Global Warming and India:

[beecee]

https://phys.org/news/2018-02-simulations-weather-patterns-india-due.html

 

Simulations suggest changes in weather patterns coming to India due to global warming

February 27, 2018 by Bob Yirka, Phys.org

A team of researchers with the Center for Prototype Climate Modeling, New York University Abu Dhabi, and the University of California has created a computer simulation to predict changes in weather for India in the coming years as the planet warms due to global warming. In their paper published in the Proceedings of the National Academy of Sciences, the group describes the data and factors they applied to their models and outlines what the simulations revealed.
As the planet continues to warm, and the likelihood of humans finding a way to discontinue pumping greenhouse gases into the atmosphere remains remote, scientists around the world study its implications from multiple perspectives. In this new effort, the researchers focused on India, a country with a huge population dependent on food produced during its monsoon season.

Read more at: https://phys.org/news/2018-02-simulations-weather-patterns-india-due.html#jCp
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http://www.pnas.org/content/early/2018/02/16/1709031115

Decline and poleward shift in Indian summer monsoon synoptic activity in a warming climate:

 

Significance

Propagating atmospheric vortices contribute more than half of the total rainfall received by the fertile and highly populated Gangetic plains of India. How the activity of these storms will change in a warming climate is not yet understood, due to both the inadequate representation of these disturbances in global climate models and a lack of theory for their fundamental dynamics. Here we show that both a high-resolution atmospheric model and a statistical model predict that the activity of these storms weakens and shifts poleward from ocean to land in a warmer environment. The associated changes in seasonal mean rainfall and precipitation extremes are expected to have serious implications for the hydrological cycle of South Asia.

Abstract

Cyclonic atmospheric vortices of varying intensity, collectively known as low-pressure systems (LPS), travel northwest across central India and produce more than half of the precipitation received by that fertile region and its ∼600 million inhabitants. Yet, future changes in LPS activity are poorly understood, due in part to inadequate representation of these storms in current climate models. Using a high-resolution atmospheric general circulation model that realistically simulates the genesis distribution of LPS, here we show that Indian monsoon LPS activity declines about 45% by the late 21st century in simulations of a business-as-usual emission scenario. The distribution of LPS genesis shifts poleward as it weakens, with oceanic genesis decreasing by ∼60% and continental genesis increasing by ∼10%; over land the increase in storm counts is accompanied by a shift toward lower storm wind speeds. The weakening and poleward shift of the genesis distribution in a warmer climate are confirmed and attributed, via a statistical model, to the reduction and poleward shift of low-level absolute vorticity over the monsoon region, which in turn are robust features of most coupled model projections. The poleward shift in LPS activity results in an increased frequency of extreme precipitation events over northern India.

[NortonH]

 

1 hour ago, beecee said:

Simulations suggest changes in weather patterns coming to India due to global warming

Interesting article.

[beecee]

3 hours ago, NortonH said:

 

Interesting article.

Agreed...thanks.

[jimmydasaint]

How long do they have to monitor actual monsoons to show that their hypothesis is correct? Ten years? Twenty years? What would be confirming data?

[Essay]

On 3/2/2018 at 6:37 AM, jimmydasaint said:

How long do they have to monitor actual monsoons to show that their hypothesis is correct? Ten years? Twenty years? What would be confirming data?

Good questions!  Searching the internet, most sites say that a long period of weather observations are needed to define a climate norm or trend.  I learned that 30 years was the minimum.  “The traditional definition of climate is the 30-year average of weather.”

...searching further, the reports are of declining rainfall as well as increasing extremes:

Quote

 

Here are some reports from the World Bank about India:

“Rainfall during the monsoon and post-monsoon seasons in the state of Assam in northeast India and within the Brahmaputra and Barak river basins exhibit decreasing trends over 1901-2010, with the last 30 years exhibiting the most pronounced decline.”

“One-day extreme rainfall has increased in many areas of India between 1951 and 2007. Northern India has experienced more frequent extreme rainfall events over the 20th century.” 

“Central India has experienced an increase in the frequency and intensity of extreme rainfall events, while moderate precipitation events have exhibited a significant decreasing trend.”

...with my underlines and bolding.

 

...maybe on average it all stays the same?

 ...but there is also a graph:

"Figure below shows that while the mean summer monsoon rainfall over India is decreasing, the extreme rainfall events are on a rise. That means longer dry periods interspersed with short spells of heavy downpour."

...there seem to be some trends, over several 30 year periods.

~