Most of us think of ice as ephemeral. It forms when it is cold and melts away once it warms up (or you dump salt on it). Yet, glaciers are evidence that ice can persist. The ice that forms glaciers takes centuries to form and may stick around for hundreds of thousands years ... and possibly much, much longer.
But that's not all! Not only is ice persistent, but it is an excellent record keeper. It can store information of all sorts of things in the Earth's atmosphere like particles (such as volcanic ash or wind-blown dust), aerosols (like sulphuric acid) or gases (like carbon dioxide trapped as bubbles). All of these data can then be used to make a record of the changes in Earth's climate in the long-term.
