1.
Ice core samples
a. are becoming harder and harder to find.
b. are a valuable tool in learning about the climate and greenhouse gases through history.
c. show that levels of greenhouse gases are higher today than they've been for thousands of yea
d. Both b and c
Ice core samples
a. are becoming harder and harder to find.
b. are a valuable tool in learning about the climate and greenhouse gases through history.
c. show that levels of greenhouse gases are higher today than they've been for thousands of yea
d. Both b and c