Rising frequency of cyclones linked to climate change, field experts warn

NEW DELHI: The severe cyclonic storm which made landfall in Maharashtra on Wednesday is an indication of an increasing frequency of severe cyclones developing in Arabian Sea in the past decade, a trend that studies have linked to climate change.

In the past two years itself, there have been seven cyclones formed in the Arabian Sea, though, according to IMD, the ratio of cyclones in the Arabian Sea and the Bay of Bengal — which just witnessed the destructive cyclone Amphan on May 21 — is 1:4. The Intergovernmental Panel on Climate Change (IPCC) last year came out with a special report in which it said that extreme rainfall and extreme sea level events associated with some tropical cyclones are being seen to have a cascading impact on coastal areas. “There is emerging evidence for an increase in annual global proportion of Category 4 or 5 tropical cyclones in recent decades,” it said.

MUMBAI: The Giant Metrewave Radio Telescope (GMRT), which is the world’s largest radio telescope facility operating at low radio frequencies, was shut down for a day on Wednesday since cyclone Nisarga’s predicted trajectory was close to its array of 30 fully steerable parabolic dishes of 45m-diameter antennas, spread out over a 30km region about 10km east of Narayangaon town on Maharashtra’s Pune-Nasik highway.

Built and operated since 2002 by the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of Fundamental Research, the GMRT facility studies a wide range of subjects in modern astronomy including the origin of the universe.

A team at NCRA was tracking the storm’s path since Tuesday. “Going by wind speed from various climate models, we decided to shut down the observatory, and all antennas have been parked in safe mode since morning, till the track of Cyclone Nisarga passes over GMRT,” said Yashwant Gupta, director, NCRA.

Gupta said that though antennas have been designed to withstand wind speed of 100-120 kmph, the maximum operating speed limit for the antennas is 45kmph.

The last time that GMRT operations were suspended was during the pre-monsoon season in 2016.

“It was an extreme episode of winds travelling at 80kmph. High winds prevail during the premonsoon months of April to mid May over the area where GMRT is located,” said Gupta. “...wind speed from Cyclone Nisarga was predicted to be 50-60kmph and could have been higher. For a major cyclone activity, we shut operations for the first time.”

The public outreach team at NCRA tweeted that antennas have been parked in the default safe position with brakes on, on both the axes.

“We would like to normalise operations tomorrow (Thursday) but that will depend whether or not power lines trip since 16 antennas are powered with electricity lines that cross farms lands, while power lines for 14 run underground on our land,” said Gupta.

Going by wind speed from various climate models, we decided to shut down the observatory, and all antennas have been parked in safe mode YASHWANT GUPTA, NCRA director