Global or local warming?3 min read . Updated: 27 May 2016, 03:51 AM IST
After a month of record-breaking heat with temperatures above mean, Bengaluru offers India a warning about warming
When my family first came to Bengaluru in 1969, we moved into a two-storey stone house. To the east lay Shivajinagar, a teeming warren of lanes, people, slaughterhouses and bakeries. To the west was a shunting yard where steam engines puffed and clanked all day.
Between the smoke and the crowds, you might imagine that 99, Broadway Road—our home—might need some sealing of windows and cooling of interiors. But the large, wooden windows stayed open day and night. Bengaluru’s famous breeze was enough to keep us cool. There were no fans in the house, and, of course, no one had heard of air-conditioning.
To the millions who now toil in Bengaluru’s air-conditioned glass-and-steel towers—often running on giant diesel generators—these stories are mostly dim fantasy. As we shall see, Bengaluru’s heating is in line with global warming, but the city is simultaneously committing environmental harakiri. If Bengaluru’s mild weather can change in half a generation, what will become of hotter cities across the subcontinent?
Between 1972—when I still lived in the house on Broadway Road—and 2012, Bengaluru lost 66% of its once vast canopy of trees and 74% of its lakes, I wrote last month, quoting an Indian Institute of Science study, which presented similarly grim scenarios for other major cities. So, three things have come to pass: Bengaluru’s natural air-conditioning elements have almost gone; the concrete and asphalt that have replaced them radiate heat; so do the millions of air-conditioners now needed to cool this self-created urban heat island.
You may contest the reasons, but Bengaluru is warming. April 2016 experienced unprecedented temperatures. Save for one day, every other day in April was hotter than 35 degree Celsius, with 19 of those 37 degree Celsius or higher, I observed while trawling temperature data from Accuweather, a weather-forecasting company. As the accompanying chart indicates, this April was substantially above the mean, which is 34 degree Celsius.
In 2015, the hottest year on record globally, Bengaluru was 0.9 degree Celsius above normal, the same as the average global temperature rise recorded across land and ocean surface areas.
Let’s zoom out a bit.
“This (2015) marks the fourth time in the 21st century a new record high annual temperature has been set (along with 2005, 2010 and 2014) and also marks the 39th consecutive year (since 1977) that the annual temperature has been above the 20th century average," said the website of the National Centers for Environmental Information of the US National Oceanic and Atmospheric Administration (NOAA).
Including 2015, 15 of the 16 warmest years on record have occurred during the 21st century.
The global land temperature in 2015 was 1.33 degree Celsius above the 20th-century average, the NOAA noted. Since water warms slower than land, the corresponding temperature rise in the oceans was a little more than half the level (0.74 degree Celsius) recorded on land.
In 2015, the Gangetic plains experienced “warmer than average" temperature, peninsular India, Jammu and Kashmir and the north-east were “much warmer than average" and the southern tip of India had record highs, according to NOAA data.
Now, 2016 is on course to being the warmest year ever in recorded human history. April was already the warmest ever recorded, making it a year of monthly temperature records set.
“This is the longest such balmy streak in the 137-year record, which dates back to 1880," said the NOAA.
April witnessed the least snow cover ever across the northern hemisphere in half a century. The average temperature on Earth and the average sea-surface temperatures for the year ending April 2016 exceeded the 20th-century global average by record margins.
And so we heard last week (19 May) of the highest temperature ever recorded in India, a searing 51 degrees Celsius in the Rajasthani salt-making town of Phalodi (The highest temperature ever recorded has been 56.7 degrees Celsius in July 1913 at Death Valley, California, according to the World Meteorological Organisation).
Back in Bengaluru, it appears somewhat clear that the city’s rapid warming is following a course laid out by climate change. But it is much clearer that Bengaluru is doomed to follow that path because it has wiped out its trees and lakes—the things that could have kept it cool and allowed it to chart its own meteorological destiny.
Samar Halarnkar is editor of Indiaspend.org, a data-driven, public-interest journalism, non-profit organization. He also writes the column Our Daily Bread in Mint Lounge.
Comments are welcome at email@example.com. To read Samar Halarnkar’s previous columns, go to www.livemint.com/frontiermail