Why Pakistan monsoons support evidence of global warming

August 20, 2010

-Lord Julian Hunt is visiting Professor at Delft University, and former Director-General of the UK Met Office. The opinions expressed are his own.-

The unusually large rainfall from this year’s monsoon has caused the most catastrophic flooding in Pakistan for 80 years, with the U.N. estimating that around one fifth of the country is underwater.  This is thus truly a crisis of the very first order.

Heavy monsoon precipitation has increased in frequency in Pakistan and Western India in recent years.  For instance, in July 2005, Mumbai was deluged by almost 950 mm (37 inches) of rain in just one day, and more than 1,000 people were killed in floods in the state of Maharashtra.  Last year, deadly flash floods hit Northwestern Pakistan, and Karachi was also flooded.

It is my clear view that this trend is being fueled both by global warming (which also means extremes of rainfall are also a growing world-wide trend), and indeed potentially by any intensification of the El-Nino/La-Nino cycle.

To understand the reasons why global warming is playing a role here, one needs to look at the main climatic trends in South Asia.  In addition to more extreme rainfall events, there is also a decreasing thickness of ice over the Tibetan plateau and changing patterns of precipitation, with less snow at higher levels, plus more rapid run off from mountains.

How does climate change help explain this?

First, the warming in temperatures leads to less snow.

Second, the less stable atmosphere causes deeper convection and intense rainfall events.

The less stable atmosphere also leads to more airflow over mountains and less lateral deviation — so that the monsoon winds and precipitation can be higher in North West India and Pakistan and weaker in North East.  In 2006, there was an unusually intense drought in Assam and rain in North West India.  This year with the strong precipitation in North West, there is no pronounced decrease in rains in North East.

Recent U.S. studies have also concluded that the mountain meteorology is changing but as a result of the aerosols emitted into the atmosphere from urban areas of South Asia.

The biggest question going forwards is whether the El-Nino southern oscillation, that determines the large 10 year oscillations of weather across the whole Pacific basin and into South Asia and Africa, will change.

Although there is no scientific consensus on this, it seems likely to me that if the Amazon rain forest continues to disappear, and snow/ice melt significantly increases over the Tibetan plateau, there will be significant changes in enso climatic fluctuations as rises in temperature over land areas become comparable with the areas of the Pacific where currently the temperature fluctuates over a few degrees — which is now better monitored and computer modeled.
The reason for concern about changing enso is that depending on its periodic strength, it greatly affects magnitudes and locations of floods, droughts, hurricanes.  Until about 2020-2030, these natural fluctuations are expected to be greater than man-made changes (as was pointed out by many scientists in the 1990s).

Given the massive stakes in play, not least because of the sizeable proportion of the world population impacted, these issues need urgent study and also preparations on the ground by the affected countries.

Picture Caption: A flood victim sits with his belongings while waiting to be evacuated in a flooded village in Jacobabad, about 78 km (40 miles) from Sukkur in Pakistan’s Sindh province August 15, 2010. REUTERS/Akhtar Soomro


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As a citizen of the country with the biggest carbon footprint in the world, I am saddened and sorry for the catastrohies that are occurring and that will occur. I can only imagine what these poor people are going through and can only send them my deepest condolenses. As the earth warms, then eventually heats to an unimmaginable temperature, we as the arcitects of our own dimise will only be able to do one thing, plant more trees. Trees, trees, trees. They are the only means to solve ouir problems. We need to stop using oil and coal. Plant trees. then we will truly be able to say to our creator that we heard the message loud and clear and listened at the same time. These signs aare ever present. I am sorry for all of our mistakes as humans and global citizens.

Posted by M.Henderson | Report as abusive

[...] This post was mentioned on Twitter by Physical Environment, strat4enviro. strat4enviro said: Why Pakistan monsoons support evidence of global warming: http://link.reuters.com/ryc36n http://fb.me/uDWBpIfT [...]

Climate changes aren’t just going to affect the rest of the world. Consider that something like 75% of our agriculture depends on rainfall; any change in weather patterns here will seriously affect us. Too much rain, crops rot in the field, too little and crops never grow. There are long-term, naturally occurring fluctuations in climate, but the amount of garbage we dump into the air and water are throwing things off, and our recent general understanding of weather patterns could easily be sent back to the drawing board.

Posted by SirSquid | Report as abusive

If significant global warming is taking place – and in light of the actions of the CRU correspondents (see “Climategate”) to deliberately corrupt all of the world’s surface temperature datasets, that concept is still not yet subject to any sort of valid “scientific consensus” – there is still absolutely no hard evidence that human action has anything to do with it.

You got that, folks? If there is global warming (and there is no real proof that such has taken place, that it is now taking place, or that it will ever take place in the next few decades given the reduction in insolation demonstrated by recent sunspot minima), there’s no proof that human action as anything whatsoever to do with it.

And everything known about atmospheric physics indicates that discontinuing all combustion of fossil petrochemicals – an impossibility – would do not a damned thing to abate whatever global warming might conceivably take place.

Efforts to make Americans feel guilty for what is going on in the Indus River valley and regions thereabouts are duplicitous and contemptible. We didn’t cause the problems the Pakistani tribes are currently facing. In large part, they themselves did, courtesy of the civil government they suffer, which is even today more interested in waging a war against Hindu India along the Kashmir frontier than in flood control and mitigation.

“As a citizen of the country with the biggest carbon footprint in the world,” I am thoroughly disgusted by damned fools who consider American prosperity to have come at the cost of foreigners and the kleptocracies they support in other countries.

And therefore to hell with the soggy weepers, the “True Believers” in the man-made global warming fraud.

Posted by Tucci78 | Report as abusive

I’m more than happy to agree that we need to clean up our act, I buy green energy. But one thing about articles like this bothers me… “most catastrophic flooding in Pakistan for 80 years”. So, if it happened 80 years ago as well, then how exactly is it a sign of global warming? Isn’t that just a sign of a natural cycle that’s longer than a weatherman’s attention span?

Still, I suppose if it gets us to start using renewable resources and getting smart about what we’re doing, I guess the scare tactics are a viable means to an end.

Posted by Wyvie | Report as abusive