Monday, 20 April 2015

Urban green spaces: Insights from Valencia

Visiting the city of Valencia in Spain for the first time, we were pleasantly greeted by the subtle aroma of orange blossoms in the air and the sight of beautiful oranges dangling from the orange trees that line the street pavements. Whilst many parts of the city are bordered with trees, there are also other green spaces,  such as beautiful small parks (like the one in the picture  shown below),
complete with Mediterranean flora such as palms, ficus, cycas, and orange trees. 

 The most impressive green space is perhaps the 9 km green belt that runs through the city-  the Jardi delTuria (Garden of the Turia), which is a credit to the city. The Turia is a Spanish river that empties into the Mediterranean near the city of Valencia. In 1957, it flooded and devastated Valencia. Consequently, the course of the river was artifically changed- now running along the city edge before meeting the Mediterranean. The original course of the river continues has been converted into an enormous green space resplendent with beautiful trees with pedestrian paths, cycle paths, and occasionally dotted with football grounds, cafes, athletics tracks, and gardens within the garden. Here city dwellers relax, play, or just get about their business, avoiding the traffic that plies overhead on the many bridges that cross the river bed. Buildings tower over either side of the Turia garden, comprising largely of apartment blocks and businesses. Our walk along the Turia garden in sweltering sunny April was very pleasant which made me realize the importance of green spaces in cities.

Urban heat islands and global warming

Cities have their own micro-climates. Human activities- buildings made of concrete,  asphalt roads , vehicular emissions, heat generated by people, and heat arising from equipment use, all contribute to temperature increases in the urban areas to levels that are significantly higher from the adjoining rural areas where temperatures remains close to air temperatures. Such urban areas are called ‘Urban heat islands’, a concept described over 200 years ago by Luke Howard, the father of meteorology. The term has been coined  as the warmer urban air lies in a ‘sea’ of cooler rural air.  According to the EPA, the annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings, going up to temperature difference as much as 22°F (12°C) on a clear, calm night.

Heat islands could not only affect the health of the urban inhabitants by causing heat -related illnesses (a topic discussed in the earlier post), but also contribute to global warming in general, and must not be ignored particularly as predictions indicate that by 2050 about 64% of the developing world and 86% of the developed world will be urbanised - leading to amplification of the issue. Whilst urbanisation cannot be halted, it must be made sustainable.

Mitigation strategies for urban heat island effects

Among the four major strategies United States EnvironmentalProtection Agency (EPA) has suggested for mitigating the effects of urban heat islands, the first one is increasing tree and vegetation cover. The others are the installation of green roofs (roofs with plants grown over a waterproof membrane), installation of cool and reflective roofs (built from materials with high solar reflectance and high heat emittance), and building cool pavements (made of material with high solar reflectivity and good water permeability).

In this post, we will look at the EPA’s primary recommendation. This, in my opinion, is the one with the maximum impact and the least costliest. The major benefits of increasing trees and vegetation covers are the following:
They reduce surface and air temperatures by providing shade and by the process of evapotranspiration. Estimates indicate that evapotranspiration, alone or in combination with shading, can help reduce peak summer temperatures by 2–9°F (1–5°C). By providing shade to buildings, trees decrease the demand for air conditioning and indirectly decrease the need for energy use which, in turn, lowers greenhouse gas emissions and provides better air quality. Trees also function as ‘sinks’ for air pollutants and carbon dioxide. Trees improve the quality of life of city dwellers by enhancing the aesthetic value of their surroundings and promote biodiversity by providing habitats for diverse species.

Interestingly, it  also appears that for some trees living in an urban environment might not be bad after all. In a study in 2012, seedlings of oak were grown for one season at four sites along an urban–rural transect from Central Park in New York City to the Catskill Mountains in upstate New York  with a difference in average maximum temperatures of 2.4 °C and  difference in minimum temperatures of 4.6 °C.  Additionally, seedlings were cultured in growth cabinets simulating the seasonal differential between the city and rural sites. The researchers found that warmer temperatures associated with the urban environment, especially high night-time temperatures, lead to enhanced growth in these seedlings.

The necessity for a Green Channel Programme for our cities

Coming back to our example - Valencia- it appears that the city is going in the right direction with its tree and vegetation cover initiatives. The green spaces and the green belts are not only aesthetically pleasing, but also reduce the heat (personal experience). Increasing the vegetation cover in cities is something where more is less. Thus, Valencia and other cities who have such initiatives cannot rest on their laurels. We really need to have green channels through our cities to cool the urban heat islands.


Searle, S., Turnbull, M., Boelman, N., Schuster, W., Yakir, D., & Griffin, K. (2012). Urban environment of New York City promotes growth in northern red oak seedlings Tree Physiology, 32 (4), 389-400 DOI: 10.1093/treephys/tps027">10.1093/treephys/tps027

Tuesday, 14 April 2015

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.

  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.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.0118577">10.1371/journal.pone.0118577>
  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.1307392">10.1289/ehp.1307392>


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