Yup. A mere 12,000 years ago, Central Park in New York City was covered by a 5,280 foot deep glacier. 12,000 years is a blink of an eye in geologic time.
Human contribution to global warming is, of course, a theory. It cannot currently be proven or disproven. One fact has been proven, however. The amount of carbon dioxide in the atmosphere has increased dramatically since the industrial revolution. Coincidence,.....perhaps. The climate IS changing. It always has and it always will. If the current trend continues, drastic planetary changes WILL occur, in very short order, in a geologic time frame. Short order is not how the earth usually behaves,.......with anything.