The Little Ice Age (LIA) and Medieval Warm Period (MWP) environments (the most recent analogs for conditions cooler and warmer, respectively, than the present century) can be characterized by interpreting the multi-parameter GISP2 series (Figure 1). The LIA appears to span the period AD1350 or 1450 to AD1900, depending upon measurement type (since each may respond to climate change differently), and the MWP includes the milder few centuries prior to the LIA.....