Figure 11.

The trajectory of Holocene climate with and without human influences. Orbital changes triggered deglaciation starting approximately 20 ka and determined when the present interglacial began, but human agriculture and land clearance began to modify global climate in the early Holocene (Ruddiman, 2014). Without these anthropogenic greenhouse effects, the Holocene climate might already be cooling into the next ice age (Ruddiman et al., 2016). Shown in green are hypothetical responses of megafauna to a Holocene climate in the absence of anthropogenic greenhouse gases (GHGs). Like the woolly mammoth, many megafaunal species retracted into cryptic refugia as climate warmed, stabilized, and caused landscapes to shift from ice‐age plaids into striped configurations. If the Holocene had ended on schedule, some megafauna – possibly including woolly mammoth – might have re‐expanded from their refugia when the plaid world was reinstated by the return of ice‐age climate. Climate trends redrawn from Ruddiman et al. (2016).