Effects of climate change on humans
Encyclopedia
Climate change has brought about severe and possibly permanent alterations to our planet
s’ geological, biological and ecological systems
. The Intergovernmental Panel on Climate Change
(IPCC) now contends that “there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities”. These changes have led to the emergence of large-scale environmental hazards to human health
, such as ozone depletion
, loss of biodiversity
, stresses to food-producing systems and the global spread of infectious disease
s. The World Health Organization (WHO) estimates that 160,000 deaths, since 1950, are directly attributable to climate change. Many believe this to be a conservative estimate. Research at the Hoover Institution
by economist Thomas Moore
indicates global warming
will lead to decreased mortality rates in the United States
.
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, economic growth
, migration, security, societal change, and public good
s, such as drinking water
, than on the geophysical changes related to global warming. Human impacts can be both negative and positive. Climatic changes in Siberia
, for instance, are expected to improve food production and local economic activity, at least in 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 be overwhelmingly negative.
The majority of the adverse effects of climate change are experienced by poor and low-income communities around the world, who have much higher levels of vulnerability to environmental determinants of health, wealth and other factors, and much lower levels of capacity available for coping with environmental change. A report on the global human impact of climate change published by the Global Humanitarian Forum
in 2009, including drawing on work done by the World Health Organization
earlier in that decade, indicated that developing countries suffer 99% of the casualties attributable to climate change. This also raises questions of climate justice
, since the 50 least developed countries of the world account for not more than 1% of worldwide emissions of greenhouse gases that cause global warming.
Since so little research has been conducted into the human impacts of climate change and because of the difficulty in differentiating the influence of climate change from other contributing factors, statistics relating to the human impact of climate change carry significant margins of uncertainty. Particularly on a global level, much of the statistical data on the human impact of climate change should only be considered as being indicative of the order of magnitude of impact.
Though there has been inadequate research (and policy-related discussion) on the human impacta of climate change, a number of organizations are raising the profile of this issue by organizing various high-level meetings and publishing reports on the topic. Such organizations include Oxfam
, the United Nations Development Programme
, the United Nations Environment Programme
, the World Health Organization
, the Office of the High Commissioner for Human Rights, the United Nations High Commissioner for Refugees
, the Office for the Coordination of Humanitarian Affairs
, the World Health Organization, the Global Humanitarian Forum
, Care International, Greenpeace
, Maplecroft, the World Bank
, and the International Federation of Red Cross and Red Crescent Societies
.
s, amplified air pollution
, and physical weather disasters), (ii) impacts mediated via climate-related changes in ecological systems and relationships (e.g. crop yields, mosquito
ecology, 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 towards reducing child under-nutrition, deaths from diarrheal diseases and the spread of other infectious diseases. Climate change acts predominantly by exacerbating the existing, often enormous, health problems, especially in the poorer parts of the world. Current variations in weather conditions already have many adverse impacts on the health of poor people in developing nations, 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 air and water, sufficient food, natural constraints on infectious disease agents, and the adequacy and security of shelter. A warmer and more variable climate leads to higher levels of some air pollutants and more frequent extreme weather events. It increases the rates and ranges of transmission of infectious diseases through unclean water and contaminated food, and by affecting vector organisms (such as mosquitoes) and intermediate or reservoir host species that harbour the infectious agent (such as cattle, bats and rodents). Changes in temperature, rainfall and seasonality compromise agricultural production in many regions, including some of the least developed countries, thus jeopardising child health and growth and the overall health and functional capacity of adults. As warming proceeds, the severity (and perhaps frequency) of weather-related disasters will increase - and appears to have done so in a number of regions of the world over the past several decades. 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 disease
s, 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 Commission on Social Determinants of Health points out that disadvantaged communities are likely to shoulder a disproportionate share of the burden of climate change because 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 younger, mostly in developing countries. Other severely affected population groups include women, the elderly and people living in small island developing states
and other coastal regions, mega-cities or mountainous areas.
Climate change can lead to dramatic increases in prevalence of a variety of infectious diseases. Beginning in the mid-70s, there has been an “emergence, resurgence and redistribution of infectious diseases”. Reasons for this are likely multicausal, dependent on a variety of social, environmental and climatic factors, however, many argue that the “volatility of infectious disease may be one of the earliest biological expressions of climate instability”. Though many infectious diseases are affected by changes in climate, vector-borne diseases, such as malaria, dengue fever
and leishmaniasis, present the strongest causal relationship
. Malaria in particular, which kills approximately 300,000 children annually, poses the most imminent threat
.
events, such as floods, earthquakes and drought. These local epidemics occur due to loss of infrastructure, such as hospitals and sanitation services, but also because of changes 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). El Nino
can lead to drastic, though temporary, changes in the environment such as temperature fluctuations and flash flood
s. In addition, with global warming, there has been a marked trend towards more variable and anomalous weather. This has led to an increase in the number and severity of extreme weather events. This trend towards more variability and fluctuation is perhaps more important, in terms of its impact on human health, than that of a gradual and long-term trend towards higher average temperature.
and travel, effectiveness of public health
and medical infrastructure in controlling and treating the disease, the extent of anti-malarial
drug resistance
and the underlying health status of the population at hand. Environmental factors 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 human hosts). Patz & Olson argue that these changes in landscape can alter local weather more than long term climate change. For example, the deforestation and cultivation of natural swamps in the African highlands has created conditions favourable for the survival of mosquito larvae, and has, in part, led to the increasing incidence of malaria. The effects of these non-climatic factors complicate things and make a direct causal relationship between climate change and malaria difficult to confirm. It is highly unlikely that climate exerts an isolated effect.
) and many regionally dominant mosquito species. These models must therefore incorporate a variety of factors including: human-induced changes in climate (e.g. temperature, precipitation, and humidity), environmental factor
s (e.g. drought and deforestation), disease factors (e.g. parasite development rate, vector population, and drug resistance) and other factors (e.g. changes in immune status of hosts and spread of disease into new areas). Various models suggest, conservatively, that people living in developing countries’ risk of malaria will increase 5-15% by 2100 due to climate change. In Africa alone, according to the MARA Project (Mapping Malaria Risk in Africa), there is a projected increase of 16-28% in person-month exposures to malaria by 2100.
emissions, we would still be faced with the potentially irreversible changes we have already brought. Thus, it is essential that we adapt to these changing conditions. Our response will be both reactive and anticipatory and will need to take place at many levels (legislative, engineering and personal-behaviour). In response to malaria we will need to, for example, improve the quality and accessibility of health services, identify and target response towards vulnerable populations, improve our modelling and surveillance capacity, and implement broad-based public education
campaigns.
resources are highly sensitive to variations in weather and climate. Climate change is projected to affect water availability. In areas where the amount of water in rivers and streams depends on snow melting, warmer temperatures increase the fraction of precipitation falling as rain rather than as snow, causing the annual spring peak in water runoff to occur earlier in the year. This can lead to an increased likelihood of winter flooding and reduced late summer river flows. Rising sea levels cause saltwater to enter into fresh underground water and freshwater streams. This reduces the amount of freshwater available for drinking and farming. Warmer water temperatures also affect water quality and accelerate water pollution
.
and rising sea levels gradually erode livelihoods and force communities to abandon traditional homelands for more accommodating environments. This is currently happening in areas of Africa’s Sahel
, the semi-arid belt that spans the continent just below its northern deserts. Deteriorating environments triggered by climate change can also lead to increased conflict over resources which in turn can displace people.
However, the links between the gradual environmental degradation of climate change and displacement are complex: as the decision to migrate is taken at the household level, it is difficult to measure the respective influence of climate change in these decisions with regard to other influencing factors, such as poverty
, population growth
or employment
options. This situates the debate on environmental migration in a highly contested field: the use of the term 'environmental refugee', although commonly used in some contexts, is disrecommended by agencies such as the UNHCR who argue that the term 'refugee' has a strict legal definition which does not apply to environmental migrants. Neither the UN Framework Convention on Climate Change nor its Kyoto Protocol
, an international agreement on climate change, includes any provisions concerning specific assistance or protection for those who will be directly affected by climate change.
The United Nations Security Council
held its first-ever debate on the impact of climate change in 2007. The links between climate change and security have been the subject of numerous high-profile reports since 2007 by leading security figures in the United States, United Kingdom and the European Union
. The G77
group of developing nations also considers climate change to be a major security threat which is expected to hit developing nations particularly hard.
The links between the human impact of climate change and the threat of violence and armed conflict are particularly important because multiple destabilizing conditions are affected simultaneously.
are not distributed uniformly within communities. Individual and social factors such as gender, age, education, ethnicity, geography and language lead to differential vulnerability and capacity to adapt to the effects of climate change. Climate change effects such as hunger, poverty and diseases like diarrhea and malaria, disproportionately impact children, i.e. about 90 percent of malaria and diarrhea deaths are among young children.
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
s’ geological, biological and ecological systems
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. The Intergovernmental Panel on Climate Change
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...
(IPCC) now contends that “there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities”. These changes have led to the emergence of large-scale environmental hazards to human health
Health
Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...
, such as ozone depletion
Ozone depletion
Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere , and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon...
, loss of biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
, stresses to food-producing systems and the global spread of infectious disease
Infectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
s. The World Health Organization (WHO) estimates that 160,000 deaths, since 1950, are directly attributable to climate change. Many believe this to be a conservative estimate. Research at the Hoover Institution
Hoover Institution
The Hoover Institution on War, Revolution and Peace is a public policy think tank and library founded in 1919 by then future U.S. president, Herbert Hoover, an early alumnus of Stanford....
by economist Thomas Moore
Thomas Moore
Thomas Moore was an Irish poet, singer, songwriter, and entertainer, now best remembered for the lyrics of The Minstrel Boy and The Last Rose of Summer. He was responsible, with John Murray, for burning Lord Byron's memoirs after his death...
indicates global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
will lead to decreased mortality rates in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
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, economic growth
Economic growth
In economics, economic growth is defined as the increasing capacity of the economy to satisfy the wants of goods and services of the members of society. Economic growth is enabled by increases in productivity, which lowers the inputs for a given amount of output. Lowered costs increase demand...
, migration, security, societal change, and public good
Public good
In economics, a public good is a good that is non-rival and non-excludable. Non-rivalry means that consumption of the good by one individual does not reduce availability of the good for consumption by others; and non-excludability means that no one can be effectively excluded from using the good...
s, such as drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
, than on the geophysical changes related to global warming. Human impacts can be both negative and positive. Climatic changes in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, for instance, are expected to improve food production and local economic activity, at least in the short to medium term. Numerous studies suggest, however, that the current and future impacts of climate change
Effects of global warming
This article is about the effects of global warming and climate change. The effects, or impacts, of climate change may be physical, ecological, social or economic. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the...
on human society are and will continue to be overwhelmingly negative.
The majority of the adverse effects of climate change are experienced by poor and low-income communities around the world, who have much higher levels of vulnerability to environmental determinants of health, wealth and other factors, and much lower levels of capacity available for coping with environmental change. A report on the global human impact of climate change published by the Global Humanitarian Forum
Global Humanitarian Forum
The Global Humanitarian Forum was a non-profit foundation in Geneva, Switzerland, active from 2007 to 2010. Presided over by former United Nations Secretary General Kofi Annan, its secretariat was led by CEO and Director General Walter Fust. The Forum intended to serve as an independent platform...
in 2009, including drawing on work done by the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
earlier in that decade, indicated that developing countries suffer 99% of the casualties attributable to climate change. This also raises questions of climate justice
Climate justice
Climate Justice is generally used as a term for viewing climate change as an ethical issue and considering how its causes and effects relate to concepts of justice, particularly social justice and environmental justice. For example examining issues such as equality, human rights and historical...
, since the 50 least developed countries of the world account for not more than 1% of worldwide emissions of greenhouse gases that cause global warming.
Since so little research has been conducted into the human impacts of climate change and because of the difficulty in differentiating the influence of climate change from other contributing factors, statistics relating to the human impact of climate change carry significant margins of uncertainty. Particularly on a global level, much of the statistical data on the human impact of climate change should only be considered as being indicative of the order of magnitude of impact.
Though there has been inadequate research (and policy-related discussion) on the human impacta of climate change, a number of organizations are raising the profile of this issue by organizing various high-level meetings and publishing reports on the topic. Such organizations include Oxfam
Oxfam
Oxfam is an international confederation of 15 organizations working in 98 countries worldwide to find lasting solutions to poverty and related injustice around the world. In all Oxfam’s actions, the ultimate goal is to enable people to exercise their rights and manage their own lives...
, the United Nations Development Programme
United Nations Development Programme
The United Nations Development Programme is the United Nations' global development network. It advocates for change and connects countries to knowledge, experience and resources to help people build a better life. UNDP operates in 177 countries, working with nations on their own solutions to...
, the United Nations Environment Programme
United Nations Environment Programme
The United Nations Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and practices. It was founded as a result of the United Nations Conference on the Human Environment in June 1972 and has its...
, the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
, the Office of the High Commissioner for Human Rights, the United Nations High Commissioner for Refugees
United Nations High Commissioner for Refugees
The Office of the United Nations High Commissioner for Refugees , also known as The UN Refugee Agency is a United Nations agency mandated to protect and support refugees at the request of a government or the UN itself and assists in their voluntary repatriation, local integration or resettlement to...
, the Office for the Coordination of Humanitarian Affairs
Office for the Coordination of Humanitarian Affairs
The United Nations Office for the Coordination of Humanitarian Affairs , is a United Nations body formed in December 1991 by General Assembly Resolution 46/182...
, the World Health Organization, the Global Humanitarian Forum
Global Humanitarian Forum
The Global Humanitarian Forum was a non-profit foundation in Geneva, Switzerland, active from 2007 to 2010. Presided over by former United Nations Secretary General Kofi Annan, its secretariat was led by CEO and Director General Walter Fust. The Forum intended to serve as an independent platform...
, Care International, Greenpeace
Greenpeace
Greenpeace is a non-governmental environmental organization with offices in over forty countries and with an international coordinating body in Amsterdam, The Netherlands...
, Maplecroft, the World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...
, and the International Federation of Red Cross and Red Crescent Societies
International Federation of Red Cross and Red Crescent Societies
The International Federation of Red Cross and Red Crescent Societies is a humanitarian institution that is part of the International Red Cross and Red Crescent Movement along with the ICRC and 186 distinct National Societies...
.
Environment
Climate change may dramatically impact habitat loss, for example, arid conditions may cause the collapse of rainforests, as has occurred in the past.Health
Climate change poses a wide range of risks to population health - risks that will increase in future decades, often to critical levels, if global climate change continues on its current trajectory. The three main categories of health risks include: (i) direct-acting effects (e.g. due to heat waveHeat wave
A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity. There is no universal definition of a heat wave; the term is relative to the usual weather in the area...
s, amplified air pollution
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
, and physical weather disasters), (ii) impacts mediated via climate-related changes in ecological systems and relationships (e.g. crop yields, mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
ecology, 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 towards reducing child under-nutrition, deaths from diarrheal diseases and the spread of other infectious diseases. Climate change acts predominantly by exacerbating the existing, often enormous, health problems, especially in the poorer parts of the world. Current variations in weather conditions already have many adverse impacts on the health of poor people in developing nations, 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 air and water, sufficient food, natural constraints on infectious disease agents, and the adequacy and security of shelter. A warmer and more variable climate leads to higher levels of some air pollutants and more frequent extreme weather events. It increases the rates and ranges of transmission of infectious diseases through unclean water and contaminated food, and by affecting vector organisms (such as mosquitoes) and intermediate or reservoir host species that harbour the infectious agent (such as cattle, bats and rodents). Changes in temperature, rainfall and seasonality compromise agricultural production in many regions, including some of the least developed countries, thus jeopardising child health and growth and the overall health and functional capacity of adults. As warming proceeds, the severity (and perhaps frequency) of weather-related disasters will increase - and appears to have done so in a number of regions of the world over the past several decades. 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
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, injuries, cardiovascular
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...
and respiratory disease
Respiratory disease
Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible in higher organisms, and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura and pleural cavity, and the...
s, 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 Commission on Social Determinants of Health points out that disadvantaged communities are likely to shoulder a disproportionate share of the burden of climate change because of their increased exposure and vulnerability to health threats. Over 90 percent of malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
and diarrhea deaths are borne by children aged 5 years or younger, mostly in developing countries. Other severely affected population groups include women, the elderly and people living in small island developing states
Small Island Developing States
Small Island Developing States are low-lying coastal countries that tend to share similar sustainable development challenges, including small but growing populations, limited resources, remoteness, susceptibility to natural disasters, vulnerability to external shocks, excessive dependence on...
and other coastal regions, mega-cities or mountainous areas.
Climate change can lead to dramatic increases in prevalence of a variety of infectious diseases. Beginning in the mid-70s, there has been an “emergence, resurgence and redistribution of infectious diseases”. Reasons for this are likely multicausal, dependent on a variety of social, environmental and climatic factors, however, many argue that the “volatility of infectious disease may be one of the earliest biological expressions of climate instability”. Though many infectious diseases are affected by changes in climate, vector-borne diseases, such as malaria, dengue fever
Dengue fever
Dengue fever , also known as breakbone fever, is an infectious tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles...
and leishmaniasis, present the strongest causal relationship
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....
. Malaria in particular, which kills approximately 300,000 children annually, poses the most imminent threat
Imminent threat
Hugo Grotius, the 17th century jurist and father of public international law, stated in his 1625 magnum opus The Law of War and Peace that "Most Men assign three Just Causes of War, Defense, the Recovery of what's our own, and Punishment."...
.
Malaria
Malaria is especially susceptible to changes in the environment as both the pathogen (Plasmodium) and its vector (mosquitoes) lack the mechanisms necessary to regulate internal temperature and fluid levels. This implies that there is a limited range of climatic conditions within which the pathogen and vector can survive, reproduce and infect hosts. Vector-borne diseases, such as malaria, have distinctive characteristics that determine pathogenicity. These include: the survival and reproduction rate of the vector, the level of vector activity (i.e. the biting or feeding rate), and the development and reproduction rate of the pathogen within the vector or host. These depend on climatic conditions such as temperature, precipitation and humidity.Temperature
The ideal temperature range for malaria-carrying mosquitoes is 15–30 °C. Temperature exerts varied effects on survival and reproduction rate of mosquitoes. If initial temperature is high, then an increase in average temperature, associated with global warming, can decrease the survival and reproduction rate of mosquitoes.Precipitation and humidity
Mosquitoes are also highly sensitive to changes in precipitation and humidity. Increased precipitation can increase mosquito population indirectly by expanding larval habitat and food supply. Mosquitoes are, however, highly dependent on humidity, surviving only within a limited humidity range of 55-80%.Extreme weather events
Infectious disease often accompanies extreme weatherExtreme weather
Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather. The most commonly used definition of extreme weather is based on an event's climatological distribution. Extreme weather occurs only 5% or less of the time...
events, such as floods, earthquakes and drought. These local epidemics occur due to loss of infrastructure, such as hospitals and sanitation services, but also because of changes 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). El Nino
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
can lead to drastic, though temporary, changes in the environment such as temperature fluctuations and flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...
s. In addition, with global warming, there has been a marked trend towards more variable and anomalous weather. This has led to an increase in the number and severity of extreme weather events. This trend towards more variability and fluctuation is perhaps more important, in terms of its impact on human health, than that of a gradual and long-term trend towards higher average temperature.
Non-climatic determinants
As one would expect, climate is not the only determining factor in the spread of malaria. A variety of sociodemographic and environmental influences determine the characteristics of the disease as well. Sociodemographic factors include, but are not limited to: patterns of human migrationHuman migration
Human migration is physical movement by humans from one area to another, sometimes over long distances or in large groups. Historically this movement was nomadic, often causing significant conflict with the indigenous population and their displacement or cultural assimilation. Only a few nomadic...
and travel, effectiveness of public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
and medical infrastructure in controlling and treating the disease, the extent of anti-malarial
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
drug resistance
Drug resistance
Drug resistance is the reduction in effectiveness of a drug such as an antimicrobial or an antineoplastic in curing a disease or condition. When the drug is not intended to kill or inhibit a pathogen, then the term is equivalent to dosage failure or drug tolerance. More commonly, the term is used...
and the underlying health status of the population at hand. Environmental factors include: changes in land-use
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...
(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 human hosts). Patz & Olson argue that these changes in landscape can alter local weather more than long term climate change. For example, the deforestation and cultivation of natural swamps in the African highlands has created conditions favourable for the survival of mosquito larvae, and has, in part, led to the increasing incidence of malaria. The effects of these non-climatic factors complicate things and make a direct causal relationship between climate change and malaria difficult to confirm. It is highly unlikely that climate exerts an isolated effect.
Future modelling
Modelling involves a prediction of the scope, geographic distribution and characteristics of a given factor (malaria in this case) over a period of time. These models are crucial in preparing an adequate public health response to future infectious disease outbreaks. Modelling malaria is particularly complex given the two common pathogen variants (Plasmodium falciparum and Plasmodium vivaxPlasmodium vivax
Plasmodium vivax is a protozoal parasite and a human pathogen. The most frequent and widely distributed cause of recurring malaria, P. vivax is one of the four species of malarial parasite that commonly infect humans. It is less virulent than Plasmodium falciparum, which is the deadliest of the...
) and many regionally dominant mosquito species. These models must therefore incorporate a variety of factors including: human-induced changes in climate (e.g. temperature, precipitation, and humidity), environmental factor
Environmental factor
Environmental factor or ecological factor or ecofactor is any factor, abiotic or biotic, that influences living organisms.- Environmental factors inducing diseases :...
s (e.g. drought and deforestation), disease factors (e.g. parasite development rate, vector population, and drug resistance) and other factors (e.g. changes in immune status of hosts and spread of disease into new areas). Various models suggest, conservatively, that people living in developing countries’ risk of malaria will increase 5-15% by 2100 due to climate change. In Africa alone, according to the MARA Project (Mapping Malaria Risk in Africa), there is a projected increase of 16-28% in person-month exposures to malaria by 2100.
Public health response
Currently, there is no evidence to suggest that the rapid onset of climate change is subsiding. Even if we miraculously managed to stop all greenhouse gasGreenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions, we would still be faced with the potentially irreversible changes we have already brought. Thus, it is essential that we adapt to these changing conditions. Our response will be both reactive and anticipatory and will need to take place at many levels (legislative, engineering and personal-behaviour). In response to malaria we will need to, for example, improve the quality and accessibility of health services, identify and target response towards vulnerable populations, improve our modelling and surveillance capacity, and implement broad-based public education
Public education
State schools, also known in the United States and Canada as public schools,In much of the Commonwealth, including Australia, New Zealand, South Africa, and the United Kingdom, the terms 'public education', 'public school' and 'independent school' are used for private schools, that is, schools...
campaigns.
Water
As the climate warms, it changes the nature of global rainfall, evaporation, snow, stream flow and other factors that affect water supply and quality. FreshwaterFreshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
resources are highly sensitive to variations in weather and climate. Climate change is projected to affect water availability. In areas where the amount of water in rivers and streams depends on snow melting, warmer temperatures increase the fraction of precipitation falling as rain rather than as snow, causing the annual spring peak in water runoff to occur earlier in the year. This can lead to an increased likelihood of winter flooding and reduced late summer river flows. Rising sea levels cause saltwater to enter into fresh underground water and freshwater streams. This reduces the amount of freshwater available for drinking and farming. Warmer water temperatures also affect water quality and accelerate water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
.
Displacement/migration
Climate change causes displacement of people in several ways, the most obvious—and dramatic—being through the increased number and severity of weather-related disasters which destroy homes and habitats causing people to seek shelter or livelihoods elsewhere. Slow onset phenomena, including effects of climate change such as desertificationDesertification
Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...
and rising sea levels gradually erode livelihoods and force communities to abandon traditional homelands for more accommodating environments. This is currently happening in areas of Africa’s Sahel
Sahel
The Sahel is the ecoclimatic and biogeographic zone of transition between the Sahara desert in the North and the Sudanian Savannas in the south.It stretches across the North African continent between the Atlantic Ocean and the Red Sea....
, the semi-arid belt that spans the continent just below its northern deserts. Deteriorating environments triggered by climate change can also lead to increased conflict over resources which in turn can displace people.
However, the links between the gradual environmental degradation of climate change and displacement are complex: as the decision to migrate is taken at the household level, it is difficult to measure the respective influence of climate change in these decisions with regard to other influencing factors, such as poverty
Poverty
Poverty is the lack of a certain amount of material possessions or money. Absolute poverty or destitution is inability to afford basic human needs, which commonly includes clean and fresh water, nutrition, health care, education, clothing and shelter. About 1.7 billion people are estimated to live...
, population growth
Population growth
Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement....
or employment
Employment
Employment is a contract between two parties, one being the employer and the other being the employee. An employee may be defined as:- Employee :...
options. This situates the debate on environmental migration in a highly contested field: the use of the term 'environmental refugee', although commonly used in some contexts, is disrecommended by agencies such as the UNHCR who argue that the term 'refugee' has a strict legal definition which does not apply to environmental migrants. Neither the UN Framework Convention on Climate Change nor its Kyoto Protocol
Kyoto Protocol
The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change , aimed at fighting global warming...
, an international agreement on climate change, includes any provisions concerning specific assistance or protection for those who will be directly affected by climate change.
Security
Conflicts are typically extremely complex with multiple inter-dependent causalities, often referred to as ‘complex emergencies.’ Climate change has the potential to exacerbate existing tensions or create new ones — serving as a threat multiplier. It can be a catalyst for violent conflict and a threat to international security.The United Nations Security Council
United Nations Security Council
The United Nations Security Council is one of the principal organs of the United Nations and is charged with the maintenance of international peace and security. Its powers, outlined in the United Nations Charter, include the establishment of peacekeeping operations, the establishment of...
held its first-ever debate on the impact of climate change in 2007. The links between climate change and security have been the subject of numerous high-profile reports since 2007 by leading security figures in the United States, United Kingdom and the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
. The G77
G77
G77 or G-77 may refer to:* The old g77 FORTRAN compiler of GCC which has been replaced by gfortran since release 4.0.* Group of 77, a loose coalition of developing nations designed to promote its members' collective economic interests and create an enhanced joint negotiating capacity in the United...
group of developing nations also considers climate change to be a major security threat which is expected to hit developing nations particularly hard.
The links between the human impact of climate change and the threat of violence and armed conflict are particularly important because multiple destabilizing conditions are affected simultaneously.
Social impacts
The consequences of climate change and povertyClimate change and poverty
Climate change and poverty link a process and a condition that are interrelated. While the effects of climate change and global warming will have direct effects on the natural environment especially on agriculture, the impact on human civilization is also of concern...
are not distributed uniformly within communities. Individual and social factors such as gender, age, education, ethnicity, geography and language lead to differential vulnerability and capacity to adapt to the effects of climate change. Climate change effects such as hunger, poverty and diseases like diarrhea and malaria, disproportionately impact children, i.e. about 90 percent of malaria and diarrhea deaths are among young children.
Further reading
- Climate Change 2007: Synthesis Report, 4th Assessment Report, Intergovernmental Panel on Climate Change
- Report on the Economics of Climate Change (2006), Stern Review
- Human Impact Report: The Anatomy of a Silent Crisis (2009), Global Humanitarian Forum
- Key Points on Climate Justice: Working Paper of the Global Humanitarian Forum
- What Happened to the Seasons?, Oxfam Research Report
- Human Development Report 2007/2008, United Nations Development Programme
- Maplecroft Climate Change Risk Report 2009/2010
- UNESCO (2011) 'Migration and Climate Change'
- Piguet, E., Pécoud, A. and de Guchteneire, P. (2010) Migration and Climate Change: an Overview
External links
- Global Humanitarian Forum
- Tck Tck Tck Time for Climate Justice campaign
- United Nations Environment Programme and climate change
- Office of the High Commissioner for Human Rights human rights and climate change
- Office of the High Commissioner for Refugees climate change
- Care International Climate Change Information Centre
- Red Cross/Red Crescent Climate Centre
- World Bank and Climate Change
- World Meteorological Organization and climate
- climate change and human health on World Health OrganizationWorld Health OrganizationThe World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
- International Alert climate change and violent conflict
- International Strategy for Disaster Reduction disaster risk reduction and climate change