Climate change is generally considered a global environmental issue and its impacts are just decades away. Recently, the IPCC (Intergovernmental Panel on Climate Change) reported that there is adequate evidence to suggest that climate change is already occurring, impacting food production, hydrology etc.

Further, the climate change will be sooner and the adverse impacts will be more severe on food production, water supply, forest biodiversity, health etc. However, the IPCC provides evidence largely at global and continental level. But the impacts of climate change will also be felt at state, district, village and farmer levels. Thus, there is a need for climate change studies at state, district and if possible, at village level.

Karnataka state is likely to be one of most vulnerable states in India to climate change risks. In Karnataka nearly 70 per cent of agricultural land is under rainfed conditions, 50 per cent of area is drought prone and most irrigation and power projects depend on timely and adequate rainfall.

In this context, a team led by the Indian Institute of Science – with participation of University of Agricultural Sciences, INRM, ISEC and London School of Economics, coordinated by BCCI (Bangalore Climate Change Initiative) and Global Green Growth Institute – prepared a comprehensive report on climate change projections, impacts and vulnerability based on the latest scientific models. Some of the key findings of study, released recently, are presented here.

The weather patterns have changed over the last century, with overall increase in minimum and maximum temperature and the rainfall has decreased by over 10 in many districts of Karnataka. Multi-modal based projections show that by even 2030s, the mean warming could be in the range of 1-3°C in different districts.

Further, by 2080s, warming could be as high as 3-5°C compared to the historical average inmost districts. Eastern districts, including Bengaluru, are likely to experience higher levels of warming. Monsoon rainfall is projected to increase by 2030s by 8-12 per cent, especially in the moisture deficient Northeastern districts. More rain may not always be good for crops; in fact, high intensity rainfall days are projected to increase, potentially causing flood or crop damage.

What is worrying is the potential adverse impacts on food production, water availability, forest biodiversity and health. Studies on climate change impacts at district or cropping system are at a preliminary stage due to modelling and data limitations.

Modelling studies shows that stream flow is projected to increase by 15 to 35 per cent for the Cauvery river basin, also projected to increase for Krishna and the West flowing rivers, due to increased rainfall and unchanged evapotranspiration.

However, high water stress is projected in some parts of Cauvery basin (parts of Hassan, Mandya, and Mysore districts) and even in Krishna river basin (parts of Bagalkot, Vijayapura, Kalaburagi, Raichur and Yadgir districts).

Given varied impact of climate change on water resources, there is a need for early warning system for extreme events of flood and drought, real-time flood forecasting, greater water use efficiency, water harvesting, ground water recharge and incorporating climate change concern in designing and management of irrigation and power reservoirs.

Analysis of crop yield trends for crops such as rice, maize, jowar, ragi, redgram and groundnut shows that many districts are experiencing decline in yields. Climate change impact assessment shows that nearly half of the districts growing rice, jowar, redgram and ragi are projected to experience decline in crop yields and the remaining districts may experience increase in yields. For example, the yield of ragi could decline by 10-20 per cent while that of redgram by 10-38.

Climate risk management

There is a need to focus on districts that are projected to experience reduction in yield. Thus, improved climate risk management through early warning system and crop insurance may be required. Changes in crop varieties suitable to changed rainfall and temperature pattern and cropping calendar such as the date of sowing or transplanting may be required.

Farmers in rainfed regions are struggling to cope with even the current climate related stresses such delay in rainfall, moisture stress and drought, at a very high cost by leaving land fallow, shifting to a low yielding crop or variety, migration, distress sale of livestock and trees.

Modelling of impact of climate change on forests shows that around a-third of area with forest is projected to undergo change in forest type by 2030s and about two-thirds by 2080s, including locations in the Western Ghats. Thus, the biodiversity and many ecosystem services such as water flow could be threatened.

The policy makers at the global level are working towards measures to reduce carbon dioxide emissions to hold warming below dangerous 2°C, but large parts of Karnataka are likely to experience warming levels higher than 2°C soon.

Thus, Karnataka will have to plan coping strategies in all sectors without waiting for global negotiations at Lima this week and in Paris next year to succeed, which seems highly unlikely.

(The writers are with the Indian Institute of Science, Bengaluru)