There is much discussion that the Spanish conquistadors brought smallpox and this killed off much of the native American population. These other civilizations died a bit earlier than that‹while there has been considerable discussion that the Chinese sailed to North America a century or two earlier than Columbus, I have seen nothing about whether that might have introduced diseases (smallpox, etc.) that might have earlier decimated at least some of the Native American populations (the Chinese did not land troops and try to conquer the continent so their disease vectors spread might have been much more limited). There is an interesting article at http://en.wikipedia.org/wiki/Pre-Columbian_trans-oceanic_contact --it discounts Chinese contact but lists many other (remote?) possibilities. Might it be that disease had an influence on collapse of the civilization as well or instead of climate?
This is all a good bit off climate sensitivity‹but I think one has to be careful in suggesting climate might have done it all. Mike MacCracken On 2/27/12 8:39 AM, "RAU greg" <[email protected]> wrote: > Further evidence of civilization//ecosystem sensitivity to climate change > here: > > http://www.sciencemag.org/content/335/6071/956.short > > ABSTRACT > > The disintegration of the Classic Maya civilization in the Yucatán Peninsula > and Central America was a complex process that occurred over an approximately > 200-year interval and involved a catastrophic depopulation of the region. > Although it is well established that the civilization collapse coincided with > widespread episodes of drought, their nature and severity remain enigmatic. We > present a quantitative analysis that offers a coherent interpretation of four > of the most detailed paleoclimate records of the event. We conclude that the > droughts occurring during the disintegration of the Maya civilization > represented up to a 40% reduction in annual precipitation, probably due to a > reduction in summer season tropical storm frequency and intensity. > > > Greg > Torres del Paine, Chile > > > > > > > From: Andrew Lockley <[email protected]>; > To: <[email protected]>; > Cc: geoengineering <[email protected]>; > Subject: Re: [geo] Re: Non-linearity of climate sensitivity > Sent: Sun, Feb 26, 2012 5:42:26 PM > > > The trouble with assuming we won't cause a collapse of the ecosystem is that > there's quite a lot to suggest we might do just that. Even setting aside the > history of various civilisations trashed by minor climate tweaks, and the > extinction of prior forms of the Homo genus caused by slightly larger climate > swings, we've still got quite a lot to think about. Apologies for banging on > about the paleo record again, but its highly relevant. There isn't a > historical precedent for taking all the fossil carbon you can find and shoving > it in the atmosphere. The paleocene eocene thermal maximum took about 50k yrs > to play out, and we are repeating this warming on a centurial timescale. The > only credible paleo analogue (of which I'm aware) for the current fossil fuel > frenzy is the permian triassic extinction event, which apparently started when > the siberian coal measures burned. As this caused an ocean anoxic event, a > hydrogen sulfide atmosphere and the removal of the ozone layer, It's a bit > rash to "assume" anything less dramatic will happen when we recreate it. All > talk of economics seems a bit silly when you try to cost the worst ever mass > extinction into the equation. Cutting down all the trees on Easter island > gives a historic analogue, if one is needed, to help illustrate the point. To > calculate the consequences of such gross stupidity accurately, you'd have to > sum the whole global economic output after extinction, then discount to net > present value. You'd the need to multiply it by a risk factor. It would > still be a largely meaningless exercise. The simple fact is that going > anywhere near these risk thresholds is a folly of the highest order. A > On Feb 26, 2012 12:11 AM, "David Appell" <[email protected] > <javascript:return> > wrote: >> On Feb 22, 8:38 am, Ken Caldeira <[email protected] >> <javascript:return> > >> wrote: >>> > On the other hand, if the Romans had discovered fossil fuels and had a >>> > fossil-fueled industrial revolution, they would have maximized their net >>> > present value and we would be here two millennia later with rising seas, >>> > acidified oceans, melting ice caps, diminished biodiversity, etc, finding >>> > little solace in the fact that they followed the path their economists >>> told >>> > them was economically optimal. >> >> Perhaps. But we would have built on that wealth and be even wealthier >> than we are now, and so better able to deal with the altered climate, >> oceans, and biosphere that they caused (assuming they didn't cause a >> complete collapse of the ecosystem). Maybe we would have already >> perfected fusion by now. >> >> One of the economists in Bjorn Lomberg's Copenhagen Consensus group >> pointed out that someone in our future, say 100 years from now and >> several times wealthier than we are, will be puzzled if he looks back >> on us and wonders why we decided not to pursue our own best economic >> interest on his behalf. >> >> I grew up in a house with a coal furnace. Should my parents -- who >> were not even middle class then and struggled to get by -- not have >> burned coal, which was the cheapest option for them where I lived >> (western PA), because it would alter the climate and oceans? I don't >> know what else they would have done for heat. Eventually my father did >> better and we bought an oil furnace and then a nicer house, and then >> an even nicer house (but still middle class) with gas heat and A/C. I >> have to admit Lomborg's economist makes a lot of sense -- today I >> would have been puzzled if my parents had not heated with coal, but >> had taken out a loan to buy an oil furnace. (They couldn't even afford >> a proper bathroom, but had a toilet in a closet and a shower in the >> basement.) And now today we have all kinds of technologies to employ >> on the energy/climate problem that they did not have, and on living >> overall -- we can build seawalls if we have to. The future will have >> even cheaper options. >> >> David >> St Helens, OR >> http://www.davidappell.com >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To post to this group, send email to [email protected] >> <javascript:return> . >> To unsubscribe from this group, send email to >> [email protected] <javascript:return> . >> For more options, visit this group at >> http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
