AROUND THE world, record temperatures have become more and more frequent in recent years. This month, Delhi reported its highest ever temperature of 48°C while Churu in Rajasthan crossed 50°C. Last week, the United Nations’ World Meteorological Organization confirmed two very recent readings as being among the hottest on record globally — 53.9°C in Mitribah, Kuwait (2016) and 53.7°C in Turbat, Pakistan (2017). India’s highest ever, too, came as recently as May 19, 2016 — 51°C in Phalodi, Rajasthan.
A new study has projected that the record-setting trend will continue for at least the next 20 years, and for longer unless measures are taken to reduce greenhouse gas emissions.
From the findings, it can be inferred that India too is projected to experience the frequent occurrence of unprecedented high temperatures over the next 20 years, study author Scott Power of the Australian Bureau of Meteorology told The Indian Express by email. Power and colleague Francois Delage have reported their findings in the journal Nature Climate Change.
The big picture
Using 22 climate models from the world’s leading climate research centres, the new study projects temperature trends in two possible scenarios — high greenhouse gas emissions (called RCP8.5) and substantially reduced greenhouse gas emissions by 2020 (RCP2.6).
If the high-emissions scenario were to continue, the study found that by the end of the century, 58% of the Earth’s surface will likely witness at least one new monthly record temperature every year. In the low-emissions scenario, however, the likelihood would drop to 14%.
Projections for India
In the high-emissions scenario, the likelihood of setting at least one high monthly record in any given year varies regionally from 60% to 70% in the late 21st century, which is larger than the global average of 58%, Power said. In the low-emissions scenario, the likelihood of setting at least one high monthly record drops to approximately 15% over the whole country.
And if the projection is for frequent record temperatures over the next 20 years, “after this, the frequency will increase if greenhouse gas emissions continue to rise or the frequency will fall if large and sustained cuts are made to global greenhouse gas emissions”, Power said.
Why 20 years?
Although the study looks at the benefits of reducing global greenhouse emissions by the end of the 21st century, these benefits take more than 20 years to become clear, Power said. “The likelihood of setting extreme temperature records is projected to remain at high levels for the next two decades.”
Rest of world
The poorest countries are projected to witness the highest pace at which records are set, and the greatest benefits from reducing emissions on this pace. Approximately 68% of years will see records set in the world’s Least Developed Countries and in Small Island Developing States by the end of the century, whereas this figure is only 54% in wealthier nations, the study said.
The authors make a distinction between temperature records being “set” and “smashed”, using the latter for records being surpassed by a high amount. “Near the end of the century the likelihood of setting records that smash the records they replace by more than 1.0°C,” Power said, “is eight times more likely if global greenhouse gas emissions are not markedly reduced, and are over twenty times more likely than would be the case if anthropogenic greenhouse gas emissions had not occurred at all.”