In my article over the weekend about the climate risks from
buried Arctic carbon, I omitted any discussion of one issue that
sometimes appears in the news: methane deposits under relatively
shallow seawater near the coasts of Siberia, Canada and Alaska.
It was a purposeful omission because my piece focused on carbon
buried on land, which presents a climate risk if it eventually
emerges as methane or carbon dioxide. However, given the
alarming headlines about methane in the ocean, as seen here and
here for example, I did some additional reporting. What I
learned about ocean methane was reasonably reassuring, with the
caveat that scientists would like to know a great deal more
about these deposits before declaring for certain that the
hazard is minimal. On land in the Arctic and sub-Arctic regions,
we are primarily worried not about methane that already exists
but about carbon locked in permafrost that may decompose into
methane or carbon dioxide once it thaws. The ocean deposits are
different: large quantities