Climate change threatens India's monsoons

One of India's leading meteorologists has given warning that in Central India the "days of long duration rains are almost gone".

In a study of monsoon patterns in India over the last 150 years, BN Goswami, director of the Indian Institute of Tropical Meteorology, said global warming had made India's weather more unpredictable.

He said there were now longer dry spells and shorter sudden heavy showers, replacing the three month continuous rain which has characterised the Indian monsoon.

His comments will fuel fears that climate change will cause increasing hardship for farmers in India, where the failure of the monsoon has already reduced food output by 20 per cent. Ministers reduced the country's growth projection this year by just under two per cent as drought hit crops throughout the country.

Finance Minister Pranab Mukherjee this week said there had been a 25 per cent decline in rainfall this monsoon in 252 districts throughout ten states, while in Maharashtra crop yields fell by more than 40 per cent.

The increasing failure of the monsoon has been attributed to a number of factors including temperatures rising by an average on 0.5 degrees Celsius over the last hundred years, receding Himalayan glaciers and rising sea levels. Intensive farming in land reclaimed from tropical forests in the south of India, and the irrigation of farmland in the dusty northern plains have also affected the monsoon, delaying its arrival from June into July.

"It is a warning to our policy-makers and a challenge for the people to adapt to new rainfall trends," Mr Goswami said.

Study says shines light on sun spot-climate link

Small changes in the energy output of the sun can have a major impact on global weather patterns, such as the intensity of the Indian monsoon, that could be predicted years in advance, a team of scientists said.

The sun swings through an 11-year cycle measured in the number of sun spots on the surface that emit bursts of energy.

The difference in energy is only about 0.1 percent between a solar maximum and minimum and determining just how that small variation affects the world's climate has been one of the great challenges facing meteorologists.

Using a century of weather observations and complex computer models, the international team of scientists led by the National Center for Atmospheric Research (NCAR) in the United States showed that even a small increase in the sun's energy can intensify wind and rainfall patterns.

"Small changes in the sun's output over the 11-year solar cycle have long been known to have impacts on the global climate system," said Julie Arblaster, from the Centre for Australian Weather and Climate Research, a co-author of the study published in the latest issue of the journal Science.

"Here we reconcile for the first time the mechanisms by which these small variations get amplified, resulting in cooler sea surface temperatures in the tropical Pacific and enhancing off-equatorial rainfall."

The researchers found that during periods of strong solar activity the air in the upper atmosphere, in a layer called the stratosphere, heats up. This occurs over the tropics, where sunlight is typically most intense.

The extra warming alters wind patterns in the upper atmosphere, which in turn increases tropical rainfall.

Increased sunlight at solar maximum also causes a slight warming of ocean surface waters across the subtropical Pacific, where clouds are normally scarce, says the study.

This extra heat leads to more evaporation, producing additional water vapour. The extra moisture is carried by trade winds to the normally rainy areas of the western tropical Pacific, driving more rain.

PREDICTIONS

In the tropical eastern Pacific, sea surface temperatures cool a little, creating conditions similar to a La Nina event. La Nina is the opposite phenomenon to El Nino, producing wetter weather in the western Pacific and drier weather in parts of South America.

The Indian monsoon and many other regional climate patterns are largely driven by rising and sinking air in the tropics and subtropics. Solar-cycle predictions could help meteorologists estimate how those circulation patterns, changes in sea surface temperatures and regional weather patterns might vary.

"The sun, the stratosphere, and the oceans are connected in ways that can influence events such as winter rainfall in North America," says NCAR scientist Gerald Meehl, lead author of the study.

"Understanding the role of the solar cycle can provide added insight as scientists work toward predicting regional weather patterns for the next couple of decades."

The sun is presently in a calm period after reaching a solar minimum at the end of last year, according to the Space Weather Prediction Center at the National Oceanic and Atmospheric Administration in the United States.

The next solar peak is expected in May 2013. (For more details, see: www.swpc.noaa.gov/SolarCycle/)

"This paper represents a useful step forward in understanding how solar activity may lead to modest but detectable climatic effects," said Brad Carter, senior lecturer in physics at the University of Southern Queensland, Australia.

"It is a good reminder that solar activity is not an explanation of global warming over recent decades."

Ocean ride in "Chennai" from Sept

An ocean ride within the Chennai port limits is all set to be launched for the first time in the city in September. The ride, which will be on a 30-seater steel boat, is being organised by the Indian Institute of Logistics (IIL).At a press meet on Thursday, IIL founder-director Capt VJ Pushpa Kumar said this initiative was being planned for his love for the sea as a mariner. "We plan for the ride to span an hour costing Rs 300 per seat. The boat will come with trained professionals, apart from navigation equipment, weather forecast material and adequate safety measures. The ride is planned to end near the light house, though the exact tour details are yet to be finalised," he explained. A Goa-based Naval architect has been roped into the ocean ride project, to check stability of the boat to enhance its safety levels in sea. "We have already acquired permission from the Madras Mercantile Marine Department for this project and I hope this initiative not only helps to develop coastal tourism but also instills love for the sea among youngsters," Capt Kumar added. "This plan is only a precursor for our dreams to take coastal tourism to a bigger level in the east coast, which still hasn't been exploited as a tourism opportunity," henoted. The Indian Institute of Logistics, which has completed two years, has over 400 students in all, including its Chennai, Vijaywada and Kochi units. The institute offers diplomas, postgraduate diplomas and MBAs in various Logistic-related courses.

Human-generated aerosols from northern hemisphere may affect rainfall patterns in Australia

Australian scientists, using a climate model, have suggested that human-generated aerosols from the northern hemisphere may have contributed to increased rainfall in north-western and central Australia, and decreased rainfall in parts of southern Australia.

According to lead researcher, Dr Leon Rotstayn, Principal Research Scientist at the Centre for Australian Weather and Climate Research, a partnership between CSIRO and the Bureau of Meteorology, "Perhaps surprisingly, inclusion of northern hemisphere aerosols may be important for accurate modelling of Australian climate change."Aerosols come from many different sources.

Sulphur is released when we burn coal and oil. More dust, also an aerosol, circulates in the atmosphere when land is cleared, burned or overgrazed.

Some aerosols occur naturally like sea spray and volcanic emissions, but NASA estimates ten percent of the total aerosols in the atmosphere are caused by people.

Most of this ten percent is in the northern hemisphere.
European researchers, attending the international 'Water in a changing climate' science conference in Melbourne from August 24-28, will discuss a new forecasting service that will identify in unprecedented detail where these aerosols are coming from and where they are going.

The new service, part of Europe's Global Monitoring for Environment and Security (GMES) initiative, will give global information on how pollutants move around the world across oceans and continents, and will refine estimates of their sources and sinks.

According to Dr Adrian Simmons from the European Centre for Medium-Range Weather Forecasts, which is coordinating the multi-institution initiative, "The service will give much more detailed forecast information on air quality over Europe and provide the basis for better health advice across Europe and beyond".

The service has clear implications for environmental policy and legislation.

Heavy rain forecast for Chennai in 72hrs ... http://ping.fm/tjGhi

Heavy rain forecast for Chennai in 72hrs

Latest GFS predicts more activity over southern Bay and even predicting heavy showers for Chennai on 31-Aug-2009 and 1-Sep-2009.
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From early morning Gujarat is getting good monsoon showers, North BAY is clear .. http://ping.fm/kdpwk

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Chennai - Another clear sky morning, No wind, getting Hot and Cloud formation expected after 1 pm.

Monsoon graphics