Australia may be ravaged by more La Nina and El Nino events as the impact of climate change takes hold, scientists warn.

Research published in the journal Nature Climate Change says the frequency of La Nina events could increase from one in 23 years last century to one in 13 years this century.

Previous studies have found global warming may lead to severe El Nino events doubling in frequency.

CSIRO scientist Wenju Cai, lead author of the La Nina study, told insuranceNEWS.com.au Australia is one of the countries most threatened by the systems.

El Nino, a warming of the central and eastern tropical Pacific, leads to a major shift in weather patterns and increasing drought, heatwave and bushfire risk.

La Nina, which is essentially the opposite condition and often follows El Nino, is associated with severe flooding.

“Both are going to increase and we will see more frequent switches from one year to the next,” Dr Cai said. He believes there is now strong consensus that climate change will bring an increase in extreme weather events, and insurers should pay close attention.

The World Meteorological Organisation says last year was the hottest on record globally, and 14 of the 15 warmest years have occurred this century.

“It is notable that the high 2014 temperatures occurred in the absence of a fully developed El Nino,” Secretary-General Michel Jarraud said. “High temperatures in 1998 – the hottest year before the 21st century – occurred during a strong El Nino year.”

The Climate Council has released a report analysing the impact of climate change on extreme heat in Australia.

It says the record hot year of 2013 would not have occurred without global warming, and the annual number of record hot days across the country has doubled since 1960.

“Carbon emissions must be reduced rapidly and deeply if the worst of extreme heat in the second half of the century is to be avoided,” the report says.