Climate: Observations, projections and impacts - India - A report by the Met Office (UK)

This was done as a part of a project that aimed at compiling scientifically robust and impartial information on the physical impacts of climate change for more than 20 countries. This was done using a consistent set of scenarios and as a pilot to a more comprehensive study of climate impacts that aimed at providing evidence on how the climate has already changed and the potential consequences of these changes on the future

The report includes:

• A description of key features of national weather and climate, including an analysis of new data on extreme events
• An assessment of the extent to which increases in greenhouse gases and aerosols in the atmosphere have altered the probability of particular seasonal temperatures
• A prediction of future climate conditions, based on the climate model projections used in the Fourth Assessment Report from the IPCC.
• The potential impacts of climate change, based on results from the UK's Avoiding Dangerous Climate Change programme ( AVOID) and supporting literature

The report is divided into the following chapters:

• Chapter 1: Climate observations
• Chapter 2: Climate change projections
• Chapter 3: Climate change impact projections

The findings indicate that:

Climate observations

• There has been a widespread warming trend over India since 1960
• Over the period 1970-2009, where data is available, there has been a decrease in the frequency of cool nights across India, an increase in the number of warm nights as well as a decrease in cool days and an increase in hot days
• There has been a general increase in seasonal temperatures averaged over the country as a result of human influence on climate, making the occurrence of warm seasonal temperatures more frequent and cold seasonal temperatures less frequent

Climate change projections

• Projected temperature increases are lower in the south of India as compared to the north
• India is projected to experience increases in precipitation across most of the country. Increases of up to 20% or higher could occur in western regions with more widespread increases of 5-10% over the rest of the country.

Climate change impacts projections

Crop yields

• Declines are generally projected for wheat and rice, two of India’s major crops
• National- and sub-national-scale studies project that the yield of coconut could increase, and those of mustard and soybean decrease. One subnational-scale study projects a decline of maize in winter in the Mid Indo-Gangetic Plains and Southern Plateau, but an increase in the Upper Indo-Gangetic Plain ( with climate change limited to a 2.7°C mean warming).

Food security

• India is currently a country with moderately high levels of undernourishment. Global scale studies project that India could face worsening food security over the next 40 years

Water stress and drought

• Both global- and national-scale studies indicate that water stress could increase in India with climate change. However, there is great variation as to the magnitude of the increase due to the application of different climate models and indicators of water stress
• Recent simulations from the AVOID programme broadly agree with the other global assessments, and project a median increase of 5% in the population exposed to increased water stress by 2100 under the A1B emissions scenario albeit with a high degree of uncertainty. There is less uncertainty in the result that around 20% of the population could be exposed to a decrease in water stress by 2100 under the same emissions scenario

Pluvial flooding and rainfall

• There will be a general increase in mean and extreme precipitation across India under climate change scenarios
• However, two key factors affecting Indian precipitation are the Asian Monsoon system and tropical cyclones, and future projections of these mechanisms are both subject to high uncertainty

Fluvial flooding

• Several recent studies suggest that by the end of the 21st century, extreme and currently rare floods could occur more frequently in India
• Generally there is still considerable uncertainty in projections of extreme precipitation with climate change as well as potential changes to the strength of the monsoon.

Tropical cyclones

• There is no clear signal from the global- and regional-scale studies as to how tropical cyclone frequency in the North Indian Ocean might be affected by climate change
• Projections of changes in cyclone intensity are hampered by a lack of reliable modelling studies
• Estimates of future tropical cyclone damages in India due to climate change remain highly uncertain

Coastal regions

• A number of recent studies indicate that India is highly vulnerable to the impacts of sea level rise (SLR).
• One study shows that a 10% intensification of the current 1-in-100-year storm surge combined with a prescribed 1m SLR could affect around 7.6 million people in India
• Another study shows that in 2070 the exposed population in India to SLR is 20.7 million under the A1B emissions scenario
• An aggressive mitigation policy could avoid an exposure of around 1.7 million people in India, relative to un-mitigated climate change

The entire report can be accessed at this link