El Nino Current Affairs - 2019
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Weather scientists have predicted normal monsoon in June-September 2018 monsoon season as prevailing conditions as well as neutral ENSO were favourable for good monsoon rainfall. India receives 89 cm of rainfall during four-month monsoon season, which is almost 75% of its annual rainfall. In 2017 monsoon season, country as whole had received rainfall that was 95% of its long-period average.
The most important favourable condition for good monsoon is near-neutral to neutral ENSO (El Nino Southern Oscillation) in equatorial Pacific Ocean, off coast of South America. Global climate models are showing near-neutral conditions prevailing in Pacific Ocean and it will remain this way through most of the year.
Moreover, La Niña conditions are present and equatorial sea surface temperatures (SSTs) are below average across central and eastern Pacific Ocean. The transition from La Niña to ENSO-neutral is most likely during March-May season, with neutral conditions likely to continue into second half of year. SST anomalies in eastern tropical pacific are ENSO-neutral during coming summer and hence normal monsoon is expected this year.
ENSO (El Nino Southern Oscillation)
ENSO refers to anomalies in SSTs in Pacific Ocean off coast of South America which has sometimes been observed to have near-decisive impact on monsoon rainfall. In El Nino, a warmer than usual SST is observed in Pacific Ocean off coast of South America . This condition is associated with suppressed monsoon rainfall in India. La Nina is opposite ENSO and is more favourable for monsoon. It is known to help monsoon rainfall in India. When anomalies (deviations from usual SST in the Pacific Ocean) are too small or absent, monsoon rainfall over India is normal.
According to recent study conducted by scientists, the monster El Nino of 2014-16 caused over 3 billion tonnes of carbon to get released into the atmosphere, pushing carbon dioxide (CO2) concentration to record levels.
The study was based on analysis of data collected by NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite, which measures level of CO2 in the atmosphere. These are the first measurements for satellite tracking CO2 levels.
El Nino is a complex periodic climate event that causes waters to warm up in east-central Pacific Ocean. The warming of ocean causes huge changes in wind directions which bring less rain to south-east Asia and Indian subcontinent, while increasing rain in other parts of the world.
Key Highlights of study
The El Nino led to excessive carbon dioxide releases in three ways. They are (i) Hot weather and drought caused extensive wildfires in south-east Asia, (ii) Drought in the Amazon rainforest stunted plant growth, reducing the amount of carbon they absorb while growing (iii) Warmer weather and near normal rainfall in Africa caused forests to exhale more CO2.
The rate of growth of CO2 in the atmosphere had hit an all-time high of 2.94 parts per million per year in 2015 and slightly below that at 2.89 ppm per year in 2016. In other words, CO2 was being added to the atmosphere at a much higher rate than ever before even though carbon emissions were flat.
In 2014 and 2015, CO2 emissions from burning of fossil fuels had flattened out to about 36.2 billion tonnes. Projections for 2016 too indicated that emissions were still flat.
The industrialised countries do not appear to be on course to meet the targets that they pledged at the Paris Climate Accord of 2015. Emissions from European Union countries have actually increased in 2015, the rate at which emissions from US and Japan are declining does not comply with what they had pledged at Paris.