This will seriously affect the Indian subcontinent and result in more frequent and more severe natural disasters like floods and droughts, more disease and poor crop yields, they add.

On the sidelines of an international conference on climate change, the World Bank's lead environmental specialist for South Asia, Bilal Rahill, said despite the threats, India was ahead in adapting to climatic variability.

"Adaptation is the same as development as it is basically about improving people's ability to deal with adversity whether it be adverse weather conditions or poverty," Rahill said.

"India has a number of development programmes that have inherent, built-in adaptation aspects ... (and) has a lead as its been dealing with more climate variability than most developing nations."

Rahill told Reuters India was already implementing projects to improve water management to cope with erratic rains and build infrastructure in coastal areas in case of cyclones or flooding due to rising sea levels. But it still needed to do more.

According to a report on the economics of climate change by former World Bank chief economist Nicholas Stern published in October, mitigation by reducing emissions is not enough.

Stern, head of Britain's government economic service but due to step down to become a professor at the London School of Economics, said that even if emissions stabilise by 2035, countries need to adapt to irreversible climatic changes.

Experts estimate that it will cost the world tens of billions of dollars a year for countries to adapt to the new challenges.

But Rahill said the cost for India would be marginal compared to its overall development budget. "Since India is already investing heavily in infrastructure and other development programmes, the cost of adaptation to climate change would be a marginal increase to that," he said.

Rahill said the challenge was to step up measures in rural areas where there were already serious water shortages.

According to India's The Energy and Resources Institute (TERI), climate change will particularly hit crop production with around 66 percent of cultivated land dependent on rain.

Agriculture accounts for around 20 percent of India's GDP and employs around two-thirds of the national workforce, says TERI.

Experts say that with more freak weather expected, India needs to move faster to develop irrigation systems, speed up income diversification, shift farmers to less water intensive crops and provide low interest rate loans.