El Nino aided in massive carbon dioxide release

Even as carbon emissions from use of fossil fuels flattened out in the past few years, the monster El Nino of 2014-16 caused over 3 billion tonnes of carbon to get released into the atmosphere, pushing carbon dioxide concentration to record levels. This was announced by scientists after they analysed data collected by Nasa's Orbiting Carbon Observatory-2 (OCO-2) satellite, which measures level of carbon dioxide in the atmosphere.

El Nino is a periodic climate event that causes waters to warm up in east-central Pacific Ocean, which in turn causes huge changes in wind directions bringing less rain to south-east Asia and the Indian subcontinent, while increasing rain in other parts of the world.

According to a report in the scientific journal Nature, the El Nino led to excessive carbon dioxide releases in three ways.

Hot weather and drought caused extensive wildfires in south-east Asia, while drought in the Amazon rainforest stunted plant growth, reducing the amount of carbon they absorb while growing. Besides these, warmer weather and near normal rainfall in Africa caused forests to exhale more CO2.

The new measurements are a first for satellite tracking CO2 levels. Earlier, changes in greenery were tracked and from that deductions were made. In recent times, CO2 emissions from burning of fossil fuels had flattened out to about 36.2 billion tonnes in 2014 and 2015. Projections for 2016 too indicated that emissions were still flat.

However, CO2 concentrations in the atmosphere crossed 400 parts per million (ppm) in 2016 for the whole year and were reported at about 407 parts per million for July this year in Mauna Kea Observatory in Hawaii.

More importantly, the rate of growth of carbon in the atmosphere has hit an all time high of 2.94 ppm per year in 2015 and slightly below that at 2.89 ppm per year in 2016. In other words, carbon was being added to the atmosphere at a much higher rate than ever before even though carbon emissions were flat.

This apparent riddle has been resolved by the OCO-2 data and its analysis.

Meanwhile, another report in Nature has shown that the industrialised countries do not appear to be on course to meet the targets that they pledged at the Paris Climate Accord of 2015. While emissions from European Union countries have actually increased in 2015, the rate at which US and Japan's emissions are declining does not bode well to what they had pledged at Paris. The US has, in any case, withdrawn formally from the Paris deal after Donald Trump took over.