Like natural thermometers, ice cores have recorded these fluctuations, which scientists can "read" by examining isotopes of oxygen and hydrogen in water trapped in the ice.
(ice cores; have recorded; these fluctuations) (water; trapped; in the ice) (scientists; can read; ) Context(scientists can read,List([77, 97))):(scientists; can read by examining; isotopes of oxygen and hydrogen in water)
scientists can read,List([77, 97))
ice cores water scientists scientists
have recorded trapped can read can read by examining
these fluctuations
in the ice
isotopes of oxygen and hydrogen in water