Choose Language 

Climate Change and Health

Contact Phone

01-4262543
01-4262802

Events Calendar

View Events

Nepal Flag

National Health Care Waste Management Standards and Operating Procedures 2020      National Health Policy 2076      Nepal Health Sector Strategy Implementation Plan 2016-2021      Launch of the official website of Climate Change and Health, Ministry of Health and Population      National Adaptation Programme of Action (NAPA) to Climate Change      Nepal Health Sector Strategy 2015-2020      National Climate Change Policy 2076 Nepali      National Framework on Local Adaptation Plans for Action     

What can be done to protect populations from climate impacts? What is Adaptation?

Published on .

Adaptation:Adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities.

Adaptive capacity:The ability of a system to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with consequences.

The extent to which human health is affected depends on: (i) the exposures of populations to climate change and its environmental consequences, (ii) the sensitivity of the population to the exposure, and (iii) the ability of affected systems and populations to adapt (Figure 11.1). We therefore need to understand how decisions are made about adaptation, including the roles of individuals, communities, nations, institutions and private sector.

The main determinants of a community’s adaptive capacity are: economic wealth, technology, information and skills, infrastructure, institutions, and equity. Adaptive capacity is also a function of current population health status and pre-existing disease burdens.

Economic resources

Wealthy nations are better able to adapt because they have the economic resources to invest, and to offset the costs of adaptation. In general, poverty enhances vulnerability – and we live in a world in which approximately one-fifth of the world’s population lives on less than US$1 per day.

Technology

Access to technology in key sectors and settings (e.g., agriculture, water resources, health-care, urban design) is an important determinant of adaptive capacity. Many health-protecting adaptive strategies involve technology – some of which is well established, some new and still being disseminated, and some still being developed to enhance coping with a changing climate.

The health risks from proposed technological adaptations should be assessed in advance. For example, increased air conditioning would protect against heat stress, but could increase emissions of greenhouse gases and other air pollutants. Poorly designed coastal "defences" may increase vulnerability to tidal surges if they engender false security and promote low-lying coastal settlements.

Information and skills

In general, countries with more “human capital” or knowledge have greater adaptive capacity (1). Illiteracy increases a population’s vulnerability to many problems (4). Health systems are labor-intensive and require qualified and experienced staff, including those trained in the operation, quality control, and maintenance of public health infrastructure (5).

Infrastructure

Infrastructure specifically designed to reduce vulnerability to climate variability (e.g., flood control structures, air conditioning, and building insulation) and general public health infrastructure (e.g., sanitation facilities, wastewater treatment systems, laboratory buildings) enhance adaptive capacity. However, infrastructure (especially if immovable) can be adversely affected by climate, especially extreme events such as floods and hurricanes.

Institutions

Countries with weak institutional arrangements have less adaptive capacity than countries with wellestablished institutions (1). For example, institutional and managerial deficiencies contribute to Bangladesh’s vulnerability to climate change.

Collaboration between public and private sectors can enhance adaptive capacity. For example, the Medicines for Malaria Venture – a joint public-private initiative to develop new antimalarial drugs – is developing new products for use in developing countries.

Equity

Adaptive capacity is likely to be greater when access to resources within a community, nation, or the world is equitably distributed (6). Under-resourced and marginal populations lack adaptive resources. While universal access to quality services is fundamental to public health, many still lack access to health care. Overall, the developing world, with 10 per cent of the world’s health resources, carries 90 per cent of the disease burden (5).

Health Status and Pre-existing Disease Burdens

Population well-being is an important ingredient and determinant of adaptive capacity. Great progress has been achieved in public health, yet 170 million children in poor countries are underweight, of whom over three million die each year. Many countries face the double burden of increases of non-communicable diseases, but with continued prevailing infectious diseases.

Conclusions

 

Adaptive strategies intended to protect public health will be needed whether or not actions are taken to mitigate climate change. Building capacity is an essential preparatory step. Adapting to climate change will require more than financial resources, technology, and public health infrastructure. Education, awareness-raising and the creation of legal frameworks, institutions and an environment that enables people to take well-informed, long-term, sustainable decisions are all needed.

(Source: WHO)

How much disease would climate change cause?

Published on .

Climate change will affect the pattern of deaths from exposure to high or low temperatures. However, the effect on actual disease burden cannot be quantified, as we do not know to what extent deaths during thermal extremes are in sick/frail persons who would have died soon anyway.

In 2030 the estimated risk of diarrhoea will be up to 10% higher in some regions than if no climate change occurred. Since few studies have characterized this particular exposure-response relationship, these estimates are uncertain.

Estimated effects on malnutrition vary markedly among regions. By 2030, the relative risks for unmitigated emissions, relative to no climate change, vary from a significant increase in the South- East Asia region to a small decrease in the Western Pacific. Overall, although the estimates of changes in risk are somewhat unstable because of regional variation in rainfall, they refer to a major existing disease burden entailing large numbers of people.

The estimated proportional changes in the numbers of people killed or injured in coastal floods are large, although they refer to low absolute burdens. Impacts of inland floods are predicted to increase by a similar proportion, and would generally cause a greater acute rise in disease burden. While these proportional increases are similar in developed and developing regions, the baseline rates are much higher in developing countries.

Changes in various vector-borne infectious diseases are predicted. This is particularly so for malaria in regions bordering current endemic zones. Smaller changes would occur in currently endemic areas. Most temperate regions would remain unsuitable for transmission, because either they remain climatically unsuitable (e.g., most of Europe) or socioeconomic conditions are likely to remain unsuitable for reinvasion (e.g., southern United States). Uncertainties relate to how reliable is extrapolation between regions, and to whether potential transmission will become actual transmission.

Application of these models to current disease burdens suggests that, if our understanding of broad relationships between climate and disease is realistic, then climate change may already be affecting human health.

The total current estimated burden is small relative to other major risk factors measured under the same framework. However, in contrast to many other risk factors, climate change and its associated risks are increasing rather than decreasing over time.

(Source: WHO)

What are the health impacts of climate extremes

Published on .

Climatic factors are an important determinant of various vector-borne diseases, many enteric illnesses and certain water-related diseases. Relationships between year-to-year variations in climate and infectious diseases are most evident where climate variations are marked, and in vulnerable populations. The El Niño phenomenon provides an analogue for understanding the future impacts of global climate change on infectious diseases.

Extreme climate events are expected to become more frequent with climate change. These disruptive events have their greatest impact in poor countries. The two categories of climatic extremes are:

  • Simple extremes of climatic statistical ranges, such as very low or very high temperatures
  • Complex events: droughts, floods, or hurricanes

The Pacific-based El Niño- Southern Oscillation (ENSO), an approximately semi-decadal cycle, influences much of the world’s regional weather patterns. Climate change is likely to increase the frequency and/or amplitude of El Niño (1). It illustrates well how climatic extremes can affect human health.

Climate, weather, El Niño and infectious diseases

Both temperature and surface water have important influences on the insect vectors of vector-borne infectious disease. Of particular importance are vector mosquito species, which spread malaria and viral diseases such as dengue and yellow fever. Mosquitoes need access to stagnant water in order to breed, and the adults need humid conditions for viability. Warmer temperatures enhance vector breeding and reduce the pathogen’s maturation period within the vector organism. However, very hot and dry conditions can reduce mosquito survival.

Malaria, today, is mostly confined to tropical and subtropical regions. The disease’s sensitivity to climate is illustrated by desert and highland fringe areas where higher temperatures and/or rainfall associated with El Niño may increase transmission of malaria (2). In areas of unstable malaria in developing countries, populations lack protective immunity and are prone to epidemics when weather conditions facilitate transmission.

Dengue is the most important arboviral disease of humans, occurring in tropical and subtropical regions, particularly in urban settings. ENSO affects dengue occurrence by causing changes in household water storage practices and in surface water pooling. Between 1970 and 1995, the annual number of dengue epidemics in the South Pacific was positively correlated with La Niña conditions (i.e., warmer and wetter) (3).

Rodents, which proliferate in temperate regions following mild wet winters, act as reservoirs for various diseases. Certain rodent-borne diseases are associated with flooding, including leptospirosis, tularaemia and viral haemorrhagic diseases. Other diseases associated with rodents and ticks, and which show associations with climatic variability, include Lyme disease, tick borne encephalitis, and hantavirus pulmonary syndrome.

Many diarrhoeal diseases vary seasonally, suggesting sensitivity to climate. In the tropics diarrhoeal diseases typically peak during the rainy season. Both floods and droughts increase the risk of diarrhoeal diseases. Major causes of diarrhoea linked to heavy rainfall and contaminated water supplies are: cholera, cryptosporidium, E.coli infection, giardia, shigella, typhoid, and viruses such as hepatitis A.

Temperature extremes: heatwaves and cold spells

Extremes of temperature can kill. In many temperate countries, death rates during the winter season are 10-25% higher than those in the summer. In July 1995, a heatwave in Chicago, US, caused 514 heatrelated deaths (12 per 100,000 population) and 3300 excess emergency admissions.

Most of the excess deaths during times of thermal extreme are in persons with preexisting disease, especially cardiovascular and respiratory disease. The very old, the very young and the frail are most susceptible. In terms of the amount of life lost, the mortality impact of an acute event such as a heatwave is uncertain because an unknown proportion of deaths are in susceptible persons who would have died in the very near future.

Global climate change will be accompanied by an increased frequency and intensity of heatwaves, as well as warmer summers and milder winters. Predictive modelling studies, using climate scenarios, have estimated future temperature-related mortality. For example, the annual excess summer-time mortality attributable to climate change, by 2050, is estimated to increase several-fold, to between 500-1000 for New York and 100-250 for Detroit, assuming population acclimatisation (physiological, infrastructural and behavioural) (4). Without acclimatisation the impacts would be higher.

The extent of winter-associated mortality directly attributable to stressful weather is less easy to determine. In temperate countries undergoing climate change, a reduction in winter deaths may outnumber the increase in summer deaths. Without better data, the net impact on annual mortality is difficult to estimate. Further, it will vary between populations.

Natural disasters

The effects of weather disasters (droughts, floods, storms and bushfires) on health are difficult to quantify, because secondary and delayed consequences are poorly reported. El Niño events influence the annual toll of persons affected by natural disasters (5). Globally, disasters triggered by droughts occur especially during the year after the onset of El Niño.

Globally, natural disaster impacts have been increasing. An analysis by the reinsurance company Munich Re found a tripling in the number of natural catastrophes in the last ten years, compared to the 1960s. This reflects global trends in population vulnerability more than an increased frequency of extreme climatic events. Developing countries are poorly equipped to deal with weather extremes, even as the population concentration increases in high-risk areas like coastal zones and cities. Hence, the number of people killed, injured or made homeless by natural disasters has been increasing rapidly.

(Source: WHO)

What are the major challenges for scientists studying climate change and health linkages?

Published on .

The challenges in identifying, quantifying and predicting the health impacts of climate change entail issues of scale, “exposure” specification, and the elaboration of often complex and indirect causal pathways. First, the geographic scale of climate-related health impacts and the typically wide timespans are unfamiliar to most researchers. Epidemiologists usually study problems that are geographically localised, have relatively rapid onset, and directly affect health. The individual is usually the natural unit of observation.

Second, the “exposure” variable – comprising weather, climate variability and climate trends – poses difficulties. There is no obvious "unexposed" group to act as baseline for comparison. Indeed, because there is little difference in weather/climate exposures between individuals in the same geographic locale, comparing sets of persons with different “exposures” is usually precluded. Rather, whole communities or populations must be compared – and, in so doing, attention must be paid to intercommunity differences in vulnerability. For example, the excess death rate during the severe 1995 Chicago heatwave varied greatly between neighbourhoods because of differences in factors such as housing quality and community cohesion.

Third, some health impacts occur via indirect and complex pathways. For example, the effects of temperature extremes on health are direct. In contrast, complex changes in ecosystem composition and functioning help mediate the impact of climatic change on transmission of vector-borne infectious diseases and on agricultural productivity.

A final challenge is the need to estimate health risks in relation to future climatic-environmental scenarios. Unlike most recognized environmental health hazards, much of the anticipated risk from global climate change lies years to decades into the future.

(Source: WHO)