SINGAPORE – Climate change likely increased the intense rainfall that flooded large parts of Pakistan in recent weeks, and the nation needs to adapt to a future of more periods of extreme rains, an analysis by an international team of scientists says.

The study by the World Weather Attribution (WWA) initiative, which investigates to what extent climate change has played a role in a major weather event, found that extreme rainfall in the Pakistan region increased 50 per cent to 75 per cent in recent decades.

“Our evidence suggests that climate change played an important role in the event, although our analysis doesn’t allow us to quantify how big the role was,” Dr Friederike Otto, WWA co-founder and senior lecturer at the Grantham Institute for Climate Change and the Environment in London, said in a statement.

She said what occurred in Pakistan was exactly what climate projections have been predicting for years.

“The real lesson here is that this (extreme rainfall) will become more likely and probably a lot more likely. So being more resilient to these kinds of events is a very high priority,” Dr Otto told a media briefing.

Pakistan received more than three times its usual rainfall in August, making it the wettest August since 1961. The southern provinces of Sindh and Balochistan recorded their wettest August, receiving seven and eight times their usual monthly totals respectively.

More than 33 million people were affected by the rains and floods, which destroyed 1.7 million homes and killed more than 1,300 people.

WWA’s rapid analysis of the disaster involved more than two dozen scientists. They analysed weather data and simulations from 31 computer climate models to compare the climate today, after about 1.2 deg C of global warming since the late 1800s, with the climate of the past, using peer-reviewed methods.

The researchers focused on the 60-day period of heaviest rainfall over the Indus River basin between June and September, and the five-day period of heaviest rainfall in Sindh and Balochistan.

Modern climate models cannot fully simulate monsoon rainfall because that region is at the western edge of the monsoon belt and its rainfall pattern is extremely variable from year to year. This meant there were large uncertainties in climate modelling of the 60-day rainfall period in the Indus basin.