shrug and think humans have survived lots of climate flucuations before, so what's all the fuss about.



Yes, I should tone that down slightly. Here's my basis:

IPCC report (FAQ):

Before 2,000 years ago, temperature variations have not been systematically compiled into large-scale averages, but they do not provide evidence for warmer-than-present global annual mean temperatures going back through the Holocene (the last 11,600 years; see Sec- tion 6.4). There are strong indications that a warmer climate, with greatly reduced global ice cover and higher sea level, prevailed until around 3 million years ago. Hence, current warmth appears unusual in the context of the past millennia, but not unusual on longer time scales for which changes in tectonic activity (which can drive natural, slow variations in greenhouse gas concentration) become relevant (see Box 6.1).

But, that's rather hedgy and non-conclusive-sounding; certainly regional temperautures have been higher by sevral degrees. Wikipedia has a nice, but not well explained, picture of fluctuations at various places http://en.wikipedia.org/wiki/Holocene_climatic_optimum

Hansen says:

with the 0.5C warming of the past 50 years, global temperature now approximately matches the peak level of the current (Holocene) inter- glacial period, which occurred about 6000–9000 years ago, (2) the global mean temperature during the penultimate (Eemian) and the several previous interglacial periods was not more than about 1 C greater than the peak Holocene temperature,



I'm rather attached to my "way back" paragraphs. Note that I do try to link them to humans...



see here for the survivability question:

Sherwood, S. C., Huber, M.. (2010). An adaptability limit to climate change due to heat stress. Proceedings of the National Academy of Sciences of the United States of America, 107(21), 9552–9555. doi:10.1073/pnas.0913352107


Glenn an dothers:

I'll add a few words on civilization.

2012-03-08 03:22:03
John Mason


I wanted to check out the Holocene Optimum as some call it a couple of years back and found the following on Realclimate:

This is a somewhat outdated term used to refer to a sub-interval of the Holocene period from 5000-7000 years ago during which it was once thought that the earth was warmer than today. We now know that conditions at this time were probably warmer than today, but only in summer and only in the extratropics of the Northern Hemisphere. This summer warming appears to have been due to astronomical factors that favoured warmer Northern summers, but colder Northern winters and colder tropics, than today.

We certainly have an atmospheric composition that was last seen prior to the Quaternary as this Royer graph from Nature indicates:


Have been wondering since I did that post on the Cenozoic CO2 record last year what caused the two main spikes in CO2 in the early-mid Miocene and at the Miocene-Pliocene boundary.

Cheers - John

2012-03-08 06:07:16
Andy S

John, I am going to make that paper and figurethebasis of my next post.
2012-03-08 09:18:43
Sarah Green

John M. -thanks, I had not found very clear references on that, either.

I've made some updates, added the quote from Perry. (Actually, I'm not sure what date he has in mind when he says "since the Earth was formed", 6000 years?)

I broke the ancient (pre-human) part into a separate section, for which I found a nifty image of the precambrian globe by Ron Blakey (http://jan.ucc.nau.edu/~rcb7/).

I'm ready for this one to be Un-Languished!

2012-03-08 10:04:55
Dana Nuccitelli

Okay, we'll publish this in the near future.