How can studying glaciers and other iceforms help climatologist, climate scientist, understand the changes in the earth's climate over time?

The glaciers and other ice forms are excellent storage of all sorts of particles that are good indicators for the climate in the past, but also their density and composition helps a lot in this.

Explanation:

There are numerous different methods and means through which the climate in the past can be examined and reconstructions to be made about it. Some of the indicators are the ice forms, rock layers, or even the very old trees if we look for climate information for the past several hundred years. The ice forms are often used for information about the climate in the past and there is a very good reason for it.

The ice forms, like the glaciers, are actually very good storage of all kinds of different particles, which are very well preserved into the ice. Some of the most important particles are the ones from pollen, as it spreads over very wide areas, gets well preserved, and manages to describe the vegetation, thus the climate based on them. Also, the density and composition of the ice is a very good indicator of the oscilliations in climate, did the climate warmed up or cooled down and how long did that lasted.