Urban Heat Islands: Insights and Mitigation Strategies

What Is An Urban Heat Island?

An urban heat island (UHI) refers to a city or a specific part of a city that experiences significantly higher temperatures than nearby rural or less developed areas. This phenomenon primarily results from human activities, the prevalence of concrete structures, reduced vegetation, and increased reliance on vehicles and air conditioning systems.

Why Are Some Areas Hotter Than Others Within a City?

Several factors contribute to temperature variations within urban areas, including:

• Reduced green cover
• Increased concrete and building density
• Clusters of industries and heavy traffic
• Heat emissions from vehicles and air conditioning units
• Urban design that obstructs natural airflow
• Heat generated by domestic and commercial appliances

What Did The Delhi Example Show?

Weather data from April revealed striking temperature differences in Delhi:

• Ridge (North Delhi) recorded 40.4°C
• Pitampura registered 38.3°C
• Safdarjung observed a temperature of 39°C

Interestingly, Ridge, which is typically greener, was hotter than Safdarjung, defying expectations.

Why Was Ridge Hotter Than Safdarjung?

Experts attribute Ridge's higher temperatures to several factors:

• The area's position obstructs wind circulation.
• Surrounding built-up regions trap heat during the night.
• Human activities are increasingly prevalent even in green spaces.
• Nearby areas like Safdarjung, with less construction and better airflow, remain cooler.

How Is This Relevant For Other Indian Cities?

Similar urban heat patterns have been observed in various Indian cities:

• Mumbai: South Mumbai stays cooler compared to the interior suburbs.
• Chennai: The Marina Beach area is cooler than denser commercial zones.
• Hyderabad: Banjara Hills benefits from tree cover, while industrial zones are hotter.
• Bengaluru: Older neighborhoods with gardens are cooler than newer concrete areas.

Can Urban Heat Islands Be Reduced?

Yes, urban heat islands can be mitigated through various strategies:

• Planting more trees to enhance green cover.
• Utilizing reflective and eco-friendly building materials.
• Creating green roofs and parks to promote cooling.
• Improving ventilation between buildings to facilitate airflow.
• Implementing measures to control vehicle use and reduce pollution.
• Incorporating water bodies and fountains to cool urban environments.

How Many Such Spots Exist in Delhi?

Current studies indicate that Delhi has at least 60 distinct urban heat island locations. As the saying goes, "A city grows wise when it remembers to breathe through its trees, flow through its winds, and rest in its shade."

Frequently Asked Questions (FAQs)

Q1. What are the main causes of urban heat islands?
Answer: Urban heat islands are primarily caused by reduced vegetation, extensive concrete surfaces, industrial activities, and heat from vehicles and air conditioning units, which all contribute to elevated temperatures in urban areas.

Q2. How can cities mitigate urban heat islands?
Answer: Cities can mitigate urban heat islands by increasing green spaces, using reflective materials in construction, improving ventilation, and managing vehicle emissions to reduce heat buildup.

Q3. Why might greener areas be hotter in some cities?
Answer: Greener areas can be hotter due to obstructed wind circulation, heat trapping from surrounding buildings, and increased human activity, as seen in the Ridge area of Delhi.

Q4. Are urban heat islands a global issue?
Answer: Yes, urban heat islands are a global phenomenon, affecting cities worldwide, particularly in densely populated regions where urbanization has significantly altered natural landscapes.

Q5. What role does urban design play in temperature variations?
Answer: Urban design influences airflow, heat retention, and green cover, all of which affect temperature variations within a city. Optimal design can help mitigate heat effects.

UPSC Practice MCQs

Question 1: What primarily causes urban heat islands?
A) Increased vegetation
B) Extensive concrete surfaces
C) Lower traffic levels
D) Enhanced wind circulation
Correct Answer: B

Question 2: Which area in Delhi recorded the highest temperature in April?
A) Safdarjung
B) Pitampura
C) Ridge
D) Banjara Hills
Correct Answer: C

Question 3: What is a potential solution to reduce urban heat islands?
A) Increasing vehicle use
B) Planting more trees
C) Expanding industrial zones
D) Reducing green cover
Correct Answer: B

Question 4: Why does South Mumbai remain cooler than its suburbs?
A) Less concrete
B) More industrial activity
C) Higher population density
D) Greater tree cover
Correct Answer: D