by bobcousins » Tue 11 Oct 2005, 20:57:22
$this->bbcode_second_pass_quote('PenultimateManStanding', 'W')ould it not be a grand irony if modern humanity has lived for thousands of years in blissful ignorance of how cold the world can get practically instantaneously only to develop the scientific ability to discover the truth about this kind of change right at precisely the same moment in time when it's about to happen again! The world is a strange place.
That is pretty much the plot of the "
Helliconia..." trilogy by Brian Aldiss, which I found absolutely fascinating, and has stuck in my mind ever since. What civilisations might have existed before the last glacial period, and have been wiped out by the glaciers, leaving no trace? Perhaps civilisation happened so quick this time because of skills gained before?
There is a lot of interesting stuff on climate which is far more than I can go into here, but William Ruddiman has done some interesting work in this area,
see
Early farmers warmed Earth's climate. He has a great graph in his paper which I can't find right now[1], which shows warming trends over recent glacial periods. The main driver seems to be a combination of 3 orbital oscillations which affect the amount of solar radiation we get. We are basically just after a peak in temperature.
Humans appear to be creating a temporary blip upwards in temperature, but presumably if we stop generating greenhouse gases, the downward trend will resume. One interesting question is the link between CO2 and temperature. Which comes first?
This cycle of ice age and warm interval has been occurring over the last few million years and appears to be stable though oscillating state. Before that there have been other wild swings, with very long warm and cold periods. The Sun has declined in power over billions of years - could we now be on the edge between a habitable planet and an icy snowball, with the climate teetering between the two?
Its a pity the subject invokes such ignorant emotional response (frm both sides) which obscures some fascinating scientific progress.
There are many random events that could cause global extinctions, they are possible but unpredictable (e.g. gamma ray bursts). The next glacial period is a certainty. Barring the unlikely, it pretty much defines how long our current civilisation could last. How much of our culture could we preserve over 120,000 years with most of the Earth covered in glaciers 1 mile thick?
Read
Helliconia Spring!
[1] I found it
THE ANTHROPOGENIC GREENHOUSE ERA see page 266.