The temperature record at each pole

The 10 000 years that intervene between the LGM and the opening of the Holocene period have come under intense scrutiny from almost every point of view. They represent the most recent and most accessible example of dramatic global warming. Consequently, both the dynamics of Earth-system changes over this period and the response of ecosystems to these changes (in so far as these can be separately distinguished as ‘responses’ within such an interactive system) are of outstanding importance.

Changing temperatures can be inferred from δ18O and δD measurements in the ice itself (see 4.2.3) The initial warming corresponds with the early stages of a rise in orbitally driven insolation at 60° N that continued into the early Holocene, peaking at 10 000 years BP (Figure 6.1). In Antarctica the isotopically inferred temperatures begin to rise beyond the preceding range of variability around 19 000 years BP. The only significant (and unexplained) exception is in the record from the Siple Dome on the coast alongside the southern Pacific (Taylor et al., 2003), where a sudden rise in surface temperature of some 6 °C is recorded as early as 22 000 years BP, followed by a decline, before temperature once more increases, rather more steadily, from ca. 18 000 BP onwards (Ahn et al., 2004). In all the ice-core records from Antarctica, temperatures increase smoothly right through into the early Holocene, with only one ‘set back’, the so-called Antarctic cold reversal (ACR).