Feb. 16: Calcutta has lost significant amount of open space over the past three decades and it has led to the creation of heat islands.

A study commissioned by the British government for the Calcutta Municipal Corporation said open space as a percentage of the total area has dropped from 25 per cent in 1990 to 10 per cent at present.

Residential and commercial land use made up 79 per cent of the city's total area. The loss of green space has contributed to the growth of urban heat islands, the study said.

These islands are places where the greenery has been replaced with concrete, leading to significantly higher temperature than the rural surroundings.

Key findings of the study conducted over the past year, along with recommendations on disaster risk management, were discussed today at a meeting between British deputy high commissioner at Calcutta Bruce Bucknell and civic officials.

The UK government had hired PwC and TARU, consultants, for the project.

Speaking about urban heat islands, Souryadeep Mukherjee, who teaches life sciences at Presidency University, said concrete absorbed more solar radiation and lost little heat at night. "Also, asphalt used in laying roads is dark in colour and absorbs more heat. Then there are electronic items such as ACs that generate its own heat."

The report, released today, suggested many short, medium and long-term measures that the civic body or the government could adopt.

It highlighted the problem narrow roads can pose during a disaster and recommended the widening of roads in vulnerable places for the easy movement of fire engines and ambulances. The study proposed the creation of emergency corridors for fire services and evacuation.

Bucknell flagged the issue of climate risk insurance. "With a large urban poor population and majority of urban infrastructure exceedingly vulnerable to climate risks, it is important for cities to prepare for calamities and safeguard its citizens and investments through innovative approaches," he said.

"One such approach is the use of advanced climate modelling and risk assessment at the municipal level coupled with effective insurance tools built into the city's disaster recovery and relief schemes."

Officials of several insurance companies were present at the meeting.

The report said if Calcutta were to receive the amount of rain Chennai received in November 2015 (480mm in 24 hours), 90 per cent of the city would go under water.

"The UK government will give us technical assistance to deal with natural disasters. A detailed report on building and improving infrastructure to mitigate natural disasters would be submitted. We can use the report to seek developmental loans," a civic official said.