This course will provide you with an overview of the most important health challenges facing the world today. You will gain insight into how challenges have changed over time, we will discuss the likely determinants of such changes and examine future projections. Successful international strategies and programs promoting human health will be highlighted and global health governance structures will be mapped and the role of the key actors explored.
9.3: Climate Change and Health (P Furu)
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Del curso dictado por University of Copenhagen
An Introduction to Global Health
323 calificaciones
De la lección
Environment, Climate and Migration
In the fifth module we are looking at some great global crises that profoundly impact the health of populations, namely environment, climate change, and migration. We will examine the health acpect of these mega trends - how are they influencing and challenging policy, health systems, and the health of individuals in both low and high income countries?
Conoce a los instructores
Flemming KonradsenProfessor, Director
Copenhagen School of Global Health
Hi, and welcome to a new session.
This time we'll focus on linkages between climate change and human health.
My name is Peter Furu.
I'm a public health scientist based at
the Department of International Health Immunology and Microbiology
of the University of Copenhagen.
Climate change is the biggest global health threat of the 21st century.
The statement on the front page of The Lancet in 2009 reflects the importance of
this topic not only for the health sciences but also for the society at large.
In my presentation, I will take a starting point on this statement and share with you
three main topics covering a broad field of
climate change issues as they relate to human health and well-being.
As a first topic,
I'll point to the linkages between earth systems and
human systems in the context of climate change.
This will provide a background for a better understanding
of the cause effect relationships between climate change and health.
Then I will narrow down and concentrate on
the effects of climate change on various determinants of human health,
and derived health outcomes.
Finally, the third topic will deal with
the vulnerability of human populations to climate sensitive health hazards,
focusing on some vulnerable regions and population groups.
Now, let's get started by first
setting the stage with respect to current observations on climate change.
The so-called Fifth Assessment working group reports of 2013 and
2014 by the United Nations Intergovernmental Panel on Climate Change IPCC,
summarizing the scientific evidence on changes in climate,
earth, and human systems,
state with medium confident that at the surface of the earth,
each of the last three decades has been successively
warmer than any preceding decade since 1850.
Furthermore, in the Northern hemisphere,
the period from 1983 to 2012 was
likely the warmest 30 year period of the last 1400 years.
Without immediate comprehensive mitigation actions against global warming,
estimates and global temperatures indicate a likely rise by one to two degrees Celsius
by year 2050 and three to four degrees by year 2100.
The patterns of precipitation will change as well with
much regional variation in terms of more or less a new rainfall,
and seque- and consequential flooding or more severe drought periods.
Globally, sea level rise and the rate of severity,
of extreme weather events such as storms and tropical cyclones,
are also expected to increase in many regions.
Then, let's take a closer look at the interlinkages between
earth systems including climate change and human systems,
as you can see relations are complex.
And in this session, we will zoom in on some of
the linkages between changing climate factors such as; temperature,
rainfall, sea level rise, extreme weather events,
and their respective impacts on human health and vulnerable communities.
Looking at the types of climate related health impacts,
the World Health Organization considers three kinds of impacts.
Firstly, those that are relatively direct usually caused by extreme weather events.
Then, the more indirect health consequences of the various climate change induced
processes of environmental change and resulting damage to ecosystems.
Finally, we have the various adverse health consequences
that occur in relation to climate induced population displacement,
conflict situation, and derive social disruption.
I would like to mention some examples from each of these three categories.
The first of three examples looking at impacts of weather extremes
relates to the thermal stress suffered by people exposed to extreme heat episodes.
Thermal stress in terms of heat waves can be defined as
episodes with the continued heat load affecting human health.
This may be reinforced by
the so-called urban heat island effect which is characterized by
significantly higher temperatures in urban areas as compared to
rural areas mainly because of the retainment of heat in concrete buildings,
tarred surfaces, and lack of open street ventilation between buildings.
Typically, the increase in temperature
will influence levels of ground level ozone and other air pollutants.
The effects of just one degree Celsius rise in temperature on ozone in
particular area may increase global death from air pollution by over 20,000 per year.
An increase in pollen and other aeroallergens may further more impact of negativity.
Extreme high air temperatures may kill directly.
Vulnerable people are often older individuals in
particular or those with a pre-existing heart or lung diseases.
For example, more than 70,000 excess deaths were
recorded in the extremely hot summer of 2003 in Europe.
Floods are forceful and very high impact events.
And at the same time, the most frequent natural or weather
disaster affecting 2.8 billion people in
the period from 1980 to 2009 and killing 540,000 people.
Impact such as injuries, communicable diseases,
or poisoning by various pollutant is seen during or soon after the flooding events.
The infiltration of drinking water with
wastewater increases the likelihood of waterborne diseases.
Later other health impacts may become visible.
Examples include malnutrition typically
as a result of loss of land for subsistence farming,
and mental health problems related to the fear and stress of
the traumatic episodes experienced by the vulnerable communities.
On a global scale,
droughts represent the greatest impacts because of their regional extent.
Seen over longer terms,
the disaster effect may be huge due to associated famines and resulting malnutrition.
For example, impacting growth and cognitive development in children.
Combined with high temperatures,
different types of pathogenic bacteria in
contaminated food and water such as salmonella and Cholera,
may proliferate more rapidly and represent hazards to
the vulnerable communities who as a result
may experience increased level of diarrhea diseases.
Furthermore, the general scarcity of water may promote
skin and eye infections due to lack of enough quantities of water for personal hygiene.
You may recall that the second type of
indirect health impacts that I mentioned is also related to environmental change.
The distribution of for example malaria is strongly influenced by climatic conditions.
Thus, higher temperatures, higher humidity,
and more places where water can collect generally favor breeding of
the Anopheles mosquito and subsequent transmission of the malaria parasite.
In certain areas, there may be shifts in
transmission seasons due to changes in water availability during the year.
And furthermore, it is important to note that the very high rainfall may reduce
mosquito populations by flushing larvae away from the habitats and thus potentially,
reducing the number of malaria cases.
The serious viral infection dengue fever
is spreading rapidly particularly and tropical cities.
Dengue virus replication is temperature sensitive and higher temperatures
will shorten the time for these mosquitoes to become infectious.
Consequently, a transmission may increase and
typically crowded urban populations are affected due to
the characteristics of the mosquito breeding sites often
found under poor environmental conditions.
Now, a third example covers some other vector borne diseases.
I will just highlight one namely the tropical blood-fluke Schistosoma,
which is transmitted by freshwater snails and
whose distribution is much dependent on temperature and rainfall patterns.
Changes in the patterns may affect the epidemiology of schistosomiasis either way.
In some places, excess rainfall and or higher temperatures may
favor conservation of snail breeding sites and create new transmission sites.
On the other hand, extreme weather events and heavy tropical rain,
may flush away snails from
potential transmission sites and thereby lower the risk of infection.
As the last example of this type of impact, I will mention again,
the poverty relay the complex of the real infections
whose distribution is not only related to extreme weather as mentioned earlier,
but altered to more permanent changes of climatic factors.
Thus, higher temperatures and scarcity of water may facilitate transmission considerably.
What we see is the faster propagation of the infectious agents at
higher temperatures combined with the lack of
sufficient water quantity for personal hygiene,
may increase the burden of disease.
In addition to changes in
environmental health determinacy in connection with climate induced ecosystem changes,
the same type of hygiene related diseases will be
equally sensitive to changes in Social Determinants of Health.
Poverty is an important social determinant of
health and climate change may increase poverty through, for example,
loss of land and the derived conflict that may
arise when struggling to find land and water for sustaining life.
Psychosocial stress and related mental disorders are on the rise and
may be reinforced during periods of crisis and conflict as well.
In summary, the described health impacts have primarily been adverse
and most frequently hitting
the vulnerable and poor communities of least developed countries.
This figure by the IPCC shows the direction and magnitude of change of
selected climate change related health impacts with
a majority of high confidence negative impacts.
The magnitude of the public health impacts will depend also on
the degree of exposure to the health hazards by vulnerable population groups.
Therefore, let's now direct the focus at some of these vulnerable populations.
Looking firstly at small island developing States and other low lying regions,
t he populations of these areas are sensitive to the increasingly severe tropical storms.
These may cause serious destruction of shelter,
and essential infrastructure including private and public housing,
the public health facilities as well as water and sanitation systems.
Parallel to this, an increasing sea level rise may
cause salinization of agricultural of land as
well as important freshwater sources thereby reducing size and quality of crop yields.
Overall, we see a change of important health determines
most frequently with a negative rather than a positive impact on people's health status.
A status reflected in the mortality and morbidity of diseases.
From storms, floods, and damaged infrastructure we may
see serious health impacts in the form of drowning and injuries.
Destroyed water and sanitation systems combined with crowding and
general poor environmental hygiene may lead to diarrhea diseases.
Considerable effects may also be seen on
the nutritional status of vulnerable groups because
of the reduced agricultural production due to salinization and destruction of farmlands.
Then let's look at other vulnerable areas and scenarios such as urban settlements.
Here I would just concentrate on the potential climate change
related changes of some specific environmental determinants of health.
I mentioned earlier the Urban Heat Island Effect.
Day and overnight temperatures may rise excessively and lead to
heat strokes and in worst cases deaths of vulnerable individuals.
In connection with heavy rainfall,
inadequate drainage will increase the potential harmful effects of
flash floods by infiltration of drinking water facilities with wastewater
leading to diarrhea infections that will multiply
when at the same time crowded informal settlements suffer
from lack of sanitation facilities and have
no or inappropriate waste disposal systems or services.
In most developing countries,
the majority of people live in rural areas often
totally dependent of availability of land for subsistence farming.
Climate change may increase food insecurity
due to a higher frequency and severity of droughts.
To mention just one example,
it is projected by the IPCC that
the population of Mali in West Africa as a result of climate change,
may experience an increase in the percentage of the population at risk of hunger from
34% to between 64% and 72% by the 2050s.
Overall, due to the very large number of people in
the developing countries that may be affected by climate change related malnutrition,
this health concern is considered to be
one of the most important adverse health consequences of climate change.
The change in rainfall patterns and associated water scarcity in
rural areas may influence mortality and morbidity of a number of
water related diseases including diarrhea diseases or the hygiene
related problems such as skin and eye diseases as well as some vector borne diseases.
Now, let's move from traditional rural areas to
mountain populations that may witness quite dramatic changes of determinants of health.
Changes that may lead to shifts in
mortality and morbidity of a number of health conditions.
For example, drowning and injuries may be seen from heavy floods from
glacier lakes filling exceptionally fast
because of the extensive melting of ice and snow.
Additionally, higher temperatures may favor
the transmission of certain vector borne diseases such as malaria,
a potential problem among mountain populations lacking immunity against such infections.
The rising winter temperatures in the polar regions
are currently thinning permanent inland ice layers and breaking up icebergs.
It may affect the patterns of animal migration and distribution will resulting
new challenges for indigenous peoples
whose traditional hunting and gathering practices may be affected.
Derived effects in terms of changes in mortality and morbidity of
malnutrition may be seen as a result of affected traditional diets.
Furthermore, the loss of traditional livelihoods in some vulnerable communities may
eventually lead to psychosocial disorders such as alcoholism and increased suicide rates.
Also here, some of the waterborne and vector borne diseases are expected
to have a wider and seasonal and geographical distribution.
On the positive side,
rising temperatures in the Arctic region are expected to reduce
both excess winter mortality due to heart and lung diseases and cold related injuries.
In conclusion, and as a summary before I end this presentation,
let me highlight four of the cross-cutting issues
related to the linkages between climate change and health.
Firstly, we have seen
that climate change is affecting a number of important environmental,
social and institutional determinants of health.
Main focus has been on the environmental determinants of health
often being directly affected by changes in climate factors.
Then, we observed that
the cause-effect relationships between climate change and health are
complex because causation on most human health disorders is multi-factorial.
And the background social economic, demographic,
and environmental factors may confound the true understanding of
relationships because of their significant climate independent changes over time.
Thirdly, you may have noticed that our focus
has mostly been on negative health impacts of climate change.
However, let's not forgot the positive health impacts,
or core benefits that may be associated with
climate change mitigation strategies and should
be promoted through intersectoral actions.
Finally, let me emphasize the continued need for research in addressing some of
the many uncertainties and gaps in knowledge
still remaining in the field of climate change and human health.
You may wish to be part of this important and challenging field in the future.
You are welcome. Thank you and good luck.
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