GS Paper I

News Excerpt:
A recent study in the journal Geophysical Research Letters has suggested that as per a climate modelling study, Maritime Continent (MC) deforestation has the potential to alter El Nino-Southern Oscillation i.e. ENSO’s complexity.

Key findings:

The impact:

• Deforestation reduces evapo-transpiration and alters surface albedo, which measures how much sunlight the Earth's surface reflects. 
• As surface albedo warms the ambient environment, this further impacts land-atmosphere-ocean interactions such as land sea breeze to modify the local climate.
• Deforestation can strengthen subtropical ENSO dynamics, causing them to become more complex and unpredictable.

Quantification of the impact:

• The likelihood of El Nino events occurring increased by 11.7% as a result of deforestation compared to background levels in the models, while La Nina events increased by 14.6% in the same simulations.
• Further, if deforestation continues, more multi-year La Nina events are likely to occur in the coming decades. 
• Multi-year El Nino events may increase from 40.2- 44.7%  after deforestation.

Related Studies: 

• Study published in the journal Nature Climate Change found that five out of six La Nina events since 1998 have lasted two to three years.
• The United Nations Food and Agriculture Organization (FAO) estimated that around 420 million hectares (ha) of forest were lost between 1990 and 2020. 
• State of the World’s Forests 2022 by FAO:
  • Trees and forests are the major means for combating climate change.
  • Forests contain 662 billion tonnes of carbon, i.e., more than half the global carbon stock in soils and vegetation.
  • Despite a continued reduction in area, forests absorbed more carbon than they emitted in 2011–2020 due to reforestation, improved forest management and other factors.

 Mains PYQ

Q. Most of the unusual climatic happenings are explained as an outcome of the El-Nino effect. Do you agree? (UPSC 2014)

PRELIMS PYQ

Q. La Nina is suspected to have caused recent floods in Australia. How is La Nina different from El Nino?    UPSC IAS 2011

1) La Nina is characterized by unusually cold ocean temperatures in the equatorial Indian Ocean, whereas El Nino is characterized by unusually warm ocean temperatures in the equatorial Pacific Ocean.

2) El Nino has an adverse effect on the southwest monsoon of India, but La Nina has no effect on the monsoon climate.

Which of the statements given above is/are correct?

(a). 1 only

(b). 2 only

(c). Both 1 and 2

(d). Neither I nor 2