But even after the cleanup is complete, experts say this year’s flooding may hold ominous portents, suggesting this type of catastrophic natural disaster may become more common in the future.
The rain had been pouring for days on end, a deluge of water that would lead to flash flooding in one region and a major river bursting its banks in another, causing extensive damage and death in its wake. The flooding that has turned a significant chunk of the state of Queensland into a watery disaster zone is already being called one of the worst in the region’s history.
Reports suggest Brisbane experienced more than 460 millimetres of rain fall in the past week. That’s more than the amount of rain Winnipeg typically receives in an entire year, according to Environment Canada. Put another way, the rain that fell in Brisbane is nearly equivalent to six months of rain in Vancouver.
In Brisbane, floodwaters reached to the tops of street signs and carried cars away. It also caused extensive damage to homes, restaurants and businesses.
Most Canadians who haven’t travelled to the tropics likely aren’t familiar with the type of rain that hit the area in recent days, said Gordon McBean, policy chair at the Institute for Catastrophic Loss Reduction at the University of Western Ontario. He described it as a “wall of water” that would soak a person to the skin the moment they stepped outside.
Officials had been warning people in affected areas to leave their homes for days.
So far, 13 people have been confirmed dead as a result of the floods, but close to 100 others are still missing.
An estimated 20,000 homes have already been hit with floodwaters, but officials say that number could rise to 40,000 before waters begin to recede in coming days. Another 120,000 residents of the area are without power and officials said it could be days before it is restored.
More devastation will come from the economic fallout of the floods. The total damages could cost the nation $13 billion (Australian currency), or one per cent of the country’s gross domestic product, Stephen Walters, chief economist for Australia at JPMorgan Chase & Co. in Sydney told Bloomberg.
For a weather pattern with a name that means “little girl” in Spanish, La Niña packs a nasty punch. It’s sometimes referred to as El Niño’s bratty little sister, bringing with it cooler ocean temperatures in the east and central parts of the Pacific Ocean, which typically causes higher amounts of rain in countries such as Australia and Indonesia.
La Niña occurs when there are strong increases in circulation of trade winds, or surface winds that blow from east to west. Typically, these winds carry warm surface water west to Australia and Indonesia But during La Niña, those surface winds are much stronger, increasing the amount of cooler water near South America’s coast, reducing water temperatures. The mass of cold water travels through the Pacific, causing a build-up of warm water along Australia’s east coast and elsewhere in the region. This, in turn, leads to significantly higher amounts of rainfall, which has caused the extensive flooding in Queensland. La Niña patterns typically only occur once every few years.
El Niño, on the other hand, occurs when there is an abnormal warming of surface ocean waters in the tropical Pacific Ocean. It’s the counterpart to La Niña and the two weather patterns are part of what’s known as Southern Oscillation, which NASA refers to as the “see-saw pattern of reversing surface air pressure between the eastern and western tropical Pacific,” when pressure is high in the east and low in the west tropical Pacific, and vice versa.
La Niña, as well as El Niño, can lead to drought, tropical storms and numerous other weather disturbances that can have a serious impact on people living in those areas.
Many experts say the force of La Niña is the strongest they’ve seen in decades and that climate change may be partly responsible for the severity, citing warmer ocean temperatures.
Oceanologist Gordon McBean said climate projections for Queensland suggest more extreme precipitation is expected to hit the area in the years to come, which could lead to floods every 15 years by 2040. He cautioned that it’s too early to conclude that Australia’s flooding is due to climate change, but that a growing amount of scientific data indicates there will be more events like it in the future.
“The frequency of these heavy rain events is projected to go up,” said Dr. McBean. “It is in the direction of what we expect to unfortunately get worse. As the climate warms, there will be more of these heavy deluges.”
Precedents
The Queensland flooding has caused loss of life and extensive damage, but this isn’t the first time the area has been hit, hard, by massive floods.
1974: The vast amount of rain that hit the area the previous year is often seen as a precursor which led to massive flooding in Brisbane in 1974. The new year got off to a bang with torrential downpours soaking many parts of Australia in addition to Queensland, which scientists attribute to a La Niña event. But the extreme weather pattern reached a boiling point when tropical Cyclone Wanda hit on January 24, two days before Australia Day, the country’s official national day of celebration. The cyclone didn’t cause extensive damage, but caused massive amounts of rain to fall over the Australia Day weekend. More than 300 millimetres fell in Brisbane in a 24-hour period. Houses were washed away, 14 people were killed and nearly 7,000 homes were flooded. At its peak, the Brisbane River reached 5.45 metres. In the aftermath of the flood, Queensland adopted new flood prevention and mitigation strategies, such as Brisbane’s Wivenhoe Dam, which is credited with helping prevent some damage due to the current flood.
1893: Although the 1974 flood is typically the yardstick by which all floods since have been measured, Brisbane has been immersed in even deeper waters. In 1893, Brisbane was hit by a massive flood following major rainfall that is linked to a tropical cyclone. The depth of the Brisbane River at the peak of the flood was 8.35 metres and led to the deaths of 11 people, as well as nearly 200 hospitalizations and costly damages. It’s considered by many experts to be the worst flood in the region’s history.
No comments:
Post a Comment