Snowball Earth describes a theory that for millions of years the Earth was entirely smothered in ice, stretching from the poles to the tropics. This freezing happened over 650 million years ago in the Pre-Cambrian, though it's now thought that there may have been more than one of these global glaciations. They varied in duration and extent but during a full-on snowball event, life could only cling on in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis.
Scientists always agreed on one ice age truth, the tropics cannot freeze... or can they?
Dropstones show that the relentlessly hot deserts of Namibia were once covered in ice. Geologists Paul Hoffman and Dan Schrag investigate. This programme was first shown in 2001.
Runaway ice sheet growth could lock the planet into a vicious circle of freezing.
Russian climatologist, Mikhail Budyko calculated that Earth's climate has a theoretical break point. Too much ice could trigger a global freeze cycle. This programme was first shown in 2001.
Massive ice sheet melt created violent climate change and unleashed Earth's elemental powers.
Snowball Earth was ended by incredibly violent climate change. Paul Hoffman and Dan Schrag explain the science behind this. This programme was first shown in 2001.
Slow-freezing, glass-clear ice enabled pockets of life to survive on Snowball Earth.
Chris Mckay of NASA investigates a particular kind of ice whose properties enabled life to survive on Snowball Earth. This programme was first shown in 2001.
Snowball Earth may inadvertently have accelerated evolution by reducing competition.
Snowball Earth may inadvertently have accelerated evolution. Biologist Guy Narbonne explains how. This programme was first shown in 2001.
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