Assessing 3-D climatic stability of world’s marine protected areas

Abstract Assessing whether marine protected areas (MPAs) will maintain stable climatic conditions over time is a major scientific challenge. Yet, such assessments often rely on sea surface temperature data, largely ignoring the vertical dimension of the ocean environment. Here, we estimated the climate space of global marine protected sites and investigated how their key spatial properties, such as surface, latitude, longitude and bathymetry, can be proxies of climatic resilience. We calculated the present and future climate space of each marine protected site by considering an n-dimensional hypervolume approach. We produced (i) 2D hypervolumes, by using only sea surface temperature data and (ii) 3D hypervolumes, by considering both surface and bottom temperature data. Our analyses projected that the vast majority of global marine sites under protection would encounter detrimental changes in their climate space, even enclosing completely novel climatic conditions by 2050. We observed that very large (over 100,000 km2), open sea marine protected sites were expected to maintain higher stability of their 2D climate space in the future, revealing potential implications for marine biodiversity largely depending on surface conditions. However, the 3D hypervolume analysis produced even more alarming results about the limited climatic stability patterns within marine protected sites and the reduction of their climate space within the following decades. Our study underlines that climate smart conservation planning is a necessity towards filling ocean conservation gaps over space and time.