From: mdhangton@gmail.com   
      
   On Monday, October 6, 2014 3:35:28 PM UTC-4, David E. Siegel (siegel@acm.org)   
   wrote:   
   > On Monday, October 6, 2014 1:53:01 PM UTC-4, William Vetter wrote:   
   >    
   > > On Monday, October 6, 2014 11:48:45 AM UTC-4, David E. Siegel   
   (siegel@acm.org) wrote:   
   >    
   > > > On Saturday, October 4, 2014 2:33:50 AM UTC-4, William Vetter wrote:   
   >    
   > > > > On Friday, October 3, 2014 10:33:22 PM UTC-4, bre...@sff.net wrote:   
   >    
   > >    
   >    
   > > > > > Weather is also an important part of worldbuilding. What would Hoth   
   be,    
   >    
   > > > > > if it were not an ice planet?   
   >    
   > >    
   >    
   > > > > I don't quite remember if that book actually had a monolithic   
   worldwide climate.  I don't think that's really plausible for an Earthlike   
   world.   
   >    
   > >    
   >    
   > > > Whether the Earth actually had an "Ice Ball" or "Slush Ball" or "White   
   Earth" climate  in the distant past is, I gather, much disputed. But it seems   
   that all   
   >    
   > > >  the climate models indicate that such a thing is at least possible for   
   a more-or-less earth-like world. And of course an "ice world" in an SF story   
   can   
   >    
   > > >  be just that little bit farther from its sun, or the sun just slightly   
   cooler, making such a state more likely.   
   >    
   > >    
   >    
   > > > In such a case the planet might well have a relatively uniform climate   
   across the globe, at least one with far ;less variation than we presently have   
   on earth.   
   >    
   > >    
   >    
   > > The planet might well have NO climate.  What kind of climate does Callisto   
   and Europa have?   
   >    
   > >    
   >    
   >    
   >    
   > William Vetter who started this sub-thread, specified "an Earthlike world".   
   Would you put Callisto or Europa  into that category?    
      
   No I say they're frozen from being too far from the Sun.  They have water and   
   rock, but not exotic atmosphere like IO.  They are utterly frozen.   
   >    
   > >    
   >    
   > > So far as I can see, the snowball has some wind, but the albedo is high   
   enough that it doesn't absorb much energy to create much weather.   
   >    
   > >    
   >    
   > That is a climate, if not a varied or interesting one, I would think.   
   >    
   > >    
   >    
   > > > Whether it is plausible to have large land animals on an iceworld is   
   another question, and doubtless depends on the exact details, but many large   
   animals on   
   >    
   > > >  Earth are basically browsers, and if you allow some vegetation, a   
   browser might be able to survive.    
   >    
   > >    
   >    
   > > Television leads me to understand that penguins in Antarctica don't   
   browse.  They eat fish underwater, walk up on an ice shelf for two months to   
   lay their eggs and starve, hope to survive until they can walk back to the sea   
   again.  My understanding    
   is that there is nothing to browse except dead penguins.   
   >    
   >    
   >    
   > But will all iceworlds be precisely like Antarctica? Or might some have   
   spare but present vegetation present?   
   >    
   As I understand Snowball Earth, all oceans are completely frozen over like the   
   northern ice cap.  All continents are frozen over like Antarctica, with   
   perhaps some exposed rocky peaks.  That is the picture that is generally   
   painted.  There is no    
   photosynthetic ocean plankton, no landborne photosynthetic plants.  There are   
   only primitive bacteria that metabolize hydrogen sulfide or whatever at   
   subocean volcanic rifts.  That is a fundamental problem, that it kills   
   everything and reboots evolution.    
    This is a difficult notion to sell, because we exist.   
      
   Slushball Earth is a scenario where a restricted equatorial region in an   
   otherwise frozen world is periodically overrun by glaciers in response to   
   minor climate variations with hundred or thousand year cycles, Ice Ages within   
   an ice epoch.  This    
   situation, supposedly, rather than wiping out life, forces it to evolve at a   
   faster rate to struggle against the glaciers.   
      
   >    
   >    
   > ObSF: I remember the YA SF novel _The Time of the Great Freeze_, by   
   Silverberg (or at least his name was on the cover, I gather that this didn't   
   always mean he actually wrote it). In that short novel, the earth has become   
   if not an iceball, at least    
   much more glaciated -- most of North America and all of the UK seem to be   
   buried under glacial ice sheets, but more tropical areas are not frozen.   
   >    
   North Americans lived in subterranean habitats.  After some time down there,   
   they came to the surface through their tunnels and traveled about in   
   jet-propelled snowmobiles.  At the end of the novel, they make contact with   
   Brazilians who travel north in    
   jet-propelled snowmobiles.  Equatorial Brazil isn't glaciated; it is   
   subtropical.  Over time, the political situation that forced North Americans   
   underground had changed, and the Brazilians now wanted to make nice-nice with   
   the North Americans.  That is    
   what I remember from reading it in Fourth Grade.  I read it because it had   
   pictures of jet-propelled snowmobiles on the cover.   
      
   This novel was not a Snowball or Slushball Earth; it was an enhanced Ice Age.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)