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Saturday, January 13, 2018, 09:46
Blowing hot and cold
By The Straits Times/ANN
Saturday, January 13, 2018, 09:46 By The Straits Times/ANN

A train, center, is stranded in Sanjo, Niigata prefecture, north of Tokyo, Jan 12, 2018. (YOHEI FUKAI / KYODO NEWS VIA AP)

SINGAPORE - The new year has barely started and already extreme weather is making headlines.

Climate change is giving the weather an extra kick and affecting atmospheric circulation, such as high-altitude jet streams, in ways scientists do not fully understand

A record deep-freeze in the United States, severe flash floods here, a blistering heatwave in Sydney, record low temperatures in normally balmy Bangladesh, plus a severe cold snap across large parts of China. And now blizzards in Hokkaido, while just to the south, Tokyo basks in unusually mild winter weather.

With each passing year, the weather seems to become more extreme, breaking new records and generating major headlines. And scientists say climate change is increasingly to blame.

That is because the planet's atmosphere and oceans are heating up. Warmer air holds more moisture, bringing more rain and snow. Warmer oceans provide more fuel to power storms.

In short, climate change is giving the weather an extra kick and affecting atmospheric circulation, such as high-altitude jet streams, in ways scientists do not fully understand.

This file photo taken on Oct 5, 2015 shows people enjoying the hot weather at Bondi Beach during the Labour Day holiday in Sydney. Australia sweltered through its third-hottest year on record in 2017 despite the lack of a warming El Nino weather phenomenon, official figures showed on Jan 10, 2018. (PETER PARKS / AFP)

Evidence 

There is strong evidence that climate change caused by burning fossil fuels and deforestation is increasing the intensity of heatwaves, droughts and coastal flooding.

Extreme heat and longer droughts also mean more severe bushfires in places such as South-East Australia and California.

Leading climate scientist Michael Mann, professor of atmospheric science at Penn State University in the US, explained the link simply last year during a presentation published by Climate Reality.

"There are various ways in which climate change can make weather more extreme. Some of them are fairly obvious - if you warm up the planet, you're going to have more frequent and intense heatwaves. Warmer planet, you're going to have more extremely hot days. You tend to see more flooding events, because a warmer atmosphere can hold more moisture, so when it does rain or snow, you actually get more precipitation. The rain and snow falls in larger amounts, and that's something we've seen as well in recent years," Dr Mann said.

A 2016 study by the United Nations' World Meteorological Organisation noted strong links to climate change exacerbating a severe summer in Australia in 2013 and Britain's extreme floods in 2014.

The authors cited analysis showing the record summer heat was made at least five times more likely by human-caused warming.

The authors also cited an analysis that concluded climate change had increased the chances of the rainfall behind the 2014 floods by an estimated 43 percent.

A man braves the heavy snow on a road in Yantai, Shandong province. (PHOTO / VCG)

Singapore not spared

Singapore, too, will face more extreme conditions as the world warms. The island will not be spared flash floods, extended dry spells or warm periods.

Experts told The Straits Times that the concerns for Singapore would be more droughts and flash flooding, due to increased rainfall.

Government statistics already show a trend of increasingly intense rainfall over the years. The annual maximum hourly rainfall was 80mm in 1980, and 90mm in 2016.

The hottest years in Singapore also took place in the past decade. The year 2016 was Singapore's hottest year, with the annual mean temperature rising to 28.4 deg C. In 2015, 1998 and 1997 - the three other warmest years here - annual mean temperature was 28.3 deg C.

Sea levels, too, are rising around the island, which is why the government is raising the height requirement for new reclamations.

Workers from the City of Erie clear snow after a record snowfall, Dec 26, 2017, in Erie, Pa. (GREG WOHLFORD / ERIE TIMES-NEWS VIA AP)

Climate link to deep freeze? 

But what about the bitter cold snap in the eastern US?

Some scientists say climate change and cold spells, which occur when cold Arctic air dips south, may be related.

The Arctic is not as cold as it used to be and studies suggest this is weakening the jet stream, which ordinarily acts like a giant lasso, corralling cold air around the pole.

The reason a direct connection between cold weather and global warming is still up for debate, scientists say, is that many other factors are involved. Ocean temperatures in the tropics, soil moisture, snow cover, even the long-term natural variability of large ocean systems, can all influence the jet stream.

"There's a lot of agreement that the Arctic plays a role, it's just not known exactly how much," the New York Times quoted Marlene Kretschmer, a researcher at the Potsdam Institute for Climate Impact Research in Germany, as saying. "It's a very complex system."

One thing is clear. As the world continues to warm and as more heat-trapping greenhouse gases are pumped into the atmosphere, expect more weather extremes, scientists say. It's the new normal.


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