An "ice age" refers to a long period of time when the Earth's climate becomes very cold, causing glaciers and ice to cover large areas of land. Full definition
There have been many warm periods, such as when the dinosaurs lived and many cold periods, such as the last ice age of about 20,000 years ago. (illconsidered.blogspot.ru)
The discovery of ice ages in the distant past proved that climate could change radically over the entire globe, which seemed vastly beyond anything mere humans could provoke. (scientificamerican.com)
There has indeed been some warming, perhaps about 0.8 degrees Celsius, since the end of the so - called Little Ice Age in the early 1800s. (edberry.com)