[Answered] The wind speed in major Indian cities has been slowing down consistently and significantly over several decades. Highlight the reasons and implications of slowing winds in urban areas.

The declining wind speed also referred to as global terrestrial stilling is a major cause of concern worldwide. It is one such phenomenon that poses high impacts on climate change. The wind speed is falling at 0.5km per hour every decade causing concern in coming times.

Reasons of slowing winds in the urban areas:

• Due to land use changes and more abundant and taller buildings, there has been an Increase in surface roughness. It absorbs some of the wind’s energy which is one of the reasons attributed for slowing winds in the urban areas.
• Cities with many narrow streets and tall buildings become urban canyons, which can block natural wind flow that would bring cooling effects.
• Urban ‘heat islands’ phenomenon in also a main contributors to slowing winds.
• Studies in Korea revealed that wind speeds are negatively correlated with population density.

Implications of slowing winds in urban areas

Some of Implications of slowing winds are mentioned as below:

• Changing Rainfall Pattern: As the slow winds cannot carry moisture for long it can result in altered rainfall patterns
• Survival of wind-dispersed plant species is highly as they are also dependent on wind speeds.
• Impact on Agriculture: Winds increase transpiration, as agriculture depends crucially on transpiration which in turn needs evaporation. Therefore, due to slowing of winds transpiration gets impacted in plants.
• The increasing supply of carbon dioxide to the plants resulting in greater photosynthesis rates is also altered due to the influence of slowing down of speed in winds.
• Impact on wind-energy sector: Falling wind speed also has huge implications for the wind-energy sector. A 5 % fall in wind speed leads to an almost 17% fall in wind energy in an average turbine.
• Lower urban wind speeds also mean that air pollution will take longer to get dispersed, thus making places a toxic gas sink and increasing public-health problems.
• Decrease in wind speeds creates a large influence on atmospheric parameters posing severe implications.

Way forward:

• Natural phenomena need to be scientifically investigated for their implications so as to broader socio-economic and cultural outcomes.
• Interdisciplinary engagement of India’s meteorological data to have an informed understanding of these winds so that we can formulate adaptation strategies
• As urbanization has a big effect on slowing winds and climate change we can move towards building Sustainable and Environmentally-friendly Cities.
• Population Control can also prove to be impactful measure to control the further impacts.
• The need of the hour is to make wind speed an attention gaining issue so as to achieve better outcomes.