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Climate Change and Health

Climate Change and Health

7 December 2018


Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activities. Human activities such as fossil fuel use, deforestation, and intensive livestock farming, have released sufficient amount of greenhouse gases to trap additional heat in the lower atmosphere and affect the global climate.

Affected by global warming and exacerbation of local urbanization, Hong Kong has also experienced temperature rises during the past several decades. More importantly, Hong Kong is expected to have an increase in the number of very hot days, average rainfall intensity, frequency of extreme rainfall events and rising sea level in this century. For more information about climate change in Hong Kong, please visit the relevant Hong Kong Observatory’s website.

Health effects of climate change

Climate change represents a fundamental threat to lives and wellbeing. Direct and indirect impacts of climate change threaten human health by affecting some of the fundamental determinants of health – weather, air, water and food as well as transmission pattern of different diseases. The climate change is one of the biggest global health issues of the 21st century.

The effects of climate change will vary in different geographical location. For example, the more hot days will increase the heat-related diseases but the warming will decrease the cold-related mortality in some regions. However, overall speaking, the negative effects are more than the positive effects.  Besides, some groups of people, such as the socially-deprived, children and elderly, are more vulnerable than others due to their particular sensitivities, high likelihood of exposure, low adaptive capacity, or combinations of these factors.

Some typical health effects by climate change are discussed below.

Extreme heat

Warmer average temperatures will lead to hotter days and more frequent and longer heat waves. Exposure to extreme heat and humidity without relief or adequate fluid intake can result in various types of heat-related illness, such as heat cramps, heat exhaustion, and even life-threatening heat stroke. Extreme high temperatures can also worsen chronic conditions such as cardiovascular and respiratory diseases.

Natural disasters and variable rainfall patterns

Global warming could increase the number and severity of extreme weather events such as storms, floods, droughts, and related landslides and wildfires. Such events could result in destruction of homes and other essential services, which cause injuries and deaths directly. Moreover, variable rainfall patterns could affect the adequate supply of fresh water and flooding could induce contamination to water supplies, in which both pose negative impact to the supply of safe drinking water.

Changes in transmission patterns of infectious diseases

Global warming also indirectly changes the transmission patterns of some infectious diseases, especially vector-borne diseases (VBDs). Changes in climate are likely to lengthen the transmission seasons of important VBDs and to expand their geographical range. Mosquitoes which transmit VBDs, such as malaria, dengue fever, and Japanese encephalitis, are particularly sensitive to meteorological conditions – warmer temperature and humid conditions increase their reproductive rate, biting activity and survival, and also shorten the incubation period of pathogens within them.

Air pollution

Burning fossil fuel produces not only carbon dioxide causing climate change, but also several pollutants resulting in air pollution. Besides, the changing climate has modified weather patterns, weather elements like temperature, humidity, wind, precipitation and extreme weather events can affect air pollutant emission, chemistry, deposition and transport. Poor air quality can negatively affect the human respiratory and cardiovascular systems.

Increasing carbon dioxide levels and temperatures could prolong pollen seasons and increase pollen concentrations which in turn contribute to allergic sensitization and trigger asthma in some people.

Further Information and Actions

You can follow the links below to find out more about climate change and its effects on human health.

World Health Organization:

US Centers for Disease Control and Prevention:

Acting on climate change is everyone’s responsibility. As responsible global citizens, we should cut down our own carbon footprint. Many mitigation measures have important direct health benefits as well as slowing down the pace of climate change. For example, active transportation such as walking and cycling, not only can reduce carbon emissions but also increase physical activity levels which can prevent some cancers, diabetes, heart diseases and obesity-related risks. Click here for more information about the health benefits of tackling climate change.