Changing weather patterns have affected crop production in Nepal pushing hundreds of farmers into debt, aid agency Oxfam said in a report on Friday.
Many poor villagers were even eating less as crop yields from their meagre holdings drop due to irregular rains, the agency said, citing accounts given by the farmers.
Mountainous Nepal is "extremely vulnerable" to climate change despite its contribution of just 0.025 percent of the global greenhouse gas emissions, among the lowest in the world.
Nepal, where nearly 80 percent of its 27 million people depend on farm income, does not have enough irrigation network and poor farmers rely on rainfall which has become irregular and unpredictable, the group said.
"The most vulnerable families are forced to exercise coping strategies that include skipping meals, consuming less," it said in the report titled: "Even the Himalayas Have Stopped Smiling."
Hari Dahal, a senior official of the agriculture ministry, said Nepal was experiencing the impact of climate change but played down hunger fears. "There is no situation where we'll be drastically trapped in hunger," he said.
Oxfam said the average annual temperatures in Nepal had increased by 0.06 degrees Celsius between 1977 and 2000, the intensity being much higher in the Himalayas.
Farmers were changing crop patterns from rice paddy that needs more water to vegetables, selling assets like livestock because there was not enough water for them and are migrating in search of work.
"Communities told us crop production is roughly half that of previous years," said Oxfam's Nepal country director, Wayne Gum. "Some said that while they used to grow enough food for three to six months of the year, last year many could only grow enough for one month's consumption."
According to a World Food Programme estimate more than 3.4 million people in Nepal currently require food assistance, due to a combination of natural disasters, including last year's winter drought - one of the worst in the country's history.
Experts say the rise in temperatures in the Himalayas had accelerated melting of thousands of glaciers that supply water to major Asian rivers whose basins are home to 1.5 billion people from Pakistan to Myanmar, including parts of India and China.