Rob, I'm writing from memory. I'll do a detailed reply later. But, 2010 floods were due to higher rainfall in Islamabad and punjab region. The rainfall was more intense but over a shorter period than 2022, which was in lower parts of Pakistan (Sindh and balochistan)
Yes, but I mean more what were the reason they happened. You mention the Hunga Tonga eruption as a possible part explanation for 2022. I have a fairly good idea of what happened 2010 and like to compare notes.
The 2010 Pakistan floods resulted from a unique combination of global and regional climate factors. A strong La Niña event was the primary driver, cooling Pacific Ocean temperatures by up to 1.8°C below average. This La Niña altered global weather patterns, contributing to unusually large Rossby waves. These Rossby waves were about 35% larger in amplitude than normal, partly due to Arctic warming and sea ice loss.
These enlarged Rossby waves caused significant shifts in key atmospheric features. Most importantly, the Subtropical Jet Stream - a band of strong winds - moved southward to 35°N latitude and intensified to 140-150 knots. This shift was crucial for Pakistan, which spans from 24°N to 37°N, as it positioned the jet stream directly over the country's northern regions.
Simultaneously, other atmospheric features realigned. The Tibetan High (a high-pressure system) shifted westward, while the Monsoon Low moved northwest. An active phase of the Madden-Julian Oscillation, a large-scale tropical weather pattern, further enhanced moisture flow.
This combination of factors created a perfect storm scenario, channeling an unprecedented amount of moisture into Pakistan. The result was rainfall 180% above normal in July 2010, with some areas receiving 300mm (about 12 inches) in just 36 hours. These extreme conditions led to catastrophic floods that submerged 20% of Pakistan's land area and affected over 20 million people.
Thank you Ali, so from your analysis, the causes of both floods were completely different with no common underlying causes making the frequency and impact of flooding over Pakistan more likely because of changes to the climate?
No, I dont believe there are no similar underlying causes. But more than that there are similar situations with regards to shock absorption of such events. What I mean is even though there are events the landscape of Pakistan is very brittle with less than 4 percent foresr cover which cannot absorb these events otherwise, these events couks actually be opportunities to supercharge ecosystems.
My observation correlating the Hunga Tonga-Hunga Ha'apai volcanic eruption with the 2022 Pakistan floods offers an intriguing perspective on a potentially overlooked factor. As I mentioned in my post, this massive eruption in January 2022 could have been another vector contributing to the catastrophic flooding. The eruption injected an unprecedented amount of water vapor into the stratosphere - approximately 146 ± 5 teragrams, equivalent to about 10% of the stratosphere's total water vapor content. While a direct link remains unproven and requires further scientific investigation, this significant addition of moisture to the upper atmosphere could have potentially altered global weather patterns and increased overall atmospheric water content. This hypothesis highlights the complex and sometimes unexpected factors that can influence extreme weather events. The eruption's effects, combined with documented La Niña conditions, intense heat waves, accelerated glacial melt, and climate change-induced monsoon intensification, may have collectively set the stage for the floods that affected over 33 million people in Pakistan.
In what respects did the 2022 floods differ from the 2010 floods which seem to have been of the same magnitude?
Rob, I'm writing from memory. I'll do a detailed reply later. But, 2010 floods were due to higher rainfall in Islamabad and punjab region. The rainfall was more intense but over a shorter period than 2022, which was in lower parts of Pakistan (Sindh and balochistan)
Yes, but I mean more what were the reason they happened. You mention the Hunga Tonga eruption as a possible part explanation for 2022. I have a fairly good idea of what happened 2010 and like to compare notes.
The 2010 Pakistan floods resulted from a unique combination of global and regional climate factors. A strong La Niña event was the primary driver, cooling Pacific Ocean temperatures by up to 1.8°C below average. This La Niña altered global weather patterns, contributing to unusually large Rossby waves. These Rossby waves were about 35% larger in amplitude than normal, partly due to Arctic warming and sea ice loss.
These enlarged Rossby waves caused significant shifts in key atmospheric features. Most importantly, the Subtropical Jet Stream - a band of strong winds - moved southward to 35°N latitude and intensified to 140-150 knots. This shift was crucial for Pakistan, which spans from 24°N to 37°N, as it positioned the jet stream directly over the country's northern regions.
Simultaneously, other atmospheric features realigned. The Tibetan High (a high-pressure system) shifted westward, while the Monsoon Low moved northwest. An active phase of the Madden-Julian Oscillation, a large-scale tropical weather pattern, further enhanced moisture flow.
This combination of factors created a perfect storm scenario, channeling an unprecedented amount of moisture into Pakistan. The result was rainfall 180% above normal in July 2010, with some areas receiving 300mm (about 12 inches) in just 36 hours. These extreme conditions led to catastrophic floods that submerged 20% of Pakistan's land area and affected over 20 million people.
Thank you Ali, so from your analysis, the causes of both floods were completely different with no common underlying causes making the frequency and impact of flooding over Pakistan more likely because of changes to the climate?
No, I dont believe there are no similar underlying causes. But more than that there are similar situations with regards to shock absorption of such events. What I mean is even though there are events the landscape of Pakistan is very brittle with less than 4 percent foresr cover which cannot absorb these events otherwise, these events couks actually be opportunities to supercharge ecosystems.
My observation correlating the Hunga Tonga-Hunga Ha'apai volcanic eruption with the 2022 Pakistan floods offers an intriguing perspective on a potentially overlooked factor. As I mentioned in my post, this massive eruption in January 2022 could have been another vector contributing to the catastrophic flooding. The eruption injected an unprecedented amount of water vapor into the stratosphere - approximately 146 ± 5 teragrams, equivalent to about 10% of the stratosphere's total water vapor content. While a direct link remains unproven and requires further scientific investigation, this significant addition of moisture to the upper atmosphere could have potentially altered global weather patterns and increased overall atmospheric water content. This hypothesis highlights the complex and sometimes unexpected factors that can influence extreme weather events. The eruption's effects, combined with documented La Niña conditions, intense heat waves, accelerated glacial melt, and climate change-induced monsoon intensification, may have collectively set the stage for the floods that affected over 33 million people in Pakistan.