Global Temperature Rise and Human Health - How is the World Coping?

Global temperatures have been on the rise since the Industrial Age due to human activity such as the emissions of greenhouse gases from fossil fuel burning, large-scale deforestation, expansion of urban areas where vegetation cover is replaced by artificial heat retaining materials such as asphalt and concrete, some agricultural practices, and waste management activities. Data from the National Climatic Data Centre that  maintains the world's largest climate data archive indicate that the average global temperature across land surfaces was 1.68°C (3.02°F) above the 20th century average of 3.2°C (37.8°F) . To put things in perspective, February 2015 was much warmer than February 2014.

 Epidemiological studies in different parts of the world have unequivocally shown a strong link between high temperature and mortality, which is a public health concern. The magnitude of the problem will only escalate as the global mean temperature continues to increase causing extreme heat events in large geographical areas. Approximately 650 deaths per year occur in United States due to heat events, which account for more fatalities than any other weather hazard. Males outnumber females in deaths cause by extreme heat events.

Vulnerable population for heat-related deaths

 Although the human body can tolerate changes in temperature by the process of thermoregulation, whereby it can protect itself from extremes in ambient temperature, there are limits. Importantly, infants and the elderly particularly those with health conditions such as cardiovascular disease, cerebrovascular disease, neurological diseases, diabetes, renal disease and respiratory disease are particularly vulnerable to mortality due to increase in ambient temperature. However, many studies indicate that there is a lack of risk perception among the population to heat-related deaths.

Global disparity in knowledge pertaining to extreme heat, its consequences, and public health responses  

 In many developed nations, data on temperature rise and its consequences on health are often readily available due to good documentation of historical temperature records and epidemiological research in these areas. Heat vulnerability maps (Heatwave maps) now exist for many areas in developed countries- particularly cities, that help identify regions that are at risk for extreme heat events. In many such places, Heat response plans that help prepare communities for heath rated illnesses exist.

However, developing nations lag behind both in research as well as public health strategies to mitigate extreme heat events. A plethora of factors such as  knowledge gaps, defective record keeping and poor research (death records, which list causes of death are often unreliable particularly in rural areas), archaic technology, lack of funds, corruption, poor public health initiatives, all lead to poor knowledge  or ignorance  pertaining to the health effects of extreme temperature. The health implications of extreme heat  is likely to be  far more pronounced in the developing countries, which are often subject to extreme climate change compared to the developed countries, but is likely staying under the radar.

Here through the pages of Ecoratorio, we have often highlighted the dangers of human activities on the environment and the need for global, personal, and corporate environmental stewardship. Specifically in the context of heat-related illnesses and deaths, a cohesive understanding of the environmental impact on human health, identification of vulnerable populations, expert recommendations on public behaviour and timely communication of these recommendations, generating public awareness through mass media of health-related illnesses and deaths, and enforcement of mitigation steps in the general public is critical. With extreme heath events anticipated to rise in the coming years due to climate change, population increase, and increase in ageing population, it is crucial that  scientific, political and public health action should take place to manage this important issue.

Useful Facts about Heat-related illnesses

• Although many studies have stressed infants and elderly as being most vulnerable to heat –related illnesses and death, other high-risk groups include young children, older adults (people over 65 years) and people who engage in strenuous activities outdoors.
• Extreme heat events disproportionately harm vulnerable populations.
• The majority of heat-related deaths are preventable.
• During periods of extreme heat, heat-related illnesses can be prevented by using air-conditioning, avoiding strenuous outdoor activities, drinking adequate amounts of fluid, wearing lightweight clothing, and avoiding alcohol consumption. 
•  Heat Response plans should be in place before extreme heat events occur.
• Major inequalities exist between developed and the developing nations in the awareness of heat- related illnesses, the contributory factors, and public health initiatives.

References:

1. http://www.ncdc.noaa.gov/sotc/global/
2.  http://monash.edu/news/show/heatwave-map-reveals-melbournes-most-vulnerable-postcodes
3.  Madrigano, J., Ito, K., Johnson, S., Kinney, P., & Matte, T. (2015). A Case-Only Study of Vulnerability to Heat Wave–Related Mortality in New York City (2000–2011) Environmental Health Perspectives DOI: 10.1289/ehp.1408178http://dx.doi.org/10.1289/ehp.1408178">10.1289/ehp.1408178>
4. Kim, C., Lim, Y., Woodward, A., & Kim, H. (2015). Heat-Attributable Deaths between 1992 and 2009 in Seoul, South Korea PLOS ONE, 10 (2) DOI: 10.1371/journal.pone.0118577http://dx.doi.org/10.1371/journal.pone.0118577">10.1371/journal.pone.0118577>
5. http://www.epa.gov/climatechange/science/indicators/health-society/heat-deaths.html
6. Bobb, J., Peng, R., Bell, M., & Dominici, F. (2014). Heat-Related Mortality and Adaptation to Heat in the United States Environmental Health Perspectives DOI: 10.1289/ehp.1307392http://dx.doi.org/10.1289/ehp.1307392">10.1289/ehp.1307392>
7. http://www.medscape.com/viewarticle/806947