incur a high opportunity cost. In responding
to this inequity, the conservation community
can apply the concept of common but differ-
entiated responsibilities that is foundational
to all global environmental agendas, including
the CBD ( 72 ) and United Nations Framework
Convention on Climate Change ( 73 ). Because
the burden of conservation is unevenly distrib-
uted, cost-sharing and fiscal transfer mecha-
nisms are likely necessary to ensure that all
national participation is equitable and fair and
that the opportunity costs of foregone agricul-
tural revenues and developments are consid-
ered ( 74 , 75 ). This is important because most of
the land that requires conservation attention
butisatriskofimmediatehabitatconversion
is found in developing economies. We are not
suggesting that subsidies go to countries that
can afford to conserve large portions of their
land, such as Canada, Australia, and the United
States, but rather that they go to developing
economies that incur a large opportunity cost
by conserving potentially profitable agricul-
tural lands. Notably, many environmental
impacts in emerging and developing economies
are driven by overconsumption in developed
economies ( 52 ). Those countries have a moral
obligation to reduce these demands [for exam-
ple, by moving away from an unsustainable
model based on promoting environmentally
destructive industries in pursuit of infinite
economic growth ( 14 )] and fund the neces-
sary local conservation efforts.
Our estimate of the land area that requires
effective biodiversity conservation to safeguard
biodiversity must be considered the bare mini-
mum needed and will almost certainly expand
as more data on the distributions of under-
represented species such as plants, invertebrates,
and freshwater species become available for
future analyses ( 76 ). Expanding this work as
new data become available is a priority for
future research. New KBAs are continuing to
be identified for underrepresented taxonomic
groups, threatened or geographically restricted
ecosystems, and highly intact and irreplaceable
ecosystems. Species and ecosystems are also
shifting during climate change and, as a result,
are leading to changes in the location of land
that requires effective conservation ( 77 ), for
which we could not account. Future analyses
could use our framework to identify the effi-
cacy of the areas we identified in conserving
shifting species rangesduring climate change.
Also, post-2020 biodiversity targets may imply
higher levels of ecoregional representation
than the 17% used in this study (materials and
methods). Higher-resolution assessments at
finer spatial scales (particularly, national, or
ecoregional for countries that fully encompass
multiple ecoregions) using detailed vegetation
and ecosystem maps are the logical next step
to make this analysis more informative for
conservation action. This is important because
of large, fine-scale variability in conservation
importance, historical conversion rates, and
future conversion risk. Many of the species’
representation targets (n = 5182, 14.6%) could
not be met within areas that have not been
converted to human use, emphasizing the im-
portance of restoration in the coming decades.
Given the prioritization approach used, any
loss of land identified as requiring conserva-
tion increases the total area that requires
conservation attention, because to meet spe-
cies and ecoregion coverage targets, the algo-
rithmwillbeforcedtofindalessoptimal
configuration of land areas.
For the aforementioned reasons, our results
do not imply that the land our analysis did not
identify (the other 56% of Earth’slandsurface)
is unimportant and can be degraded. Much of
this area will be important for sustaining the
provision of ecosystem services to people, from
climate regulation to provisioning of food, ma-
terials, drinking water, and crop pollination,
in addition to supporting other elements of
biodiversity not captured in our priority areas
( 6 , 17 ). Furthermore, many human activities
can affect the entire Earth system regardless
of where they occur (e.g., fossil fuel use, pes-
ticide use, synthetic fertilizers, and pollution),
so management efforts that focus on limiting
the ultimate drivers of biodiversity loss are
essential ( 78 ).Lastly,wehavenotconsidered
how limiting environmentally damaging de-
velopment within land area that needs con-
servation may affect solutions for meeting
human needs, such as increasing energy and
food demands. Integrated assessments of how
we can achieve multiple social objectives while
effectively conserving biodiversity at a global
scale are important avenues for future re-
search ( 79 – 81 ).
The world’s nations are discussing post-
2020 biodiversity conservation targets within
the CBD and wider Sustainable Development
Goals international agenda. These targets will
define the global conservation agenda for the
next decade, so they must be adequate to
achieve biodiversity outcomes ( 10 ). Our analyses
show that to safeguard biodiversity, a minimum
of 44% of land would require conservation
attention, through both site- and landscape-
scale approaches, which should serve as an
ecological foundation for negotiations. Gov-
ernments failed to meet the CBD’s previous
Aichi Targets, which suggests a need to
reimagine how conservation is done ( 82 ). If
CBD signatory nations are serious about safe-
guarding the biodiversity and ecosystem ser-
vices that underpin all life on Earth ( 1 , 79 ), then
they need to recognize that conservation action
must be immediately and substantially scaled
up in extent, intensity, sophistication, and ef-
fectiveness. At the same time, our finding that
>1.8 billion people live on lands that require
conservation attention further supports theneed for substantial shifts in conservation
strategies. The implementation of conserva-
tion actions must put the rights of Indigenous
peoples and local communities, socioenviron-
mental justice, and culturally appropriate
human rights frameworks at their center. We
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