Content uploaded by Indur Goklany
Author content
All content in this area was uploaded by Indur Goklany on Oct 31, 2022
Content may be subject to copyright.
Conservation Practice and Policy
Reduction in global habitat loss from
fossil-fuel-dependent increases in cropland productivity
Indur M. Goklany
8726 Old Courthouse Rd, Vienna, VA 22182, U.S.A
Abstract: Terrestrial biodiversity loss and climate change, driven mainly by loss of habitat to agriculture and
fossil fuel (FF) use, respectively, are considered among the world’s greatest environmental threats. However, FF-
dependent technologies are currently essential for manufacturing synthetic nitrogen fertilizers (SNFs) and syn-
thetic pesticides (SPs) critical to increasing agricultural productivity, which reduces habitat loss. Fossil fuel use
increases CO2levels, further enhancing agricultural productivity. Based on estimates of global increases in yields
from SNFs, SPs, and atmospheric CO2fertilization, I estimated that FF-dependent technologies are responsible for
at least 62.5% of current global food production (GFP) from cropland. Thus, if FF use is eschewed in the future,
maintaining current GFP means croplands would have to increase from 12.2% of global land area (GLA) excluding
Antarctica to 32.7%. The additional 20.4% of GLA needed exceeds habitat lost currently to cropland (12.2% of
GLA) and cumulative conservation areas globally (14.6% of GLA). Thus, although eliminating FF use could reduce
climate change, its unintended consequences may be to significantly exacerbate biodiversity loss and indirectly
increase food costs, reducing food security which, moreover, disproportionately affects the poor. Although it may
be possible to replace SNFs and SPs with FF-free technologies, such substitutes have not yet been demonstrated
to be sufficiently economical or efficient. In the interim, meeting global food demand and keeping food prices
affordable would increase habitat conversion and food prices. These trade-offs should be considered in analyses
of climate change policies.
Keywords: agriculture, biodiversity, carbon dioxide, conservation, crop yields, fertilizers, land saving, pesti-
cides
Reducción de la Pérdida Mundial de Hábitat a Partir de Incrementos Dependientes de Combustibles Fósiles en la
Productividad de los Terrenos de Cultivo
Resumen: La pérdida de la biodiversidad terrestre y el cambio climático, causados principalmente por la pérdida
del hábitat debido a la agricultura y al uso de combustibles fósiles (CF) respectivamente, están consideradas entre
las más grandes amenazas ambientales a nivel mundial. Sin embargo, las tecnologías dependientes de los CF
son actualmente de mucha importancia para la manufactura de fertilizantes sintéticos de nitrógeno (FSN) y de
pesticidas sintéticos (PS) fundamentales para el incremento de la productividad agrícola, lo cual reduce la pérdida
del hábitat. El uso de los CF incrementa los niveles de CO2, mejorando todavía más la productividad agrícola.
Con base en los estimados de los incrementos mundiales de producción de FSN, PS y la fertilización por CO2
atmosférico estimé que las tecnologías dependientes de los CF son las responsables de al menos el 62.5% de la
producción mundial de alimentos (PMA) en las tierras de cultivo. Por esto, si en el futuro se evita el uso de los FF,
para mantener la PMA actual los terrenos de cultivo tendrían que incrementar de 12.2% del área global de suelo
(AGS) (excluyendo a la Antártida) a 32.7%. El 20.4% adicional del AGS necesaria excede a los hábitats perdidos
hasta ahora por terrenos de cultivo (12.2% del AGS) y a las áreas acumuladas de conservación (14.6% del AGS) en
todo el mundo. Por lo tanto, mientras que la eliminación de los CF podría reducir el avance del cambio climático,
las consecuencias imprevistas de esto podrían exacerbar significativamente la pérdida de la biodiversidad e in-
directamente incrementar el costo de los alimentos, reduciendo así la seguridad alimentaria. Aunque puede ser
posible reemplazar los FSN y los PS con tecnologías libres de CF, no se ha demostrado que dichos sustitutos sean
suficientemente económicos o eficientes. Mientras tanto, cumplir la demanda mundial de alimentos y mantener
Article impact statement: Fossil fuel technologies saved at least 20% of global land area from agricultural conversion; by contrast, 15% is
protected in nature preserves.
Paper submitted October 2, 2019; revised manuscript accepted August 7, 2020.
1
Conservation Biology, Volume 0, No. 0, 1–9
© 2020 Society for Conservation Biology
DOI: 10.1111/cobi.13611
2Habitat Loss
costeables los precios alimentarios incrementa la conversión de los hábitats. Estas compensaciones deberían ser
consideradas en los análisis de las políticas para el cambio climático.
Palabras Clave: agricultura, biodiversidad, conservación, cosechas de cultivos, dióxido de carbono, econo-
mización de terrenos, fertilizantes, pesticidas
:,
,
,
,
62.5% ,,
()12.2% 32.7% 20.4%
(12.2%) (
14.6%) ,,,
,,
,
,:;:
:,,,,,,,
Introduction
Habitat loss has been driven mostly by demand for agri-
cultural land to meet human needs (Goldewijk et al.
2011; FAO 2019a). High-yield agriculture reduces this
demand through the use of synthetic nitrogen fertiliz-
ers (SNFs) and synthetic pesticides (SPs) (Goklany 1998;
Green et al. 2005; Phalan et al. 2011). But SNFs and SPs
threaten biodiversity. Moreover, they are manufactured
using feedstocks derived from fossil fuels (FFs) via FF-
dependent energy-intensive processes, and FF usage is
itself a potential threat to biodiversity because it is the
foremost contributor to climate change (via greenhouse
gas emissions) and is a source of pollution (NRC 2010).
So, although FF use threatens biodiversity, it paradoxi-
cally reduces the major threat to biodiversity by limiting
habitat loss to agriculture.
I estimated a lower bound for the share of current
global food production (GFP) from cropland attributable
to FF-dependent technologies. I assumed that non-FF
technologies (including practices) would partially com-
pensate for production losses if FF use is eschewed. I esti-
mated a lower bound for the additional cropland needed
to compensate for these losses, assuming a FF-free world,
as some advocate (CBD 2019). Others would postpone
such a transition to midcentury; yet others would ac-
cept FF use to the extent they employ net-zero strate-
gies (Friedman & Trip 2019) to allow some FF use in
agriculture and other sectors. I compared the increase
in habitat loss (assuming no FF use) with habitat cur-
rently used as cropland and currently protected land
worldwide.
It is unlikely FFs will be abandoned in the near
term, and if they were there would be economic ad-
justments to rebalance supply and demand that would
change the extent of cropland and food security. But,
this scenario helps illustrate the current contribution
of FF-dependent technologies to food security and land
conservation.
I focused on current GFP, so possible future increases
in demand are not considered (Tilman et al. 2011). Sim-
ilarly, I did not consider future advances that may obvi-
ate the need for FF-intensive processes to manufacture
fertilizers and pesticides, which may occur considering
current investments in research on alternatives to SNFs
and SPs and the general acceleration of scientific and
technological advances.
I also did not account for all the avenues through
which FF-dependent technologies can affect agricultural
productivity (and, therefore, habitat converted to agri-
culture), for example, extra cropland to feed livestock
needed to replace FF-dependent power and energy used
on and off the farm and a reduction in cropland because
in an FF-free world air pollutants (e.g., ozone, partic-
ulate matter) would be reduced, increasing crop yield
(NRC 2010; Schiferl et al. 2018; Ainsworth et al. 2020).
I assumed that near-term substitution of FFs by nuclear
power is infeasible because of long construction lead
times and lack of political will.
Until the 20th century, increased human demand
for food and other agricultural goods was met largely
through habitat conversion to cropland and pasture
(Fig. 1) (Goklany 1998; Green et al. 2005). By 1990 over
67% of the area of 2 of the world’s 14 major terres-
trial biomes and more than half of the area of 4 other
biomes had been converted primarily to agriculture (Mil-
lennium Ecosystem Assessment 2005). By 2017 agricul-
ture occupied 37.4% of global land area (GLA) (excluding
Antarctica), of which 67% was pastureland and 33% crop-
land (FAO 2019a). In recent decades increases in agri-
cultural productivity, driven by FF-dependent technolo-
gies, have limited habitat conversion to agricultural uses,
Conservation Biology
Volume 0, No. 0, 2020
Goklany 3
Figure 1. Global land area used for cropland and other agricultural (ag) land, and global population, 1700–2016
(Goldewijk et al. 2011; Maddison 2010; FAO 2019a) (LS, left scale; RS, right scale; cap, capita).
notwithstanding explosive growth in populations and
per capita wealth, which drive increases in per capita
food consumption (Tilman et al. 2011). Mine is the first
attempt to estimate the cumulative increase in cropland
productivity resulting from the FF-dependent technolo-
gies of SNFs, SPs, and FF combustion (which increases
carbon fertilization). I used these estimates to develop a
lower-bound estimate of habitat saved from conversion
to cropland due to higher crop yields from FF-dependent
technologies.
Figure 1 shows global trends in population, cropland,
agricultural land, per capita cropland, and per capita agri-
cultural land (the latter 2 are proxies for land productiv-
ity). I used HYDE 3.1 project data for 1700–1950 (Gold-
ewijk et al. 2011) and data from the U.N. Food and Agri-
cultural Organization (FAO 2019a) for 1961–2017. The
quality of FAO’s land-use data has been questioned. Data
are collected via questionnaires sent to member coun-
tries, but response rate, accuracy, and data quality vary
by country (World Bank 2011; See et al. 2015; APCAS
2016). Nevertheless, FAO’s is the longest time series with
worldwide coverage obtained using relatively consistent
methods. Figure 1 shows that until the 19th century
there was little variation in per capita agricultural land,
notwithstanding some productivity gains, particularly in
cropland per capita in the 18th century (Koning et al.
2008). Consequently, agricultural land loosely tracked
population. As agriculture expanded into sparsely
populated areas in the Americas and Australia in the 19th
century, per capita cropland and per capita pastureland
increased. However, cropland per capita peaked around
the early 20th century. With continuing improvements
in productivity and declining global population growth
rates, area of agricultural lands apparently peaked in the
late 1990s; cropland currently seems to be approaching
its peak.
Three major FF-dependent technologies and prac-
tices that have increased agricultural productivity since
the early 20th century are SNFs, manufactured via the
Haber–Bosch process, generally powered by natural gas
or coal (in China) to fix nitrogen from the air (Erisman
et al. 2008; Yara 2018); SPs, derived from petroleum and
coal (in China) (Oerke 2006; Chen et al. 2019); and FF
combustion, which has increased global CO2levels and
fertilized plant life (Ciais et al. 2013).
Methods
To estimate the cumulative contribution of SNF, SP, and
FF technologies to current GFP, I used the peer-reviewed
literature to obtain or derive estimates of the direct or
indirect increase in GFP for each technology. Assuming
that increases in GFP from each technology are indepen-
dent of each other, I estimated their cumulative contri-
bution. When faced with a choice of alternative assump-
tions, I generally selected the assumption that would
result in a lower-bound estimate for the increase in GFP.
Increase from SNFs
Erisman et al. (2008) estimate that SNFs were responsi-
ble for 44% of GFP in 2004 and 48% in 2008. They as-
sumed that in the absence of the Haber–Bosch process,
substitute yield-enhancing technologies would increase
productivity by 20% from 1950 to 2000.
Conservation Biology
Volume 0, No. 0, 2020
4Habitat Loss
From 2008 to 2016, global SNF use increased 15.3%,
and cropland and total cereal production (proxy for food
production) increased by 2.8% and 15.4%, respectively
(FAO 2019a). Because SNF use has increased and agricul-
tural technologies and practices have evolved to increase
nitrogen-use efficiency (Mueller et al. 2019), the contri-
bution of SNFs to GFP has probably increased since 2008.
Nevertheless, I assumed that it has stayed at its 2008 level
(48%).
Increase from SPs
I based increase in food production from SPs on Oerke’s
(2006) estimates for global losses to pests for soybean,
wheat, maize, rice, potatoes, and cotton, which cumu-
latively account for 47.2% of all harvested cropland in
2016 (FAO 2019a). Oerke (2006) estimated that global
losses for these crops ranged from a potential 50–77%
absent pesticide use to an actual 26–40% with SP use
(Table 1). Using these estimates, I calculated the share of
GFP that may be attributed to SPs. I estimated increases
in yield due to SPs for each of the crops based on the
ratios of actual-to-potential yields (Table 1). I calculated
the globally weighted yield increase for all 6 crops to
be 104.3% by weighting the increase in yield for each
by its harvested area as a share of the cumulative area
harvested for the crops. I assumed that, absent FFs, cur-
rently available substitute crop protection technologies
would be 50–75% as effective as SPs. This range may be
an overestimate, considering it is impossible for fertiliz-
ers and pesticides to be manufactured, transported, and
distributed without involving FFs in the quantities and
scale necessary for effective and efficient functioning of
global agriculture.
I assumed that the 104.3% weighted yield increase
applies to all cropland and that non-FF-dependent pes-
ticides would be 75% as effective as FF-dependent pes-
ticides. This also assumes that pest pressure and ef-
fectiveness of crop protection technologies are un-
changed since Oerke’s assessment. Both are probably
different today. In particular, increases in attainable
yields are often associated with increased vulnerabil-
ity to damage from pests (Oerke 2006), and yields
have increased for all important crops from 2008 to
2016 (from 5% for cotton to 14% for soybeans) (FAO
2019a). Changes in pest pressure and pesticide effec-
tiveness are expected because climate change should
have modified ranges and severity of pest infesta-
tion and effectiveness of crop protection (IPCC 2014);
increased international trade in agricultural products
probably increases risks from invasive species (Paini
et al. 2016); and pests evolve, as do crop protection
techniques.
Changes in the latter include use of genetically mod-
ified insect-resistant (Bt) crops, herbicide-tolerant (HT)
crops, and mixed Bt/HT crops (currently grown on 1.5%,
Table 1. Estimates of changes in crop yield with and without use of synthetic pesticides.
Crop
Global area
harvested in 2016
(ha)a
Potential crop loss
without synthetic
pesticides (%)b
Actual crop loss
with synthetic
pesticides use
(%)b
Ratio of
actual-to-potential
yield
Increase in yield
with synthetic
pesticides use (%)
Area-weighted
yield increase
with synthetic
pesticides (%)c
Maize 197,185,936 68.5 31.2 2.18 118.4 30.77
Potatoes 19,302,642 74.9 40.3 2.38 137.8 3.51
Rice 167,249,103 77 37.4 2.72 172.2 37.95
Cotton 32,979,140 74.9 40.3 2.38 137.8 5.99
Soybeans 123,551,146 60 26.3 1.84 84.3 13.72
Wheat 218,543,071 49.8 28.2 1.43 43.0 12.39
Total 758,811,038 104.33
aFAO 2019a.
bOerke 2006.
cArea weighted, calculated using area for crops per FAO (2019).
Conservation Biology
Volume 0, No. 0, 2020
Goklany 5
5.4%, and 4.7% of global cropland, respectively) (FAO
2019a; ISAAA 2016). Herbicide-tolerant crops have in-
creased the use of broad-spectrum pesticides at the ex-
pense of more specialized pesticides targeting different
pests and reduced production costs by decreasing the
need for labor and alternative practices (e.g., mechanical
weeding) but have not necessarily increased yields (e.g.,
by enabling cultivation of second crops) (Brookes & Bar-
foot 2018). Although Bt crops reduce rather than elim-
inate the need for pesticides, they sometimes provide
higher yields (ISAAA 2016). Because global assessments
of potential and actual GM crop losses due to SPs use are
unavailable and area currently occupied by such crops
is relatively small, I assumed no differences between GM
and conventional crops in terms of yields and pesticide
effectiveness.
Increase from CO2Fertilization
Doubling CO2relative to the preindustrial level (277
ppm in 1755) (IPCC 2013) would increase net primary
productivity by 20–25% (Ciais et al. 2013). These es-
timates may underestimate yield increases by 20–30%
because the experiments used to derive these esti-
mates subject plants to higher-than-natural CO2fluc-
tuations (Allen et al. 2020), but I defer to the IPCC.
Accordingly, if productivity increases linearly with CO2
concentration, then at the current atmospheric concen-
tration (412 ppm) (NOAA 2019), fertilization should have
increased yields by 10–12%. This is an underestimate, be-
cause the relationship between productivity increase and
CO2bends downward (i.e., CO2increases, productivity
increases rapidly, and then rate of increase slows) (von
Caemmerer et al. 2012).
An alternative estimate can be derived from data on
the effect of CO2concentrations on crop yields main-
tained by the Center for the Study of Carbon Dioxide
and Global Change (Idso 2013). Its data indicate that a
300-ppm increase in CO2concentrations would increase
the production-weighted yield of 45 crops, accounting
for 95% of global crop production by 35%. Assuming lin-
earity, an increase from 277 to 412 ppm implies a 15.8%
yield increase. To be conservative, I assumed a yield in-
crease of 10%.
Results
I found that SNFs alone increased current food produc-
tion by at least 92.3%. Hence, to maintain current GFP
absent FF use, and assuming average productivity stays
constant, cropland would have to increase from 12.2% to
23.5% of GLA. Use of SPs increased GFP by 26.1% above
what it would have been absent FFs. Fertilization via CO2
increased GFP by 10%.
Together SNFs, SPs, and FFs increased GFP by at least
167% (=1.923 ×1.261 ×1.1 ×100 – 100) assuming that
increases for each are independent. Thus, I found that
FF-dependent technologies were responsible for 62.5%
of current GFP and absent any FFs, cropland would need
to expand by at least 167% to maintain current GFP (i.e.,
cropland would have to expand by 20.4% of GLA from
12.2% to 32.7%).
Discussion
Assumptions
Implicit in these estimates are 2 heroic assumptions. The
firstassumptionisthatthecurrentglobalagricultural
system, connecting 570 million farms with 7.8 billion
consumers distributed worldwide through millions of in-
termediaries mainly through harnessing relatively cheap
FFs, can be maintained without FFs and major price in-
creases (which would reduce consumption but fail to
maintain GFP). Consider that FF-free agriculture is essen-
tially organic agriculture (OA), which abjures SNFs and
SPs, and has no access to all other energy services pro-
vided by FFs. Despite centuries’ head start on develop-
ing FF-free agriculture and the possibility of premiums
for organic produce, globally only 1.4% of cropland (and
0.5% of farms) were under OA in 2017 (FAO 2014; FIBL
2019), suggesting that non-FF-based alternatives to SNFs
and SPs are not currently competitive on a wide scale. An
FF-free agriculture would require scaling up OA area and
farms worldwide by 70- and 200-fold, respectively, while
abandoning FFs.
Second, my estimates are based on the assumption that
various agricultural processes that use energy (e.g., irri-
gation, mechanical weeding, packaging, and transport-
ing [Ziesemer 2007]) would continue without loss of
productivity or increase in costs in the absence of FFs
and that it is possible for raw and intermediate materi-
als and finished products to be extracted, mined, pro-
cessed, transported, and distributed to and from manu-
facturers to farms, then to markets, and eventually to all
consumers without involving FFs in the quantities and
scale necessary to sustain global agriculture. This seems
highly unlikely in the medium term, considering that FFs
currently supply 81% of global energy (IEA 2018), which
reaffirms that currently non-FF-based alternatives are not
broadly competitive. Despite renouncing SNFs and SPs,
organic systems use 49–79% (Fess & Benedito 2018) to
85% (Clark & Tilman 2017) as much energy as conven-
tional systems. These heroic assumptions suggest that
global replacement of FF use in agriculture is unlikely in
the medium term.
My estimate that absent FFs an extra 20.4% of GLA
would be needed to maintain current GFP is also based
on the following 11 assumptions.
Conservation Biology
Volume 0, No. 0, 2020
6Habitat Loss
Additional cropland cultivated in the absence of FF
is as productive as current cropland (assumption 1). If
economically more productive lands were available, they
would probably already have been converted and culti-
vated, given that transportation costs are sufficiently low
that even relatively low-value agricultural products can
be produced and moved profitably worldwide (Trading
Economics 2020).
Production increases from irrigation, often an energy-
intensive activity and, therefore, partly FF-dependent, are
captured in the yield increase from SNFs (2). On average,
an irrigated acre (0.4 ha) has a 167% greater yield than an
unirrigated acre (FAO 2019b). In the absence of cheap
FFs, at least some irrigation activity would be reduced,
which would reduce agricultural productivity in areas
where yields are water limited.
It is economically feasible to manufacture and dis-
tribute non-FF-derived fertilizers and pesticides to
570 million farms worldwide without FFs or raising
prices to meet demand (3).
Yield increase from CO2fertilization is at the low end
of the IPCC range (4).
The share of GFP due to SNFs has not increased since
2008, despite increases in SNF use and nitrogen-use effi-
ciencies (5).
Present-day energy demands will be met without ad-
ditional terrestrial habitat loss (6). Onshore, nonnuclear
substitutes (solar, wind, hydro, and biomass) have larger
footprints than FFs per energy unit produced (Ausubel
2015). Wind and solar power, by harnessing energy at
different elevations, may coexist with farming on the
same footprint, although existing large-scale examples
are few. Moreover, renewable energy projects inadver-
tently degrade habitat for wildlife (FWS 2018; Rehbein
et al. 2020).
Society (and agriculture) will not partially revert to
animate power (7). Substantial land would be required
to feed draught animals needed to replace FF-powered
machinery (Goklany 2012). In 1910, before FF-powered
tractors displaced animate power, 23% of U.S. cropland
was devoted to feeding on-farm draught animals. By
1960, U.S. on-farm horsepower from draft animals had
shrunk 84% despite total horsepower increasing 4.6-fold
(Olmstead & Rhode 2001). Also, most farm machinery
runs on and is manufactured with FFs.
Land productivity due to climate change (excluding
yield increase from carbon fertilization) will not change
(8). Zhu et al. (2016) estimated Earth’s vegetated area
(i.e., area covered by leaves) has increased 8% from 1982
to 2009 due to climate change.
Effectiveness of crop protection technologies and pest
pressure stays at 2008 levels despite increasing yields and
climate changes postdating Oerke’s analysis (9).
There is no effect from loss of other FF-dependent
technologies and practices (e.g., rapid and timely dis-
tribution of inputs and outputs continues, including in
the cold food supply chain; no spoilage due to changes
in packaging, storage, and processing) (10). These FF-
dependent technologies increase the amount of consum-
able food without increasing cropland or yields (Goklany
1998).
No net effect from reduced ozone, particulate mat-
ter, and acidification on yields (11). Ozone has reduced
global yields by about 10% for wheat and soybean and 3–
5% for maize and rice (Porter et al. 2014), whereas par-
ticulate matter and nitrogen deposition increases global
yields for maize and wheat by 2.3–11% and for rice by 2%
(Schiferl et al. 2018). In aggregate, air pollutants probably
reduce GFP.
These assumptions, except assumption 11, underesti-
mate extra cropland needed to maintain GFP, some sub-
stantially. Extra cropland is unlikely to be as productive as
current cropland because additional land will be needed
to supply energy on and off the farm and to feed draught
animals. It is also unlikely that SNFs and SPs can be
manufactured and distributed worldwide economically,
absent FFs, without reducing food security. Thus, con-
sidering the preponderance of assumptions that under-
estimate extra cropland needed to maintain GFP in a
FF-free world, and their potential magnitudes, my esti-
mate is probably a lower bound for habitat saved by FF-
dependent technologies.
Estimating additional habitat converted more broadly
to agriculture would have involved including extra pas-
tureland to compensate for lower pasture productivity
due to lack of SNFs, SPs, and carbon fertilization (IFGC
2010; Polley et al. 2019).
Currently Available Alternatives
I assumed that in the absence of FFs, alternative tech-
nologies would compensate partially for loss of SNFs and
SPs. Technological advances will undoubtedly expand fu-
ture FF-free options available for agriculture, but a short-
fall in GFP, no matter how brief, should be avoided, dur-
ing any transition to FF-free agriculture.
Alternatives to SNFs include recycling manure, catch
crops, and crop residues. Such practices can reduce yield
gaps between conventional and organic cropping sys-
tems, without always enhancing total productivity of the
latter (Shah et al. 2017).
About 11% of nitrogen inputs to global crop produc-
tion come from animal manure and another 8% from
crop residues (Seufert & Ramankutty 2017). Replacing
SNFs would mean significantly increasing livestock num-
bers and crop residues, which may be counterproductive
to the goal of reducing, or eliminating, FFs (Meemkem &
Qaim 2018; Lamb et al. 2016; Balmford et al. 2018). In
rice paddies in China, pastures for beef cattle in Latin
America, and dairy farming in Europe, increased use of
organic nitrogen may reduce land use but it may increase
greenhouse gas emissions, whereas there is little or no
Conservation Biology
Volume 0, No. 0, 2020
Goklany 7
emissions increase from boosting yield with inorganic
nitrogen (Balmford et al. 2018).
Despite burgeoning research interest in displacing the
Haber–Bosch process (e.g., Johnson 2018), deploying re-
sulting technologies globally would be challenging be-
cause it annually fixes almost twice as much reactive ni-
trogen globally as natural terrestrial sources (Fowler et al.
2013).
Alternatives to SPs include, for example, crop rota-
tion, pest-resistant crops, pheromones to disrupt pest
reproduction, thermal and mechanical weeding, phys-
ical barriers (plastic fabrics and mulch), and biopesti-
cides derived from naturally occurring biological pre-
cursors (e.g., plants, microbes, fungi, and nematodes).
They include Bt and Bt crops. Since 2010 new biopesti-
cides have entered the market more rapidly than conven-
tional pesticides (McDougall 2018). The SP alternatives,
however, frequently cost more and demand closer mon-
itoring by skilled labor and more frequent applications
(especially for vegetables). Because many biocontrols tar-
get specific pests, they are often incorporated into in-
tegrated pest management, which can include SPs, but
are knowledge and monitoring intensive. This increases
costs and inconvenience and often lowers yields (Moss
2019). Reliance on multiple technologies adds costs and
complexity to operations (McDougall 2018; Damalas &
Koutroubas 2018). Thus, some crops are unprofitable un-
der OA, and many farmers would continue conventional
practices despite recognizing their health and environ-
mental costs (Cabasan et al. 2019). Biopesticides had
only 5% of the global crop protection market in 2019
(IHS Markit 2020. Alternatives, such as thermal weeding,
frequently also require use of FFs or animate power. But
the latter requires additional land for feed and fodder.
Reliance on human labor would also raise costs. Alter-
natively, if labor is expensive, farmers may, instead, culti-
vate more land. Another alternative is using plastic sheets
or mulch for weed control, but plastic is an FF product.
Obtaining plastic or alternative fabrics from plant-based
material would not necessarily relieve pressure on the
land.
Orderly Transition to a FF-Free Agriculture
If FF-dependent technologies contribute at least 62.5%
of GFP, then cutting off FFs would reduce average daily
global food supply per capita from 2917 kcal (in 2017) to
1100 kcal (FAO n.d.)—24% below the average daily food
supply of 1439 kcal per capita for China in 1961 at the
end of its Great (1959–1961) Famine, in which tens of
millions perished and some descended into cannibalism
(Becker 1996).
Even a brief shortfall in food supply, beyond reduc-
ing food security and human well-being, would increase
pressure from hunger beset populations to clear land for
crops worldwide, with potentially disastrous effects on
ecosystems and biodiversity. The effects of such clear-
ing would persist perhaps long after the transition to
a mainly FF-free agriculture (Haddad et al. 2015). Un-
less one deals with nearer-term problems successfully,
addressing longer-term problems may be futile. Transi-
tioning to an FF-free agriculture should, therefore, be ac-
complished in a fashion that precludes significant food
supply shortfalls.
My estimates did not consider that, absent FFs, both
food supplies and population would be lower. But if
food supplies are reduced, it does not necessarily fol-
low that population would be proportionally lower be-
cause medical and public health advances might reduce
mortality from malnutrition. Thus, reduced food supplies
per capita could increase pressure to convert habitat to
cropland, despite a population decrease. In India from
1918 to 1945, food supplies were relatively constant, yet
the population increased by 25% (Cipolla 1978) and life
expectancy rose from 25 to 33 years from 1921 to 1941
(OWID 2019). An increase in population, not matched by
increases in food supplies, would increase hunger and,
therefore, pressure for land conversion. Thus, lower agri-
cultural productivity, while limiting food supplies, could
reduce population and human well-being without neces-
sarily reducing land conversion (Goklany 1998).
Adoption of high-yield seeds, which characterizes the
Green Revolution, require greater use of fertilizers, pes-
ticides, and irrigation to realize seed potential and result
in significant (p<0.01) reductions in infant and adult
mortality rates (i.e., improved health), fertility, and pop-
ulation growth rate, whereas per capita income increases
and harvested area decreases (p<0.1) (Gollin et al.
2018).
If humanity desires to maintain GFP at present levels,
forsaking FF usage could increase habitat loss and, with
it, the already considerable existing threats to ecosys-
tems and biodiversity. It could trigger ecological tipping
points. Barnosky et al. (2012), for example, postulated
a global tipping point at 50% for the transformation of
GLA. Dinerstein et al. (2019) proposed a “global deal for
nature” to formally protect 30% of Earth and designate an
additional 20% as a climate stabilization area by 2030. But
37.4% of GLA is already under cultivation. An extra 20.4%
of cropland to meet current human needs in the absence
of FFs would push this to at least 57.8%, beyond the pos-
tulated tipping point, and preclude the global-deal-for-
nature target. Similarly, Rockstrom et al. (2009) proposed
a safe “planetary boundary” limit of 15% for cropland,
less than half of the 32.7% of GLA I estimated would be
needed to meet current demand absent FFs. For perspec-
tive on these numbers, 14.6% of GLA is designated as
protected for nature conservation (UNEP-WCMC & IUCN
2019).
Thus, the increase in agricultural productivity realized
through FF use, advertently (via SNFs and SPs) or in-
advertently (via CO2fertilization), may paradoxically be
Conservation Biology
Volume 0, No. 0, 2020
8Habitat Loss
the single most effective strategy for conserving nature,
notwithstanding all its other threats to natural ecosys-
tems. However, it does not necessarily follow that FFs are
a net plus ecologically or from a conservation perspec-
tive. To make such a determination requires a compre-
hensive benefit–cost analysis that would include consid-
eration of CO2emissions from additional land converted
to agriculture and its broader effects via climate change,
which could be substantial (Hannah et al. 2020). Efforts
to limit FF use should recognize that among the unin-
tended consequences might be greater loss of biodiver-
sity due to additional land conversion needed to maintain
global food supplies, which could also counteract some
hoped-for climate change gains or it could lead to higher
food prices that would reduce global food security.
Acknowledgments
I acknowledge, with appreciation, 3 anonymous review-
ers for their constructive criticism, which have substan-
tially improved this paper.
Literature Cited
APCAS (Asia and Pacific Commission on Agricultural Statistics). 2016.
Issues in the collection of FAO data (APCAS/16/4.2). Statistics Divi-
sion, Food and Agriculture Organisation, Rome, Italy.
Ainsworth EA, Lemonnier P, Wedow JM. 2020. The influence of rising
tropospheric carbon dioxide and ozone on plant productivity. Plant
Biology 22:5–11.
Allen LH, Kimball BA, Bunce JA, Yoshimoto M, Harazono Y, Baker JT,
Boote KJ, White JW., 2020. Fluctuations of CO2in Free-Air CO2En-
richment (FACE) depress plant photosynthesis, growth, and yield.
Agricultural and Forest Meteorology 284:107899.
Ausubel JH. 2015. Power density and the nuclear opportunity. Electric
Power Research Institute, Washington, D.C.
Balmford A, et al. 2018. The environmental costs and benefits of high-
yield farming. Nature Sustainability 1:477–485.
Barnosky AD, et al. 2012. Approaching a state shift in Earth’s biosphere.
Nature 486:52–58.
Becker J. 1996. Hungry ghosts: Mao’s secret famine. Free Press, New
York .
Brookes G, Barfoot P. 2018. Farm income and production impacts of
using GM crop technology 1996–2016. GM Crops & Food 9:59–89.
Cabasan MTN, Tabora JAG, Cabatac N, Jumao-As CM, Soberano JO,
Turba JV, Dagamac NHA, Barlaan E. 2019. Economic and ecologi-
cal perspectives of farmers on rice insect pest management. Global
Journal of Environmental Science and Management 5:31–42.
(CBD) Center for Biological Diversity. 2019. 600+environmental
groups urge Congress to phase out fossil fuels. Ecowatch, 10 Jan-
uary. Available from https://www.ecowatch.com/environmental-
groups-congress-fossil- fuels-2625636784.html (accessed Septem-
ber 2019).
Chen XM, Liang QM, Liu LC, Wang C, Xue MM. 2019. Critical structural
adjustment for controlling China’s coal demand. Journal of Cleaner
Production 235:317–327.
Ciais P, et al. 2013. Carbon and other biogeochemical cycles. Pages
465–570 in Stocker TF, et al., editors. Climate change 2013: the
physical science basis. Contribution of Working Group I to the
Fifth Assessment Report of the Intergovernmental Panel on Climate
Change. Cambridge University Press, Cambridge, United Kingdom.
Cipolla CM. 1978. The economic history of world population. Har-
vester Press, Brighton, United Kingdom.
Clark M, Tilman D. 2017. Comparative analysis of environmen-
tal impacts of agricultural production systems, agricultural in-
put efficiency, and food choice. Environmental Research Letters
12:064016.
Damalas CA, Koutroubas SD. 2018. Current status and recent devel-
opments in biopesticide use. Agriculture 8:13. https://doi.org/10.
3390/agriculture8010013.
Dinerstein E, et al. 2019. A global deal for nature: guiding principles,
milestones, and targets. Science Advances 5:eaaw2869.
Erisman J W, Sutton MA, Galloway J, Klimont Z, Winiwarter W. 2008.
How a century of ammonia synthesis changed the world. Nature
Geoscience 11:636–639.
FAO (Food and Agriculture Organization). 2019a. FAOSTAT database.
FAO, Rome, Italy. Available from http://www.fao.org/faostat/en/
#data. (accessed June 2019).
FAO (Food and Agriculture Organization). 2019b. Did you know…?
Facts and figures about. FAO, Rome, Italy. Available from
http://www.fao.org/nr/water/aquastat/didyouknow/index3.stm
(accessed September 2019).
FAO (Food and Agriculture Organization). 2014. The state of food and
agriculture 2014. FAO, Rome, Italy.
FAO (Food and Agriculture Organization). n.d. FAO indices of agri-
cultural production. Available from http://www.fao.org/waicent/
faostat/agricult/indices-e.htm (accessed May 2020).
Fess TL, Benedito VA. 2018. Organic versus conventional cropping sus-
tainability: a comparative system analysis. Sustainability 10:272.
FiBL (Research Institute of Organic Agriculture). 2019. Data on or-
ganic agriculture in the world 2000–2018. FiBL, Frick, Switzerland.
Available from https://statistics.fibl.org/world.html (accessed April
2020).
Fowler D, et al. 2013. The global nitrogen cycle in the twenty-first cen-
tury. Philosophical Transactions of the Royal Society B: Biological
Sciences 368:20130164.
FWS (Fish and Wildlife Service). 2018. Energy development.
Available from https://www.fws.gov/ecological- services/energy-
development/solar.html (accessed May 2020).
FriedmanL, Trip G. 2019. A new deal at once possibleand problematic.
The New York Times, 21 February:A1.
Goklany IM. 1998. Saving habitat and conserving biodiversity on a
crowded planet. BioScience 48:941–953.
Goklany IM. 2012. Humanityunbound: how fossil fuels saved humanity
from nature and nature from humanity. Policy Analysis 715. Cato
Institute, Washington, D.C.
Goldewijk KK, Beusen A, Van Drecht G, De Vos M. 2011. The HYDE
3.1 spatially explicit database of human-induced global land-use
change over the past 12,000 years. Global Ecology and Biogeogra-
phy 20:73–86.
Gollin D, Hansen CW, Wingender A. 2018. Two blades of grass: the
impact of the green revolution (No. w24744). National Bureau of
Economic Research, Cambridge, Massachusetts.
Green RE, Cornell SJ, Scharlemann JP, Balmford A. 2005. Farming and
the fate of wild nature. Science 307:550–555.
Haddad NM, et al. 2015. Habitat fragmentation and its lasting impact
on Earth’s ecosystems. Science Advances 1:e1500052.
Hannah L, et al. 2020. The environmental consequences of climate-
driven agricultural frontiers. PLOS ONE 15(e0228305) https://doi.
org/10.1371/journal.pone.0228305.
Idso C. 2013. The positive externalities of carbon dioxide: estimating
the monetary benefits of rising atmospheric carbon dioxide con-
centrations on global food production. Center for the Study of Car-
bon Dioxide and Global Change, Phoenix, Arizona.
IFGC [Iowa Forage & Grassland Council]. 2010. Ten ways to
get more grass production from pasture. IFGC, Des Moines,
Conservation Biology
Volume 0, No. 0, 2020
Goklany 9
Iowa. Available from https://iowaforage.org/2010/11/ten-ways-to-
get-more-grass- production-from- pasture/ (accessed May 2020).
IHS Markit. 2020. Pesticides market analysis. IHSMarkit, London. Avail-
able from https://agribusiness.ihsmarkit.com/sectors/crop-science/
pesticides.html (accessed June 2020).
IPCC (Intergovernmental Panel on Climate Change). 2013. Climate
change 2013: the physical science basis. Cambridge University
Press, Cambridge, United Kingdom.
IPCC (Intergovernmental Panel on Climate Change). 2014. Climate
change 2014: impacts, adaptation, and vulnerability. Cambridge
University Press, Cambridge, United Kingdom.
IEA (International Energy Agency). 2018. Key world energy statistics.
IEA, Paris, Italy.
ISAAA (International Service for the Acquisition of Agri-
biotech Applications). 2016. Global status of commercialized
biotech/GM crops: 2016. ISAAA Brief 52. Available from https:
//www.isaaa.org/resources/publications/briefs/52/download/isaaa-
brief-52- 2016.pdf (accessed June 2019).
Johnson B. 2018. Billionaires and bacteria are racing to save us from
death by fertilizer. Available from https://geneticliteracyproject.
org/2018/10/12/billionaires-and-bacteria-are- racing-to- save-us-
from-death-by-fertilizer/ (accessed June 2020).
Koning NBJ, et al. 2008. Long-term global availability of food: contin-
ued abundance or new scarcity? NJAS-Wageningen Journal of Life
Sciences 55:229–292.
Lamb A, et al. 2016. The potential for land sparing to offset greenhouse
gas emissions from agriculture. Nature Climate Change 6:488–492.
Maddison A. 2010. Historical Statistics of the World Economy: 1–2008
AD. Available from http://www.ggdc.net/maddison/Historical_
Statistics/horizontal-file_02- 2010.xls (accessed January 2020).
McDougall P. 2018. Evolution of the crop protection industry since
1960. Vineyard Business Centre, Midlothian, United Kingdom.
Meemkem EM, Qaim M. 2018. Organic agriculture, food security, and
the environment. Annual Review of Resource Economics 10:39–63.
Millennium Ecosystem Assessment. 2005. Ecosystems and human well-
being. Synthesis. Island Press, Washington, D.C.
MossS. 2019. Integrated weedmanagement (IWM): why are farmers re-
luctant to adopt non-chemical alternatives to herbicides? Pest Man-
agement Science 75:1205–1211.
Mueller SM, Messina CD, Vyn TJ. 2019. Simultaneous gains in grain
yield and nitrogen efficiency over 70 years of maize genetic im-
provement. Scientific Reports 9:1–8.
NOAA (National Oceanic and Atmospheric Administration). 2019.
Trends in atmospheric carbon dioxide. Available from https://www.
esrl.noaa.gov/gmd/ccgg/trends/.
NRC (National Research Council). 2010. Hidden costs of energy:
unpriced consequences of energy production and use. National
Academies Press, Washington, D.C.
Oerke EC. 2006. Crop losses to pests. The Journal of Agricultural Sci-
ence 144:31–43.
Olmstead AL, Rhode PW. 2001. Reshaping the landscape: the impact
and diffusion of the tractor in American agriculture, 1910–1960.
Journal of Economic History 61:663–698.
OWID (Our World in Data). 2019. Life expectancy. Available
from https://ourworldindata.org/life-expectancy (accessed January
2020).
Paini DR, Sheppard AW, Cook DC, De Barro PJ, Worner SP, Thomas
MB. 2016. Global threat to agriculture from invasive species.
Proceedings of the National Academy of Sciences 113:7575–
7579.
Phalan B, Onial M, Balmford A, Green RE. 2011. Reconciling food pro-
duction and biodiversity conservation: land sharing and land spar-
ing compared. Science 333:1289–1291.
Polley HW, et al. 2019. CO2enrichment and soil type additively regu-
late grassland productivity. New Phytologist 222:183–192.
Porter JR, et al. 2014. Food security and food production systems.
Pages 485–533 in Field CB, et al., editors. Climate change 2014:
impacts, adaptation, and vulnerability. Cambridge University Press,
Cambridge, United Kingdom.
Rehbein JA, Watson JE, Lane JL, Sonter LJ, Venter O, Atkinson SC, Allan
JR. 2020. Renewable energy development threatens many globally
important biodiversity areas. Global Change Biology 26:3040–3051.
Rockström J, et al. 2009. A safe operating space for humanity. Nature
461:472–475.
Schiferl LD, Heald CL, Kelly D. 2018. Resource and physiological
constraints on global crop production enhancements from atmo-
spheric particulate matter and nitrogen deposition. Biogeosciences
15:4301–4315.
See L, et al. 2015. Improved global cropland data as an essential ingre-
dient for food security. Global Food Security 4:37–45.
Seufert V, Ramankutty N. 2017. Many shades of gray—the context-
dependent performance of organic agriculture. Science Advances
3:e1602638.
Shah A, Askegaard M, Rasmussen IA, Jimenez EM, Olesen JE. 2017. Pro-
ductivity of organic and conventional arable cropping systems in
long-term experiments in Denmark. European Journal of Agronomy
90:12–22.
Tilman D, Balzer C, Hill J, Befort BL. 2011. Global food demand and
the sustainable intensification of agriculture. Proceedings of the Na-
tional Academy of Sciences 108:20260–20264.
Trading Economics. 2020. European Union imports from Chile. Avail-
able from https://tradingeconomics.com/european-union/imports/
chile (accessed May 2020).
UNEP-WCMC and IUCN. 2019. World database on protected areas.
Available from https://www.protectedplanet.net/c/unep- regions
(accessed June 2019).
von Caemmerer S, Quick WP, Furbank RT. 2012. The development of
C4 rice: current progress and future challenges. Science 336:1671–
1672.
World Bank. 2011. Global strategy to improve agricultural and rural
statistics. Report No. 56719-GLB. World Bank, Washington, D.C.
Yara. 2018. Fertilizer industry handbook. Available from
https://www.yara.com/siteassets/investors/057-reports- and-
presentations/other/2018/fertilizer-industry- handbook-2018-with-
notes.pdf/ (accessed April 2020).
Zhu Z, et al. 2016. Greening of the Earth and its drivers. Nature climate
change 6:791–795.
Ziesemer J. 2007. Energy use in organic food systems. Natural Re-
sources Management and Environment Department, Food and Agri-
culture Organization of the United Nations, Rome, Italy.
Conservation Biology
Volume 0, No. 0, 2020
A preview of this full-text is provided by Wiley.
Content available from Conservation Biology
This content is subject to copyright. Terms and conditions apply.
