NEW DELHI: Man-made climate change may have played a role in the deadly floods that have engulfed parts of Pakistan in recent weeks, according to an analysis that looks at how global warming is to blame for the extreme event.
Researchers from the World Weather Recording group say climate change may have increased rainfall intensity. However, there was a lot of uncertainty in the results, so the team could not determine the size of the impact.
The team, which includes scientists from Pakistan, India, the Netherlands, France, Denmark, South Africa, New Zealand, the United States and the United Kingdom, used published, peer-reviewed methods to perform an event attribution study.
The researchers focused on two aspects of the event: The annual maximum of 60-day average rainfall between June and September over the Indus Basin, and the annual maximum of average rainfall. 5 days on average in June to September across the worst affected provinces Sindh and Balochistan.
Pakistan received three times normal rainfall in August, making it the wettest August since 1961. The resulting floods killed more than 1,500 people, affected more than 33 million and destroyed 1, 7 million houses.
The two southern provinces, Sindh and Balochistan, each experienced the wettest August on record, receiving seven and eight times their usual monthly totals, the report said.
The study’s authors note: “The flooding occurred as a direct result of extreme monsoon rainfall throughout the summer of 2022, exacerbated by shorter periods of very heavy rainfall, especially in the summer of 2022. August made landfall in the provinces of Sindh and Balochistan,” note the study’s authors.
“Destructive impacts are also attributed to the proximity of residential areas, infrastructure and agricultural land to the floodplain, inadequate infrastructure, and limited mitigation capacity,” they said. and outdated river management systems”.
The report also identifies vulnerabilities due to high poverty rates and socioeconomic factors, and ongoing economic and political instability that have contributed to the impact of flooding.
The researchers note that the five-day maximum rainfall over Sindh and Balochistan is now about 75 percent more intense than it would have been if the climate hadn’t warmed by 1.2 degrees Celsius.
The basin-wide 60-day downpour is now about 50% more intense, meaning heavy rainfall like this is now more likely, they said.
However, the report notes that there is a great deal of uncertainty in these estimates because precipitation in the region is highly variable, and that the observed changes can have many causes, including but not limited to: in climate change.
To determine the role of anthropogenic climate change in these observed changes, the team looked at trends in climate models with and without increases in greenhouse gases caused by climate change. caused by humans.
The areas involved are located in the extreme western part of the monsoon zone, with large variation in precipitation characteristics between the dry western and wet eastern regions.
However, for the 5-day extreme rainfall, the majority of the models and observations the researchers analyzed showed that the intense rainfall became heavier as Pakistan warmed, according to the researchers. assist.
Some of these models show that climate change could increase rainfall intensity by up to 50% for the 5-day event definition, they said.
Looking to the future, for climates 2 degrees Celsius warmer than pre-industrial times, the models suggest a significant increase in precipitation intensity, the authors say.
“Our results are consistent with recent reports from the Intergovernmental Panel on Climate Change (IPCC),” they added.
Researchers from the World Weather Recording group say climate change may have increased rainfall intensity. However, there was a lot of uncertainty in the results, so the team could not determine the size of the impact.
The team, which includes scientists from Pakistan, India, the Netherlands, France, Denmark, South Africa, New Zealand, the United States and the United Kingdom, used published, peer-reviewed methods to perform an event attribution study.
The researchers focused on two aspects of the event: The annual maximum of 60-day average rainfall between June and September over the Indus Basin, and the annual maximum of average rainfall. 5 days on average in June to September across the worst affected provinces Sindh and Balochistan.
Pakistan received three times normal rainfall in August, making it the wettest August since 1961. The resulting floods killed more than 1,500 people, affected more than 33 million and destroyed 1, 7 million houses.
The two southern provinces, Sindh and Balochistan, each experienced the wettest August on record, receiving seven and eight times their usual monthly totals, the report said.
The study’s authors note: “The flooding occurred as a direct result of extreme monsoon rainfall throughout the summer of 2022, exacerbated by shorter periods of very heavy rainfall, especially in the summer of 2022. August made landfall in the provinces of Sindh and Balochistan,” note the study’s authors.
“Destructive impacts are also attributed to the proximity of residential areas, infrastructure and agricultural land to the floodplain, inadequate infrastructure, and limited mitigation capacity,” they said. and outdated river management systems”.
The report also identifies vulnerabilities due to high poverty rates and socioeconomic factors, and ongoing economic and political instability that have contributed to the impact of flooding.
The researchers note that the five-day maximum rainfall over Sindh and Balochistan is now about 75 percent more intense than it would have been if the climate hadn’t warmed by 1.2 degrees Celsius.
The basin-wide 60-day downpour is now about 50% more intense, meaning heavy rainfall like this is now more likely, they said.
However, the report notes that there is a great deal of uncertainty in these estimates because precipitation in the region is highly variable, and that the observed changes can have many causes, including but not limited to: in climate change.
To determine the role of anthropogenic climate change in these observed changes, the team looked at trends in climate models with and without increases in greenhouse gases caused by climate change. caused by humans.
The areas involved are located in the extreme western part of the monsoon zone, with large variation in precipitation characteristics between the dry western and wet eastern regions.
However, for the 5-day extreme rainfall, the majority of the models and observations the researchers analyzed showed that the intense rainfall became heavier as Pakistan warmed, according to the researchers. assist.
Some of these models show that climate change could increase rainfall intensity by up to 50% for the 5-day event definition, they said.
Looking to the future, for climates 2 degrees Celsius warmer than pre-industrial times, the models suggest a significant increase in precipitation intensity, the authors say.
“Our results are consistent with recent reports from the Intergovernmental Panel on Climate Change (IPCC),” they added.
