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Climate models consistently underestimate the speed with which many regions of the northern Africa turned
               arid relative to the proxy record (Claussen et al., 2017). Poor parameterization of climate models accounts
               for some of the discrepancy (Hopcroft

               &  Valdes,  2021),  but  the  pace  of
               aridification  in  some  portions  of
               northern  Africa  appears  to  have
               exceeded  orbital  forcing.  Figure  2.2
               shows  the  discrepancy  between  the
               expected  pattern  of  termination
               based on orbital change (if this forcing
               would  be  normative),  and  the
               measured    pattern   based   on

               paleoclimate  records  and  sediment   Figure 2.2. The expected AHP termination associated with orbital forcing is
               cores. The rate of degradation in the   indicated by the green curve. The calibrated ages from paleoclimate records
                                                  for the ending of AHP is given by the red circles. Figure from Pausata et al.
               northern  latitudes  was  faster,  and  it
                                                  (2020) (CC BY 4.0).
               begins  prior  to  what  would  be
               expected  based  on  orbital  forcing

               2.2  History of human settlements and mobility patterns

               The    first   agriculture-
               dependent  economies  and
               Neolithic   cultures   likely
               arose   independently   in
               several  different  locations
               scattered  over  the  globe
               (Diamond   &    Bellwood,
               2003), the earliest of which
               was found to have emerged
               in  the Fertile  Crescent  (see
               Figure    2.3).    Major
               migrations   (DeMenocal,
               2001) and the development
               of  subsistence  practices
               (Kuper & Kröpelin, 2006) are
                                          Figure 2.3 Map showing approximate centres of origin of agriculture and its spread
               often driven by climatic and
                                          throughout history in western Eurasia (dates in years B.C.) Detlef Gronenborn, Barbara
               environmental  changes.  As   Horejs, Börner, Ober, CC BY 4.0, via Wikimedia Commons.
               humans make up an integral
               part of Earth’s System, the question remains whether we might have contributed to the environmental
               changes that caused us to migrate from our ancestral homelands to new locations. Examples of abandoned
               settlements  can  be  found  in  several  locations  throughout  Northern  Africa,  suggesting  environmental
               conditions changed and were no longer favourable for humans to live in. The ecological dynamics that led
               up to that point are, however, more challenging to reconstruct (Brooks et al., 2005; Clarke et al., 2016). Many
               attempts  have  been  made  to  use  computer  models  to  reproduce  the  exact  outcomes  as  indicated  by
               paleoclimate records, but capturing the interactions between humans, ecosystems and the climate during
               these climatic shifts remains limited (Hély et al., 2009).

               A strategic ‘living systems’ approach to climate stabilization                          8/26
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