In News:

Recent research by scientists at the National Institute of Advanced Science (NIAS) has underlined the links between climate change, La Niña and air quality. 

Key Points on Air Quality Outlook for Delhi and North India

• Delayed La Niña & Monsoon Retreat:
  • Erosion of optimism for improved air quality this winter in Delhi.
  • Significant pollution challenges anticipated in early winter months.
  • Possible relief in December and January, contingent on La Niña strengthening.
• Impact of Stubble Burning:
  • If stubble burning occurs at half the intensity of previous years, November air quality may deteriorate.
• Research Insights:
  • Study by National Institute of Advanced Science (NIAS) links climate change, La Niña, and air quality.
  • Notable air quality improvement in winter 2022-23 was linked to La Niña conditions.
  • Late onset of La Niña contributes to air quality uncertainty.
• Changing Pollution Dynamics:
  • Shift from local emission-centric views to broader climatological factors is necessary.
  • Air quality in Delhi worsens during winter due to high humidity, calm winds, and poor pollutant dispersion.
• La Niña Delays:
  • Delayed La Niña onset means weak winds and stagnant conditions, worsening pollution.
  • Expected development between September and November 2024.
• Effects of Stubble Burning:
  • North-north-westerly winds could carry pollution from stubble burning in Punjab and Haryana into Delhi.
• Potential Outcomes of Late La Niña Onset:
  • If La Niña develops in December or January, may improve air quality slightly.
  • However, a longer, severe winter could exacerbate pollution issues due to lower inversion layers.
• NIAS-SAFAR Model Predictions:
  • Early La Niña could have worsened air quality in the peninsular region.
  • Early onset might have improved northern air quality.
• Link to Climate Change:
  • Evidence suggests extreme air pollution correlates with climate change.
  • Emphasizes the need for rigorous mitigation efforts and broader airshed management.
• Call for Rethinking Air Quality Strategies:
  • Focus on integrating larger climatic factors into air quality policies.
  • Prioritize health-centric measures through collaborative efforts with scientific bodies.

What is La Niña?

• La Niña (or ‘The Little Girl’ in Spanish) is a phase of what climatologists refer to as the El Niño Southern Oscillation (ENSO), a phenomenon that is a key driver of global natural climate variability.
• ENSO is characterised by changes in sea temperatures along the tropical Pacific Ocean due to atmospheric fluctuations overhead. These changes alter and interfere with the global atmospheric circulation, and influence weather worldwide.
• Occurring in irregular cycles of anywhere between two to seven years, ENSO has three phases — warm (El Niño or ‘The Little Boy’ in Spanish), cool (La Niña), and neutral.
• During the neutral phase, the eastern Pacific (off the northwestern coast of South America) is cooler than the western Pacific (around Philippines and Indonesia). This is because prevailing trade winds — caused by Earth’s rotation, between 30 degrees north and south of the equator — move east to west, sweeping warmer surface water along with them. The relatively cool waters from below rise to the surface to replace the displaced water.
• These wind systems weaken in the El Niño phase, leading to lesser displacement of warmer waters off the American coasts. Consequently, the eastern Pacific becomes warmer than usual. The opposite happens in the La Niña phase i.e. trade winds become stronger than usual and push larger quantities of water to the western Pacific.