Even more important, thanks to the recovered ice cores, they were bringing highly informative portions of that past up to the present, to the scrutiny of modern analytical tools and techniques. The sort of information they may have found was illustrated in the July 15 issue of the British journal Nature which contains an article on findings from a neighboring hole into Greenland's ice cap. This endeavor, the Greenland Ice-Core Project or GRIP for short, was staffed chiefly by European scientists, and the 40 authors listed have surnames hinting at homelands from Italy to Iceland. Those 40 people, and doubtless scores more of unnamed students and technicians, have been putting together bits of evidence to sketch and outline past climates. Temperature changes show up in differing proportions of isotopes of oxygen trapped in the frozen layers.
Pollens tell something of plant growth on adjacent lands.
Rock dust tells of dry times on northern continents. Volcanic ash points to eruptive activity. Even differences in electrical conductivity within the ice provide hints. More salt blown up from the sea increases the conductivity of ice laid down in that layer. All of these clues tell about atmospheric circulation, and trapped bubbles reveal something of atmospheric chemistry.