A new publication in the Journal Science by Dorale et. al., looked sporadically submerged cave formations on the coast of Spain. Dr. Dorale says in an article in Time: "Dorale’s paper suggests the possibility that ice sheets may respond much more dynamically to changes in temperature, forming and melting at rates that are quicker than previously thought. "There might be a feedback with regards to ice melting," says Dorale. "This is speculation, but it might point at some sort of catastrophic ice sheet dynamic."
Dorale, et. al., Sea-Level Highstand 81,000 Years Ago in Mallorca, Science, February 2010.