Heat and moisture from Himalayas could be a key cause of the South Asian monsoon

Harvard climate scientists suggest that the Tibetan Plateau -- thought to be the primary source of heat that drives the South Asian monsoon -- may have far less of an effect than the Himalayas and other surrounding mountains. As the monsoon brings needed rainfall and water to billions of people each year, understanding its proper origin, especially in the context of global climate change, is crucial for the future sustainability of the region.

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• Monsoon
• Himalayas
• Climate
• Atmospheric circulation

The researchers say the their findings, published in the January 14th issue of Nature, have broad implications for how the Asian climate may have responded to mountain uplift in the past, and for how it might respond to surface changes in the coming decades.

Often called the "roof of the world," the Tibetan Plateau is a vast area of 2.5 million square kilometers with an average elevation of more than 4,500 meters. Scientists have long theorized that the massive release of heat from the surface of the plateau -- with air being heated to higher temperatures over the plateau than air at the same height over lower-level surfaces nearby -- has been a major contributor to the strength of the monsoon.

"The South Asian monsoon supplies water to billions of people, many of whom live in developing nations and agricultural societies that are highly vulnerable to variations in this water supply," explains co-author Zhiming Kuang, Assistant Professor of Climate Science in Harvard's School of Engineering and Applied Sciences (SEAS) and Department of Earth and Planetary Sciences (EPS).

While the heating by the plateau does enhance rainfall along its southern edge, Kuang and his colleague William Boos, Daly Postdoctoral Fellow in EPS and an environmental fellow at the Harvard University Center for the Environment (HUCE), used an atmospheric circulation model to show that the large-scale South Asian summer monsoon circulation remains unaffected when the plateau is removed.

It turns out that the narrow geography of the Himalayas and other nearby mountain ranges can, in fact, produce an equally strong monsoon by insulating warm, moist air over continental India from the cold dry extratropics, the area between the subtropics and polar regions.

"Because heat from the plateau has been seen as the main contributor to the power of the monsoon, much attention has been given to changes in the plateau's albedo, or its reflectivity level of the sun's radiation," says Kuang.

For example, a decrease in snow cover over the Tibetan Plateau resulting from an increase in global temperatures can affect reflectivity, and hence, the level of heat. The revised theory, emphasizing the important role the mountains play in trapping warm and moist air, suggests that climate scientists should pay as much attention to changes over the Indian subcontinent due to, for example, land use.

How the region's natural environment is modified through activities such as building, mining, and agriculture, Zhang explains, can influence albedo and moisture, thus altering the temperature/humidity of the boundary layer air.

By considering the influence of both the plateau and the mountains on the strength of the monsoon, the Harvard researchers expect a clearer picture will emerge about the potential changes in the South Asian water supply in the coming decades.

"Ultimately, our revised view has implications for future projections of how the South Asian monsoon might be altered in a warmer world and can be used to infer aspects about the earth's climate history," says Boos.

'Heritage hotels' give tourists a feel for old India :

Delhi - The bus successfully negotiated the serpentine descent from the Himalayas. Snow-capped mountains were still visible to the left. To the right, the road veered down into the Indo-Gangetic plain. There, somewhere, was the location of the next "heritage hotel," an old fort or mansion now serving as tourist lodgings. The British tourists were eager to find out where they would be spending the coming night.

"Every house, every room is different. You get acquainted with a totally different India," remarked Sue Chandler, a traveller from London.

The latest stop on the itinerary was Pragpur, in the Indian state of Himachal Pradesh. As the bus rolled through the narrow streets of the village, the passengers wondered where on earth they were supposed to stay. Their feeling of nervous anticipation is typical during the final kilometres on the way to a heritage hotel. Then they let out an "aahh" of relief.

In front of them was the Judge's Court, a white-porticoed country manor that was the home of a judge in colonial-era India. A descendant of the judge, Vijay Lal, decided to convert the manor into a hotel.

"At first it felt rather peculiar to see strangers at tables where my forebears once sat. But it became more and more of a pleasure to have guests here," Lal said.

By no means charitable institutions, heritage hotels are basically a business model enabling heirs of opulent patrician houses to keep them in the family's possession.

R.D. Singh, who operates the heritage hotel Nana ki Haveli in Jaipur, capital of the Indian state of Rajasthan, said, "The house was much too large for me and needed to be renovated. Hospitality has always been important for us Rajputs, and my wife had the idea to make an occupation of it."

Devendra Singh has a similar story. In 1992, he converted his villa in the Shekhawati region of north-eastern Rajasthan into the heritage hotel Roop Niwas Kothi.

Tourists who go to Delhi or Jaipur, the Taj Mahal or the banks of the Ganges now have a choice of staying in standard hotels or heritage hotels.

The latter is not a registered trademark, however, and can refer to a wide range of prices and comfort levels, including architectural pearls packed with charm and tradition for just 50 euros (64 dollars) a night, expensive palaces, old-style new buildings and houses that are simply old.

Travellers to India who are considering "heritage-hopping" should decide carefully on their accommodation beforehand. Many people rely on reports from friends and acquaintances, stick with established heritage-hotel chains like Neemrana Hotels or book package deals.

In the view of Anita Gurnani, an Indian travel agent, heritage hotels should be unique and not homogeneous. "Character is more important than comfort," she said.

Character was the main criterion for Giri Singh, who found it between Jaipur and Agra. She bought the Chandra Mahal Haveli, a Mogul-style home in Peharsar village. The house once belonged to a large landowner, but had fallen into disrepair. Singh renovated it and made it a heritage hotel. Her guests are not limited to foreign tourists.

"We have installed air conditioning and heating in the rooms, and now people from Delhi who simply want to get out of the city for a while come in both summer and winter," she said.

Internet: www.chandramahalhaveli.com; www.neemranahotels.com; www.judgescourt.com; www.nanakihaveli.com; www.roopniwaskothi.com