Table 2 Combined milestones and measurable targets for a GDN to better protect biodiversity and biosphere function in the terrestrial, freshwater, and marine realms.

Feature2018 BenchmarkMilestone for 2030Target outcome for 2050References
Protecting natural habitats and species
Global percent natural habitat protected
Global surface protected area
coverage for Terrestrial,
Freshwater, and
Marine Realms
Under Aichi Biodiversity
Target 11 currently:
(i) 14.9% of the world’s
terrestrial and inland
waters, and
(ii) Approximately 4% of the
global ocean is covered by
implemented MPAs but only
2% in fully protected areas
30% in protected areas:
(i) 30% of terrestrial surface
(incorporates freshwater),
strategically located to better
protect biodiversity and
biosphere function
(ii) at least 30% of each ocean
habitat in fully to highly
protected MPAs
(iii) an additional 20% surface
area designated as CSAs
50% in protected areas
composed of:
(i) 50% of terrestrial surface
(incorporates freshwater),
strategically located to better
protect biodiversity and
biosphere function
(ii) networks of fully to highly
protected MPAs cover at least
30% of exclusive economic
zones and 80% of the high seas
(24, 40, 43)
Biodiversity representation by ecoregions (terrestrial and freshwater)
Ecoregion-based
representation in global
protected area system
(i) Less than half of the world’s
846 terrestrial ecoregions
have at least 17% of their
area in protected areas
(ii) Only one-third of the 232
marine ecoregions (coastal)
have at least 10% of their
area protected
(i) 300 terrestrial ecoregions have
reached half protected;
563 terrestrial ecoregions have
reached 30% protected
(ii) All marine ecoregions
have reached at least
30% protected
(i) 650 terrestrial ecoregions half
protected
(ii) All marine ecoregions at least
half protected
(16)
Priority natural sites and species within ecoregions
Alliance for Zero Extinction
sites
56% of 600 AZE sites protected100% of 600 sites are effectively
conserved including
1-km buffer
100% of target species have IUCN
status improved
(46)
IUCN range rarity of vertebrate
species
Rasterized map of hotspots50% of areas identified on
map of hotspots of range
rarity protected
100% of areas with hotspots of
threatened and small-ranged
species protected
(92)
Key Biodiversity Areas15,000+ KBAs identified as of
2018; 60% protected in 2018
90% of extant and future,
formally identified KBAs are
protected, including a 1-km
buffer around all KBAs
100% of extant and future,
formally identified KBAs are
protected, including a 1-km
buffer around all KBAs
(27)
High Biodiversity Importance
Ecoregions
455 HBIEs11.4% new protected areas
added to reach 30% globally
Addition of all other megafaunal
areas overlapping with
carbon sinks as CSAs
Fig. S1H
Specific management actions
targeting wide-ranging
megafauna and large
mammal migration routes
As examples, range collapse
and steep declines in
populations of African
elephants, most rhinoceros
species, and many tiger
populations. Rampant
poaching in many regions;
historic migration routes of
large mammals under threat
from development
(i) Populations of 10 target
species are doubled from 2018
baseline by 2030
(ii) Sport and commercial hunting
of endangered megafauna
and all trade in live animals
and parts are banned
(iii) 10 migration hotspots are
secured and routes protected
as globally recognized
corridors
(i) Populations of 20 target species
are doubled
(ii) Restoration of relatively intact
megafaunal assemblages in
40 priority landscapes
(iii) 20 migration hotspots are
secured and protected as
globally recognized corridors
(iv) Achieving the above three
targets leads to a delisting of
these megafaunal species by
the IUCN Red List
(28, 49, 71)
Primary habitatsCombined, old-growth or intact
habitats across all biomes
cover less than 23% of the
Earth’s surface; for some
biomes, few large examples
remain
80% of 2018 extant is placed in
protected areas or OECMs
100% of old-growth habitats under
protected areas or OECMs
(15)
Stabilizing and restoring ecosystem function
CSAs as OECMs with the
explicit goals of conserving
the carbon storehouses and
global forest cover
(i) Potential CSAs are currently
intact and
(ii) 2017 forest cover =
11.61 m km2
(i) Designated CSAs are 80%
intact and 80% conserved
through OECMs
(ii) International and national
protection for all mangrove,
coastal marshes, wetlands,
seagrass beds, swamp forest,
peat forest, peatlands by
2030 and
(iii) 80% natural forest cover
remains intact globally
(i) Designated CSAs remain intact
as OECMs
(ii) Increase in forest cover via
Bonn Challenge and other
means by 10%
(3)
Indigenous landsIndigenous peoples’ lands
account for 37% of all
remaining natural lands on
Earth and store >293
gigatons of carbon
High-priority indigenous lands
that self-nominate and are
identified as crucial to
contributing to 2030 global
targets are declared as OECMs
with tenure and management
financing secure
All high-priority indigenous lands
self-nominated as OECMs
receive designation, tenure
rights, and support for
management effectiveness
(74)
Maintain and restore
connectivity of terrestrial
protected areas
7.5% terrestrial protected areas
well connected
20% terrestrial protected areas
well connected
40% protected areas
well connected
(37)
Maintain and restore
connectivity of
inland waters
More than 800,000 dams and
45,000+ large dams exist;
more than half of the world’s
rivers blocked by large dams,
thousands of smaller dams
being planned, 35% of
wetlands have been lost
since 1970
(i) No further planning or
building of large- to
medium-sized dams on the
world’s rivers; concentration of
dams on tributaries with
existing structures
(ii) Maintain two-thirds of all
headwaters of the Earth’s
major river systems
undammed by 2030 through
protection and removal of
blocking infrastructure
(iii) Protect and restore riparian
habitats along one-third of all
rivers by 2030
(iv) Adequate protection and
1-km buffer zones for all
RAMSAR wetlands by 2030
(v) Protection of one-third of the
world’s forested upper
watersheds by 2030
(i) Restoration of 25% of the
world’s rivers to free-flowing
state by 2050 through removal
of dams and barrages
(ii) Protection and restoration of
riparian habitats along
two-thirds of all rivers by 2050
(iii) Adequate protection and 1-km
buffer zones for all globally
mapped wetlands by 2050
(iv) Protection of one-half of the
world’s forested upper
watersheds by 2050
(57, 93)
Maintain and restore
connectivity of marine
waters
Scant formal protection of
critical marine habitats
(reproduction, nurseries) for
threatened species and
migratory corridors for
endangered species of fish,
marine mammals, and sea
turtles
(i) Full protection of all critical
habitats (reproduction,
feeding, and nurseries) for
threatened species
(ii) Full protection of critical
migratory corridors within
local networks of MPAs for
endangered species of fish,
marine mammals, and
sea turtles
(i) Full protection of all critical
habitats (reproduction, feeding,
and nurseries) for commercial
and threatened species
(ii) Full protection of critical
migratory corridors within local
networks of MPAs for
commercial and endangered
species