3
Searching for the key of
the gas
was difficult to understand the memory.
It
this core
Because
but it was
The level of
it was
?
necessary
more
CO₂
climate change,
was expected that
was
not
a
complicate structure
for earth to
for the
the researchers
enter
cake structure which we had thought
lower that it is today.
the low concentration
measured
ice age sycle.
level of CO₂ ir