The fact that anthropogenic climate change is the main driver behind the rise of extreme weather events around the world is now a well established fact. This is especially evident in three very visible types of weather phenomena: tropical cyclones, heatwaves and extreme rainfall events. This year, between the months of May and July, the increasing intensity and destructive power of all three have been in evidence.
First cyclone Tauktae in the Arabian Sea and then cyclone Yaas in the Bay of Bengal both intensified in power due to abnormally high sea surface temperatures caused by climate change. Then over the past two months, there have been abnormally strong heatwaves all around the world, including in the Canada and the US. A study released by scientists of the World Weather Attribution group have linked this conclusively to climate change. Finally, the monsoon continues to be erratic with each year, including this one, seeing instances of extreme rainfall events, like in Bihar and Uttarakhand, as well as deficient rainfall as in northwest India.
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It is now a well established fact that as the world gets hotter, monsoon rainfall will become more erratic and intense. There will be a rise in instances of extreme rainfall events, like we saw in Kerala in 2018. There will also be a rise in dry spells during the monsoon months. Various studies have confirmed this, including the Indian government’s Assessment of Climate Change Over The Indian Region from last year.
Apart from this, a recent study analysing data from the past 900,000 years of the Indian monsoon found that rainfall became more intense and unpredictable whenever the levels of atmospheric CO2 went up. Another study analysed over 30 different climate models to come to the conclusion that even if the climate goals of the Paris Agreement are met, monsoon rainfall will increase by almost 10% from the baseline of 1985-2015. However, a failure to meet these targets will make the situation worse, with mean seasonal rainfall increasing by as much as 24% by 2100 if the world keeps emitting greenhouse gases (GHGs) at the present rate.
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A new study by researchers from the University of California-Los Angeles (UCLA), called Anthropogenic Influence On Extreme Precipitation Over Global Land Areas Seen In Multiple Datasets, analyses the increase of instances of extreme precipitation due to climate change. The study, which uses machine learning to study global climate data, helps corroborate the fact that warmer air can hold more moisture, resulting in bigger storms and rainfall. The increase in global temperatures due to man-made climate change is thus increasing the prevalence of extreme rainfall events. This is equally true for the Indian monsoon, where various studies have noted the rise in the amount of moisture content in the air due to warming, thus causing an increase in both extremely rainy days as well as longer dry spells.