Fires claim homes in NSW
At least three homes are lost in Minnimbah, near Wagga Wagga, as bushfires rage on says NSW Rural Fire Service deputy commissioner Rob Rogers. Nine News.PT1M47S http://www.canberratimes.com.au/action/externalEmbeddedPlayer?id=d-313ke 620 349 January 20, 2014
The worst El Nino weather events, which are linked to devastating natural disasters and reduced Australian rainfall, will double with dangerous climate change, research has found.
In a study published on Monday in the journal Nature Climate Change, an international team of researchers, including Australian scientists, for the first time predict ''extreme'' El Nino events will occur once every 10 years - instead of every 20 years as in the previous century - as the planet continues to warm due to human activity.
El Nino is a natural climatic event that occurs when water temperatures in the Pacific Ocean periodically rise, shifting rainfall patterns. A lead author of the study, Dr Wenju Cai from CSIRO, said the further the warming in the east Pacific stretched, and the higher the temperatures reached, the more extreme the El Nino.
Australian scientist involved in the report: Dr Wenju Cai. Photo: CSIRO
The researchers used 20 climate models to project the impact on extreme El Nino frequency of global greenhouse emissions continuing at current high rates.
They concluded that total occurrences of El Nino would remain largely unchanged but extreme events will occur twice as often between 1991-2090 as they did in the previous hundred years.
The researchers defined an extreme El Nino event as such a large pattern shift occurs that rainfall exceeded five millimetres a day in the ''eastern equatorial Pacific'' region around parts of Central and South America. They found global warming would alter background climate conditions, meaning it would take weaker changes in ocean temperatures to prompt an extreme El Nino.
''With a projected large increase in extreme El Nino occurrences, we should expect more occurrences of devastating weather events, which will have pronounced implications for 21st-century climate,'' the study says.
The researchers point to El Nino in 1982-83 and 1997-98 as examples of extreme events that wreaked havoc and foreshadowed the dangers increased occurrences would present.
El Nino typically results in higher rainfall in some parts of South America, risking floods, and lower than average rain in south-east Asia and Australia, prompting drought, heatwaves and bushfire.
Previous US studies have found that the 1997-98 extreme El Nino - sometimes called ''the climate event of the 20th century'' - alone caused between $US35 billion and $US45 billion in damage and 23,000 deaths worldwide.
Dr Cai said the event sparked huge wildfires in Indonesia and floods in Ecuador and Peru.
In the natural world, the 1997-98 event destroyed much of the anchovy population in the eastern equatorial Pacific, caused coral bleaching and decimated the native bird populations of the Galapagos Islands.
Dr Cai said the 1982-83 El Nino event created the dry conditions that led to the 1983 dust storms in Melbourne and subsequent Ash Wednesday bushfires in southern Australia that killed 75 people.
''One of the characteristics of an extreme El Nino event is it tends to hit us a lot earlier. So it really creates a scene for dry conditions in terms of bushfire risk,'' he said.
Previous research by the Bureau of Meteorology of the 12 strongest El Nino events last century found the phenomenon caused significantly below-average winter and spring rainfall across eastern Australia.
The research came as Victoria, South Australia and parts of NSW sweltered through a fierce heatwave last week. But while heatwaves are often associated with the presence of El Nino, last week's temperatures came in ''neutral'' climatic conditions.