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Current pace of planet-warming could hit Singapore hard

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Cities could suffer if emissions do not come down to net zero by 2050: IPCC

Punishing heatwaves, severe coastal flooding events and bouts of heavier rain could be on the cards for cities such as Singapore, if planet-warming emissions do not come down to net zero by around 2050.

"Cities intensify human-caused warming locally, and further urbanisation together with more frequent hot extremes will increase the severity of heatwaves," noted the Intergovernmental Panel on Climate Change (IPCC) in its summary for policymakers.

Singapore has already experienced warming higher than the global average because of the urban heat island effect - a phenomenon of urban structures trapping heat.

Local temperatures are 1.8 deg C higher than they were in 1948, data from the National Environment Agency's Meteorological Service Singapore (MSS) showed.

Global temperatures have warmed by about 1.1 deg C from pre-industrial times, which ended around 1850.

And the Centre for Climate Research Singapore - a unit under the MSS - said the latest report suggests that even higher temperatures will be felt here in the coming decades.

Singapore Management University climate scientist Winston Chow, an expert on the impact of climate change on cities and who contributes to IPCC reports, said temperatures above 35 deg C here would be an uncomfortable experience as humidity magnifies thermal discomfort.

Humans can adapt to this with air-conditioning and shade, but the country's native flora and fauna cannot.

"Our trees and animals on land and sea don't have that luxury if there's a prolonged heatwave," Associate Professor Chow said.

Another worrying indicator of climate change for the island will be rising tides.

As the world warms, ocean waters expand and land ice melts, raising water levels.

Global mean projections in the latest report, of sea levels rising up to about 1m by 2100, do not differ significantly from past IPCC reports.

DOORSTOPPER

The Centre for Climate Research Singapore said processes such as instabilities in marine ice cliffs - which are sea-facing blocks of ice that act as a "doorstopper" preventing land ice from entering the ocean - could potentially contribute more than one additional metre of sea-level rise by the end of the 21st century, adding to the current projected global mean sea level rise.

Professor Benjamin Horton, director of Nanyang Technological University's Earth Observatory of Singapore and a review editor for the IPCC report's chapter on sea-level changes, said a big concern for the future is the melting of the planet's two ice sheets - Greenland and Antarctica.

While melting has been mostly limited to mountain glaciers in the 20th century, he said, satellite-based measurements of the ice sheets show their melting is accelerating.

If all the ice in Greenland melted, it would raise global sea levels by 7m, he said. And Antarctica has enough water to raise sea levels by 65m.

He said: "If a few per cent of the Antarctic ice sheet were to melt, it would cause devastating impacts."

As for rainfall, the IPCC report said that in general, bouts of rain could become more intense and frequent with each additional degree of warming.

South-east Asia would also be likely to experience this, resulting in flash floods if ground is covered with concrete and if drainage systems are overwhelmed, but more research has to be done to see if Singapore will experience this.

"The science around climate change attribution is still evolving, and MSS will continue to study this, along with the impact of climate change on Singapore's weather," said a spokesman for the service.

The latest report, which has more than 1,000 pages, produced by the IPCC's Working Group 1, examines the physical basis of climate change. It is the first of three reports that will make up the IPCC's Sixth Assessment Report to be published next year.

The Centre for Climate Research Singapore said it is studying the latest report and working to contextualise the findings for the Republic.

Environment