This course will examine current conditions and trends in water and sanitation services in low and middle income countries. Within it we will take a critical look at the underlying political, economic, social, and technical reasons why almost a billion people lack access to improved water supplies and almost 2 billion still do not have improved sanitation services.
Video 5.4: Climate Change, Water and Health
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来自 University of Manchester 的课程
发展中国家的水供应和卫生政策
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从本节课中
Exploring Health Benefits and Climate Change Issues
与讲师见面
Prof Dale WhittingtonProfessor
Manchester Business School
Dr Duncan ThomasLecturer
Alliance Manchester Business School
[BLANK_AUDIO]
Climate change is one of the main factors or drivers
in the dynamic baseline, along with economic growth and demographic changes.
Water and sanitation policy interventions will
occur in a world with increasing temperature.
Sea level rise and more extreme weather events.
For water sanitation and hygiene sector professionals, it's
important to consider the question of whether wash
investments will be more or less effective or
economically attractive in a world with a changing climate.
The consequences of climate change for the water supply and sanitation sector are
complex and multifaceted, and [UNKNOWN] the answer to this question is not clear.
In this video and the next, we're going to
look at the effects of climate change from two perspectives.
First, in this video, we'll look at the effects of
climate change, health and water from the perspective of the household.
In the next video, we'll look at the effects
of climate change from the perspective of a water utility.
Two of the principle economic benefits from water and sanitation investments
are the reductions in mortality and
morbidity risks compared to baseline conditions.
But these baseline conditions are revolving due to climate change.
How climate change will affect these
baseline health conditions is still uncertain.
The question of how climate change will affect public health is a huge
and complex topic, one which we cannot explore in depth in this MOOC.
But, as current and future professionals in the
wash sector, we do want to encourage you
to think carefully about climate change and health
from both the household and the utility perspective.
We especially want you to reflect on how challenging it is to predict
how households will respond or adapt to the increased risks of their health.
And what this means for the economic
evaluation and selection of water and sanitation investments.
This figure shows eight pathways through which climate
change may affect a household's health and well-being.
The size of the arrows here suggests some preliminary
estimates of the size or importance of these pathways.
But these are highly uncertain, and likely to change from one location to another.
Note that most of these 8 pathways involve water.
If you look at the problem from a poor household's perspective, you can
see how difficult it is to adapt to so many increased health risks.
There are so many pathways, the effects are
uncertain, and the payoff from adaptation measures is uncertain.
Water and foodborne infections may increase due to higher temperatures.
Increasing the chances of household members getting sick.
This is especially a problem for poor households who lack refrigeration.
Increased temperatures and changing rainfall patterns may expand the
range of vector born diseases such as malaria dengue.
These risks may increase if more irrigation is
needed to adapt to erratic or less rainfall.
If increased temperatures and more erratic rainfall, decrease crop yield, this may
decrease the food supply of poor
subsistence households, leading to reduced health.
Increased temperatures will lead to increased crop water requirements.
Irrigation may be an important adaptation measure.
>> But a house hold will need money for this.
Increased temperatures may directly affect health through heat stroke.
Increased temperatures and increasing health risks will hit some
occupations, such as those that require outdoor labor, especially herd.
For example, for farmers and unskilled laborers, working outside during the heat
of the day is going to become increasingly difficult as temperatures rise.
Drinking and cooling water requirements for
laborers will increase and productivity will fall.
Wages may adjust downward.
There is increasing evidence too that
rising temperatures increase violence and civil conflict.
These effects are added to the stresses associated with floods and droughts.
A household may move or try to protect themselves from crime.
Note, that to the extent that climate change
contributes to migration, this may be a reason
not to increase in investments in water and
sanitation infrastructure in locations that are left behind.
Extreme weather events such as typhoons and
droughts directly threaten the lives of household members.
The risk of fires will increase in many areas.
Households have multiple ways to adapt to extreme events.
Including the purchase of insurance, moving to better
locations and increasing liquidity, to deal with emergencies.
Another important link between climate change
and health, is through air pollution.
And higher temperatures exasperate air pollution.
Particularly ozone and fine particulate matter, which
has a large, adverse effect on health.
Including respiratory disease associated with ozone and cardiopulmonary disease.
And lung cancer associated with particulate matter.
This next slide shows that the size of the effects
from these different pathways will increase by 2030 to 2040.
If no adaptations measures are taken.
This is based on estimates by the IPCC Working Group
II on health from both the literature and from expert judgement.
Water and sanitation investments are one adaptation method
that can address some of these adverse effects.
For example, pipe water services may enable
a household to irrigate a home garden.
To reduce the effects of malnutrition.
Improved household sanitation will likely become more important
as food contamination increases due to higher temperatures.
But, there are other climate change and public health
pathways that wash investments can do little to alleviate.
This next slide show that the magnitude of these health effects are
likely to increase over time if mitigation and adaptation measures are not adopted.
As shown, after the malnutrition pathway, the direct adverse
effects of increased temperatures on health are increasingly important.
Access to pipe water supplies can help household members
keep cool through increased opportunities for baths and showers.
Bringing water sources outside the home closer to dwellings
will reduce collection times and the exertion of household members.
Especially during periods of high heat.
But pipe water in the home will likely become
an increasingly important priority to households as temperatures rise.
In this slide, the arrows show how the size of the effects may increase
from the present state, shown in yellow, to that of 2030 to 2040 showing orange.
Enter 2080 to 2100 shown here in red.
[BLANK_AUDIO]
This light shows the magnitude of the effects through
the different pathways without additional adaptation shown in red.
And how these could be reduced with a high level of adaptation shown here in blue.
But all these calculations are highly uncertain.
They're really just educated guesses.
We now turn to one of the eight
pathways through which climate change can affect health.
The food and water borne infections pathway.
Wash professionals are especially concerned how
climate change might affect water borne diseases.
What do we know about how increased temperatures
and increased precipitation affect the incidences of diarrhea?
It turns out that this is not an easy question to answer.
Nor as we've emphasis is it likely to
be the pathway of greatest concern to the household.
One reason that this is not an easy question
to answer is that Diarrhea is caused by multiple pathogens.
These different pathogens will respond in different
ways in increases to temperature and precipitation.
For example, diarrhea caused by bacteria and protozoa tend to peak in and
warmer seasons while viral diarrhea cases tend to peak in cold and dry seasons.
Also, the relative importance of different pathogens
will vary from one location to another.
Diarrheal incidents often has stink seasonal patterns.
This slide shows seasonality in the pattern of
hospital admissions of Peruvian children for all-cause diarrhea.
As shown, admissions tend to increase
when temperatures increase and humidity decreases.
This is an arid setting where rainfall is low all year round,
but in other settings, rainfall has
been significantly associated with diarrheal disease.
Thus to the extent that climate change affects seasonal
temperature, rainfall and humidity patterns,
diarrheal incidence may be affected.
This next slide show seasonal patterns in norovirus cases in China and Germany.
The vertical axis shows the proportion of cases normalized by
location over all years for each study presented by month.
The pattern is most pronounced in Germany, where Norovirus
cases increase and peak in the winter when temperatures fall.
This is the opposite seasonal pattern from diarrheal cases in
Peru, where it is likely that bacterial and/or protozoan pathogens dominate.
Warm temperatures might first decrease the number of norovirus cases or affect
the relative dominance of different pathogens
in a location at different seasons.
These patterns illustrate the spacial
heterogeneity of diarrhoeal seasonality where local
weather patterns, geography and other
factors affect diarrhoeal incidents over time.
This slide presents a third example of seasonality
in water borne disease incidents, this time for cholera.
The figure on the left shows monthly cholera deaths in
Dakar between 1893 and 1940 from historical reference for India.
The typical seasonal pattern exhibits two peaks a year.
And is modulated by longer cycles with considerable
variation in total depths from year to year.
The figure on the right shows average monthly changes in cholera
cases from Bengal and Madras which have two peaks per year.
Both regions have high annual rainfall.
The shift shown in the bimodal seasonal cycles in Bengal and Madras.
Depends on the seasonal timing of the southwest mong,
monsoon in Bengal and the northeast monsoon in Madras.
Also shown is the Punjab which has drier climate and a single color peak per year.
Again these data show distinct patterns in disease incidence and weather.
Suggesting that climate change is likely to affect
the timing and patterns of disease in complex ways.
This final slide summarizes the results
from several studies that have investigated
the relationship between mean ambient temperature
in degree celsius and diarrheal disease.
The figure show the estimated percent
increase in relative risk of diarrhea cases.
Often this is hospital admissions.
Incidents or zed scores associated with each
1 degree celsius increase in mean ambient temperature.
Single empirical studies are shown in black, meter
analyses summarizing multiple studies are underlined in blue.
These studies use different models, time
stamps, and control for different covariants.
So they should be compared with caution.
The six studies summarized in the top half of the
figure used all cause diarrhea
or infectious gastroenteritis for their outcomes.
The three studies in the bottom half report results for rotavirus.
Since the six studies summarized in the top half
are not pathogen-specific the causes for diarrhea may include protozoa.
For example Giardia, Crytosporidium, or bacteria, for example, E
Coli, or Campylobacter, or viruses, for example Rotavirus and Norovirus.
The results for all cause diarrhea suggest a three to 11% increase
in cases with each one degree celsius increasing in mean ambient temperature.
However, one matter analysis by Lloyd and Co authors from 2007
did not find a significant relationship between temperature and diarrheal disease.
However, this study used large annual or multi annual study length time
steps instead of shorter weekly or monthly time steps like the individual studies.
and found rainfall to be significant.
Two of the rotovirus studies, both Gigiatahl and
leviatahl, found a negative correlation between temperature and rotovirus.
This corroborates the general findings that
rotovirus cases expand in colder months.
Likely because of greater time spent indoors.
With the hypothesis being that part of the transmission is through inhalation or air.
Rotavirus seasonality is similar to norovirus
seasonality that we observed in prior slides.
However, one study by Hashizume et al, in 2008,
reports nonlinear threshold effects for rotavirus at high temperatures.
They found that above 29 degrees celsius, there was a 40% increase
in rotavirus cases with each additional
one degree celsius increase in temperature.
Because bacteria and protozoa incidents increases in warm temperatures,
all cause diarrhea results, albeit biased, towards the null hypothesis.
Of no effect when there are multiple pathogens contributing to the outcome.
The bottom line here is that there is a lot of
variability in the results and lots of different factors at play.
A key message from this video is
that understanding households budget priorities and a demand
for improved water and sanitation services in a
world of climate change will become increasingly challenging.
Water and sanitation investments are likely to
be an important adaptation measure in many circumstances.
But this can not simply be assumed because households will have
so many adaptation needs, and priorities will be different in different locations.
There is still a great deal of uncertainty
about the effects of climate change on waterborne diseases.
Higher temperatures are likely to increase diarrhea cases modestly.
But there is likely to be a great deal of spatial and
temporal heterogeneity in the effects of climate change onwards to borne diseases.
Some of effects from the various pathways discussed in this video can be
dealt with at the household level but others must be addressed by the State.
But all the adaptation measures, whether paid for
by the household or by the state require money.
Thanks for watching this video.
