Page 8 - Perspective Paper

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
alone.

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