  With the recent expansion of urban greening interventions, the definition of
spatial indicators to measure the provision of urban greenery has become of
pivotal importance in informing the policy-design process. By analyzing the
stability of the population and area rankings induced by several indicators of
green accessibility for over 1,000 cities worldwide, we investigate the extent
to which the use of a single metric provides a reliable assessment of green
accessibility in a city. The results suggest that, due to the complex
interaction between the spatial distribution of greenspaces in an urban center
and its population distribution, the use of a single indicator might lead to
insufficient discrimination across areas or subgroups of the population, even
when focusing on one form of green accessibility. From a policy perspective,
this indicates the need to switch toward a multi-dimensional framework that is
able to organically evaluate a range of indicators at once.
