To meet the ambitious objectives of biodiversity and climate conventions, countries and the international community require clarity on how these objectives can be operationalized spatially, and multiple targets be pursued concurrently 1 . To support governments and political conventions, spatial guidance is needed to identify which areas should be managed for conservation to generate the greatest synergies between biodiversity and nature's contribution to people (NCP). Here we present results from a joint optimization that maximizes improvements in species conservation status, carbon retention and water provisioning and rank terrestrial conservation priorities globally. We found that, selecting the top-ranked 30% (respectively 50%) of areas would conserve 62.4% (86.8%) of the estimated total carbon stock and 67.8% (90.7%) of all clean water provisioning, in addition to improving the conservation status for 69.7% (83.8%) of all species considered. If priority was given to biodiversity only, managing 30% of optimally located land area for conservation may be sufficient to improve the conservation status of 86.3% of plant and vertebrate species on Earth. Our results provide a global baseline on where land could be managed for conservation. We discuss how such a spatial prioritisation framework can support the implementation of the biodiversity and climate conventions.

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paragraph 64 65To meet the ambitious objectives of biodiversity and climate conventions, countries and the 66 international community require clarity on how these objectives can be operationalized spatially, 67and multiple targets be pursued concurrently 1 . To support governments and political conventions, 68 spatial guidance is needed to identify which areas should be managed for conservation to generate 69 the greatest synergies between biodiversity and nature's contribution to people (NCP). Here we 70 present results from a joint optimization that maximizes improvements in species conservation 71 status, carbon retention and water provisioning and rank terrestrial conservation priorities globally. 72We found that, selecting the top-ranked 30% (respectively 50%) of areas would conserve 62.4% 73 (86.8%) of the estimated total carbon stock and 67.8% (90.7%) of all clean water provisioning, in 74 addition to improving the conservation status for 69.7% (83.8%) of all species considered. If 75 priority was given to biodiversity only, managing 30% of optimally located land area for 76 conservation may be sufficient to improve the conservation status of 86.3% of plant and vertebrate 77 species on Earth. Our results provide a global baseline on where land could be managed for 78conservation. We discuss how such a spatial prioritisation framework can support the 79 implementation of the biodiversity and climate conventions. 80 81 82(SDGs), the United Nations Framework Convention on Climate Change (UNFCCC) and the CBD 97 emphasize that habitat conservation and restoration should contribute simultaneously to 98 biodiversity conservation and climate change mitigation 4 . Recent analyses of conservation 99priorities for biodiversity and carbon have spatially overlaid areas of importance for both assets, 100effectively treating the two goals as to be pursued separately (e.g. 6,9 ). However, multi-criteria 101 spatial optimization approaches applied to conservation and restoration prioritisation have shown 102 that carbon sequestration could be doubled, and the number of extinctions prevented tripled, if 103 priority areas were jointly identified rather than independently 10,11 . Yet, no comparable 104 optimization analyses exist at a global scale. 105A number of recent studies have attempted to map spatial conservation priorities on land 12 , 106relying on spatial conservation prioritisation (SCP) methods . However, these approaches are 107 limited, in that: they (i) are limited by geographic extent 22 or focus on only a subset of global 108 biodiversity, notably ignoring either reptiles or plant species, which show considerable variation 109 in areas of importance compared to other taxa 18,19 ; (ii) focus on species representation only, rather 110 than reducing extinction risk, as per international biodiversity targets, and often ignore other 111 dimensions of biodiversity, e.g. evolutionary distinctiveness 20,21 ; (iii) do not investigate the extent 112 to which synergies between biodiversity and NCPs, such as carbon seq...

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