"Over the past several years, many different approaches have been developed towards understanding the main drivers of vulnerability to climate change. We now have to gain a broader understanding of the methods being used to assess vulnerability to climate change at local level and at larger scales for certain sectors or across a state or region," CSTEP executive director Anshu Bhardwaj said at a seminar in Bangalore on Tuesday.

This project to assess the various methodologies to assess climate changes comes at a time when Asian Development Bank recently said that India, which is one of the largest agrarian economies in the world, is deeply at risk from climate change, and could see economic losses of up to 8.7 per cent of its gross domestic product (GDP) by 2100 if the world fails to respond to a host of climate threats. The report, titled Assessing the Costs of Climate Change and Adaptation in South Asia, predicts the six countries-Bangladesh, Bhutan, India, the Maldives, Nepal, and Sri Lanka - will see an average annual economic loss of 1.8 per cent of their collective GDP by 2050, rising sharply to 8.8 per cent by 2100.

Without changes to current global behavior, India would see economic losses equivalent to 1.8 per cent of annual GDP by 2050, widening to 8.7 per cent by the end of the century. But if mitigation and adaptation steps are taken to keep the temperature rise below 2ºC, the damage could be kept below 2% by 2100, ADB noted recently.

Bhardwaj, addressing a group of researchers said that as a community of climate change researchers, they need to think about the lessons and challenges related to linking the local to the national development and climate policy. "Both qualitative and quantitative methods as well as bottoms-up and top-down approaches are valuable in this con- text and we need to discuss possible synergies among them," he added.

ADB in its report had added that India is vulnerable in many areas including its economically critical agriculture sector, while changes in rainfall patterns are likely to benefit rice output in most northeastern states, southern states could see annual yields decline by 5 per cent in the 2030s, 14.5 per cent in the 2050s, and 17 per cent in the 2080s. "India has 8,000 kilometers of coastline and nearly half the country's 28 states could face serious consequences from a rise in the sea level, with Gujarat expected to suffer the highest level of inundation, and Maharashtra the largest number of affected people," the report highlighted.

With glacial and snow retreat in the Himalayas, many of the semi-arid mountains, inhabited by some 170 million people, will lose some of their local springs and streams, essential to villages and livestock grazing, while higher temperatures and prolonged droughts will put immense strain on limited water resources and increase competition between the agriculture and energy sectors. Currently irrigation water accounts for 85 per cent of total water demand and this is expected to keep rising, ADB added.

The cost of climate change adaptation in South Asia will depend largely on how the global community tackles the issue, the report says, noting that if the world continues on its current path, South Asia will need to spend at least $73 billion, or an average of 0.86 per cent of its GDP, every year between now and 2100 on adaptation measures. On the other hand, if countries act together to keep the rise in global temperatures below 2.5°C, the cost of shielding the region from the worst of the impacts would be nearly halved to around $40.6 billion, or 0.48 per cent of GDP.

The report also details adaptation measures that countries should consider in responding to climate threats, including the use of drought, flood and saline-resistant crop varieties, more integrated coastal zone management, increased efficiencies in the energy sector, improved disease and vector surveillance, and more protection of groundwater resources and greater use of recycled water.