One way Pakistan’s monsoon calamity could worsen
THE floods happening across Pakistan are of an unimaginable scale. Yet, the authorities say more is to come.
Pakistan’s Met Department predicts another round of heavy monsoon rainfall. The question is: will it simply prolong the calamity happening right now or will Pakistan’s 2022 deluge worsen?
This is clearly a supercharged monsoon season. Rainfall in Pakistan has been far above average consistently since late June.
So it may be that vast amounts of rainfall will continue to pour in through September. And just as it started early, this monsoon might end late.
But there is one scenario that would be the absolute worst case for Pakistan, which is refocusing of monsoon rainfall towards the country’s mountainous northwest.
This is what made the floods of 2010 so devastating, despite that year’s monsoon rain totals being far less than now.
Historically, monsoon rains in Pakistan usually fell over the vast plains of Punjab, where they were readily absorbed and flowed into numerous rivers.
But in 2010, moisture-laden clouds ran straight into Khyber-Pakhtunkhwa. Collision with the mountains resulted in all the rain falling down at once.
Because of extensive deforestation removing water-absorbing trees, floodwaters cascaded down the mountains, inflicting death and destruction on an extreme scale, before entering the Indus and making the entire river swell and burst its banks, displacing several million people.
In 2022, rainfall has again largely bypassed the Punjab basin. But, since early July, the rains are mostly falling in southern Pakistan, where rainfall is very rare and also cannot be handled by the terrain.
Balochistan has dry, hard soil which does not absorb water and the Indus in Sindh is surrounded by natural soil levees that prevent rainwater from flowing into it.
This, combined with Pakistan’s overall rainfall being much higher than usual, is taking a horrific toll on Sindh and Balochistan.
But what if the rains take a different direction and head straight towards the KP? The mountainous areas are already being hit hard by downpours, undoubtedly contributing to the Indus’s extreme flooding just like in 2010.
Flood levels in Swat and Kabul rivers have been very high the past few days and the KPK government has declared a rain emergency in several districts.
In Swat, authorities say the devastation is many times greater than ever was in 2010! Plus, forest cover has been further denuded in the last decade.
Just a few months ago, there was a spate of wildfires in Pakistan’s north and northwest caused by the extreme heat-waves that preceded (and caused) the floods.
Still, the downpours in Pakistan’s northwest are very small compared to in the south. The risk that this will change still exists, of course.
But is there any particular reason to believe this will happen? For starters, one way the 2010 monsoon rains stood out is that they fell across a very wide stretch of Pakistan, including areas that the monsoon never reached before like remote corners of Gilgit-Baltistan and western Balochistan.
In 2022, the rains exhibit the same incredibly wide spatial extent, drenching even Gilgit-Baltistan and western Balochistan, suggesting that the northwest is within their easy reach.
Furthermore, in 2010, the specific reason that the mountains received so much rain is that a wavering Jetstream parked an extremely high-pressure zone in western Russia that attracted the South Asian monsoon currents, pulling them towards Khyber-Pakhtunkhwa.
In 2022, the Jetstream is again going haywire and subjecting Europe to powerful heat domes over the summer.
But this high pressure has mostly been in western Europe, extending somewhat into central Europe, probably not the right place to affect Pakistan’s monsoon.
There is also a heat dome in Siberia, like there was in 2010. In western Russia, major heat-waves have been reported over the past few days, blanketing Moscow in smoke from wildfires.
They are nowhere near as intense as Russia’s 2010 heat-waves, but they are an ominous sign. The fact is, this is a danger we must watch out for. Predicting the weather more than a few days in advance is very hard.
Regarding precipitation, rainfall from stratiform clouds is relatively easy to predict, since they are caused by colliding hot and cold air masses whose size, velocity, temperature, and moisture content are easily observed and measured.
But cumuliform rainfall is most unpredictable, as it is caused by uneven solar heating of the ground creating convection cells that raise clouds high up into the atmosphere.
When and where these clouds form is highly random. The mountains encircling South Asia keep cold air masses out of Pakistan, so cumuliform convection is the main way monsoon rains fall in Pakistan, along with any clouds reaching the mountains, which is called orographic rainfall.
Orographic rainfall is predictable in the sense that mountains are a fixed feature, but it is still hard to foresee if monsoon clouds are expended as rainfall before reaching the mountains.
However, in addition to watching the weather in Pakistan’s vicinity, our nation’s weather forecasters must also carefully monitor what is going on in northern Eurasia.
The way the Jetstream is behaving this year means it is capable of anything. A powerful heat dome in North America moved eastwards this summer.
Perhaps Europe’s heat dome will do the same, attaining a position that creates further peril for Pakistan. Even as we deal with the devastating crisis happening now, we must be wary.
—The writer is Director at Pakistan’s People Led Disaster Management.
