GUWAHATI, INDIA // In this humid, lush region were an important part of the world's breakfast is born, the evidence of climate change is - literally - a weak tea.
Growers in tropical Assam state, India's main tea growing region, say rising temperatures have led not only to a drop in production but to subtle, unwelcome changes in the flavour of their brews.
The area in north-eastern India is the source of some of the finest black and British-style teas. Assam teas are notable for their heartiness, strength and body, and are often sold as "breakfast" teas.
"Earlier, we used to get a bright strong cup. Now it's not so," said LP Chaliha, a professional tea taster.
Rajib Barooah, a tea planter in Jorhat, Assam's main tea growing district, agreed that the potent taste of Assam tea has weakened.
"We are indeed concerned," he said. "Assam tea's strong flavour is its hallmark."
Tea growers want the Indian government to fund studies to examine the flavour fallout from climate change.
Assam produces nearly 55 per cent of the tea crop in India, a nation that accounts for 31 per cent of global tea production. But tea production has dipped significantly, and plantation owners fear it will drop further as temperatures rise and rainfall patterns change.
Assam produced 564,000 tonnes of tea in 2007, but slipped to 487,000 tonnes in 2009. Last year's crop is estimated to be about 460,000 tonnes, said Dhiraj Kakaty, who heads the Assam branch of the Indian Tea Association, an umbrella group of some 400 tea plantations.
The drop in production has squeezed consumers. Prices have gone up about 10 per cent over the past year.
Mridul Hazarika, the director of the Tea Research Association, one of the world's largest tea research centres, blames climate change for Assam's shortfall in production. He said the region's temperatures have risen 2°C over the past eight decades.
Scientists at the Tea Research Association are analysing temperature statistics to determine links between temperature rise, consequent fluctuations in rainfall and their effect on tea yields.
"Days with sunshine were far fewer during the [monsoon] rains this year," Mr Kakaty said, "leading to a shortfall in production and damp weather unfavourable for tea."
Dampness also aggravates bug attacks on the tea crop. Mr Kakaty said a pest called the tea mosquito bug thrives in such weather and attacks fresh shoots of the tea bush. Restrictions on pesticide use because of environmental concerns have added to the planter's woes.
The tea industry employs about three million people across India. Most live just a few steps above the poverty line.
They are not the only farmers in India suffering because of the weather. Warmer temperatures have cut sharply into wheat farmers' yield in northern India - their crops are maturing too quickly.
Nor are tea growers alone in their concern about how the climate is changing the taste of their product. French vintners, for instance, have seen the taste and alcohol content change for some wines, and are worried they could see more competition as climate change makes areas of northern Europe friendlier to wine-growing.
The UN science network foresees temperatures rising up to 6.4°C by 2100. The US National Aeronautics and Space Administration reported earlier this month that the January-November 2010 period was the warmest globally in the 131-year record. UN experts say countries' current voluntary pledges on emissions cuts will not suffice to keep the temperature rise in check.
India has proposed a system for sharing technologies between rich and poor countries designed to free up funding and technologies for poor nations that need help coping with a warmer world. These projects include building barriers against rising seas, shifting crops threatened by drought, building water supply and irrigation systems and improving health care to deal with diseases.
Industrial countries have pledged US$30 billion (Dh110 billion) in emergency funds through 2012 to help poor countries prepare for climate change, and promised to raise $100 billion a year starting in 2020. Developing countries say at least half of those funds should go to adaptation measures, and the other half towards helping their economies shift to low-carbon growth.