How are ice cores used to study climate change?

Question

Is it that they study the amont of CO2 and methane in each layer of ice? (each layer of ice representing a year)

Answer 1

Each air bubble in the ice core tells you the composition of the air at the time that layer was formed.  

And yes, it's a hoax.  Did you know the earth is flat?

Answer 2

good ?, and yes you are partly right the c02 and methane are checked, also ice comes in various forms, the ice itself that is and the water that compriaises the ice, minute particles are retained in the ice, theses, be it pollen, or other natural agents are checked, say for instance volcanic ash. animal cells

Answer 3

People say they "study" ice cores because they are in the middle of no where, to make you believe in this hoax.