Climate change may already be affecting your health

  • Published: 13 December 2017
  • Author: Rita Yu

Climate change is commonly seen as an environmental issue and a distant, future threat. In reality, climate change is happening and already harming health for millions worldwide through heatwaves, disease and air pollution with “impacts far worse than previously understood,” according to the Lancet Countdown’s 2017 report published at the end of October.

The Lancet Countdown is a collaboration between 24 academic institutions across the globe and intergovernmental organisations, including the World Health Organization (WHO), World Bank and World Meteorological Organization (WMO). The Lancet Countdown tracks progress on health and climate change and independently assessed the health effects of climate change, the implementation of the Paris Agreement and the associated health implications. The 2017 report assessed 40 indicators across five domains: climate impacts, exposures and vulnerability; climate resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement.

Over the past few decades, the changing climate has overwhelmingly negatively affected public health. This has exacerbated social, economic and demographic inequalities, with the impacts eventually felt by all populations.

Extreme Heat

Heatwaves are becoming more frequent and intense, especially in urban areas where temperatures are higher. The report estimated that between 2000 and 2016, 125 million people older than 65 years were exposed to extreme heat, and a record 175 million people suffered from heatwaves in 2015 alone.

Extreme heat can cause heat stress and heat stroke. The elderly, children under 12 months, and people with chronic cardiovascular and renal disease are particularly vulnerable to heat. Higher temperatures can exacerbate pre-existing health problems such as heart failure, and introduce new health threats such as increased incidence of acute kidney injury from dehydration in vulnerable populations. This is troublesome when considering the growing ageing population.

Global labour capacity in rural populations fell by 5.3% between 2000 and 2016 due to hotter and more humid weather, along with other conditions that make outdoor manual work more difficult. Loss of labour capacity has significant livelihoods consequences for individuals, families, and communities, especially those relying on subsistence farming.


According to the WHO, over 40% of the world’s population, an equivalent of over 2.5 billion people, are at risk from dengue fever. This disease is endemic in Southeast Asia. Severe dengue affects most Asian countries and is a leading cause of hospitalisation and death among children and adults.

Altered climatic conditions are boosting the spread of dengue fever by two types of mosquito (A aeqypti and A albopictus), with a global increase estimated at 3% and 6% since 1990, and 9% and 11% since 1950. The report warns of an increase in mortality. These two mosquito vectors also carry other important emerging or re-emerging arboviruses, such as Yellow Fever, Chikungunya, Mayaro, and Zika viruses, which are probably also climate-sensitive.

Air Pollution

The report finds that 71% of the 2,971 cities in WHO’s database do not satisfy WHO annual fine particulate matter (PM) exposure recommendations. While PM2.51 concentrations in most cities are well above the WHO’s annual guideline of 10 μg/m2, and cities throughout Asia have particularly high concentrations. In 2015, 87% of randomly selected cities in the Sustainable Healthy Urban Environments database had PM2.5 concentrations that exceeded recommended concentrations of 10 μg/m2 (Figure 1).

Figure 1. Annual mean fine particulate matter (PM2.5) concentration versus per capita gross domestic product (GDP) for 246 cities in the Sustainable Healthy Urban Environments database

Human-induced air pollutants primarily come from the energy sector (both production and consumption), with coal power being largely responsible. In 2015, the building sector contributed to 48% and 59% of energy-related emission of PM2.5 in China and Southeast Asia, respectively. The industry and transport sectors were also big emitters of PM2.5 (Figure 2).

Figure 2. Energy-related emission of fine particulate matter (PM2·5) emissions in 2015.

Long-term exposure to ambient PM2.5 and other air pollutants is known to cause increased mortality and morbidity from cardiovascular and pulmonary diseases, and millions of premature deaths globally every year. Since the sources of air pollution and greenhouse gases (GHG) often overlap, climate policies that aim to lower GHG emissions, such as replacing coal-fired power plants with wind and solar, have direct benefits for human health. For example, replacement of household combustion of coal in China would result in health benefits from both ambient (outdoor) and household (indoor) exposure to air pollution.

Other Climate Impacts

Overall, the frequency of climate-related disasters has increased by 46% since 2000, and impacts are projected to worsen with time. Such events can reduce crop yields and raise the number of undernourished people. In addition, climate change can affect fish stocks and aquatic food security. This has significant implications for shoreline communities that depend on marine sources for food, as well as the one billion people in the world who rely on fish as their principal protein source.

Also, low-income countries tend to experience higher economic loss from climate disasters as a proportion of GDP than high-income countries. More strikingly, roughly half of economic losses are insured in high-income countries, but this figure drops rapidly to under 10% in upper-middle income countries, and to well under 1% in low-income countries. From 1990 to 2016, uninsured losses in low-income countries were equivalent to over 1.5 % of their GDP. In 2016, a total of 797 extreme climatic events resulted in US$129 billion in overall economic losses, with 99% of losses in low-income countries uninsured.


The role of human activities in observed warming is clear, and the health of hundreds of millions of people is already suffering from climate-related impacts. Climate change often magnifies existing pressures on housing, food and water security, poverty and other determinants of good health. Climate impacts are disproportionately affecting the health of vulnerable populations and people in low-income and middle-income countries. The report also argues that health professionals have the responsibility to advance progress by communicating the threats and opportunities to the public and policy makers. This is essential in helping them realise the resultant health benefits, and maximise the opportunities for better health.

The disconcerting level of delayed response and inaction over the past 25 years has jeopardised human lives and livelihoods. However, in the past 5 years, momentum for change has been building, particularly in the media and academia. The public and governments are also beginning to respond with growing political consensus and ambition as reflected in the Paris Agreement. These signs of progress are encouraging, but quicker progress is urgently needed.

How CSR Can Help

Climate change can have adverse effects on the health of employees and business partners, as well as workers along the supply chain such as farmers that produce raw materials and outdoor workers that help with logistics. These have implications for business operations and performance.

CSR Asia can help identify which areas of your organization are potentially vulnerable to the impacts of climate change. For more information, please contact Rita Yu at [email protected]

Recommended Reading:
Watts, N., et al. (2017) The Lancet Countdown on health and climate change: from 25 years of inaction to a global transformation for public health 
WHO (2017) Dengue and severe dengue – Fact sheet

1. Fine particulate matter with diameter smaller than 2.5 micrometers (μm). PM2.5 can penetrate deeply into the lung, irritate and corrode the alveolar wall, and consequently impair lung function.