In its most direct and unequivocal report on the dire threat of climate change, the UN’s inter-governmental panel on climate change on Monday projected global temperature to reach or exceed 1.5°C of warming over the next 20 years under all scenarios.
Calling the report a “code red for humanity”, the UN said the world would have to drastically cut greenhouse gas emissions in the next two decades if it wants to spare humanity from climate change’s disastrous consequences, leading to destruction of natural habitats.
The IPCC studied 14,000 reports and its projection is seen to be based on solid scientific evidence and reasoning. There is a chance to pull back from the precipice, the report says, if governments believe and act on “strong and sustained reductions in emissions of carbon dioxide and other greenhouse gases” to limit climate change by reaching ‘net-zero’ emissions by mid-century.
UN Secretary-General António Guterres urged immediate action to deal with the crisis. He said, “All nations, especially the G20 and other major emitters, need to join the net zero emissions coalition and reinforce their commitments with credible, concrete and enhanced nationally determined contributions and policies before COP26 in Glasgow.”
Currently, global average temperature rise is approximately 1.1° C above the pre-industrial level (1850-1900). A further rise of 0.4°, as projected in the report, may lead to more heat wave events, longer warm and shorter cold seasons and faster sea-level rise globally. India would face similar impacts as also frequent glacial lake bursts in the Himalayan region and inundation of low-lying coastal areas.
For India, possible increase in annual mean precipitation could be accompanied by more severe rainfall events over southern parts of the country in the next few decades.
Overall, the high northern latitudes show the largest temperature increase with clear effects on sea ice and glaciers. This is especially true for the Greenland and Antarctic ice sheets, which grow much more slowly than they retreat.
“If the current melting of these ice sheets continues for long enough it becomes effectively irreversible on human timescales, as does the sea level rise caused by that melting,” said the IPCC’s report titled, Climate Change 2021: the Physical Science Basis.
Globally, coastal areas will see continued sea level rise (3-4 mm per year in 2015 to 3-8 mm per year by 2100 in a very low emission scenario) throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion.
“Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century,” said the report with experts underlining the possibility of once such event every six to nine years by 2050.
The IPCC, which assesses science behind climate change, has for the first time provided a more detailed “regional assessment of climate change” (across 11 regions globally) which will help in risk assessment and taking necessary adaptation measures.
Though the report has not assessed the city-specific details, the prediction of faster sea-level rise in Asia (3.7mm annually in the Indian Ocean) may see coastal flooding in low-lying areas of India’s vast coastline of 7,517 km dotted with big port cities such as Mumbai, Chennai, Kochi, Kolkata, Surat and Visakhapatnam.
“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,” said the report.
In this context, the report mentioned how mean temperature in Kolkata is 2.6 degree C higher than surrounding rural areas due to urban heat island effect and its map shows this trend for almost all big cities across the country.