New Delhi: Globally human-induced heat and humidity will create conditions beyond human tolerance if emissions are not rapidly eliminated. India is among the places that will experience these intolerable conditions, the Intergovernmental Panel on Climate Change (IPCC), a United Nations body, said on Monday.
The landmark report refers to wet-bulb temperatures, a measure that combines heat and humidity. A wet-bulb temperature of 31 degrees Celsius is extremely dangerous for humans, while a value of 35 degrees is unsurvivable for more than about six hours, even for fit and healthy adults resting in the shade.
Even below these levels the heat can be deadly, especially for old or young people or those doing hard physical work.
Currently, wet-bulb temperatures in India rarely exceed 31 degrees, with most of the country experiencing maximum wet-bulb temperatures of 25-30 degrees, according to a study cited by the UN body in its report that is the summary for policymakers of the Working Group II contribution to the Sixth Assessment Report.
The Working Group II report is titled “Climate Change 2022: Impacts, Adaptation and Vulnerability”.
It notes that if emissions are cut, but only by the levels currently promised, many parts of northern and coastal India would reach extremely dangerous wet-bulb temperatures of over 31 degrees towards the end of the century; if emissions continue to rise, wet-bulb temperatures will approach or exceed the unsurvivable limit of 35 degrees over much of India, with the majority of the country reaching wet-bulb temperatures of 31 degrees or more.
The study also mentions that under RCP8.5 (high emissions scenario), at the end of the century, Lucknow and Patna are among the cities predicted to reach wet-bulb temperatures of 35 degrees if emissions continue to rise, while Bhubaneswar, Chennai, Mumbai, Indore and Ahmedabad are all identified as at risk of reaching wet-bulb temperatures of 32-34 degrees with continued emissions.
Overall, Assam, Meghalaya, Tripura, West Bengal, Bihar, Jharkhand, Odisha, Chhattisgarh, Uttar Pradesh, Haryana and Punjab will be the most severely affected, but if emissions continue to increase, all Indian states will have regions that experience wet-bulb 30 degrees or more by the end of the century.
In South Asia particularly, intense heat waves of longer duration and higher frequency are projected with medium confidence over India.
At the city-level, these projections could translate into significant impacts: at 1.5 degrees, on average, Kolkata will experience heat equivalent to the 2015 record heat waves every year and under two degrees warming, it could expect such heat annually.
Critically, the impact of extreme heat is experienced disproportionately within cities with the poorest populations and those with lower access to green spaces are affected the most.
The sea-level rise will threaten people, land use patterns and infrastructure in India.
The global sea levels will likely rise 44cm-76cm this century if governments meet their current emission-cutting pledges. With faster emission cuts, the increase could be limited to 28cm-55cm. But with higher emissions, and if ice sheets collapse more quickly than expected, sea levels could rise as much as two metres this century.
As sea levels rise, more land will be submerged, flooded regularly, eroded, or become unsuitable for agriculture due to saltwater intrusion.
India is one of the most vulnerable countries globally in terms of the population that will be affected by sea-level rise.
By the middle of the century, around 35 million people in India could face annual coastal flooding, with 45-50 million at risk by the end of the century if emissions are high — with far fewer at risk if emissions are lower, according to a study cited by the IPCC report.
The economic costs of sea-level rise and river flooding for India would also be among the highest in the world. Direct damage is estimated at between $24 billion if emissions are cut only about as rapidly as currently promised, and $36 billion, if emissions are high and ice sheets are unstable, according to another study cited by the report.
This might in fact be a large underestimation; the report cites another study that found that damage from sea-level rise in Mumbai alone could amount to up to $162 billion a year by 2050 if emissions continue to rise.
So food production and food security will be hit by the climate change.
Globally, high temperatures and extreme weather events, such as droughts, extreme rainfall events, heatwaves and floods, are damaging crops and will increasingly limit crop production if temperatures continue to rise.
Climate change and rising demand mean that about 40 per cent of the people in India will live with water scarcity by 2050 compared with about 33 per cent now, according to a study cited by the IPCC report.
Both the Ganga and the Brahmaputra river basins will also see increased flooding as a result of climate change, particularly if warming passes 1.5 degrees.
These factors, along with saltwater intrusion from sea-level rise, will harm agriculture in India, which is considered by the report as the most vulnerable country in terms of crop production.
Rice, wheat, pulses, coarse and cereal yields could fall almost nine per cent by 2050. In South India, maize production could decrease 17 per cent if emissions are high. These disruptions to crop production are expected to cause price spikes in India, threatening food affordability, food security and economic growth.
India will also face severe economic damage without emission cuts.
India’s GDP per capita is already 16 per cent lower than it would have been without human-caused warming since 1991, according to a study cited by the IPCC report.
India is the country that is economically harmed the most by climate change, with every tonne of carbon dioxide emitted globally costing the country around $86, according to a separate study cited by the report.
In 2021 the world emitted 36.4 billion tonnes of carbon dioxide.
Continued warming will further damage India’s economy, particularly if emissions are not rapidly eliminated. Heat will reduce labour capacity, particularly in agriculture: A study cited by the IPCC report projects that agricultural labour capacity in India would fall 17 per cent if warming continues to 3 degrees — only a little more than current planned emissions would lead to — or 11 per cent if emission cuts are accelerated.