Case 5
What is climate change?
Climate change is a long-term change in the average weather pattern that has come to define Earth’s local,
regional and global climates.
The primary cause of climate change is the burning of fossil fuels, such as oil and coal, which emit greenhouse
gases into the atmosphere—primarily carbon dioxide. Other human activities, such as agriculture and
deforestation, also contribute to the proliferation of greenhouse gases that cause climate change.
How can climate change influence health?
Climate change, together with other natural and human-made health stressors, influences human health
and disease in numerous ways. Some existing health threats will intensify and new health threats will
emerge.
National health topics
o Air pollution
Can harm human health by increasing
ground-level ozone and or particulate
matter air pollution in some locations.
Ground-level ozone (smog) is
associated with many health problems
such as diminished lung function,
increased hospital admissions and
emergency room visits for asthma,
increase in premature deaths
If not treated then estimated 1,000-
4,300 additional premature deaths
nationally per year by 2050
o Allergens and pollens
Climate change will increase pollen
concentration and longer pollen season.
Pollen distribution can trigger various allergic reactions such as hay fever.
o Diseases carried by vectors
Climate change influences the distribution of diseases borne by vectors (fleas, tricks,
mosquitoes).
Infectious disease transmission is sensitive to local, small-scale differences in
weather, human modification of the landscape, the diversity of animal hosts, and
human behavior that affects vector-human contacts
o Food and waterborne diarrheal disease
Air and water temperatures, precipitation patterns, extreme rainfall events, and
seasonal variations are all known to affect disease transmission.
Includes salmonellosis and campylobacteriosis, more common when temperature is
high
o Food security
Climate change is expected to threaten food production and certain aspects of food
quality, as well as food prices and distribution systems.
Food insecurity increases with rising food prices. People cope by turning to nutrient
poor but calorie rich foods and or they endure hunger, with consequences ranging
from micronutrient malnutrition to obesity.
Nutritional value of some foods is projected to decline. Elevated atmospheric CO2 is
associated with decreased plant nitrogen concentration, and therefore decreased
protein, in many crops.
Nutrient content of crops is projected to decline if soil nitrogen levels are suboptimal.
Farmers are expected to use more pesticides because of increased growth of pests and
weeds. More exposure to these substances which are toxic.
o Floods
Waterborne diseases spread easily
Populations living in damp indoor environments experience increases prevalence of
asthma and other upper respiratory tract and lower respiratory tract symptoms.
, o Mental health and stress-related disorders
Mental illness following disasters (hurricanes, flooding, earthquakes, wildfires)
Suicide rates vary with weather, rising with higher temperatures, suggesting potential
impacts from climate change on depression and other mental illnesses.
o Temperature extremes
Heat waves are associated with increased hospital admissions for cardiovascular,
kidney and respiratory disorders.
o Wildfires
Wildfire smoke contains carbon monoxide, nitrogen oxides, and various volatile
organic compounds and can significantly reduce air quality, both locally and in areas
downwind of fires.
Is there data being gathered for future purposes?
The biggest challenge is scale. Both the geographical spread of climate-related health problems and the much
elongated time spans that often apply, are largely unfamiliar to public health researchers. Research on climate
change typically is conducted on 3 time scales
Relatively short periods between altered climate (expressed as weather) and the effects on health
Intermediate time periods that include recurring, inter-annual events
Longer interval (decades or centuries) between the release of greenhouse gases and subsequent change
in the climate. The category of research is most troublesome to standard epidemiological methods.
A broad range of data is needed to monitor climate effects on health. Where possible, monitoring systems
should assemble data on all components required for statistical analysis (including assessment of effect
modification) or process-based/biological models. Many relevant variables already are recorded by existing
systems and may require only access and cross-referencing with other data sources. For others, new monitoring
systems or radical changes to existing systems may be necessary. Relevant measurements fall into the following
broad classes:
Meteorology: various meteorological factors influence health processes either directly or indirectly
Temperature, relative humidity, rainfall and wind-speeds are the most important and all are predicted
(with a greater or lesser degree of certainty) to be affected by future climate change a specific data
asured (through satellites) at different times to cross-reference meteorology and time.
Health markers: climate effects on health ultimately depend on reliable recording of health status, at suitable
temporal and spatial resolution.
Such monitoring should be sensitive and specific enough to quantify changes in intensity and temporal
and geographical distribution of climate-sensitive health impacts.
One way to address the complex causality of most health outcomes is carefully to select indicators that
are highly sensitive to climate changes but relatively insensitive to other influences. This approach
already has given clear evidence of climate-change driven effects in other ecological systems. à
mortality data is routinely collected at regional and national levels & quite complicated because health
is influences by many other factors.
Other explanatory factors: it has been stated that monitoring will need to measure more than just climate and
health à data that is collected is compared with age, underlying rates of disease et cetera. to see the actual impact
of climate change.
Data on time varying risk factors and changes in potential population susceptibility are equally
important in order to begin to assess the climatic contribution to any observed change in health status à
this is particularly true of infectious diseases transmitted by water, food or vectors: often these are
highly sensitive to climate, but human infections are only the end product of a complex chain of
environmental processes.
In some situations, it may be informative to define the relationship between climate and environmental
intermediates, even in the absence of the disease itself.