Science - USA (2022-06-10)

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carbon (see the figure and tables S2
and S3). Land use–related CH 4 and
N 2 O cause more than half of the
climate impacts from the land sec-
tor. However, only 2% of the credits
issued for land-based projects from
1996 to 2021 aimed to reduce emis-
sions of CH 4 , and practically none
addressed N 2 O ( 1 ). In terms of num-
ber of all land-based projects, 17%
aimed to reduce CH 4 and 1% N 2 O
(fig. S2). As an example of the imbal-
ance between sources of emissions
and credits in the market to reduce
those emissions, enteric fermen-
tation emits almost as much CO 2
equivalents ( 100-year time frame)
globally as does forest conversion,
yet only about 300 credits (two
projects) addressed CH 4 reductions
through feed additives in contrast
to more than 300 million (140 proj-
ects) for forest-focused projects, de-
spite the relatively low or negative
costs per tonne of CO 2 equivalent of
many of these activities.
For the carbon market to make
substantial contributions to reduc-
ing emissions of multiple GHGs, the
disproportionately high reliance on
forest-related projects needs to be
augmented by increased focus on
enteric fermentation in livestock,
irrigation management, and other
agricultural projects. In particu-
lar, projects to reduce and avoid
CH 4 are underrepresented in com-
parison to its contribution to land-
based emissions. Methods to es-
tablish accurate baselines will help
legitimize these initiatives.

LOCAL BENEFITS
Initiatives that reduce, avoid, or
remove emissions benefit people
indirectly through the global effect
on climate. Local people involved
in land management where the
projects are implemented do not
necessarily benefit directly beyond
financial payments, which are of-
ten meager after accounting for
transactions costs and low carbon prices.
However, some buyers will pay premiums
for projects with social and environmental
co-benefits that contribute to Sustainable
Development Goals. Co-benefits can accrue
locally, such as employment opportunities.
Other co-benefits, such as habitat conserva-
tion, affect local land users only indirectly
or could have negative impacts such as in-
creased human-wildlife conflict or displace-
ment. In those cases, local land users are
less likely to participate over the long term

or across larger regions, resulting in unreal-

ized potential for climate mitigation.

Evidence from land management projects

indicates stronger outcomes for conserva-

tion if local land users receive tangible ben-

efits and participate in regional land use and

management decisions ( 5 ). Direct benefits to

local land users through sustained returns of

financial capital, tangible ecosystem services,

or cultural value are necessary for land-based

activities to successfully reduce, avoid, or re-

move emissions over the long term and at

the scale required to meaningfully

contribute to climate mitigation.

Without such direct benefits, car-

bon mitigation efforts are likely to

be short-lived and small-scale with

limited effect on climate mitigation.

With direct benefits, land users can

experience the advantages and pro-

mote shifts to low-GHG practices

within their communities.

A carbon market that facilitates

transformations to low-GHG land

management will value activities

that are participatory and locally

perceived as beneficial. For example,

large-scale tree-planting schemes

that aim to improve carbon seques-

tration and livelihoods are more

effective if they include tree spe-

cies preferred by local people for

fuelwood, fodder, and grazing ( 6 ).

Similarly, cookstoves that reduce

the need for fuelwood, improve air

quality, and save labor can shift

norms toward more carbon-efficient

sources of energy for cooking, and

agroforestry can provide income

for the local population while stor-

ing almost as much carbon as native

forests ( 7 ). This focus on local needs

and preferences will likely prove

more effective for climate mitigation

than short-term projects with more

indirect co-benefits. Carbon market

standards should ensure that local

benefits occur.

Security of land tenure underpins

the ability of the carbon market to

both deliver benefits to local land us-

ers and create confidence for inves-

tors in land-use initiatives. Insecure

tenure, gaps between de facto and

de jure tenure, and colonial legacies

of state control over land are com-

mon throughout the world, particu-

larly in developing regions. In such

places, which account for as much

as 65% of the world’s total land area

( 8 ), the carbon market can incentiv-

ize local land users to participate

only if outside parties will not lay

claim to the benefits. Robust land-

based initiatives in the carbon market need

to clarify and ensure that benefits flow to

those who manage the land.

LARGE AREAS, REGIONALLY BASED

A shortcoming of the current project-based

carbon market is its small-scale, piecemeal

approach through individual projects.

Consequently, the market has difficulty

fostering transitions to low-GHG land man-

agement over larger areas for a meaningful

aggregated impact.

INSIGHTS | POLICY FORUM

Reduce CO 2 Reduce CH 4 Reduce N 2 O

0

200

400

600

800

Credits issued (millions)

Other

Sustainable agriculture

Nitrogen management

Manure methane digester

Wetland restoration

REDD+

Improved forest

management

CO 2 CH 4 N 2 O

0

1000

2000

3000

4000

5000

CO

equivalents (millions of tons) 2

Other

Manure left on pasture

Synthetic fertilizers

Enteric fermentation

Rice cultivation

Net forest conversion

Drained organic soils

Ample emissions, insufficient credits

(Top) Global emissions are shown from land-based sources of CO 2 , CH 4 ,

and N 2 O in 2019 (in CO 2 equivalents on a 100-year time frame) ( 15 ).

(Bottom) Credits issued from all four major registries in the voluntary

carbon market from 1996 through November 2021 ( 1 ) are categorized by

the main greenhouse gas affected by the project. The top two highest-

emission sources (top) and project types for credits issued (bottom)

are shown for each gas (along with “other” indicating all source and

project types not encompassed by the top two categories shown for

each gas). Approximately 10% of credits issued for forest projects are

buffers for reserve credits in the event of reversal. Tables S2 and S3 list

all land-based sources and project types. REDD+, Reducing emissions

from deforestation and forest degradation.

1164 10 JUNE 2022 • VOL 376 ISSUE 6598