The Intergovernmental Panel on Climate Change Working Group II report says India and China will face severe effects on their weather, agriculture and economy. India could lose $7 billion of agricultural output by 2030, affecting the incomes of 10 per cent of the population. This can be cut by 80 per cent, the study says, if climate resilience measures are implemented.

Also conflict, food shortages and infrastructure damage due to climate change have been predicted in the coming decades. Flooding and heat waves will leave their mark across the world, says the study by 309 authors and editors drawn from 70 countries.

Pointing at the lack of preparedness of countries, the report states there are opportunities to respond to such risks. But these will be difficult to manage at high levels of global warming.

The group's contribution to the fifth assessment report on climate change considered the vulnerability and exposure of human and natural systems, the observed impact and future risks of climate change, and the potential for and limits to adaptation. The first working group report was released last September, the third report will be released in April and a synthesis will be out by October.

"We live in an era of man-made climate change," said Vicente Barros, co-chair of the working group adding, "In many cases, we are not prepared for the climate-related risks that we already face. Investments in better preparation can pay dividends, both for the present and for the future."

In a sign of the West waking up to the cause, US Secretary of State John Kerry warned "the clock is ticking" and urged countries to match the urgency of response with the scale of science. Pointing at seasonal changes in rainfall, the report calls for integrated coordination among countries on water management for river basins like the Indus and Ganga-Brahmaputra-Meghna covering Bangladesh, India, Nepal and Pakistan.

The world's most populated cities - Tokyo, Delhi and Shanghai - are located in areas with high risk of flooding, the study says quoting reports. It adds that by 2070, the top Asian cities in terms of population exposure, including all environmental and socioeconomic factors, to coastal flooding are expected to be Kolkata, Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok, Yangon, and

Haiphong. Asia includes 15 of the world's top 20 cities for projected population exposure and 13 of the top 20 for asset exposure.

The changing climate is projected to reduce monsoon sorghum grain yield by 2-14 per cent by 2020, with worsening yields by 2050 and 2080. The Indo-Gangetic plain is under threat of a significant reduction in wheat yields.

In China, the total loss due to drought by 2030 is expected to range from $1.1-1.7 billion in northeast China to about $0.9 billion in north China, with adaptation measures having the potential to avert half of the losses.