The Oligocene to the Quaternary: climate and biology - Climate Change: Biological and Human Aspects - page 134

Fennoscandian
ice sheet

Fig. 4.4 ApproximateglacialiceextentoverEuropeduringthedeepestpartoflate-Quaternaryglacials.Extendingover

allofnorthernEurope,thisicesheetixedaconsiderablebodyofwaterandwasinplacesmorethan1.5km
thick.Notethatthepresent-daycoastlineisportrayedwhereasduringglacialsthelowersealevelswouldhave
meantalargerlandarea.

reveals a time-lagged exchange of interglacial and glacial heat change between the
hemispheres. The temperatures around Greenland and Antarctica vary by about 4-
6 ◦ C with a period of about 2500 years, each being out of phase with the other (Knutti
et al., 2004). Heat is thought to be transferred from one hemisphere to the other
through the Broecker thermohaline conveyor (see Figure 4.7; and see below) of
surface and submarine currents that connect all the oceans. The result is that there
is a time delay during a glacial between when one hemisphere feels the effects of
warmth and when the other hemisphere does. Having said that - which is regards
to major glacial and interglacial heat change and exchange between hemispheres
via the Broecker ocean circulation - there is also more immediate atmospheric
heat exchange. For this reason, could it be that some northern hemisphere climate
events are reflected in the southern hemisphere Antarctic record? (See Figure 4.12a,
below.)
Climate change and biosphere science arguably have more than their fair share
of seeming contradictions, which is one reason why climate sceptics can present
(specious) arguments that gain traction with some of the public. The northern and