ESS101C
Prof.
Jin-Yi Yu
Orbital-Scale Changes in CO2 and CH4
qMethane (CH4) levels have
fluctuated mainly at the 23,000-year orbit rthym of precession.
č These changes may be linked to
fluctuations in the strength
of monsoon in Southeast Asia.
qDuring glaciations, atmospheric
CO2 values have repeatedly
dropped by 30% from the levels typical of warm interglaciations.
č Most of the explanation for
lower glacial CO2 appears to
be tied to a transfer of carbon into the deep ocean.
qWHY?
(from Earth’s Climate: Past and Future)