The recent publication by the Ministry of Earth Sciences (MoES) was the first ever assessment of climate change over the Indian region. This forecast, which predicts the impact of global warming on the subcontinent over the coming century, forms a significant part of India’s climate policy and science. The projections were developed at the Indian Institute of Tropical Meteorology in Pune and will contribute to the next report from the Intergovernmental Panel on Climate Change, expected to be completed in 2022.
Understanding the Context
The climate change projections are presented in the context of historical trends regarding land and ocean temperatures, monsoon rainfall, floods, droughts, and changes in Himalayan warming and glacier loss. These historical factors are integral to understanding how climate change could affect the Indian subcontinent, particularly given the intricate relationship between its diverse ecosystems and weather patterns.
Temperature Projections
In a worst-case scenario, average surface air temperatures across India may increase up to 4.4°C by the end of the century compared to levels recorded between 1976 and 2005. This scenario is founded on the Representative Concentration Pathway (RCP) 8.5, a climate forecasting model that calculates radiative forcing caused by increasing greenhouse gas emissions. The country’s average temperature could rise by up to 2.4°C under the RCP 4.5 or intermediate scenario. The Hindu Kush-Himalayan region may experience even more pronounced changes, with average temperature increases reaching up to 5.2°C.
Climate Variability and Extreme Weather
Researchers predict that by 2100, warm days and nights may increase by 55% and 70% respectively under the RCP 8.5 scenario. Also, the frequency and duration of heat waves could increase three to four times. These trends may have severe implications for the country’s health and agricultural sectors. Between 1900 and 2018, India’s average temperatures increased by 0.7°C. This rise is primarily attributed to global warming due to greenhouse gas emissions and changes in land use and cover.
Global Climate Change
Current global climate change assessments indicate a worldwide average surface air temperature rise of 5°C by this century’s end. The increase is based on the continuation of current human activities and emission levels. Despite this potential increase, global average temperature has risen by only 1.1°C over the last century, according to the IPCC estimates.
The Paris Agreement and National Contributions
If nations meet their Nationally Determined Contributions (NDCs) under the Paris Agreement 2015, the global average temperature could still rise by around 3°C. Such an increase could have serious implications, demanding attention at policy and practical levels.
Rainfall Projections
Significant variability in rainfall, particularly during the monsoon season, is another critical finding of the assessment. Monsoon rainfall contributes to 70% of India’s total rainfall, directly affecting its rural agrarian economy. By 2100, monsoon rainfall could change by an average of 14%, reaching highs of up to 22.5%. The report did not clarify whether this change would result in increased or decreased rainfall, but the variability alone is cause for concern.
Changes in Monsoon Patterns
Between 1950 and 2015, overall monsoon rainfall decreased by 6%. More recently, there has been an increased frequency of dry spells during the monsoon season—an increase of 27% between 1981-2011 compared to 1951-1980. Conversely, instances of extreme rainfall events have increased, with central India reporting a 75% increase in such events between 1950 and 2015. This climatic volatility, where dry spells are broken by extremely heavy rainfall, has resulted in alternating flood and drought cycles in many regions of India.