Despite negligible emissions, lower-middle income countries (LMIC) are typically more vulnerable to the health impacts of climate change. Many LMICs are in a state of economic transition and are subject to significant burdens of
communicable and non-communicable disease, both of which will be exacerbated under climate change.
The impacts of climate change on human health are multi-faceted, varying greatly from region to region and going far beyond the commonly discussed direct effects of natural hazards. A robust evaluation of health risks associated with
climate change requires one to consider a holistic picture with a consideration of the prevalence of communicable and non-communicable diseases (NCD), the latter being diseases that are not transmitted between humans.
The disease regime of any given country is largely dependent on economic conditions, most ‘developed’ countries are characterized by relatively minimal communicable (such as HIV, measles, hepatitis A/B/C) and nutrient deficient disease
(such as scurvy, rickets, hypocalcemia) but higher burdens of non-communicable disease (such as stroke, heart disease, and cancer).
Opposingly, many low-to-middle income countries (LMIC) are in a state of transition, where the burden of communicable disease remains high, while economic development is increasing the prevalence of NCDs and injuries. Hence, many LMIC are
subject to a ‘triple burden of disease’ of communicable disease, NCD, and injuries, all of which are likely to worsen under
Of particular concern is the impact of climate change on the spread and prevalence of various parasites and pathogens responsible for serious disease, with projected climatic changes expected to lengthen the transmission seasons of
important vector-borne diseases and alter their geographic range.
Higher global temperatures are likely to
facilitate range expansions in vector-borne diseases such as dengue fever, malaria, and communicable diarrhoeal diseases and encourage bacterial growth, with
evidence already detailing the spread of malaria to regions of higher elevation within the
Furthermore, while natural hazards, such as flooding, landslides, and wildfires, evidently cause unexpected direct morality, especially among LMICs with limited adaptive capacity and preparedness, they also lead to clustered disease outbreaks and can compound existing health issues
associated with water, sanitation, and hygiene (WASH) infrastructure. Such events
are set to occur more frequently and less predictably in space and time under climate change.
Climate change also affects environmental determinants of health, such as air quality, safe drinking water, and food security. Around two-thirds of the global population are already subject to water scarcity for at least one month of the
year, with climate change likely to further exacerbate water scarcity.
Beyond water availability, climate may also undermine water quality, which is heavily dependent on numerous climatic parameters including rainfall and temperature. Evidence suggests outbreaks
of waterborne disease disproportionately occur in response to heavy rainfall
events, with such events projected to increase in frequency.
Although all countries will be subject to increased injury and potential mortality associated with natural hazards, changes in communicable disease prevalence will mainly impact LMICs. Furthermore, demographic and lifestyle changes among
many LMICs are increasing NCDs, such as cancer and chronic respiratory or cardiovascular
disease, as the burden of communicable disease grows.
Climate change also further increases the burden of NCDs, with higher temperatures and changing climatic conditions linked to acute respiratory and cardiovascular disease, as well
as cancer. Big questions also center around food security
under climate change, with any reductions in yield,
quality, or affordability likely to lead to malnutrition and chronic disease.
This triple burden of communicable, NCD, and injuries is likely to lead to significant mortality with LMICs. The World Health Organisation (WHO) estimates that between 2030 and 2050, climate change will result in roughly 250,000 additional
globally per year; 38,000 due to heat exposure in elderly people, 48,000 due to diarrhoea, 60,000 due to malaria, and 95,000 due to childhood undernutrition. The vast majority of these deaths are projected to occur in economically
These figures also do not account for premature deaths related to air pollution, which is thought to cause roughly nine million deaths annually. Beyond mortality, climate change is projected to result in direct health costs (excluding costs in health-determining
sectors such as agriculture and sanitation) of between two and four billion USD annually by 2030.
Hence, in the run-up to COP26, scientists, professionals, and health organizations are urging world leaders to consider the health benefits of climate actions, especially within LMICs. Although many solutions to address climate change have
numerous health co-benefits, there is still a need to ensure climate initiatives are explicitly designed to also deliver health benefits. Efforts must also be made to increase the resilience of healthcare facilities under climate change and to reduce emissions (4% to 5% of
global total) associated with health care.
Given the amplified interest in human disease following the onset of the pandemic, there is clear scope for health to form a central pillar of COP26 negotiations and ‘green’ recoveries. The increased attention on the health costs of climate
change further strengthens the argument for early and decisive measures. Although there is still a need for a more holistic approach when it comes to health.
Additive impacts of climate changes on existing disease burdens with LMICs remain largely overlooked, despite the potential of substantial instability and economic losses within these countries. This triple burden of disease represents a
plausible barrier to development and requires effective, proactive, and integrated health and climate policy. Given the limited culpability of LMIC in climate change, the failure of richer countries to initiate the urgent measures required
would represent a serious moral failure.
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