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Interdisciplinary Environmental Review, Vol. 11, Nos. 2/3, 2010
Population, poverty, environment, and climate
dynamics in the developing world
Jason Bremner*
Population Reference Bureau,
1875 Connecticut Ave., NW/Suite 520,
Washington, DC, 20009-5728, USA
Fax: 202-328-3937
E-mail: [email protected]
*Corresponding author
David López-Carr
Department of Geography,
Human-Environment Dynamics Lab,
4836 Ellison Hal, UC Santa Barbara, CA, 93106-4060, USA
E-mail: [email protected]
Laurel Suter and Jason Davis
Department of Geography,
Human-Environment Dynamics Lab,
4840 Ellison Hal,
UC Santa Barbara, CA, 93106-4060, USA
E-mail: [email protected]
E-mail: [email protected]
Abstract: This paper reviews extant evidence and offers a conceptual
framework for the investigation of complex dynamics among human
population growth, environmental degradation, poverty, and climate change.
The paper introduces theories relating to population growth, environmental
degradation, the impact on human well-being, and potential relations with
climate change. Poverty is discussed in detail as both a contributing factor to
and consequence of population growth and environmental change. The
empirical literature on land cover change and environmental change in coastal
and marine resources and potential relations with climate change are examined.
Despite notable limitations to current knowledge on links among population
growth, ecosystems, climate, and poverty, implications for further research and
policy application are rich.
Keywords: climate; population; poverty; development; environment;
developing world; land use and land cover change; coastal and marine
resources.
Reference to this paper should be made as follows: Bremner, J.,
López-Carr, D., Suter, L. and Davis, J. (2010) ‘Population, poverty,
environment, and climate dynamics in the developing world’, Interdisciplinary
Environmental Review, Vol. 11, Nos. 2/3, pp.112–126.
Copyright © 2010 Inderscience Enterprises Ltd.
Population, poverty, environment, and climate dynamics
113
Biographical notes: Jason Bremner is the Program Director for population,
health and environment at Population Reference Bureau.
David López-Carr is an Associate Professor at the Human-Environment
Dynamics Lab, Department of Geography.
Laurel Suter is a PhD candidate in the Department of Geography at the
University of California at Santa Barbara.
Jason Davis is a Researcher at the University of California at Santa Barbara.
1
Introduction
The world’s population of nearly one billion in 1800 has grown to approximately
6.9 billion today, and population projections suggest that the world population will fall
somewhere between 7.5 and 10.5 billion by 2050, depending on changes in national level
fertility and mortality rates (UNPD, 2009). All of the world’s net population growth over
the coming 40 years will occur in cities in less developed countries.
At the same time the ecosystems that support people’s livelihoods and well-being are
being rapidly degraded. The recently completed Millennium Ecosystem Assessment
examined 24 critical ecosystem services upon which humans depend for their well-being
and found that 60% were being degraded or used unsustainably (2005). The impacts of
degraded ecosystem services are being disproportionately borne by the poor, are a
principal factor contributing to poverty, and are a barrier to achieving the Millennium
Development Goals set by the United Nations (MEA, 2005). Population growth is
identified as one of the key indirect drivers of the degradation of these ecosystem
services. Population growth itself, however, remains an insufficient explanation of the
relationship between population, ecosystems, and poverty. Increases in human population
size have dynamic, non-linear impacts on the environment, with feedbacks, thresholds,
and synergies amplifying risk and speeding environmental degradation beyond the rate of
population growth (Harte, 2007).
Nonetheless, current trends in population growth and ecosystem health suggest a
challenging future for the world’s poorest. More than 1.4 billion people live in extreme
poverty (less than US$1 per day) (Chen and Ravillion, 2008), and many of them depend
on degraded ecosystems. Furthermore, the poor are more vulnerable to further declines in
ecosystem services (MEA, 2005), as their livelihood strategies are significantly more
likely to be dependent upon the natural resource base (Hope, 2002; Sen, 1981). And
environmental degradation leaves especially the most poor vulnerable to natural disasters.
The goal of this paper then is to further describe the complex relationships among
human population growth, environmental degradation, and poverty, and its potential
feedbacks with climate change. The chapter begins with a discussion of several theories
on the relation between population growth, environmental degradation, the impact on
human well-being, and its impact on climate change. Poverty is then discussed in more
detail as both a contributing factor to and consequence of population growth and
environmental change. Empirical examples related to land cover change and coastal and
marine resources and their potential relations with climate change are examined to
illustrate the complexity and diversity of these dynamics. We limit this discussion to rural
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environments and to direct resource exploitation as opposed to indirect effects, though
underlying relationships will be touched upon. The paper concludes with a brief
discussion of the limitations of current knowledge on the links among population growth,
ecosystems, climate, and poverty and the implications for future research and policy.
2
Theory: population growth, climate change, and poverty
The connections that bind human and natural systems are innumerable, but arguably one
of the most discussed through human history has been the ever increasing size of the
human population and its relation with the natural resources upon which it depends.
Modern theories on the association between population growth and the environment date
to 1798, with Thomas Malthus’s statement that, “The power of population is indefinitely
greater than the power in the earth to produce subsistence for man”.
Malthus envisioned an impending doomsday scenario where excessive human
population growth would overtax a limited supply of natural resources (Malthus, 1798).
He argued that agricultural production grows geometrically and arable land is finite while
population growth is exponential. He hypothesised that as human numbers grew, food
supplies would be insufficient to feed humankind and human numbers would be pushed
back below the carrying capacity of agricultural systems by “positive and preventative
checks.” Positive checks would encompass increases in mortality due to outbreaks of
disease, famine, higher infant mortality, malnutrition, and war. Preventative checks
would include lowering of fertility through delays in marriage, contraception, abortion,
and infanticide.
The agronomist Ester Boserup countered Malthus’ contentions and described an
alternate response of humans and their agricultural systems to increasing population
growth (Boserup, 1965, 1981, 1990). Boserup argued that humans would respond to the
food demands of a growing population by intensifying land use, increasing agricultural
yields, and developing new agricultural technologies. Examples of agricultural
intensification include multi-cropping, increased labour to land ratios, and the
development and use of better tools, irrigation systems and soil amendments. Boserup
thus argued that there are no limits to human population growth assuming sufficient
changes in agricultural systems. Boserup, however, largely overlooked Ricardo’s law of
diminishing returns, did not discuss poverty as a barrier to intensification, and ignored
other natural systems such as forests, oceans, rangelands, and freshwater ecosystems
upon which humans depend.
3
Population-poverty-environment relationships
Recent research on demographics, livelihoods, and the environment has suggested
the use of a livelihoods approach as an organising framework to examine
population-environment relationships. The livelihoods framework characterises
households as making decisions regarding livelihood activities based on available natural,
social, human, physical, and financial capital (Ellis, 2000). The examination of different
types of capital allows for a more complete understanding of population, poverty, and
environment relationships. de Sherbinin et al. (2008) have demonstrated that the
livelihoods framework can be applied to assess a vicious circle model (VCM) of
Population, poverty, environment, and climate dynamics
115
population, poverty, and environment. According to the VCM, positive feedbacks at the
household level among population growth, poverty, and environmental degradation lead
to a downward spiral for poor households. The VCM concept of multiple feedbacks is
useful and encourages examination of not just how population growth impacts on the
environment, but also how population growth affects poverty, poverty affects population
growth, poverty affects environmental degradation, environmental degradation affects
population growth, and environmental degradation affects poverty.
The importance of this feedback cycle and its contribution to climate change will be
examined here relative to direct impact on the natural resource base. Human modification
of land cover accounts for approximately 35% of the anthropogenic contribution to C02
emissions (Houghton and Hackler, 2001). Conversely, locally felt effects of climate
change may necessitate a shifting of livelihood strategy from a changing resource base, or
may engender a demographic response such as out-migration. Climate change as
represented in greater frequency and magnitude of precipitation and drought can effect
population and poverty through changes in access to environmental services as depicted
in Figure 1 below.
Figure 1 The VCM
Climate
Population
Environment
Poverty
3.1 How population growth affects poverty
Conceptually high fertility can be envisioned as contributing to the poverty of households
through several mechanisms: health and educational needs of large numbers of children
generally reduce household savings rates and reduce investments in production activities;
high fertility lowers female labour force participation and thus tends to decrease
household income; finally, population growth due to high fertility may exacerbate
resource scarcity in areas where a large proportion of the population already relies on
natural resource-based livelihoods including, agriculture, grazing, forest products, and
fishing for income and subsistence on marginal lands and less productive natural
ecosystems (MEA, 2005). In addition to strain on the natural resource base, rising
population also creates challenges for the equitable provisioning of adequate schooling,
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material resources, and civic order, thereby straining social conditions. Degraded social
order impedes problem solving for environmental problems, causing further strain
(Harte, 2007). Empirical research examining population growth’s impact on poverty,
however, is still largely inconclusive, and the results of a set of nearly 60 recently
initiated studies examining the relationship through the Population and Poverty Research
Network are not yet published.
3.2 How poverty affects environmental change
Poverty may also limit the responses that households have to environmental change
(Carr, 2008). Impoverished households may be less likely to have adequate land
resources to parcel to offspring, and have fewer resources to be able to obtain new land.
They may also have little access to the financial capital necessary to intensify resource
use through technological or physical inputs, invest in new agricultural products and
techniques in response to changing markets, or have the means of accessing those
markets. Finally, poor households are less likely to have the financial and human capital
necessary to migrate elsewhere in search of land or employment in response to limited
local opportunity.
3.3 How poverty contributes to population growth
Poverty may contribute to higher fertility as well (Birdsall et al., 2001). Infant mortality
in poor households tends to be higher than national averages meaning that poor families
may perceive the need to have more births in order to achieve desired family size (Palloni
and Rafalimanana, 1999). Furthermore, women in poor households are less likely to have
knowledge of and access to means of preventing unwanted pregnancies (Dreze and
Murthi, 2001). Finally, young women from poor households are more likely to marry
early and have less education, both of which are associated with higher fertility in most
contexts (Davis, 1963).
3.4 How environmental change affects population growth
The effect of environmental change on fertility and population growth has received
limited scholarly attention. There are some indications that land scarcity may result in
couples making decisions to reduce fertility, but empirical evidence is still lacking and
further research is needed (Shreffler and Nii-Amoo Dodoo, 2009). Water and fuel wood
scarcity results in women and girls spending more time gathering water and fuel wood.
More time allocated to gathering resources may affect girls schooling and women’s
labour force participation both of which are importantly related to fertility. Little
evidence, however, illustrates these relationships (Sutherland et al., 2004). One way in
which environmental degradation, including that which contributes to or results from
climate change, can have a strong and rapid impact on positive population growth is in
the form of contributing to people migrating due to worsening environmental conditions.
3.5 How population growth affects environmental change
Population growth is a frequently cited culprit of environmental change. Population
growth is generally recognised as an important contributing factor to land cover change
Population, poverty, environment, and climate dynamics
117
though the importance of this relationship has been the subject of some debate
(Houghton, 1991; Myers, 1991; Vanclay, 1993; Wibowo and Byron, 1999). Some have
declared population growth and poverty to be the primary causes of global deforestation
(Allen and Barnes, 1985; Amelung and Diehl, 1992; Mather and Needle, 2000), while
others recognise population growth and poverty as underlying factors (Geist and Lambin,
2002; Lambin et al., 2001; Rudel and Roper, 1996). As discussed below, however, the
relationship between population growth and environmental change is rarely a directly
proportional relationship, as it is influenced by population dynamics, consumption
patterns, and mediated by institutions.
3.6 How environmental change affects poverty
Poorer rural populations tend to be more dependent on their natural resource environment
and therefore are more vulnerable to changes in their environment, whether it be as a
result of climate change or as a result of a locally felt phenomena which alters their
landscape (Eakin and Lemos, 2010).
In all of the relationships discussed above, attention to spatial and temporal scale is
important, as relationships often do not hold across changing scale. For example,
numerous multi-country studies have professed a strong connection between population
growth, deforestation and other forms of land cover change at the national level
(Amelung and Diehl, 1992; Rudel and Roper, 1997) but when viewed at finer scales (e.g.,
regional, community, and household levels) fewer studies have identified a strong linkage
(Carr, 2002; Rindfuss et al., 2004). Temporal factors may also result in mixed findings as
evidence of changes in ecosystems may take years or many decades to develop while
demographic processes can shift dramatically on the scale of a human generation.
Underlying political, economical, and institutional factors may also contribute to
population growth, poverty, and environment relationships. While proximate population
growth can drive the expansion of natural resource extraction from local ecosystems,
multifaceted underlying factors that exert their influence may actually be significant
drivers of ecosystem degradation (Geist and Lambin, 2002). For example, a frontier
farmer may expand his agricultural holdings deeper into primary forests to properly
provide for his family, but outside factors such as displacement from other regions,
facilitating land distribution policies (or lack there of), improved access due to expanding
roads, and global demand for agricultural and forest resources also underlie farmers’
decisions (Carr, 2004; Geist and Lambin, 2001). All together, the theories and challenges
suggest few simple statements regarding population growth, poverty, and environment
relationships. Understanding linked human-natural systems demands specific knowledge
of local patterns, processes, and underlying factors.
4
Empirical observations of population growth, poverty, and climate
interactions
4.1 Population growth, poverty, and land cover change
The shift of hunter-gathers to agriculture launched a cycle of change that has had the
largest impact on land cover in the history of humankind (Davis, 2006; Myers, 1991;
Parsons, 1994). Today more than 40% of the world’s surface is under agriculture
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(Ramankutty and Foley, 1999; Sanderson et al., 2002), and forest clearing for agricultural
expansion in the tropics is currently the most significant land conversion happening on
Earth (Geist and Lambin, 2002). It is estimated that 85% of the land surface is human
impacted to some degree (Sanderson et al., 2002). Environmental models have
demonstrated that large-scale deforestation may result in a warmer and drier climate
(Nobre et al., 1991), both on the local scale and through positive feedbacks towards
global warming. We therefore first examine potential population links to tropical
deforestation.
4.2 Population effects on deforestation
Surveys reveal high rates of fertility throughout remote rural areas of the Amazon
(Bremner and Dorelien, 2008), and it is likely that high fertility in the Amazon will
contribute to deforestation for years to come as the children of colonists create new
households, clear land, and migrate to new areas of the frontier (Barbieri and Carr, 2005).
Few studies, however, have examined how fertility and the migration of children are
related to local land availability or perceptions of land availability, and this represents a
next step in understanding relationships among fertility, poverty, and the environment
(de Sherbinin et al., 2008). Yet in a review of 152 case studies of tropical deforestation,
Geist and Lambin (2002) report that population growth is just one of numerous factors
that act synergistically to cause tropical deforestation. Population growth and poverty
interact with a host of economic, environmental, political, and sociological factors to
effect land-cover change (Lambin et al., 2001; Turner et al., 2001). Economic
inducements include the basic desire for products of consumption (timber, fuelwood and
agricultural products), but they also include market failures, the desire of national
governments to generate capital, and the lack of economic disincentives to prevent
deforestation (cheap land, labour and fuel). Other factors of import include political
inducements to colonise forested lands and cultural factors that deemphasise the intrinsic
value of these habitats (Geist and Lambin, 2002).
4.3 Poverty effects on land cover change
On marginal lands the rural poor often find themselves pushed to over-exploit the natural
resource environment through low-input and low productivity agricultural practices such
as deforestation, overgrazing, and soil-mining, which may contribute to land degradation
(UNFPA, 2001). Indigenous populations manage 25% of the remaining forests of the
Amazon and are characterised by high fertility and extreme poverty. Relatively little is
known about indigenous resource management institutions and their resilience in the face
of population growth and poverty (Bremner and Lu, 2006). Future research may fruitfully
explore relationships between land use and other natural resources among these important
and rapidly changing populations (Bremner et al., 2009; Gray et al., 2008).
At the household level positive correlations between high fertility, poverty, and
deforestation are often assumed, but the relationships have not been so clear-cut
(de Sherbinin et al., 2007). In the Ecuadorian Amazon lower fertility among colonist
households was associated with larger plots of cleared land, secure tenure, and more
wealth (Carr et al., 2006), while in other settings negative and/or neutral associations
between household fertility, poverty, and land holdings are observed (Carr et al., 2005).
In most cases these mixed results do not seem to support the VCMs predictions of
Population, poverty, environment, and climate dynamics
119
positive feedbacks leading to spiralling poverty and deforestation, but rather indicate the
complexities of local context in determining population, poverty, and environment
relationships.
4.4 Poverty and environmental effects on population
It is noteworthy that the majority of the rural poor inhabit low-potential land, with 60% of
the rural poor in fragile and vulnerable areas such as arid and semi-arid lands, steep
slopes, or in forests. The reason behind this is usually a combination of factors which
vary from country to country, but which often includes demographics (United Nations,
1995). Two studies have shown that rising labour requirements associated with rising
scarcity of open access resources (such as firewood) are associated with higher fertility
and in some cases additional births during the period of study. This has been noted in
Pakistan (Filmer and Pritchett, 2002) and in Nepal (Biddlecom et al., 2005). There is also
evidence that in impoverished rural settings where there is an immediate dependence on
open access natural resources for meeting basic needs such as fuelwood, fodder, and
water, that human capital in the form of additional children may be complimentary to the
open access nature of the natural capital (de Sherbinin et al., 2008).
In sum, population and poverty processes are intimately linked to land cover change
both as drivers and outcomes. Consonant with the vicious cycle model, deforestation
exacerbates climate change while a warming climate may in turn accelerate forest loss.
When population growth and poverty interact with these processes climate change may
speed up and make more salient the vicious cycle dynamics of human-environment
systems. We now turn to coastal ecosystems and potential links among climate change,
population, poverty, and the environment.
5
Population growth, poverty, climate, and coastal and marine
environments
Given that historic and contemporary trends of worldwide population distribution show
increasing human settlements in coastal zones, and given the ecological importance of
these coastal zones for both local and remote populations, these areas merit greater
attention (Cassels et al., 2005). Yet the overwhelming majority of studies examining
population impact on the environment have focused on the terrestrial environment,
largely ignoring coastal and marine resources which are more and more subject to human
population pressures and concomitant poverty. Human populations settle preferentially in
coastal areas, with 33.5% of the 1994 population living within 100 vertical meters of sea
level, despite this area occupying only 15.6% of all inhabited land (Cohen and Small,
1998). The 1992 United Nations Conference on Environment and Development consider
the rapidly growing coastal population a priority area of concern for sustainable
development and the environment (Cassels et al., 2005). Most population growth along
coastlines is not attributable to natural increase, but instead to in-migration and
urbanisation (Hinrichsen, 1998). Coastal ecosystems and coastal cities are often
destination areas for migrants, and many of the world’s largest cities are located along
coasts. As such, most studies which examine population’s impact on coastal and marine
resources examine the role of migrants. The impact migrants have on their destination
environment, however, is not simply a function of the increase in population, but is
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subject to a whole host of mediating factors, such as technology, knowledge systems,
modes of incorporation, kinship, poverty, and resource valuation (Cassels et al., 2005).
5.1 Population effects on the coasts
Concomitant with rising population, world wide coastal areas and marine resources have
suffered widespread damage, spurred on by population pressure and accelerated
economic activity. Coastal resources such as mangroves, fisheries, and tourism oriented
beaches are some of the most prominent areas negatively affected by consumption
practices along coastlines (Naylor et al., 2002). Marine ecosystems are taking hits from
both deliberate destruction and as a sink for refuse. Alterations to land cover, fishing and
harvesting, and pollution associated human settlements and activities contribute to
modifications of the coastal environments (Curran et al., 2002). Human activities have
made their impact on coastal ecosystems: the world lost half of it’s wetlands in the 20th
century (FAO, 2001), 60% of coral reefs are threatened worldwide, most acutely in Asia
(Bryant et al., 1998) and mangroves are being widely destroyed (Curran et al., 2002).
Despite the conventional wisdom that more people exact more damage upon an
environment, the precise mechanisms by which humans effect these changes in coastal
environments is an area of study still under consideration.
Not many studies have addressed household demographic processes, poverty, and
their impact on mangroves. One study was conducted in the island of Kosrae in the
Federated States of Micronesia, where it was hypothesised that changes in the population
size and structure could have significant impacts on the natural resource base when
combined with a decrease in the availability of public sector employment. Mangrove
forests were thought to be potentially vulnerable as economic crowding could have lead
former employees of the public sector to revert to their more traditional sources of
mangrove wood for building and burning, as well as mangrove crabs for consumption
and sale. The researchers found that in contrast to predictions, household consumption of
mangrove resources held steady despite increased population size and a reduction of the
numbers of people in government employment. Researchers attributed this effect largely
to remittance incomes from relatives overseas, import substitution, and/or foraging
elsewhere (upland forest for fuelwood, for example) for household needs traditionally
obtained from mangrove forests (Naylor et al., 2002). Findings of this study, therefore,
provide evidence contrary to the cut and dry notion that equates larger population with
increased degradation of a given natural resource.
Increases in the number of resource users along coasts can have varied impacts on
common pool resources, and the relationship between population and coastal ecosystems
is largely mediated by the institutions (either public or common property institutions) and
social relations that govern local resource use (Curran and Agardy, 2002). In areas in
which institutions are weak, an increase in the number of users or new fishing
techniques introduced by migrants may lead directly to degradation of coastal resources
through direct overharvesting or indirectly by destabilising weak institutions’ abilities to
regulate resources (Begossi, 1998; Bremner and Perez, 2002; Cassels et al., 2005). In
areas where institutions do play an active role in resource management, an increased
number of users may nevertheless result in decreased per capita income and a situation
where institutions and social bonds breakdown as some users employ deleterious
Population, poverty, environment, and climate dynamics
121
fishing methods to maintain their existing income (Curran and Agardy, 2002; Pauly et al.,
1998).
Coral reefs receive much attention for their rapid degradation, resulting both from
rising sea temperature and from large and growing human populations in coastal areas
(Bell et al., 2006). Coral reefs certainly are threatened by climate change, and the human
impacts are also wreaking significant impact via direct mining, overfishing, increased
sediment runoff, pollution, and anchor damage. However, direct human impacts on the
coral reefs are not contributing to climate change (and in fact, may reduce the amount of
greenhouse gasses released to the atmosphere (Gattuso et al., 1999) and therefore will not
be addressed here. Likewise, overexploitation of other coastal and marine resources such
as over-fishing, by-catch, and sea turtle egg harvesting are often unsustainable and carry
deleterious effects for coastal ecosystems but they are not directly contributing to climate
change.
5.2 Poverty effects on coastal environments
It is unsurprising that migration and population growth are often cited as causes of coastal
resource and fisheries degradation (Curran et al., 2002). Coastal population growth,
poverty, and environment relationships differ markedly, however, from the land use
relationships, principally because coastal resources tend to be common pool resources
(Curran and Agardy, 2002). Pauly (1997) describes the population, poverty, and
environmental change responses occurring in many parts of inland Africa, Asia and
South America where high population density in upland areas creates landlessness and
out-migration. He cites examples of Filipino rice farmers, Peruvian Highlanders, and
Senegalese pastoralists, who due to a lack of land or pasture access, are pushed to coasts
where fishing is unrestricted in order to meet subsistence needs.
Like coral reefs, mangroves also serve as a valuable ecological and economic
resource. Mangroves are critical breeding sites for many categories of animals, such as
birds, fish, crustaceans, shellfish, reptiles and mammals. They are a source of wood, and
provide a physical barrier protecting against coastal erosion and serve as a site where
sediments, contaminants, carbon and nutrients accumulate (Alongi, 2002). Mangroves
occupy a relatively miniscule portion of global forested areas (0.4%), but serve as an
important sink for atmospheric CO2 (Bouillon et al., 2008; Komiyama et al., 2002).
Mangroves are extremely productive ecosystems and despite their diminutive land cover
account for around 11% o the total input of terrestrial C into the oceans. Extremely
conservative estimates put their carbon storage in excess of 4.0 gigatons (Jennerjahn and
Ittekkot, 2002), with storage both above and below ground, with rootstock contributing
half or more of the total biomass (Briggs, 1977; Twilley et al., 1992). Despite mangrove
forests’ productive and protective benefits for coastal communities and the global
environment, large swaths have been destroyed in recent decades, totalling almost 50% of
the mangrove forests lost in the past 20 years. As such, they are one the world’s most
endangered landscapes (Osti et al., 2009). Mangrove losses are acutely felt in affected
area, as it means declining fisheries, degradation of clean water, salinisation of coastal
soils, erosion, and land subsidence. Globally, mangrove loss contributes to the release of
stored carbon dioxide into the atmosphere, and the curtailing of future uptakes of CO2
(Barbier and Cox, 2002).
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5.3 Environmental change and poverty effects on population growth
The authors know of no examples specifically linking in situ change of the coastal
environment to population growth. Some portion of environmental migrants or persons
grown impoverished from a degraded environment may settle on the coastal environment,
increasing population in their destination area. But we remain unaware of a study
documenting how a diminished coastal natural resource base resulted in increased family
size in order to increase their ability to partake in the resource, or for that matter whether
diminishing coastal resources were a driver of lower fertility and smaller family size.
6
Conclusions
In this paper we have tried to illustrate the complexities of population growth, poverty,
and environment relationships to climate. Our understanding of these relationships has
progressed greatly from the original Malthusian roots, yet still today few generalisations
can be made unambiguously. VCM scenarios of downward spiralling poverty, population
growth, and environmental degradation exacerbated by climate change appear
oversimplified given the complexity, and perhaps more importantly, the scarcity of
empirical cases. Research has demonstrated across multiple scales that populationenvironment-poverty synergies tend to be non-linear, ecosystem specific, and involve
multiple pathways among population and environmental change, population and poverty,
and poverty and environmental change. Furthermore, in most cases population growth’s
relation to poverty and the environment is mediated by various types of capital available
to households and institutions, culture, and social relations.
Human-tropical forest systems seem to illustrate some aspects of the vicious cycle
model. However, even in well studied systems such as frontiers of the Amazon
relationships tend to vary according to local context and temporal scale. Even less is
understood about population, poverty, and climate linkages in coastal systems or for that
matter desert, grassland, and freshwater systems, which are not discussed here. Human
conversion of mangroves both contributes to climate change and makes populations more
vulnerable to changing weather and sea level rise, but in general coastal systems have not
been well studied in relation to population.
Despite research findings and conceptual changes, neo-Malthusian perspectives,
linear associations, and VCM scenarios still largely dominate public dialogue and
professional development narratives concerning population growth, environmental
change, and concomitant poverty. This gap between research findings and public
knowledge suggests the need for further interdisciplinary human-environment research
examining how, where, and when population growth and poverty interact with climateinduced environmental change. This knowledge is increasingly germane to our
understanding of human-environment systems and potential vicious cycle dynamics.
Additionally, researchers need to strengthen their efforts to communicate what is know
about the complexity of population, poverty, and environment relationships to
policymakers and the public. These communication efforts will ensure that future support
for climate adaptation approaches, policies, and funding priorities don’t depend on overly
simplistic explanations of population, poverty, and environmental change.
Population, poverty, environment, and climate dynamics
123
Acknowledgements
The author would like to thank the reviewers for their inputs to the development of this
manuscript.
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