Yet more conjecture
November 8th, 2008 by SecureCareto “add fuel to the fire”
“If climate disasters are to be averted, atmospheric carbon dioxide (CO2) must be reduced below the levels that already exist today, according to a study…by a group of 10 scientists…who…assert that to maintain a planet similar to that on which civilization developed, an optimum CO2 level would be less than 350 ppm…” Full Slice
“…researchers…have uncovered surprising effects of climate patterns on social upheaval and the fall of dynasties in ancient China…the study showed that the dry period at the end of the Tang Dynasty coincided with a previously identified drought halfway around the world, in Meso-America, which has been linked to the fall of the Mayan civilization.
The study also showed that the ample summer rains of the Northern Song Dynasty coincided with the beginning of the well-known Medieval Warm Period in Europe and Greenland…A second major finding concerns the relationship between temperature and the strength of the monsoons….” Full Slice
“…Over these 65 million years, the Earth has undergone several major warming and cooling episodes, which were largely mitigated by the expansion and contraction of sea ice in the Arctic…Currently, the Earth is in the midst of an interglacial period, characterized by retracted ice sheets and warmer temperatures.
In the past three decades, changes in Arctic climate and ice cover have led to several reorganizations of northern ocean circulation patterns….” Full Slice
So how strong might be the connection(s) if there are any ?
And a FAQ on climate models and some discussion.
November 9th, 2008 at 10:04
“assert that to maintain a planet similar to that on which civilization developed, an optimum CO2 level would be less than 350 ppm…”
Bold statement with a civilization sample size of one.
Their advice about curtailing coal burning is commonsensical, but barring unexpected technological advances may take a generation or more to implement.
“…Over these 65 million years, the Earth has undergone several major warming and cooling episodes, which were largely mitigated by the expansion and contraction of sea ice in the Arctic…”
Complicated by the fact the the North Pole has only occasionally been surrounded by land in the past 65 million years and it’s only been the last few million years that both poles were dominated by continental masses. Still an interesting study; it reminds me of Lovelock’s Daisyworld.
November 9th, 2008 at 14:11
I find this graph, 100,000 Years of Greenland Temperature, “interesting” for what it appears to suggest about agriculture & human behavior prior to the Fossil Fuel Age. From “2004 Arctic Climate Impact Assessment”.
It is part of this discussion if you are interested in following it.
November 9th, 2008 at 16:35
The following seems ridiculous to me:
Attempting to justify complacency in the face of evidently drastic changes in the environment (for example, the constituents of the atmosphere).
Why? Oh, the association of mass extinction events with drastic environmental changes, and the perception that the enlightened culture in which I am an active participant seems rather frail in the face of thermodynamics and chemistry.
Granted: perhaps by going through a nuclear/climate winter/summer, surviving only through the domination of highly polluting, breeder-reactor exploiting yeast-eating, stench-enduring anarcho-capitalistic Randian/Extropian blase-faire Adamsmithian humiliation-of-liberals patriots, we could, in fact, eventually dominate the entire universe.
If so, I’m glad I’m probably not immortal. Maybe there will be a time drill and the whales and I will be resurrected when assholes grow up.
November 11th, 2008 at 16:41
SecureCare wrote:
“I find this graph, 100,000 Years of Greenland Temperature, “interesting”…”
So do I. It makes sense that agriculture and other human activity effects the climate. Which came first, however, the warming or the farming, is still an open question.
It could be that general warming allowed agriculture to spread enough for it to become a major influence on climate. An interglacial at that time would not be unwarranted; after all, they had happened before.
It would be interesting to find strong evidence that humans caused the warming, or at least strongly encouraged it. I wonder, should I feel proud? Ashamed? Scientifically aloof?
November 11th, 2008 at 17:12
Walter wrote :
“… Which came first, however, the warming or the farming, is still an open question….”
I agree.
When I first saw that graph my immediate thought was that humans began agriculture at the “correct” time, a peak in the natural cycle. Of course more thought on the topic led to some questioning along the lines you suggest. I tend to think there was, most likely, some long term mutual positive feedback going on between human activity and the “natural” (non-human) cycle stuff such as orbital dynamics, axis tilt wobble, solar activity etc.
Dynamic cybernetic behavior ya know.
Walter finishes :
“…I wonder, should I feel proud? Ashamed? Scientifically aloof?”
All of the above ?