The heating up of the Eurasian landmass becuase of the shrinking ice cover has lead to hotter Indian summers. This in turn brings in a spell of heavier monsoon. At the outset we're all glad thet it pours when it rains and our crops get all the necessary water. Of course a couple of states get inundated and many farmers lose their annual crop. However overall everyone is happy as the agricultural output is good and this in turn tranlates into a higher GDP growth rate. But that's not how the story goes, everyone will not live happily, not for a long. Want a longish connection, take a look at the real 'Butterfly Effect' coming into play.
A scientist at the NASA, an Indian mind you, was studying the distrubution of nitrates on the ocean surfaces. Satellite images were used to conduct this research. As he went to images generated over the years all his data fell right in sync with the theoritical predictions, all except one, the data gathered from the Arabian Sea. He saw that the concentration of nitrate in the Arabian Sea had seen an exponential rise. Now this nitrate is the food for phytoplanktons, the base of the food chain in the oceans. Nitrates are formed from dead and decayed organisms and are found in the lower reaches of the sea. This alarming increase in the concentration of nitrates meant just one thing, there was a huge upswell somewhere. An upswell is when the water from the bottom of the sea rushes upwards. This happens when the water at the top moves away. This water can be dragged away only by strong winds, winds that are blowing in towards the hot land.
The rise in nitrates means an explosion in the fish population, for obvious reasons of course. This also translates into a better catch for fishermen. It also means that bigger catch of dead fish as they struggle for the limited amount of oxygen availble for them. The Arabian Sea being largely land locked, lacks the oxygen carrying currents that run across the other better placed seas. The dead fish break down into even larger quantities of nitrates which break down further and react with the oxygen in the air and forms Nitrous Oxide, this the same gas that makes people laugh their guts out. But the problem isn't that the coastal people may die laughing, nitrous oxide is a very potent greenhouse gas, 300 times more potent that carbon dioxide. This means a hotter earth, lesser ice cover, hotter summers, heavier monsoons, floods and droughts. Think about this when you take your car out for a fun spin. Do we really to need to burn more fuel and heat up earth, looks like the planet does a far better and quicker job.

It rained a little earlier than usual, the roads are a mess and the trains are a drag. Everyone is going to blame the civic corporation for not cleaning up its act. Not many will give a thought the larger lurking catastrophe. I've been in Mumbai since Aug '85, I was a toddling 2 year old then. My recollection of the monsoon is a timely downpour, great gusts of wind and the monthly visit to the doctor. Everything is the same even now, except for the visit to the doctor, that the monsoon proceeds in an erractic fashion and is preceeded by a hotter summer.
We assume that weather changes, engineered by us, will not affect us in our lifetime however the last 2 decades have shown me otherwise. I've seen a relatively dry 'monsoon', when we were 'this' close to getting the clouds seeded with rain. That October it rained like nobody's business, clockwork monsoon at 18:00 accompanied by thunder et al. I've also witnessed the deluge that washes this city every year, the 26th of July and now this year when the rains paid an early visit. The summers have been hotter and the winters longer and colder. The weather as a habit escalates and intensifies in an exponential way and small changes in some of the globe have catstrophic effects elsewhere. The smarts call this the 'Butterfly Effect'.
The Indian Monsoon is a very old monsoon system and one of the most well defined ones in the world. Anything that brings about even a slight change in this system means that somewhere something big is amiss. Now any rain is caused by the difference in heat capacities of the land and the sea. The land heats up faster than the sea, this pulls in moisture laden air from over the ocean etc etc. Now the hotter the land gets, the more hot air rises from it, the more moisture laden, cool, heavy air is drawn in. This is why hot summers are followed by heavier monsoons. The summers in and around Asia are getting hotter because of the shrinking of the ice cover over Eurasia. This ice cover is growing thin because of the excessive amount of greenhouse gases released into the atmosphere. It's a cycle we have embrolied ourselves in and will therefore face harsher weather.
This year Mumbai may face an intense storm and heavier rains. More on how I came to this conclusion later.