As vegetation has been replaced by non-reflective construction materials for roofing walls and pavements - Our cities have become steadily warmer. With the increase in city temperatures peak energy demand and smog have grown along with an escalation in respiratory health related issues. Our Cities are now known as “ Urban Heat Islands”.

The effects of Urban Heat Island in Atlanta Georgia 1978 to 1993. Captured by Satellite thermal imaging.
 
 
The plot left shows the 1985-94 Summer Mean Minimum Potential Temperature contours for Melbourne. This plot shows a UHI of 1.81 deg C, which is determined by subtracting the average value of Melbourne and Laverton airports from the average value of the three inner city sites of Melbourne, Paisley and Alphington. The peak in the contours is located over Melbourne's CBD. The key shows a UHI of 2.0 deg C, with a contour interval of 0.1 deg C
The plot shows the 1985-94 Winter (JJA) Mean Minimum Observed Temperature recorded
at 15 sites around Melbourne.		  
 
The effects of “urban heat island” in Tokyo Japan 1981 to 1999. Captured by Satellite thermal imaging.
   
 

The exponential growth of urban areas has produced what science now calls “ urban heat islands” with the major contributing factor being heat-absorbing roofing walls and pavements.

The temperature in the air above the urban heat islands can be as much as twelve degrees hotter than the surrounding areas.

As a result of these higher temperatures air conditioning costs and power consumption are increased.

An alarming result of this excess heat and required increase in energy production for cooling, are the high levels of ozone and smog our cities experience.
 

Government Authorities:

 

In 1998 the “Urban Heat Island Project” was formed. The project was developed in co-operation with the ENVIROMENTAL PROTECTION AGENCY AND LOCAL GOVENMENTS. The focus of this group is to develop ways to make our cities cooler and thereby reduce pollution, and save energy. Data from these groups have shown there is a steady increase in the “urban heat island” effect over several decades.

Japan is averaging an increase in temperature of 0.60 F per decade; Los Angeles 0.80 F and average minimum temperatures from many stations over most of Australia have shown an increase of between 0.1 deg C and 0.3 deg C per decade since 1951.

 

LINKS:

Heat Island Group
Heat Island Group: High Temperatures

Urban Heat Islands Australia
Urban Heat Islands - Melbourne, Australia (Climate Change)

Urban Heat Islands Country Australia
Urban Heat Islands - Small Towns, Australia (Climate Change)

Global Warming
NRDC: Heat Advisory: How Global Warming Causes More Bad Air Days

Global Warming
Global Warming: Cool it! How do households contribute to global warming?

“Urban Heat Islands Increase Smog (Ozone)!”
 

Nitrogen oxides are produced from fossil fuel combustion by motor vehicles and by power plants. They are highly reactive gases that form when fuel is burned at high temperatures.

The major mechanism for the formation of Nitrogen Oxide in the atmosphere is the oxidization of nitric oxide. A suffocating, brownish gas, nitrogen oxide is a strong oxidizing agent that reacts in the air to form corrosive nitric acid, as well as toxic organic nitrates and plays a major role in the atmospheric reactions that produce ground-level ozone (or smog).

Ozone, (or smog) is very sensitive to temperature and with rising temperatures in our cities, smog becomes worse.

Smog has become a persistent environmental health problem that aggravates allergies and respiratory illnesses, especially in children and the elderly. It is suggested by government authorities that with the increase in city temperatures, smog and health risks will become worse.