Based on a long-range statistical analysis by scientists at IIT Bombay, the eastern province is set to release an updated state action plan to deal with climate change

The skyline of Kolkata, capital of West Bengal, seen from the west bank of Hoogly River (Photo by Koustav Ghosh)

In a move expected to spur policy action, West Bengal has updated its State Action Plan for Climate Change after consultations with scientists at IIT Bombay and will release it by August. The plan aims to aid various government departments for climate-friendly planning and policymaking. It is the latest in line of such plans being formulated and implemented by various provincial administrations across the country.

Officials in the state’s Department of Environment claimed that West Bengal is the first state in India that has sought and obtained information regarding climate — about temperature and precipitation — in a decadal series up to the year 2100. The department, which first wrote its state action plan in 2012, is using the currently generated data to put in place adaptation options.

The plan has been updated based on the output generated by a statistical exercise of General Circulation Models of climate scenarios done by scientists at IIT Bombay, the officials said. It has helped in answering questions such as what the models of future scenarios of climate change would mean to the general public and the ways in which technical information could connect scientists and policymakers with the person on the street.

The Intergovernmental Panel on Climate Change (IPCC), which represents the international consensus science on climate change, says in its 2014 Assessment Report: “In climate change research, scenarios describe plausible trajectories of different aspects of the future that are constructed to investigate the potential consequences of anthropogenic climate change. Scenarios represent many of the major driving forces – including processes, impacts (physical, ecological, and socioeconomic), and potential responses that are important for informing climate change policy. … The goal of working with scenarios is not to predict the future but to better understand uncertainties and alternative futures, in order to consider how robust different decisions or options may be under a wide range of possible futures.”

General Circulation Models (GCMs), on which West Bengal’s plan is based, are numerical models representing physical processes in the atmosphere, ocean, cryosphere and land surface, and are the most advanced tools available for simulating the response of the global climate system to increasing greenhouse gas concentrations. Since the scale of these models is global, the relevance of the information they generate cannot satisfy specific and detailed requirements at the regional level, or even more importantly, at the level of a country or a component state.

Representative pathways

Therefore, these models have to be downscaled in keeping with the institutional requirements, especially within countries. As a result of the current modelling exercise, information has been generated regarding West Bengal with all its districts and geo-climatic regions with reference to four representative concentration pathways (RCPs).

The RCPs have been developed to be representative of possible future emissions and concentration scenarios published in existing literature. They focus on the concentrations of greenhouse gases that lead directly to a changed climate, and include a pathway — the trajectory of greenhouse gas concentrations over time till year 2100.

“Climate modelling has huge implications in the long term across all sectors. For example, if you can see the information on likely temperature and precipitation changes, then crop-specific planning for the future becomes easier,” Subimal Ghosh, Professor at the Department of Civil Engineering, IIT Bombay who led the downscaling exercise for West Bengal, told “Modelling and its equivalent statistical downscaling can equip policy planners with information needed to plan ahead.”

“It is very difficult to pin point which RCP will be accurate. It depends on human activities and how much greenhouse emissions will take place as a result of that. They have a direct impact on the variables,” Ghosh clarified. “But pragmatically speaking, it appears that RCP 4.5 is a notable assumption regarding the future.”

The statistical analysis projects significant increase in maximum and minimum temperatures and decrease in precipitation till 2100 over West Bengal. In the near future (2021-30), the average maximum temperature is projected to rise by a little over 1 degree Celsius for the concentration pathway RCP 4.5. Rainfall is expected to decrease by as much as 11% for RCP 4.5. However, the 30 year mean annual precipitation projections for RCP 2.6 — which is the best case scenario — indicate that the maximum rainfall may increase by 1 mm per day for the hilly Darjeeling-Jalpaiguri region.

When the first action plan was written for the period 2012-17 in West Bengal, socio-economic factors rather than numerical ones determined planning for climate uncertainties. It is generally agreed that the accuracy of such scenario modelling is lower compared to RCPs.

In spite of temperature rise and irregularities in rain, the economic review of West Bengal 2016-17 indicated that this did not lead to a loss of productivity in the state for agriculture and allied sectors. On the contrary, higher production was recorded in food grains (12%), fish (3.36%) and livestock (14%).

Extended projections

In 2012-17, “the department undertook projects to obtain extended weather projections to assess vulnerability for coastal districts and Darjeeling Himalaya,” a senior officer of the Department of Environment told “The information generated by IIT Bombay was completed by 2016, but it took time to put in place adaptation planning for 17-18 departments of the government.”

Does the experience of working for West Bengal provide any learning for an academic-policy interface in the context of decoding climate information and utilising it? “Climate literacy of policy planners is fundamental to understand the relevance of information generated on climate change and the uncertainties involved. Only then can such information be gainful for the government. We found this factor very positive in West Bengal’s case.” Ghosh said. “At the end of the day, only states with climate-literate policy planners will be able to prepare their constituencies with a better set of options for the future.”


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