Environmental effects on humans
Content
lobal climate change will affect people and the environment in many ways. Some o
f these impacts, like stronger hurricanes and severe heat waves, could be life t
hreatening. Others, like spreading weeds, will be less serious. And some effects
, like longer growing seasons for crops, might even be good! However, as the Ear
th keeps getting warmer, the negative effects are expected to outweigh the posit
ive ones.
The more we learn about how climate change will affect people and the environmen
t, the more we can see why people need to take action to reduce the greenhouse g
as emissions that are causing climate change. We can also take steps to prepare
for the changes we know are coming.
Climate change has brought about possibly permanent alterations to our planet s ge
ological, biological and ecological systems.[1] The Intergovernmental Panel on C
limate Change (IPCC) contended in 2003 that there is new and stronger evidence th
at most of the warming observed over the last 50 years is attributable to human
activities .[2] These changes have led to the emergence of large-scale environment
al hazards to human health, such as extreme weather,[3] ozone depletion, increas
ed danger of wildland fires,[4] loss of biodiversity,[5] stresses to food-produc
ing systems and the global spread of infectious diseases.[2] The World Health Or
ganization (WHO) estimates that 160,000 deaths, since 1950, are directly attribu
table to climate change.[6] Many believe this to be a conservative estimate.[7]
To date, a neglected aspect of the climate change debate, much less research has
been conducted on the impacts of climate change on health, food supply, economi
c growth, migration, security, societal change, and public goods, such as drinki
ng water, than on the geophysical changes related to global warming. Human impac
ts can be both negative and positive. Climatic changes in Siberia, for instance,
are expected to improve food production and local economic activity, at least i
n the short to medium term. Numerous studies suggest, however, that the current
and future impacts of climate change on human society are and will continue to b
e overwhelmingly negative.[8][9]
The majority of the adverse effects of climate change are experienced by poor an
d low-income communities around the world, who have much higher levels of vulner
ability to environmental determinants of health, wealth and other factors, and m
uch lower levels of capacity available for coping with environmental change. A r
eport on the global human impact of climate change published by the Global Human
itarian Forum in 2009, estimated more than 300,000 deaths and about $125 billion
in economic losses each year, and indicating that most climate change induced m
ortality is due to worsening floods and droughts in developing countries.[10] Th
is also raises questions of climate justice, since the 50 least developed countr
ies of the world account for not more than 1% of worldwide emissions of greenhou
se gases.[11]
A changing climate impacts our health and wellbeing. The major public health org
anizations of the world have said that climate change is a critical public healt
h problem. Climate change makes many existing diseases and conditions worse, but
it may also help introduce new pests and pathogens into new regions or communit
ies. As the planet warms, oceans expand and the sea level rises, floods and drou
ghts become more frequent and intense, and heat waves and hurricanes become more
severe. The most vulnerable people children, the elderly, the poor, and those wit
h underlying health conditions are at increased risk for health effects from clima
te change. Climate change also stresses our health care infrastructure and deliv
ery systems.
Steps can be taken to lessen climate change ( mitigation ) and reduce its impacts on
our health and the health of future generations ( adaptation ). Some of these steps
can yield benefits for our health, environment, economy, and society at the sam
e time. The federal government has called for efforts to support adaptation and
mitigation of climate change to create healthier, more sustainable communities.
The goals of the NIEHS Climate Change and Human Health Program align with these
efforts.
Health
Main article: Effects of climate change on human health
It has been suggested that this section be merged into Effects of global
warming on human health. (Discuss) Proposed since January 2013.
Climate change poses a wide range of risks to population health - risks that wil
l increase in future decades, often to critical levels, if global climate change
continues on its current trajectory.[6] The three main categories of health ris
ks include: (i) direct-acting effects (e.g. due to heat waves, amplified air pol
lution, and physical weather disasters), (ii) impacts mediated via climate-relat
ed changes in ecological systems and relationships (e.g. crop yields, mosquito e
cology, marine productivity), and (iii) the more diffuse (indirect) consequences
relating to impoverishment, displacement, resource conflicts (e.g. water), and
post-disaster mental health problems.
Climate change thus threatens to slow, halt or reverse international progress to
wards reducing child under-nutrition, deaths from diarrheal diseases and the spr
ead of other infectious diseases. Climate change acts predominantly by exacerbat
ing the existing, often enormous, health problems, especially in the poorer part
s of the world. Current variations in weather conditions already have many adver
se impacts on the health of poor people in developing nations,[13] and these too
are likely to be 'multiplied' by the added stresses of climate change.
A changing climate thus affects the prerequisites of population health: clean ai
r and water, sufficient food, natural constraints on infectious disease agents,
and the adequacy and security of shelter. A warmer and more variable climate lea
ds to higher levels of some air pollutants and more frequent extreme weather eve
nts. It increases the rates and ranges of transmission of infectious diseases th
rough unclean water and contaminated food, and by affecting vector organisms (su
ch as mosquitoes) and intermediate or reservoir host species that harbour the in
fectious agent (such as cattle,[14] bats and rodents). Changes in temperature, r
ainfall and seasonality compromise agricultural production in many regions, incl
uding some of the least developed countries, thus jeopardising child health and
growth and the overall health and functional capacity of adults. As warming proc
eeds, the severity (and perhaps frequency) of weather-related disasters will inc
rease - and appears to have done so in a number of regions of the world over the
past several decades.[15] Therefore, in summary, global warming, together with
resultant changes in food and water supplies, can indirectly cause increases in
a range of adverse health outcomes, including malnutrition, diarrhea, injuries,
cardiovascular and respiratory diseases, and water-borne and insect-transmitted
diseases.
Health equity and climate change have a major impact on human health and quality
of life, and are interlinked in a number of ways. The report of the WHO Commiss
ion on Social Determinants of Health points out that disadvantaged communities a
re likely to shoulder a disproportionate share of the burden of climate change b
ecause of their increased exposure and vulnerability to health threats. Over 90
percent of malaria and diarrhea deaths are borne by children aged 5 years or you
nger, mostly in developing countries.[16] Other severely affected population gro
ups include women, the elderly and people living in small island developing stat
es and other coastal regions, mega-cities or mountainous areas.[11]
Psychological impacts
Further information: Effects of global warming on human health § Mental health
A 2011 article in the American Psychologist identified three classes of psycholo
gical impacts from global climate change:[17]
Direct - "Acute or traumatic effects of extreme weather events and a changed
environment"
Indirect - "Threats to emotional well-being based on observation of impacts
and concern or uncertainty about future risks"
Psychosocial - "Chronic social and community effects of heat, drought, migra
tions, and climate-related con?icts, and postdisaster adjustment"
Extreme weather events
Further information: Extreme weather
El Nino can lead to drastic, though temporary, changes in the environment such a
s temperature fluctuations and flash floods.[18] In addition, with global warmin
g, there has been a marked trend towards more variable and anomalous weather.[ci
tation needed] This has led to an increase in the number and severity of extreme
weather events.[citation needed] This trend towards more variability and fluctu
ation is perhaps more important, in terms of its impact on human health, than th
at of a gradual and long-term trend towards higher average temperature.[18] Infe
ctious disease often accompanies extreme weather events, such as floods, earthqu
akes and drought.[citation needed] These local epidemics occur due to loss of in
frastructure, such as hospitals and sanitation services, but also because of cha
nges in local ecology and environment. For example, malaria outbreaks have been
strongly associated with the El Nino cycles of a number of countries (India and
Venezuela, for example).[citation needed]
Diseases
Further information: Effects of global warming on infectious diseases
Climate change may lead to dramatic increases in prevalence of a variety of infe
ctious diseases. Beginning in the mid-'70s, there has been an emergence, resurgen
ce and redistribution of infectious diseases .[18] Reasons for this are likely mul
ticausal, dependent on a variety of social, environmental and climatic factors,
however, many argue that the volatility of infectious disease may be one of the e
arliest biological expressions of climate instability .[18] Though many infectious
diseases are affected by changes in climate, vector-borne diseases, such as mal
aria, dengue fever and leishmaniasis, present the strongest causal relationship.
Observation and research detect a shift of pests and pathogens in the distribut
ion away from the equator and towards Earth's poles.[19]
Malaria
Increased precipitation can increase mosquito population indirectly by expanding
larval habitat and food supply. Malaria kills approximately 300,000 children an
nually, poses an imminent threat through temperature increase.[20] Models sugges
t, conservatively, that risk of malaria will increase 5-15% by 2100 due to clima
te change.[21] In Africa alone, according to the MARA Project (Mapping Malaria R
isk in Africa),[22] there is a projected increase of 16-28% in person-month expo
sures to malaria by 2100.[23]
Non-climatic determinants
Sociodemographic factors include, but are not limited to: patterns of human migr
ation and travel, effectiveness of public health and medical infrastructure in c
ontrolling and treating disease, the extent of anti-malarial drug resistance and
the underlying health status of the population at hand.[24] Environmental facto
rs include: changes in land-use (e.g. deforestation), expansion of agricultural
and water development projects (which tend to increase mosquito breeding habitat
), and the overall trend towards urbanization (i.e. increased concentration of h
uman hosts). Patz and Olson argue that these changes in landscape can alter loca
l weather more than long term climate change.[20] For example, the deforestation
and cultivation of natural swamps in the African highlands has created conditio
ns favourable for the survival of mosquito larvae, and has, in part, led to the
increasing incidence of malaria.[20] The effects of these non-climatic factors c
omplicate things and make a direct causal relationship between climate change an
d malaria difficult to confirm. It is highly unlikely that climate exerts an iso
lated effect.
Environment
Climate change may dramatically impact habitat loss, for example, arid condition
s may cause the collapse of rainforests, as has occurred in the past.[25]
Temperature
A sustained wet-bulb temperature exceeding 35°, is a threshold at which the resili
ence of human systems is no longer able to adequately cool the skin. A study by
NOAA from 2013 concluded that heat stress will reduce labor capacity considerabl
y under current emissions scenarios.[26]
Water
See also: Water crisis
The freshwater resources that humans rely on are highly sensitive to variations
in weather and climate. In 2007, the IPCC reported with high confidence that cli
mate change has a net negative impact on water resources and freshwater ecosyste
ms in all regions.[27] The IPCC also found with very high confidence that arid a
nd semi-arid areas are particularly exposed to freshwater impacts.[27]
As the climate warms, it changes the nature of global rainfall, evaporation, sno
w, stream flow and other factors that affect water supply and quality. Specific
impacts include:
Warmer water temperatures affect water quality and accelerate water pollutio
n.[28]
Sea level rise is projected to increase salt-water intrusion into groundwate
r in some regions. This reduces the amount of freshwater available for drinking
and farming.[28][29]
In some areas, shrinking glaciers and snow deposits threaten the water suppl
y.[30] Areas that depend on melted water runoff will likely see that runoff depl
eted, with less flow in the late summer and spring peaks occurring earlier.[28]
This can affect the ability to irrigate crops. (This situation is particularly a
cute for irrigation in South America,[31] for irrigation and drinking supplies i
n central Asia, and for hydropower in Norway, the Alps, and the Pacific Northwes
t of North America.)
Increased extreme weather means more water falls on hardened ground unable t
o absorb it, leading to flash floods instead of a replenishment of soil moisture
or groundwater levels.
Increased evaporation will reduce the effectiveness of reservoirs.
At the same time, human demand for water will grow for the purposes of cooli
ng and hydration.
Displacement and migration
See also: Environmental migrant
A refugee camp.
Climate change causes displacement of people in several ways, the most obvious and
dramatic being through the increased number and severity of weather-related disas
ters which destroy homes and habitats causing people to seek shelter or liveliho
ods elsewhere. Effects of climate change such as desertification and rising sea
levels gradually erode livelihood and force communities to abandon traditional h
omelands for more accommodating environments. This is currently happening in are
as of Africa s Sahel, the semi-arid belt that spans the continent just below its n
orthern deserts. Deteriorating environments triggered by climate change can also
lead to increased conflict over resources which in turn can displace people.[32
]
f these impacts, like stronger hurricanes and severe heat waves, could be life t
hreatening. Others, like spreading weeds, will be less serious. And some effects
, like longer growing seasons for crops, might even be good! However, as the Ear
th keeps getting warmer, the negative effects are expected to outweigh the posit
ive ones.
The more we learn about how climate change will affect people and the environmen
t, the more we can see why people need to take action to reduce the greenhouse g
as emissions that are causing climate change. We can also take steps to prepare
for the changes we know are coming.
Climate change has brought about possibly permanent alterations to our planet s ge
ological, biological and ecological systems.[1] The Intergovernmental Panel on C
limate Change (IPCC) contended in 2003 that there is new and stronger evidence th
at most of the warming observed over the last 50 years is attributable to human
activities .[2] These changes have led to the emergence of large-scale environment
al hazards to human health, such as extreme weather,[3] ozone depletion, increas
ed danger of wildland fires,[4] loss of biodiversity,[5] stresses to food-produc
ing systems and the global spread of infectious diseases.[2] The World Health Or
ganization (WHO) estimates that 160,000 deaths, since 1950, are directly attribu
table to climate change.[6] Many believe this to be a conservative estimate.[7]
To date, a neglected aspect of the climate change debate, much less research has
been conducted on the impacts of climate change on health, food supply, economi
c growth, migration, security, societal change, and public goods, such as drinki
ng water, than on the geophysical changes related to global warming. Human impac
ts can be both negative and positive. Climatic changes in Siberia, for instance,
are expected to improve food production and local economic activity, at least i
n the short to medium term. Numerous studies suggest, however, that the current
and future impacts of climate change on human society are and will continue to b
e overwhelmingly negative.[8][9]
The majority of the adverse effects of climate change are experienced by poor an
d low-income communities around the world, who have much higher levels of vulner
ability to environmental determinants of health, wealth and other factors, and m
uch lower levels of capacity available for coping with environmental change. A r
eport on the global human impact of climate change published by the Global Human
itarian Forum in 2009, estimated more than 300,000 deaths and about $125 billion
in economic losses each year, and indicating that most climate change induced m
ortality is due to worsening floods and droughts in developing countries.[10] Th
is also raises questions of climate justice, since the 50 least developed countr
ies of the world account for not more than 1% of worldwide emissions of greenhou
se gases.[11]
A changing climate impacts our health and wellbeing. The major public health org
anizations of the world have said that climate change is a critical public healt
h problem. Climate change makes many existing diseases and conditions worse, but
it may also help introduce new pests and pathogens into new regions or communit
ies. As the planet warms, oceans expand and the sea level rises, floods and drou
ghts become more frequent and intense, and heat waves and hurricanes become more
severe. The most vulnerable people children, the elderly, the poor, and those wit
h underlying health conditions are at increased risk for health effects from clima
te change. Climate change also stresses our health care infrastructure and deliv
ery systems.
Steps can be taken to lessen climate change ( mitigation ) and reduce its impacts on
our health and the health of future generations ( adaptation ). Some of these steps
can yield benefits for our health, environment, economy, and society at the sam
e time. The federal government has called for efforts to support adaptation and
mitigation of climate change to create healthier, more sustainable communities.
The goals of the NIEHS Climate Change and Human Health Program align with these
efforts.
Health
Main article: Effects of climate change on human health
It has been suggested that this section be merged into Effects of global
warming on human health. (Discuss) Proposed since January 2013.
Climate change poses a wide range of risks to population health - risks that wil
l increase in future decades, often to critical levels, if global climate change
continues on its current trajectory.[6] The three main categories of health ris
ks include: (i) direct-acting effects (e.g. due to heat waves, amplified air pol
lution, and physical weather disasters), (ii) impacts mediated via climate-relat
ed changes in ecological systems and relationships (e.g. crop yields, mosquito e
cology, marine productivity), and (iii) the more diffuse (indirect) consequences
relating to impoverishment, displacement, resource conflicts (e.g. water), and
post-disaster mental health problems.
Climate change thus threatens to slow, halt or reverse international progress to
wards reducing child under-nutrition, deaths from diarrheal diseases and the spr
ead of other infectious diseases. Climate change acts predominantly by exacerbat
ing the existing, often enormous, health problems, especially in the poorer part
s of the world. Current variations in weather conditions already have many adver
se impacts on the health of poor people in developing nations,[13] and these too
are likely to be 'multiplied' by the added stresses of climate change.
A changing climate thus affects the prerequisites of population health: clean ai
r and water, sufficient food, natural constraints on infectious disease agents,
and the adequacy and security of shelter. A warmer and more variable climate lea
ds to higher levels of some air pollutants and more frequent extreme weather eve
nts. It increases the rates and ranges of transmission of infectious diseases th
rough unclean water and contaminated food, and by affecting vector organisms (su
ch as mosquitoes) and intermediate or reservoir host species that harbour the in
fectious agent (such as cattle,[14] bats and rodents). Changes in temperature, r
ainfall and seasonality compromise agricultural production in many regions, incl
uding some of the least developed countries, thus jeopardising child health and
growth and the overall health and functional capacity of adults. As warming proc
eeds, the severity (and perhaps frequency) of weather-related disasters will inc
rease - and appears to have done so in a number of regions of the world over the
past several decades.[15] Therefore, in summary, global warming, together with
resultant changes in food and water supplies, can indirectly cause increases in
a range of adverse health outcomes, including malnutrition, diarrhea, injuries,
cardiovascular and respiratory diseases, and water-borne and insect-transmitted
diseases.
Health equity and climate change have a major impact on human health and quality
of life, and are interlinked in a number of ways. The report of the WHO Commiss
ion on Social Determinants of Health points out that disadvantaged communities a
re likely to shoulder a disproportionate share of the burden of climate change b
ecause of their increased exposure and vulnerability to health threats. Over 90
percent of malaria and diarrhea deaths are borne by children aged 5 years or you
nger, mostly in developing countries.[16] Other severely affected population gro
ups include women, the elderly and people living in small island developing stat
es and other coastal regions, mega-cities or mountainous areas.[11]
Psychological impacts
Further information: Effects of global warming on human health § Mental health
A 2011 article in the American Psychologist identified three classes of psycholo
gical impacts from global climate change:[17]
Direct - "Acute or traumatic effects of extreme weather events and a changed
environment"
Indirect - "Threats to emotional well-being based on observation of impacts
and concern or uncertainty about future risks"
Psychosocial - "Chronic social and community effects of heat, drought, migra
tions, and climate-related con?icts, and postdisaster adjustment"
Extreme weather events
Further information: Extreme weather
El Nino can lead to drastic, though temporary, changes in the environment such a
s temperature fluctuations and flash floods.[18] In addition, with global warmin
g, there has been a marked trend towards more variable and anomalous weather.[ci
tation needed] This has led to an increase in the number and severity of extreme
weather events.[citation needed] This trend towards more variability and fluctu
ation is perhaps more important, in terms of its impact on human health, than th
at of a gradual and long-term trend towards higher average temperature.[18] Infe
ctious disease often accompanies extreme weather events, such as floods, earthqu
akes and drought.[citation needed] These local epidemics occur due to loss of in
frastructure, such as hospitals and sanitation services, but also because of cha
nges in local ecology and environment. For example, malaria outbreaks have been
strongly associated with the El Nino cycles of a number of countries (India and
Venezuela, for example).[citation needed]
Diseases
Further information: Effects of global warming on infectious diseases
Climate change may lead to dramatic increases in prevalence of a variety of infe
ctious diseases. Beginning in the mid-'70s, there has been an emergence, resurgen
ce and redistribution of infectious diseases .[18] Reasons for this are likely mul
ticausal, dependent on a variety of social, environmental and climatic factors,
however, many argue that the volatility of infectious disease may be one of the e
arliest biological expressions of climate instability .[18] Though many infectious
diseases are affected by changes in climate, vector-borne diseases, such as mal
aria, dengue fever and leishmaniasis, present the strongest causal relationship.
Observation and research detect a shift of pests and pathogens in the distribut
ion away from the equator and towards Earth's poles.[19]
Malaria
Increased precipitation can increase mosquito population indirectly by expanding
larval habitat and food supply. Malaria kills approximately 300,000 children an
nually, poses an imminent threat through temperature increase.[20] Models sugges
t, conservatively, that risk of malaria will increase 5-15% by 2100 due to clima
te change.[21] In Africa alone, according to the MARA Project (Mapping Malaria R
isk in Africa),[22] there is a projected increase of 16-28% in person-month expo
sures to malaria by 2100.[23]
Non-climatic determinants
Sociodemographic factors include, but are not limited to: patterns of human migr
ation and travel, effectiveness of public health and medical infrastructure in c
ontrolling and treating disease, the extent of anti-malarial drug resistance and
the underlying health status of the population at hand.[24] Environmental facto
rs include: changes in land-use (e.g. deforestation), expansion of agricultural
and water development projects (which tend to increase mosquito breeding habitat
), and the overall trend towards urbanization (i.e. increased concentration of h
uman hosts). Patz and Olson argue that these changes in landscape can alter loca
l weather more than long term climate change.[20] For example, the deforestation
and cultivation of natural swamps in the African highlands has created conditio
ns favourable for the survival of mosquito larvae, and has, in part, led to the
increasing incidence of malaria.[20] The effects of these non-climatic factors c
omplicate things and make a direct causal relationship between climate change an
d malaria difficult to confirm. It is highly unlikely that climate exerts an iso
lated effect.
Environment
Climate change may dramatically impact habitat loss, for example, arid condition
s may cause the collapse of rainforests, as has occurred in the past.[25]
Temperature
A sustained wet-bulb temperature exceeding 35°, is a threshold at which the resili
ence of human systems is no longer able to adequately cool the skin. A study by
NOAA from 2013 concluded that heat stress will reduce labor capacity considerabl
y under current emissions scenarios.[26]
Water
See also: Water crisis
The freshwater resources that humans rely on are highly sensitive to variations
in weather and climate. In 2007, the IPCC reported with high confidence that cli
mate change has a net negative impact on water resources and freshwater ecosyste
ms in all regions.[27] The IPCC also found with very high confidence that arid a
nd semi-arid areas are particularly exposed to freshwater impacts.[27]
As the climate warms, it changes the nature of global rainfall, evaporation, sno
w, stream flow and other factors that affect water supply and quality. Specific
impacts include:
Warmer water temperatures affect water quality and accelerate water pollutio
n.[28]
Sea level rise is projected to increase salt-water intrusion into groundwate
r in some regions. This reduces the amount of freshwater available for drinking
and farming.[28][29]
In some areas, shrinking glaciers and snow deposits threaten the water suppl
y.[30] Areas that depend on melted water runoff will likely see that runoff depl
eted, with less flow in the late summer and spring peaks occurring earlier.[28]
This can affect the ability to irrigate crops. (This situation is particularly a
cute for irrigation in South America,[31] for irrigation and drinking supplies i
n central Asia, and for hydropower in Norway, the Alps, and the Pacific Northwes
t of North America.)
Increased extreme weather means more water falls on hardened ground unable t
o absorb it, leading to flash floods instead of a replenishment of soil moisture
or groundwater levels.
Increased evaporation will reduce the effectiveness of reservoirs.
At the same time, human demand for water will grow for the purposes of cooli
ng and hydration.
Displacement and migration
See also: Environmental migrant
A refugee camp.
Climate change causes displacement of people in several ways, the most obvious and
dramatic being through the increased number and severity of weather-related disas
ters which destroy homes and habitats causing people to seek shelter or liveliho
ods elsewhere. Effects of climate change such as desertification and rising sea
levels gradually erode livelihood and force communities to abandon traditional h
omelands for more accommodating environments. This is currently happening in are
as of Africa s Sahel, the semi-arid belt that spans the continent just below its n
orthern deserts. Deteriorating environments triggered by climate change can also
lead to increased conflict over resources which in turn can displace people.[32
]
