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The potential of agricultural land management to contribute to lower global surface temperatures


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Removal of atmospheric carbon dioxide (CO2) combined with emission reduction is necessary to keep climate warming below the internationally agreed upon 2°C target. Soil organic carbon sequestration through agricultural management has been proposed as a means to lower atmospheric CO2 concentration, but the magnitude needed to meaningfully lower temperature is unknown. We show that sequestration of 0.68 Pg C year⁻¹ for 85 years could lower global temperature by 0.1°C in 2100 when combined with a low emission trajectory [Representative Concentration Pathway (RCP) 2.6]. This value is potentially achievable using existing agricultural management approaches, without decreasing land area for food production. Existing agricultural mitigation approaches could lower global temperature by up to 0.26°C under RCP 2.6 or as much as 25% of remaining warming to 2°C. This declines to 0.14°C under RCP 8.5. Results were sensitive to assumptions regarding the duration of carbon sequestration rates, which is poorly constrained by data. Results provide a framework for the potential role of agricultural soil organic carbon sequestration in climate change mitigation.
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The potential of agricultural land management to
contribute to lower global surface temperatures
Allegra Mayer
*, Zeke Hausfather
, Andrew D. Jones
, Whendee L. Silver
Removal of atmospheric carbon dioxide (CO
) combined with emission reduction is necessary to keep climate warming
below the internationally agreed upon 2°C target. Soil organic carbon sequestration through agricultural management
has been proposed as a means to lower atmospheric CO
concentration, but the magnitude needed to meaningfully
lower temperature is unknown. We show that sequestration of 0.68 Pg C year
for 85 years could lower global tem-
perature by 0.1°C in 2100 when combined with a low emission trajectory [Representative Concentration Pathway (RCP)
2.6]. This value is potentially achievable using existing agricultural management approaches, without decreasing land
area for food production. Existing agricultural mitigation approaches could lower global temperature by up to 0.26°C
under RCP 2.6 or as much as 25% of remaining warming to 2°C. This declines to 0.14°C under RCP 8.5. Results were sen-
sitive to assumptions regarding the duration of carbon sequestration rates, which is poorly constrained by data. Results
provide a framework for the potential role of agricultural soil organic carbon sequestration in climate change mitigation.
The uptake of atmospheric carbon (C) by plants and subsequent storage
in soils may be an effective means to lower atmospheric carbon dioxide
) concentrations and to help mitigate climate change. Integrated
assessment models (IAMs), which are used to explore future energy,
land-use, and greenhouse gas (GHG) emission scenarios, currently rely
on bioenergy with carbon capture and storage (BECCS) as a principal
negative emission technology to reach climate change mitigation targets,
butgenerallydonotconsiderthepossibility of C drawdown and soil
organic C (SOC) sequestration from improved land management (1,2).
Improved land management, without changing land use, may be an ad-
ditional C sequestration option that does not require more land con-
version. Land-use change and poor management practices have resulted
in the loss of more than 130 Pg C from agricultural soil (3), leaving
>1 billion hectares of degraded soil worldwide (4). Site-based studies
and ecosystem-scale models have shown that degraded and managed
agricultural lands have great potential to contribute to increased SOC
sequestration through improved management (57). We define soil C
sequestration as a net increase in SOC storage. Several agricultural
(cropland and grazing land) management practices have been shown
to increase soil C sequestration including organic amendments (810),
cover crops, reduced tillage, improved crop rotations (5,11,12), and im-
proved grazing management (13,14). Citing these proven practices and
others, France and 33 other countries recently instituted a challenge to
increase soil C by 4 per mil per year (15). However, the actual potential
of these practices to contribute to lowering global temperature over time
is poorly understood, despite recent efforts to quantify the amenable
global land area and near-term sequestration rates associated with various
practices (1618). This is primarily due to uncertainty regarding the
maintenance of soil C sequestration rates over time, the C sequestration
capacity of different soils under different managements, and the sen-
sitivity of global temperature changes to CO
emission and sequestration.
Here, we use a climate model emulator to translate SOC sequestra-
tion from agricultural management into a range of potential global
mean surface temperature changes over time, consistent with global-
scale outputs from the latest generation of Earth system models (ESMs;
see Materials and Methods and fig. S1). Much of the research to date on
the potential of land usebased SOC sequestration has focused on quan-
tifying current sequestration rates with the implicit assumption that
rates remain constant over time, often assuming a constrained time pe-
riod of 20 to 50 years (12,16). The potential for SOC sequestration to
contribute to a portfolio of mitigation strategies aimed at reducing cli-
mate change depends not only on the rates soon after C sequestering
practices are implemented but also on the time-integrated dynamics of
those rates, that is, how quickly land-use changes can be adopted, how
long they remain in effect, and how SOC stocks change over time (19).
This temporal dynamic is poorly understood but is critical to accurately
estimate the potential for land-based management to slow climate change.
In practice, rates of SOC sequestration are likely to decline over time
at any one site as soils reach new equilibria (20), but the time scale and
shape of these declines are not well constrained by data and are likely to
vary significantly among locations and management practices. To help
bound this uncertainty, we model the effects of SOC sequestration on
global surface temperature with and without consideration of effective
sequestration years, defined as the number of years it would take to
reach the maximum SOC stock (SOC max) at the current potential
sequestration rate (see fig. S3). The SOC max is a concept proposed
by Six et al.(21) and is poorly constrained by data at both site and global
scales. An SOC max provides a theoretical limit on the amount of SOC
storage in soils. As opposed to applying an arbitrary SOC max at a fixed
time period (for example, 20 or 50 years), we model effective sequestra-
tion years as a continuum of time periods required to reach an SOC max
(from 0 to 85 years) for a range of SOC sequestration rates. The current
potential sequestration rate was taken from values reported in the liter-
ature (table S1). Our analysis focuses specifically on the temperature re-
sponse to SOC sequestration. SOC storage is sensitive to a suite of global
change factors such as elevated atmospheric CO
concentration and
changes in climate, among others (22,23). These factors will likely have
additional, albeit poorly constrained, impacts on management-induced
SOC sequestration (24). Our goal here is not to quantify the ecological
controls on SOC storage and loss in agricultural ecosystems but to de-
termine the magnitude of SOC sequestration needed at a global scale to
meaningfully affect temperatures and to explore the sensitivity of atmo-
spheric temperature change to a range of possible temporal limits to soil
C sequestration (effective sequestration years).
Department of Environmental Science, Policy and Management, University of
California, Berkeley, Berkeley, CA 94720, USA.
Energy and Resources Group, Uni-
versity of California, Berkeley, Berkeley, CA 94720, USA.
Climate and Ecosystem
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94705, USA.
*Corresponding author. Email:
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 1of8
on August 29, 2018 from
The model shows that a global SOC sequestration rate of 0.68 Pg C year
from 2015 to 2100 would be required to yield a 0.1°C reduction in mean
surface temperature in target year 2100 when coupled with an aggressive
emission reduction scenario [Representative Concentration Pathway
(RCP)2.6;Fig.1].Theseresultsassumed a constant sequestration rate
global sequestration rate is at
the low end of the ranges of published estimates, which vary from a
low of 0.36 Pg C year
to a high of 1.56 Pg C year
(12,17,25,26). There
is considerable uncertainty in the actual time horizon of soil C sequestra-
tion rates within sites, which is likely to vary in response to social, econom-
ic, and biophysical factors (17,27). Few studies have measured long-term
(>20 years) patterns in soil C sequestration with agricultural management,
and those have shown a wide range of continued sequestration rates from
20 to over 150 years (11,2830).Forthisreason,weappliednoapriori
assumption on the time horizon required of soil C sequestration and, in-
stead, modeled a continuum of effective sequestration years at SOC
sequestration rates from 0 to 2.0 Pg C year
. It is important to note that,
while the model assumes constant annual rates of SOC sequestration at a
global scale, it does not require constant rates at individual sites.
Results were dependent on the underlying RCP scenario, assuming
3°C warming per doubling of CO
. In scenarios with greater emission
trajectories and thus higher atmospheric CO
concentrations (RCP 8.5
and RCP 6), greater SOC sequestration rates were required to reach the
same reduction in global surface temperatures due to the logarithmic
nature of CO
forcing (31). To achieve a 0.1°C reduction by the year
2100, the RCP 6.0 emission scenario would require a sequestration of
0.98 Pg C year
, while 1.25 Pg C year
would be required in the RCP
8.5 scenario. Management-based SOC sequestration had the highest
efficacy in the RCP 2.6 scenario, indicating the importance of simulta-
neous emission reductions and SOC sequestration activities resulting
from management. The sensitivity of climate to changes in atmospheric
concentration is a key uncertainty in the model and had a large
influence on the temperature effect of C sequestration activities, as sce-
narios with lower climate sensitivity would require increased sequestra-
tion to result in the same temperature reduction (Fig. 1, black bars).
Estimates of climate sensitivity range from 1.5° to 4.5°C warming per
doubling CO
, with a median estimate of around 3°C (32).
A synthesis of the literature yielded a mean annual SOC sequestra-
tion potential from agriculture of 0.83 Pg C year
, with an upper value
of 1.78 Pg C year
(table S1). This value is greater than our estimate of
0.68 Pg C year
needed to reduce global temperatures by 0.1°C in 2100
under RCP 2.6 (Fig. 1), and results in a temperature reduction of 0.12°C
in 2100 if sustained for 85 years. Greater SOC sequestration and associated
temperature reduction may potentially be achieved with biochar amend-
ments (see the Supplementary Materials); this approach is less well constrained
than the other approaches and could require at least some utilization of
abandoned lands (10,33),andisthusnotconsideredfurtherhere.
Fig. 1. Impact of constant global rates of C sequestration (Pg C year
) on mean surface temperatures by target year (20162100) for a climate sensitivity of
3°C per doubling of atmospheric CO
.A 0.1°C reduction is highlighted by white lines. Different graphs indicate different RCP scenarios. Bars show the range of
continued C sequestration rates needed to achieve a 0.1°C reduction in 2050, 2075, and 2100, respectively, under a range of alternative climate sensitivities from 1.5°C
per doubling (upper bound) to 4.5°C per doubling (lower bound) (32). Upward arrows represent low CO
sensitivity upper bounds that are higher than the range of C
sequestration rates (0 to 2 Pg C year
) considered in this study; error bars are not symmetric around the 0.1°C reduction line due to nonlinearities in CO
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 2of8
on August 29, 2018 from
Uncertainties in potential global rates of SOC sequestration with
improved land management can be partitioned into two primary
factors: the range of field-scale SOC sequestration rates reported for each
practice and the global land area over which the technique was considered
effective. Both area and rate assumptions affect the estimate of total SOC
sequestration potential. Area-dependent SOC sequestration rates varied from
0.02 to 1.15 Mg C ha
through improved cropland management
(12,34) and from 0.03 Mg C ha
through improved grazing land management (Table 1) (10,26). The
range of amenable land area varied from approximately 2900 Mha
for grazing land (36) to 400 Mha for cropland (16). We used the bio-
physical potential as the upper limit of SOC sequestration potential and
the minimum reported SOC sequestration estimate as the lower limit
(16,17,37). Nutrient availability at the field scale could theoretically limit
SOC sequestration rates (38,39), although the increase in soil organic
matter content can alleviate at least some of this limitation (18). We note
that agricultural management to increase SOC storage can interact
with soil inorganic C, by increasing storage or facilitating losses to the
atmosphere (40). However, the long-term impacts of SOC sequestration
on soil inorganic C dynamics are poorly understood. Economic con-
straints influenced the uncertainty regarding the amount of land
amenable to improved management (17,37), as well as whether man-
agement strategies could be implemented quickly and maintained over
multiple decades on the available and amenable land area. The manage-
ment practices explored here are likely to simultaneously provide the
co-benefit of improved soil fertility and water holding capacity, thus
increasing the financial desirability for implementation.
The results were sensitive to effective sequestration years (Fig. 2),
with the reduction in warming increasing roughly linearly with the
number of years that soils could continue to sequester C. If we assume
a limited effective sequestration period of 20 years (11,28), irrespective
of the mechanism limiting C storage, then the climate impact in the year
2100 associated with a sequestration rate of 0.83 Pg C year
from 0.12° to 0.03°C under RCP 2.6. If the effective sequestration period
is 50 years (12), then the climate impact in the year 2100 was 0.07°C
under RCP 2.6. These values highlight the potential negative impact
of short effective sequestration years. However, much of the worlds
soils are degraded with regard to SOC (4). Sanderman et al.(3)esti-
2 m of soil, respectively, due to human land use. If we assume that the
maximum soil C sequestration potential is equivalent to the amount of
C that has been lost from soils due to land use, then soils globally would
have the capacity to store an additional 0.9 Pg C year
until 2100 in the
top meter alone and 1.62 Pg C year
in the top 2 m. To determine the
impact of effective sequestration years on a given soil C sequestration
rate from any combination of management strategies, we assessed the
effect of the number of effective sequestration years (from 1 to 85) on
the year 2100 global mean surface temperatures for the range of SOC
sequestration rates (0 to 2.0 Pg C year
) previously considered (Fig. 2).
In practice, SOC sequestration rates would likely exhibit a gradual de-
use, climate, and soil type and is not well understood (41,42). Some
studies have found that SOC stocks reach an asymptote over time (28).
This can be indicative of the development of equilibrium conditions
under a given rate of inputs (11). It has also been hypothesized that
soils may become saturated with regard to SOC, with stocks ceasing
to increase even at increasing input rates (21,41,43,44). Understanding
of the long-term potential for soilsto sequester C is limited, and mech-
anisms such as C stabilization and protection are not consistently
represented in coupled climateC cycle models and major ESMs (45).
Our approach using effective sequestration years allows us to bound the
uncertainty arising from these poorly understood mechanisms.
Our results show that existing management strategies on current ag-
ricultural lands have the potential to reduce global temperatures by
the end of the century, sequestering as much as 1.78 Pg C year
rate of sequestration could result in warming reductions of as much as
0.26°C in 2100 (assuming an effective sequestration period of at least
85 years). These model results are dependent on the effective seques-
tration years at a global scale and concurrent trends in emission reduc-
tion. The time horizon of SOC sequestration is poorly understood but
is critical for determining the long-term viability of these approaches.
In particular, we note that climate change is a millennial-scale phenom-
enon that stretches beyond the 2100 target. Therefore, the residence time
of organic C in soils, which can affect the long-term efficacy of SOC
sequestration (46), is an additional concern. SOC has the potential to
be stored for millennia [as evidenced by numerous radiocarbon studies
(47,48)], particularly when considering the entire soil depth profile (49),
but this may require a long-term commitment to maintaining soil C in
the future.
Management-based soil C sequestration strategies were significantly
more effective at reducing global warming under RCP 2.6 due to the
atmospheric saturation of CO
in high emission scenarios (for example,
in RCP 8.5). This result points to the value of combining aggressive
emission reduction with C removal strategies for climate change mitiga-
tion. The management strategies we evaluated here are different from
the measures assumed in the modeled RCP scenarios (50,51)andthere-
fore provide additional negative emissions if applied simultaneously
with emission reductions. The RCP scenarios can be realized through
many alternative energy, land-use, and land-cover pathways, but current
IAMs largely rely on land-cover change (for example, afforestation) and
C capture and storage technology combined with bioenergy (BECCS) to
reach goals of reduced radiative forcing (50). In contrast, this study
examined the effects of improving management practices on agricultural
Table 1. Published global estimates of management amenable agricultural land and the C sequestration potential of land management techniques.
Management Land type Range of published amenable
land area estimates (Mha)
Range of published potential C
sequestration rates (Mg C ha
Improved cropland management Cropland 3801910 0.081.85 (16,17,26,34,36)
Improved grazing land management Grazing land 5002900 0.091.70 (16,17,26,35,36)
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 3of8
on August 29, 2018 from
land currently in production. We note that future changes in the overall
size of the agricultural land area will affect the area amenable to these
practices and that heavy reliance on bioenergy could compete with some
management activities on cropland or grazing land. This is one reason
that we emphasize consideration of a large range of possible sequestration
rates and time frames. Extensive adoption of land management strategies
could moderately reduce the need for BECCS, which is considered ex-
tensively in most 1.5° and 2°C target scenarios (52). Sequestering an
additional 1.78 Pg C year
through BECCS would require devoting
89 Mha of agricultural land to bioenergy production [equivalent to
roughly half of current global maize area harvested (53)]. Growing bio-
energy crops for BECCS on abandoned agricultural land could reduce
the impact on food prices and ecosystem carbon storage (33), although
lower crop yields and economic limitations on the use of abandoned
lands must be accounted for in this context (54).
Our analysis also points to the importance of the long-term potential
for SOC sequestration. The largely underappreciated scientific un-
certainty of effective sequestration years greatly affected the climate
change mitigation potential of land management strategies. A better
understanding of the long-term regional potential of specific man-
agement applications for C sequestration, as well as the controls and
limits on C sequestration, will facilitate better predictions of future land-
atmosphere C cycle feedbacks and also inform the potential for long-
term stabilization of C beyond the 2100 temperature target. As new
strategies are identified for sequestering C through land management
such as repurposing urban and rural nutrient and C waste streams
(7,55), our model provides a framework for translating these into
warming reductions.
Climate model
We used a climate model that has been used previously in the literature
(5659) to evaluate the impact of emissions or emission reductions/C
sequestration on future transient climate responses (fig. S1). The model
takes a particular emission scenario for three major GHGs (CO
and N
O) and converts these emissions into atmospheric concentra-
tions, radiative forcing, and transient temperature response. This
emulator model has the benefit of enabling us to consider many possible
permutations of sequestration rates and effective sequestration years
while matching the global mean surface temperature response found
in more complex ESMs such as those included in the Coupled Model
Intercomparison Project 5 (CMIP5) featured in the Intergovernmental
Panel on Climate Change 5th Assessment Report (IPCC AR5; fig. S1).
Fig. 2. Impact of SOC sequestration rate (Pg C year
) and effective sequestration years on 2100 global mean surface temperature for a climate sensitivity of
3°C per doubling CO
with a 0.1°C reduction (highlighted by a white line). A range of potential C sequestration rates are shown in the center of the chart, as well as
their combined potential (black solid). The vertical dashed line shows the mean estimated potential of 0.83 Pg C year
for reference.
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 4of8
on August 29, 2018 from
As a single run of a coupled ESM would take 5 days, it would be pro-
hibitively difficult to perform the 6800 separate combinations of se-
questration rates and effective sequestration years examined in this paper.
To translate the rate of SOC sequestration into a transient global mean
surface temperature response, we perturbed the emission scenarios in the
RCPs by all possible sequestration rates between 0 and 3.0 Pg C year
from 2016 to 2100. We used simplified atmospheric lifetime functions for
each GHG (60) to calculate both perturbed and unperturbed atmospheric
concentrations, translated these CO
concentrations into radiative
forcing (61), and used a continuous diffusion slab ocean model to
estimate transient temperature response (62). Reduction in warming
associated with sequestration rates was calculated from the difference
between the temperatures at a given point in time between the un-
perturbed and perturbed RCP scenario. We did not consider the
potential effects of temperature change on SOC dynamics as this was
beyond the scope of this study. These effects are poorly constrained,
and different studies find both increases and decreases of the SOC stock
with warming (24).
The model approximates the life cycle of each GHG using atmo-
spheric lifetime functions adapted from Joos et al.(60). These model
the percent of a discrete pulse remaining in the atmosphere after tyears
GCO2ðtÞ¼0:217 þ0:259et=172:9þ0:338et=18:51 þ0:186et=1:186
and N
O were assumed to have e-foldingtimesof10and114years
(for example, the time scale for a quantity to decrease to 1/eof its
initial value), respectively, while CO
reflects more complex C cycle
dynamics. These were converted into atmospheric concentrations
(t) by treating each annual emission (or emission reduction) as
a discrete pulse and summing all pulse responses over the time pe-
riod of interest t
where E
is the emissions in year iand G(tt
) is the fraction of the
gas remaining in the atmosphere after time tt
. The mass of each
gas in the atmosphere was converted into concentrations in parts per
million (ppm) [or parts per billion (ppb)] based on their respective
molar mass.
The resulting atmospheric GHG concentrations closely mirror the
results of CMIP5 runs (fig. S2) for the most part, although there is some
divergence in high emissions (RCP 6 and RCP 8.5) scenarios where
changes in ocean chemistry associated with acidification reduce the
airborne fraction in a manner not captured by our emulator model.
For this analysis, however, because we are looking at small perturbations
in the net CO
emissions of underlying RCP scenarios, the limitations of
the simple atmospheric carbon cycle model used should be minimal. We
did not explicitly consider feedbacks or interactions between carbon
sequestration and other GHG emissions (methane and nitrous oxide, in
particular). These fluxes were poorly constrained for most of the land uses
considered here, and thus, this was beyond the scope of the current analysis.
To convert atmospheric GHG concentrations into direct radiative
forcing, we used the simplified radiative forcing functions from the
IPCC AR5 (61). These are functional fits to more complicated absorp-
tion models derived from line-by-line radiative transfer functions that
have relatively small uncertainties: about 1% for CO
radiative forcing
and 10% for CH
radiative forcing calculations (31).
Forcing from a change in atmospheric concentration of CO
given by
DFCO2¼5:35ln ðPCO2þaCO2Þ
Here, PCO2represents the initial concentration of CO
in the atmo-
sphere before the industrial era, while aCO2represents the additional
parts per million CO
added for any given scenario. For the purposes
of this analysis, PCO2was set to 277 ppm, the approximate value for the
preindustrial era (for example, 1765).
The direct radiative forcing of a given increase of CH
O in the atmosphere can be approximated by (61)
fðM;NÞ¼0:47 lnð1þ2:01105ðMNÞ0:75 þ
In this equation, PCH4is the initial concentration of atmospheric
, while bCH4is the addition being evaluated. PN2Ois the initial
concentration of N
O, and bN2Ois the addition being evaluated. The
radiative forcing of both CH
and N
O is a function of the combination
of both, reflecting their interacting atmospheric chemistry. For this anal-
ysis, PCH4was set to 722 ppb and PN2Owas set to 272 ppm, reflecting
preindustrial atmospheric concentrations. f(M,N) is a function that
accounts for the interrelationship between CH
and N
Radiative forcing was translated into a transient temperature re-
sponse by using a continuous diffusion slab ocean model adapted from
Caldeira and Myhrvold (62) and based on the study of Hansen et al.
(63). It is governed by the equations
pf cp;wkv
z¼zmax ¼0
where fis the fraction of the earth covered by ocean (0.71), pis the
density of water, c
is the heat capacity of water, z
is the maximum
ocean depth (4000 m), lis the feedback parameter (DT¼DF
lat equi-
librium, with l=1.25 chosen to reflect a climate sensitivity of 3 C per
doubling CO
), and k
is the ocean vertical thermal diffusivity (assumed
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 5of8
on August 29, 2018 from
to be 5.5 × 10
). The land fraction of the earth was assumed to
follow its equilibrium temperature response, with global surface tem-
peratures being the area-weighted average of the two.
Literature analysis
We used published global estimates of C sequestration potential in
grazing and croplands (table S1). Improved management approaches
included conversion to reduced or conservation till (12,17,64), crop
residue management (64,65), crop rotation and cover crop manage-
ment (12,17,66),optimizedirrigationandnutrient amendment strate-
gies (6,12,17), biochar amendments (10,16,26), increased productivity
of both cropland and grasslands (6,12,17), and improved grazing
management (17,25,26,35,67). To better determine the impact of soil
C sequestration on temperature, we used only estimates of soil C sinks,
and not addition or avoidance of CO
emissions due to management.
However, some global estimates account for nitrous oxide emissions
stimulated or avoided due to management, and report C estimates in
units of CO
eor C equivalents. We therefore compared global estimates
using the unit CO
e-C, which was converted using the ratio of atomic
mass: 1 Pg C = 12/44 × 1 Pg CO
e. We reported estimates for biochar
separately because of continuing interest in biochar as a means to se-
quester atmospheric CO
despite poorly constrained estimates of its
persistence in soil and notwithstanding its potential land conversion re-
quirements (10,25,33,68). Other management strategies, including
compost and other organic amendments, could also be applied over
large and diverse areas, but large-scale estimates for the potential of C
sequestration from these strategies are lacking.
We differentiated between total soil C sequestration potential and
the combined potential. Total C sequestration potential is an aggrega-
tion of literature estimates of the total global agricultural C sink potential
(12,17,25,26,37). For the combined potential, we summed recent land-
use and management-specific estimates for potential sequestration in
cropland (16,17,26,34,69) and grazing lands (16,17,26,35,69)together
with the available land area given in the same sources for these practices.
We report this combined potential with and without biochar contribu-
tions, as biochar application can be used alone or coupled with other
land-use practices for the same land area. Values given in the text are
means ± 1 SE when multiple estimates were available.
Supplementary material for this article is available at
Fig. S1. SimMod emulator climate model transient (solid red) temperature response compared
to CMIP5 multimodel mean (black line) and 2.5 to 97.5% spread (gray area) for each RCP
Fig. S2. RCP (solid lines) and SimMod emulator climate model (dashed lines) atmospheric
concentrations of CO
O, and CH
for each scenario (53).
Fig. S3. A schematic illustration of the concept of effective sequestration years (ESY).
Fig. S4. Same as Fig. 2 in the text but with the inclusion of biochar and for a range of
sequestration rates from 0 to 3 Pg C year
Table S1. Summary of global soil C sequestration potential (Pg C year
) by agricultural land
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Acknowledgments: We thank P. Smith for advice, support, and help with data
interpretation. We also thank B. Collins for supporting the conception of the project, I. Fung
for her challenge and friendly review, and J. Wick for encouragement. Funding: We thank the
Rathmann Family Foundation for funding this project. This work was supported in part by the
U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research
under contract DE-AC02-05CH11231. Author contributions: A.M. contributed to conceptual
development, conducted literature review, made figures, and led the writing effort. Z.H.
contributed to conceptual development, updated and ran the carbon-climate model, made
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 7of8
on August 29, 2018 from
figures, and contributed to writing. A.D.J. and W.L.S. guided conceptual development and
contributed to writing. W.L.S. conceived the project. Competing interests: The authors declare
that they have no competing interests. Data and materials availability: The simple CMIP
emulator model used in this analysis along with the underlying RCP scenario emissions
are available on GitHub ( All data needed to evaluate the
conclusions in the paper are present in the paper and/or the Supplementary Materials.
Additional data related to this paper may be requested from the authors.
Submitted 29 September 2017
Accepted 23 July 2018
Published 29 August 2018
Citation: A. Mayer, Z. Hausfather, A. D. Jones, W. L. Silver, The potential of agricultural land
management to contribute to lower global surface temperatures. Sci. Adv. 4, eaaq0932 (2018).
Mayer et al., Sci. Adv. 2018; 4: eaaq0932 29 August 2018 8of8
on August 29, 2018 from
The potential of agricultural land management to contribute to lower global surface
Allegra Mayer, Zeke Hausfather, Andrew D. Jones and Whendee L. Silver
DOI: 10.1126/sciadv.aaq0932
(8), eaaq0932.4Sci Adv
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... Technology deployment and new land management practices offer an alternative if not synergist path for GHG emission reductions and CDR, with the potential to achieve sector wide net negative GHG emissions [13,14]. Some of the more promising technological interventions include those related to fertilizer production, agricultural and land management practices, and post-processing of farmland biomass and waste recycling [15][16][17]. CDR in the agricultural sector spans bioenergy carbon capture and storage (BECCS), agroforestry, land conservation, organic and rock dust soil amendments, and strategies to mitigate and upcycle food-loss and -waste through the soil [13]. These emerging technologies span the research and development spectrum as climate mitigation tools [18], however, further research is needed to overcome implementation barriers and understand known feedback effects and potential unintended consequences. ...
... , which generated a mean GHG reduction of 42.44% (Table 2). Biochar CDR data were obtained by Mayer et al. [17], which synthesizes data from multiple sources. CDR rate was reported in gigatonnes CO 2 eq and converted based on application area; Mayer et al. report a CDR rate of 1.05 Pg C/yr, which converts to 3.89 Gt CO 2 eq/yr. ...
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... Measures to achieve carbon-neutrality include lowering GHG emissions and capturing C in the system and storing it underground (Mallapaty, 2020). For agro-ecosystems, many studies have shown that GHG emissions reduction and soil CS can be done simultaneously (Mayer et al., 2018;Han et al., 2022;Zhang et al., 2022a). Optimizing agricultural management, improving land use and enhancing soil carbon storage are effective ways to reduce atmospheric CO 2 (Mayer et al., 2018). ...
... For agro-ecosystems, many studies have shown that GHG emissions reduction and soil CS can be done simultaneously (Mayer et al., 2018;Han et al., 2022;Zhang et al., 2022a). Optimizing agricultural management, improving land use and enhancing soil carbon storage are effective ways to reduce atmospheric CO 2 (Mayer et al., 2018). Studies have shown that optimizing the amount of N fertilizer and the method of fertilizer application can significantly reduce GHG emissions (Kim and Dale, 2008;Wang et al., 2020b). ...
Reducing greenhouse gas (GHG) emissions and increasing carbon sequestration (CS) in agricultural systems are critical to realize carbon neutrality, and slowdown global climate change. However, a comprehensive analysis of GHG emissions, CS and the ways to achieve carbon neutrality of citrus production systems in China has not been reported. In this study, a NUFER-Citrus-LCA (citrus nutrient flows in food chains, environment, and resource use model combined with life cycle assessment) combined model was used to quantify the spatial and temporal characteristics of GHG emissions and CS from citrus production in China from 2004 to 2018 to determine the potential and the means to achieve carbon neutrality. The results showed that the GHG emissions varied remarkably among major citrus-producing provinces, with a decreasing trend in the last decade except for Guangdong province. However, the estimated emission for 2014-2018 (12,261 kg CO 2-eq ha − 1 yr − 1) was 2-3 times greater than that of other countries, with Guangdong province recording the highest GHG emissions (24,403 kg CO 2-eq ha − 1 yr − 1). Nitrogen fertilizer accounted for 71.5% of the total GHG emissions. The total carbon sequestration (TCS) during 2014-2018 was 24.1-74.5% of the total greenhouse gas (TGHG) emissions, depending on the province, indicating a net positive carbon emission in China's citrus production system. The scenario analysis showed considerable potential for transforming the Chinese citrus production system from a carbon source to a carbon sink. This will, however, require a crop management system that combines optimized nitrogen fertilizer management, 50% replacement of chemical fertilizer with organic fertilizer and use of cover crops, resulting in a total net carbon sequestration of 15.2 Mt CO 2-eq yr − 1 nationally. Implementation of this crop management model is imperative for transitioning the Chinese citrus production toward carbon neutrality.
... For instance, natural rubber production and improvemens in key ecosystem services such as water retention, soil retention and carbon sequestration have been realized through sustainable intensification 18 . Other studies have found that food production and carbon sequestration can be jointly promoted in croplands through soil quality improvements and related management practices 19,20 . Additionally, natural forests in agricultural landscapes can benefit biodiversity maintenance while improving crop production by up to 20% (refs. ...
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Globally, rising food demand has caused widespread biodiversity and ecosystem services loss, prompting growing efforts in ecological protection and restoration. However, these efforts have been significantly undercut by further reclamation for cropland. Focusing on China, the world’s largest grain producer, we found that at the national level from 2000 to 2015, reclamation for cropland undermined gains in wildlife habitat and the ecosystem services of water retention, sandstorm prevention, carbon sequestration and soil retention by 113.8%, 63.4%, 52.5%, 29.0% and 10.2%, respectively. To achieve global sustainability goals, conflicts between inefficient reclamation for cropland and natural capital investment need to be alleviated.
... Also, the effects of changes in temperature, humidity, and air composition continuously reduce the nutritional value of fruits and vegetables (Zainalabidin et al. 2019). Therefore, to prolong the preservation period, methods including controlled atmosphere storage (Caleb et al. 2012), edible coatings (Gol et al. 2013) ventilation storage, and refrigeration (Lal Basediya et al. 2011), and application of chemicals such as Hydrogen sulfide (H2S), Sulfur dioxide (SO2) (Sivakumar et al. 2010;Cantín et al. 2012), short water brushing treatment and more, have been employed (Molinett et al. 2021;Mayer et al. 2018;Porat et al. 2000;Mahajan et al. 2014). ...
The physiological process of ripening occurs rapidly when fruits and vegetables become mature, and beyond a specific stage after the harvest, they to undergo rapid deterioration in quality. Melatonin, a nontoxic biological molecule with significant antioxidant capacity, plays several roles, including delaying senescence, alleviating chilling injury, enhancing resistance to diseases, and tolerance to stress conditions during postharvest preservation of fruits and vegetables. Interestingly, the application of exogenous melatonin to prolong the shelf life of fruits and vegetables augment the endogenous molecule, thereby promoting these functions. There is crosstalk among different physiological and biochemical processes involved in melatonin action, which remain largely elusive. This chapter provides insights into those mechanisms and discusses several case studies demonstrating the promising effects of melatonin treatment on the postharvest preservation of fruits and vegetables.KeywordsMelatoninPostharvest biologyFruits and vegetablesCrosstalk, melatonin augmentation
... While biochar and soil carbon sequestration can remove carbon dioxide from the atmosphere over agricultural lands, the permanence of carbon sequestration is still to be verified [144,145]. Biochar is a carbon-rich material produced through pyrolysis-heating biomass in a low-oxygen environment-that is applied to soil for carbon sequestration [146]. Soil carbon sequestration consists of the uptake of atmospheric carbon by plants and subsequent storage in soils [147]. ...
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Agriculture accounts for 12% of global annual greenhouse gas (GHG) emissions (7.1 Gt CO2 equivalent), primarily through non-CO2 emissions, namely methane (54%), nitrous oxide (28%), and carbon dioxide (18%). Thus, agriculture contributes significantly to climate change and is significantly impacted by its consequences. Here, we present a review of technologies and innovations for reducing GHG emissions in agriculture. These include decarbonizing on-farm energy use, adopting nitrogen fertilizers management technologies, alternative rice cultivation methods, and feeding and breeding technologies for reducing enteric methane. Combined, all these measures can reduce agricultural GHG emissions by up to 45%. However, residual emissions of 3.8 Gt CO2 equivalent per year will require offsets from carbon dioxide removal technologies to make agriculture net-zero. Bioenergy with carbon capture and storage and enhanced rock weathering are particularly promising techniques, as they can be implemented within agriculture and result in permanent carbon sequestration. While net-zero technologies are technically available, they come with a price premium over the status quo and have limited adoption. Further research and development are needed to make such technologies more affordable and scalable and understand their synergies and wider socio-environmental impacts. With support and incentives, agriculture can transition from a significant emitter to a carbon sink. This study may serve as a blueprint to identify areas where further research and investments are needed to support and accelerate a transition to net-zero emissions agriculture.
... Moreover, training and better agricultural facilities and technologies are also effective measures to enable adaptation to the adverse effects of climate change 37 . Improving cropland NUE and managing cropland sustainably would in turn slow down the temperature rises and promote the reduction of greenhouse gas emissions from agriculture 38,39 . Thus, early actions should be taken to ease the projected future impact of climate change on agriculture to achieve global sustainable goals 40,41 . ...
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Maintaining food production while reducing agricultural nitrogen pollution is a grand challenge under global climate change. Yet, the response of global agricultural nitrogen uses and losses to climate change on the temporal and spatial scales has not been fully characterized. Here, using historical data for 1961–2018 from over 150 countries, we show that global warming leads to small temporal but substantial spatial impacts on cropland nitrogen use and losses. Yield and nitrogen use efficiency increase in 29% and 56% of countries, respectively, whereas they reduce in the remaining countries compared with the situation without global warming in 2018. Precipitation and farm size changes would further intensify the spatial variations of nitrogen use and losses globally, but managing farm size could increase the global cropland nitrogen use efficiency to over 70% by 2100. Our results reveal the importance of reducing global inequalities of agricultural nitrogen use and losses to sustain global agriculture production and reduce agricultural pollution.
... The review 'The potential of agricultural land management to contribute to lower global surface temperatures' observes, "Land-use change and poor management practices have resulted in the loss of more than 130 peta-grams carbon (130 peta-grams = 130 billion tonnes=130 gigatons) from agricultural soil, leaving >1 billion hectares (10 million sq. km.) of degraded soil worldwide" (Mayer et al., 2018). ...
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Eco-degradation or Regeneration? The Crucial Climate Role of Agriculture – soil carbon storage, through the synergistic interaction between plants and the soil biome, is part of the evolved planetary regulatory ecosystem for partition of oxygen and carbon dioxide, between; the atmosphere, oceans, soil, and living organisms. James Lovelock christened the product of competitive evolution, arising out of laws of matter; the interdependent self-regulating ecosphere system that is the basis of sophisticated terrestrial life; a ‘Gaian’ system, after a key Greek ‘Earth Goddess’, the mother of all creation, one of the “primordial elemental deities (protogenoi) born at the dawn of creation”, (Theoi Greek Mythology, n.d.). Lovelock alluded to the system having the characteristics of a ‘complex living organism’. We humans often fail to respect the fact, terrestrial soil based, and oceanic, photosynthetic organisms, and their wider bacterial and fungal symbionts, are central obligate enabling pillars of more complex forms of life, and thus essential parts of the Gaian system. Plant captured sunlight energy, powers; the oxygen-carbon-dioxide-cycle; production of the complex carbon-dioxide derived, carbon-based organic molecules that underlie our very existence; incorporation of mineral elements; and other processes and resources absolutely central to and underlying most terrestrial life, and all ‘sophisticated’ life. We humans, by taking agricultural control of billions of hectares of formerly natural green spaces and related eco-services, have substituted ourselves for crucial aspects of the evolved Gaian system, without understanding the implications and consequent responsibilities, this places upon us. The ‘Fertiliser-Agrochemical-Tillage-Bare-soil-Agricultural-System’ hereinafter (FATBAS), takes no account of the obligate need for maintenance of planetary ecosystem health, including the central necessity to optimise the photosynthetic light energy capture potential of plants, by maximising soil carbon and life in the soil biome, which is essential to plant health and productivity, thus life itself. Incident sunlight energy, that powers the planetary ecosystem through plants, is ultimately a finite resource, which can build life, or destroy it by heating bare soils. Fertiliser-agrochemical-tillage bare-soil, based farming, FATBAS, by failing to recognise the role of soils and plants as essential parts of our planetary ecosystem, is unthinkingly inevitably damaging soil biology and health, reducing; soil carbon, water infiltration-penetration and storage, increasing; flooding and erosion, drying crusting and heating of bare soils; killing biology; adding energy to atmospheric heat domes, contributing to drought, degrading regional hydrology, and more widely contributing to and accelerating, the planetary ecosystem service degradation we call ‘climate change’. Further, FATBAS fertiliser-and-agrochemical-based farming, contributes to pollution including eutrophication, thus river and ocean deoxygenation, ultimately adding to risk of ocean sulphidication and major Anthropocene extinction event. FATBAS, also, reduces the nutritional value of food, contributing to human and livestock ill-health, and degraded human intellect, empathy, co-operation and behaviour, which if unaddressed, will ultimately lead to species devolution, further increasing risk of Anthropocene self-extinction.
The ongoing climate crisis merits an urgent need to devise management approaches and new technologies to reduce atmospheric greenhouse gas concentrations (GHG) in the near term. However, each year that GHG concentrations continue to rise, pressure mounts to develop and deploy atmospheric CO2 removal pathways as a complement to, and not replacement for, emissions reductions. Soil carbon sequestration (SCS) practices in working lands provide a low-tech and cost-effective means for removing CO2 from the atmosphere while also delivering co-benefits to people and ecosystems. Our model estimates suggest that, assuming additive effects, the technical potential of combined SCS practices can provide 30%-70% of the carbon removal required by the Paris Climate Agreement if applied to 25%-50% of the available global land area, respectively. Atmospheric CO2 drawdown via SCS has the potential to last decades to centuries, although more research is needed to determine the long-term viability at scale and the durability of the carbon stored. Regardless of these research needs, we argue that SCS can at least serve as a bridging technology, reducing atmospheric CO2 in the short term while energy and transportation systems adapt to a low-C economy. Soil C sequestration in working lands holds promise as a climate change mitigation tool, but the current rate of implementation remains too slow to make significant progress toward global emissions goals by 2050. Outreach and education, methodology development for C offset registries, improved access to materials and supplies, and improved research networks are needed to accelerate the rate of SCS practice implementation. Herein, we present an argument for the immediate adoption of SCS practices in working lands and recommendations for improved implementation.
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Compost amendments to rangelands is a proposed nature-based climate solution to increase plant productivity and soil carbon sequestration. However, it has not been evaluated using semi-continuous ecosystem-scale measurements. Here we present the first study to utilize eddy covariance and footprint partitioning to monitor carbon exchange in a grassland with and without compost amendment, monitoring for one year before and one year after treatment. Compost amendments to an annual California grassland were found to enhance net ecosystem removal of C. Our study confirmed that compost-amended grasslands, similar to non-amended grasslands, are net carbon sources to the atmosphere; however amendments appear to be slowing down the rate at which these ecosystems lose carbon by 0.71 Mg C ha-1 per growing season. Digital repeated imagery of the canopy revealed that compost-amended grasslands experienced an earlier green-up, resulting in an overall longer growing season by more than 30 days. Scale-emergent processes such as changes in phenology are understudied in nature-based climate solutions and need to be better investigated before widespread adoption. Notably, we did not detect significantly higher amounts of soil C in compost-amended soils. High variability in soil C demands greater sampling replication in future studies. A longer growing season and higher productivity are hypothesized to be a result of greater availability of macro and micronutrients in the top layer of soil (specifically N, P and Zn).
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Carbon efflux from soils is the largest terrestrial carbon source to the atmosphere, yet it is still one of the most uncertain fluxes in the Earth’s carbon budget. A dominant component of this flux is heterotrophic respiration, influenced by several environmental factors, most notably soil temperature and moisture. Here, we develop a mechanistic model from micro to global scale to explore how changes in soil water content and temperature affect soil heterotrophic respiration. Simulations, laboratory measurements, and field observations validate the new approach. Estimates from the model show that heterotrophic respiration has been increasing since the 1980s at a rate of about 2% per decade globally. Using future projections of surface temperature and soil moisture, the model predicts a global increase of about 40% in heterotrophic respiration by the end of the century under the worst-case emission scenario, where the Arctic region is expected to experience a more than two-fold increase, driven primarily by declining soil moisture rather than temperature increase.
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The role of soil organic carbon in global carbon cycles is receiving increasing attention both as a potentially large and uncertain source of CO2 emissions in response to predicted global temperature rises, and as a natural sink for carbon able to reduce atmospheric CO2. There is general agreement that the technical potential for sequestration of carbon in soil is significant, and some consensus on the magnitude of that potential. Croplands worldwide could sequester between 0.90 and 1.85 Pg C/yr, i.e. 26–53% of the target of the “4p1000 Initiative: Soils for Food Security and Climate”. The importance of intensively cultivated regions such as North America, Europe, India and intensively cultivated areas in Africa, such as Ethiopia, is highlighted. Soil carbon sequestration and the conservation of existing soil carbon stocks, given its multiple benefits including improved food production, is an important mitigation pathway to achieve the less than 2 °C global target of the Paris Climate Agreement.
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Significance Most nations recently agreed to hold global average temperature rise to well below 2 °C. We examine how much climate mitigation nature can contribute to this goal with a comprehensive analysis of “natural climate solutions” (NCS): 20 conservation, restoration, and/or improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We show that NCS can provide over one-third of the cost-effective climate mitigation needed between now and 2030 to stabilize warming to below 2 °C. Alongside aggressive fossil fuel emissions reductions, NCS offer a powerful set of options for nations to deliver on the Paris Climate Agreement while improving soil productivity, cleaning our air and water, and maintaining biodiversity.
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Significance Land use and land cover change has resulted in substantial losses of carbon from soils globally, but credible estimates of how much soil carbon has been lost have been difficult to generate. Using a data-driven statistical model and the History Database of the Global Environment v3.2 historic land-use dataset, we estimated that agricultural land uses have resulted in the loss of 133 Pg C from the soil. Importantly, our maps indicate hotspots of soil carbon loss, often associated with major cropping regions and degraded grazing lands, suggesting that there are identifiable regions that should be targets for soil carbon restoration efforts.
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The '4 per mille Soils for Food Security and Climate' was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New and Russia). We asked whether the 4 per mille initiative is feasible for the region. The outcomes highlight region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates globally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha −1), and at the first twenty years after implementation of best management practices. In addition, areas which have reached equilibrium will not be able to further increase their sequestration. We found that most studies on SOC sequestration only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille number was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille in the top 1m of global agricultural soils, SOC sequestration is between 2-3 Gt C year −1 , which effectively offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become viable. The challenge for cropping Geoderma j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / g e o d e r m a farmers is to find disruptive technologies that will further improve soil condition and deliver increased soil carbon. Progress in 4 per mille requires collaboration and communication between scientists, farmers, policy makers, and marketeers.
Rising levels of atmospheric CO2 frequently stimulate plant inputs to soil, but the consequences of these changes for soil carbon (C) dynamics are poorly understood. Plant-derived inputs can accumulate in the soil and become part of the soil C pool ("new soil C"), or accelerate losses of pre-existing ("old") soil C. The dynamics of the new and old pools will likely differ and alter the long-term fate of soil C, but these separate pools, which can be distinguished through isotopic labeling, have not been considered in past syntheses. Using meta-analysis, we found that while elevated CO2 (ranging from 550 to 800 parts per million by volume) stimulates the accumulation of new soil C in the short term (<1 year), these effects do not persist in the longer term (1-4 years). Elevated CO2 does not affect the decomposition or the size of the old soil C pool over either temporal scale. Our results are inconsistent with predictions of conventional soil C models and suggest that elevated CO2 might increase turnover rates of new soil C. Because increased turnover rates of new soil C limit the potential for additional soil C sequestration, the capacity of land ecosystems to slow the rise in atmospheric CO2 concentrations may be smaller than previously assumed.