Select Page

ashone27 (Chapter 27 ** )

Chapter Twenty-seven — Ice Time

A Short History of Nearly Everything – by Bill Bryson

Chapter 27 — Ice Time

  • In 1815, a mountain named Tambora in Indonesia exploded spectacularly, killing 100,000 people with its blast and associated tsunamis.  It was the biggest volcanic explosion on our planet in 10,000 years, being 150 times the size of Mount St. Helens’ explosion.  It was equivalent to 60,000 Hiroshima-sized atom bombs.  Spring and summer of 1816 never arrived, planet-wide.  That year was called the year without summer.  The atmosphere was filled with 36 cubic miles of smoke, ash, dust, and grit.  Crops failed planet-wide.
  • As Earth moves through space, it is subject not just to variations in the length and shape of its orbit, but also to rhythmic shifts in ins angle of orientation tot he Sun – its tilt, pitch, and wobble.  This affects the length and intensity of sunlight falling on any patch of land.
  • The cause of ice ages is found in cool summers, not brutal winters.  If summers are too cool to melt all the accumulated snow, more sunlight is bounce back by the reflective surface, exacerbating the cooling effect.
  • We are still very much in an ice age, just a somewhat shrunken one.  At the height of the last period of glaciation, about 20,000 years ago, about 30% of the Earth’s land surface was under ice.  75% of all the fresh water on earth is locked up in ice even now, and we have ice caps at both poles.
  • The current ice age (ice epoch really) started about 40 million years ago, and has ranged from very bad to not bad at all.  Ice ages tend to wipe out evidence of earlier ice ages, so the further back you go the more sketchy the picture grows.
  • With the way that the oceans and continents are arranged presently, it appears that ice will be a long-term part of our future.  One expert predicts that about 50 more glacial episodes can be expected, each one lasting about 100,000 years.
  • A massive freezing occurred about 2.2 billion years ago, followed by a billion years or so of warmth.  Then there was another ice age even larger than the first.  Some scientists refer to that age as the Cryogenian, or super ice age.  It is also called ‘Snowball Earth’.  This Snowball phase saw a fall in solar radiation of about 6% and a drop-off in the production and retention of greenhouse gases.  Earth lost its ability to hold on to its heat.  Earth became an ‘over-all Antarctica’.
  • If ice sheets start to form again for whatever reason, there will be much more water for them to draw from (the Great Lakes, Hudson Bay, countless Canadian lakes).
  • If a warming phase ensued and all the ice sheets melted, sea levels could rise by 200 feet and every coastal city would be inundated.

Click here to return to the ASHONE index