  As shown in previous work, there is a well-defined nonperturbative
gravitational path integral including an explicit sum over topologies in the
setting of Causal Dynamical Triangulations in two dimensions. In this paper we
derive a complete analytical solution of the quantum continuum dynamics of this
model, obtained uniquely by means of a double-scaling limit. We show that the
presence of infinitesimal wormholes leads to a decrease in the effective
cosmological constant, reminiscent of the suppression mechanism considered by
Coleman and others in the four-dimensional Euclidean path integral. Remarkably,
in the continuum limit we obtain a finite spacetime density of microscopic
wormholes without assuming fundamental discreteness. This shows that one can in
principle make sense of a gravitational path integral which includes a sum over
topologies, provided suitable causality restrictions are imposed on the path
integral histories.
