Since most paper is made from organic sources, such as trees, bark and other materials, it is biodegradeable. Problem is, if it's packed densley, such as stacked and tied newsprint, it may take a long time since it becomes waterproof when packed tightly. Additionally, unless sulight can interact with the papers, degradation is slowed considerably...
A recent newspaper found rolled up in an old ranch dump here in the western U.S. was entirely readable and it was nearly 70 years