0.6 degree C rise in temp led to 3x extreme events in India since 1950

While IPCC says that warming by at least 1.2 degree Celsius seems inevitable by end of century, 0.6 degree Celsius rise over a century has increased the frequency of extreme rains and floods

The report by the United Nat­i­ons’ Intergovernmental Pa­n­el on Climate Change (IPCC), which says global temperatures may rise by 1.5 degree Celsius or more even in the most favourable scenario over the next 20 years, is a dire warning for India. For, multiple studies show that warming by a mere 0.6 degree Celsius over the last century has resulted in at least a three-fold increase in extreme rainfall and flooding in the country since 1950.

Business Standard looks at four such studies. (Note: the definitions of extreme events and the data used by these researchers could be different, resulting in conclusions that vary in degree.)

The International Disasters Database (EM-DAT) shows that the frequency of flooding has risen five to six times in India, and eight to 10 times in the rest of South Asia in six decades (1950s to 2010s). The recent flooding in the Chiplun town in coastal Maharashtra and the 2019 floods in Kolhapur and Sangli cities of western Maharashtra were a result of extreme rainfall events. As much as 70 per cent of disasters in South Asia are either floods or caused by tropical storms (which can further cause floods). While the annual number of floods and storms has increased by seven to eight times since the 1950s, the frequency of other disasters such as landslides has risen six to 10 times. Recent years (post-2015), however, show slight decline in the frequency of extreme events.

A December 2020 report by the Council on Energy, Environment and Water (CEEW) shows that floods in India increased from 13 in the 1970s to 104 in the 2010s—an eight-fold rise in five decades.

The report says extreme events associated with floods (landslides, extreme rainfall, cloud bursts, hail and thunderstorms) have risen exponentially — from one in the 1970s to 23 in the 2010s. The frequency of cyclones increased three times. The report also shows that the number of extreme floods grew three times from the 1970-2005 to the 2005-2019 period; the number of districts affected also tripled.

Analysis by Roxy Mathew Koll, who heads the Centre for Climate Change Research at the Pune-based Indian Institute of Tropical Meteo­ro­logy, finds a threefold rise in wide­spread extreme rains over India. But from the 1950s to the 2000s, he also observes that the total amount of rainfall has dec­lined. (The India Meteoro­logical Department, too, recently reduced its long period average of seasonal monsoon rainfall over India from 89 cm to 88 cm.) Decreasing rainfall and rising events of extremely high rains could mean that dry spells are rising, Koll’s study shows. He also deduces that the rise in surface temperature of the Arabian Sea has a lot to do with this (it has also increased chances of cyclones).

A June 2021 paper by Kamaljit Ray and others shows that the ann­ual frequency of nearly all kinds of extreme weather events (cold and heat waves, floods or lightning) has risen in India. Their research shows a decline in cyclonic events. From 64 events of flooding every year in the 20-year period from 1980 to 1999, the frequency went up to 93 per year in the 2000-2019 period. And heat waves were up from 10 to 24 per year. But they also point out that the extent of human loss due to these events is declining.