  The existence of steady-state multiplicity or multistationarity in the Earth
System raises the possibility that the Earth may reach a "tipping point" and
rapidly transition to a warmer steady-state from which recovery may be
practically impossible. In detailed Earth models that require extensive
computation time, it is difficult to make an a priori prediction of the
existence of steady-state multiplicity. In this study, we demonstrate Chemical
Reaction Network Theory (CRNT) analysis of a simple heuristic box model of the
Earth System carbon cycle with the human intervention of direct air capture.
The analysis reveals necessary conditions for the combination of system
parameters where steady-state multiplicity may exist. With this method, other
negative emissions technologies (NET) may be screened in a relatively simple
manner to aid in the priority setting by policymakers.
