Increasing heat waves and droughts, rainfall events and a likelihood of more cyclonic activity — this is what is in store for India and the subcontinent over the coming decades, according to a report released by the Intergovernmental Panel on Climate Change (IPCC) on Monday.
The report, ‘Climate Change 2021: the Physical Science Basis’, is the first part of IPCC’s Sixth Assessment Report (AR6) — its latest evaluation of the state of Earth’s climate and the impact on the planet and life forms.
In a grim reminder of the threat posed by climate change, the report raises a crucial red flag — that global temperatures have already risen by about 1.1 degrees Celsius from pre-industrial times, and warns that the 1.5-degree-Celsius threshold was likely to be breached before 2040.
The stated objective of the 2015 Paris Agreement, the international architecture to fight climate change, is to limit temperature increase to within 2 degrees Celsius from pre-industrial times, hopefully within 1.5 degrees Celsius itself. Scientists say a temperature rise beyond 2 degrees Celsius would result in catastrophic and irreversible changes that would make it difficult for human beings and other species to survive.
On India, the report says heat waves and humid heat stress will be more intense and frequent in the 21st century. Changes in monsoon precipitation are also expected, with both annual and summer monsoon precipitation projected to increase.
“Heat extremes have increased while cold extremes have decreased, and these trends will continue over the coming decades,’’ it says for the Indian subcontinent.
The report says the presence of aerosols and particulate matter due to human activity have influenced rainfall events in the Indian subcontinent. The dominant cause of the observed decrease of South and Southeast Asian monsoon precipitation since mid-20th century is the increase in aerosols and particulate matter due to human activity, the report said, while predicting that in the long-term, South and Southeast Asian monsoon and East Asian summer monsoon precipitation will increase.
The report also says there is now “unequivocal” evidence that global warming was being caused by human activities. “The main finding of the report is that climate change is a fact, warming is a fact and that the warming has taken place because of human influence is now well established… There is no going back from some of these changes. Even if we limit temperatures to 1.5 degrees Celsius from pre-industrial levels, we will continue to see extreme weather events,’’ said Dr Friederike Otto, Associate Director, Environment Change Institute, University of Oxford and one of the authors of the report.
Otto added that some changes are locked in, such as rising sea levels and melting glaciers, which can now no longer be reversed.
“For India, increase in heat waves is marked by other emissions like aerosol emissions. If there is a reduction in aerosols, we will see a further increase in heat waves,’’ she said.
Dr Swapna Panickal of the Pune-based Indian Institute of Tropical Meteorology, one of the authors of the report, added India is and will experience an intensifying of the water cycle which will affect rainfall patterns as well as increased monsoon precipitation.
“In the Indian Ocean, the sea temperature is heating at a higher rate than other areas, and therefore may influence other regions. The South West Monsoon has declined over the past few decades because of the increase of aerosols, but once this reduces, we will experience heavy monsoon rainfall,’’ she said.
The global mean sea level in the Indian Ocean is rising at 3.7 mm annually. Extreme sea-level events, that previously occurred once every 100 years, will now be seen nearly every year, she added.
The report projects that in the coming decades, all regions will witness the effects of climate change.
Coastal areas will see continued sea-level rise throughout the 21st century, resulting in coastal erosion and more frequent and severe flooding in low-lying areas. For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea-level rise in coastal cities.
“Given that India is one of the most climate-vulnerable countries, we must recognise that even geographically faraway climatic changes can have consequences for our monsoons and intensity of extreme events,” said Dr Arunabha Ghosh, CEO, Council on Energy, Environment and Water (CEEW.)