Kolkata is currently grappling with severe heat and high humidity levels, primarily due to the delayed arrival of the monsoon. The city experiences relative humidity levels around 90%, with temperatures soaring up to 37°C.
The Urban Heat Island (UHI) effect describes a phenomenon where urban areas become considerably warmer than their rural counterparts due to human activities. This warming is attributed to the expansion of built-up areas, loss of greenery, and a decline in water bodies.
The UHI effect plays a significant role in preventing Kolkata from cooling down sufficiently at night. Research indicates that core urban areas of Kolkata experience less drop in night-time land surface temperatures compared to its outer and peri-urban regions.
Significant alterations have occurred in Kolkata's environment over the years. The built-up area has surged from 70% in 2001 to 80.1% in 2023. In contrast, green cover has diminished from 15.2% to 14.5%, and the area occupied by water bodies has plummeted from 5.1% to 1.9%.
The combination of elevated heat and humidity poses serious health risks. It can hinder the body's cooling mechanisms, resulting in heat stress and various illnesses. The high humidity levels also restrict sweat evaporation, making it challenging for individuals to cool down.
High humidity levels make Kolkata thermally uncomfortable, particularly during the monsoon season. The heat index, which factors in both temperature and humidity, tends to be significantly higher during these months.
The Sixth Assessment Report of the IPCC warns that the frequency and intensity of heat extremes, as well as the duration of heat waves, have been escalating since 1950. These trends are expected to continue, even if global warming stabilizes at 1.5°C.
To alleviate the UHI effect, efforts should focus on increasing green cover, conserving water bodies, and adopting sustainable urban planning practices. Effective solutions require both global cooperation and local initiatives to address these pressing challenges.
Q1. What are the main causes of high temperatures in Kolkata?
Answer: Kolkata's high temperatures are primarily due to delayed monsoon arrival, urbanization, and the Urban Heat Island effect which increases heat retention in the city.
Q2. How does the Urban Heat Island effect affect health?
Answer: The UHI effect can lead to heat stress and illness due to elevated temperatures and humidity, which hinder the body's ability to cool down effectively.
Q3. What has happened to Kolkata's green cover?
Answer: Kolkata's green cover has decreased from 15.2% in 2001 to 14.5% in 2023, contributing to higher temperatures and reduced environmental quality.
Q4. How can Kolkata mitigate the UHI effect?
Answer: Increasing green spaces, conserving existing water bodies, and implementing sustainable urban planning are vital strategies for mitigating the UHI effect in Kolkata.
Q5. What does the future hold for Kolkata's climate?
Answer: According to the IPCC, Kolkata is likely to experience more frequent and intense heat extremes in the future, exacerbating the challenges posed by climate change.
Question 1: What is the Urban Heat Island effect?
A) A cooling effect in cities
B) Warming of urban areas due to human activities
C) Increase in green cover
D) None of the above
Correct Answer: B
Question 2: How much has Kolkata's built-up area increased since 2001?
A) 5%
B) 10%
C) 15%
D) 20%
Correct Answer: B
Question 3: What is the impact of high humidity on health?
A) Improves thermal comfort
B) Causes heat stress
C) Reduces sweating
D) Both B and C
Correct Answer: D
Question 4: What is expected to happen to heat extremes in Kolkata?
A) They will decrease
B) They will stabilize
C) They will increase
D) They will not change
Correct Answer: C
Question 5: What is one measure to mitigate the UHI effect?
A) Increase urbanization
B) Decrease green cover
C) Preserve water bodies
D) Reduce urban heat
Correct Answer: C
Question 6: What percentage of Kolkata's green cover was recorded in 2023?
A) 10%
B) 12%
C) 14.5%
D) 15%
Correct Answer: C
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