Extinctions Caused by the Ice that Burns Methane may be answer
to 56-million-year question Nobody knows for sure what started
the incident, but there's no doubt Earth's temperature rose by
as much as 6 degrees Celsius. That affected the planet for up to
150,000 years, until excess carbon in the oceans and atmosphere
was reabsorbed into sediment. Earth's ecosystem changed and many
species went extinct during the Paleocene-Eocene Thermal Maximum
(PETM) 56 million years ago, when at least 2,500 gigatonnes of
carbon, eventually in the form of carbon dioxide, were released
into the ocean and atmosphere. (The era is described in great
detail in a recent National Geographic feature.) A new report by
Rice scientists in Nature Geoscience suggests that at the time,
even though methane-containing gas hydrates – the "ice that
burns" – occupied only a small zone of sediment under the seabed
before the PETM, there could have been as much stored then as
there is now. This is a concern to those who believe the
continued burn