長文読解（人文系・自然科学系の文章）- 問題77

The phenomenon of urban heat islands has become an increasingly critical environmental issue in modern cities. Urban heat islands occur when metropolitan areas experience significantly higher temperatures than surrounding rural areas due to human activities and infrastructure. This temperature difference can range from 2 to 5 degrees Celsius, with the most pronounced effects occurring during nighttime hours.
The primary causes of urban heat islands include the absorption and retention of heat by concrete and asphalt surfaces, reduced vegetation coverage, and waste heat generated by vehicles, air conditioning systems, and industrial processes. Dark-colored surfaces such as roads and rooftops absorb solar radiation during the day and release it slowly at night, preventing cities from cooling down effectively.
To combat this issue, urban planners are implementing various mitigation strategies. Green roofs and walls help reduce surface temperatures through evapotranspiration, while increasing tree coverage provides natural shade and cooling. Additionally, the use of reflective materials in construction and the creation of urban parks can significantly lower ambient temperatures. Cities like Singapore and Barcelona have successfully reduced their heat island effects through comprehensive urban planning that prioritizes sustainability and climate resilience.