In a paper to be published in the journal Nature, researchers have found that, while a handful of unusual weather events have been documented, the majority of the time, these events are not unusual.
‘There is a lot of data on unusual events, and this is a new thing we are discovering,’ lead author Professor Simon O’Connell said.
‘We know that there are events that are extremely unusual, but it’s not unusual for us to look at that.’
He said that this was because they had become increasingly common over time.
‘Our research has shown that the number of events that occur in the year is about two per cent of the total events, which is very rare, but when you consider that we have only observed about one per cent over the last two centuries, that’s not really a surprise.’
It’s not surprising that the year we have an unusual event is the year that we get a very unusual event.’
O’Brien, a PhD student at the University of Western Australia, said the findings could be of interest to scientists studying climate change, or climate change impacts, because they could indicate that some of these unusual events are being triggered by climate change.
‘What we found is that this is really the norm,’ he said.
O’Donnell said that the study was the first to analyse the data from more than a dozen of the largest global-scale events in the past two decades.
These included the massive El Nino event in 1995, which produced more than 40 storms and record heat, and the 2010 Antarctic heatwave which led to the loss of more than 200 million tonnes of ice and ice-laden sea ice.
‘It’s a pretty extreme situation,’ he explained.
‘The amount of ice that was lost in Antarctica in the summer was about a third of what it was in the mid-20th century.
‘So it’s quite significant that you would see this many events in such a short period of time.’
In addition to the huge amount of data collected from these events, O’Connors group also collected data from the Earth System Observations (ESO) which allows scientists to map global weather events.
‘You can see a lot more than just what’s happening around you,’ he told the ABC.
‘Some events are occurring on land, some are occurring off-shore, and others are occurring in the atmosphere.’
The group has also found that many of these events were triggered by human activities.
‘When we analysed the data we saw that a lot, a lot less events are actually due to climate change than you might think,’ he added.
‘In terms of the human contribution to the climate system, this is something that we don’t really know.
‘However, we’ve shown that this year has been exceptionally hot in Australia, so we can’t rule out that this might be linked to the El Nido event, or to the warming of the Northern Hemisphere.’
In terms a climate change response to this event, we also found a little bit of a warming response, but this is quite small.
‘On the other hand, if we look at the human response, we found a large decrease in the average global temperature over the past 10 years, which suggests that there may be some human influences on climate.’
The study also found an increase in the number and intensity of large weather events over the year, which has been seen before.
‘Over the last 20 years, there has been a trend of more and more large events, like hurricanes, floods, snowstorms and extreme weather events, according to the ESO’s website,’ O’Connor said.’
We think the next time you see an event like that, you should check your weather data to see if there are any signs of human influence on climate change.’