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Rain getting heavier as temperatures rise

Friday February 1, 2013 - 17:20 EDT

A review of worldwide rainfall data has found the intensity of the heaviest downpours is increasing across the globe as temperatures rise.

The research collated data from more than 8000 observation stations in the period from 1900 to 2009 and was led by the University of Adelaide's Dr Seth Westra.

The study involved adding up rainfall totals from the heaviest downpours and comparing that information with changes in the mean global temperature.

Dr Westra says the research revealed a 7 per cent increase in the amount of rain for every 1C increase in temperature.

"In the tropics it's actually about double that number, close to 15 per cent and then in the northern hemisphere we're also seeing an increase," he said.

Dr Westra says the results mean devastating floods are more likely if climate change continues as predicted.

"If we have warming of 3 to 5 degrees [by the end of the century] which is quite possible given the current rate of emissions, we could see quite a significant increase in rainfall extremes and by implication we could also see an increase in flood risk," he said.

"Having floods is a natural part of the climate. The only thing that changes is the intensity of those events or how frequently they occur.

"But there's other factors that need to be taken into account as well.

"If you take the Queensland example, there's a lot more people living in flood plains and there's a lot more areas that are highly developed now than they would have been 50 of 100 years ago.

"Part of the reason why we're seeing this so much more is just because there's more people living in these sorts of regions. There's a lot more assets. The global population's a lot higher than it used to be and we're also reporting a lot more.

"But having said all that, we do see this gradual change in extreme rainfall that's probably exacerbating the risk compared to what we might have seen in the past."

Dr Westra says the research gives a theoretical basis to anecdotal evidence storms are getting heavier as a result of climate change.

"This is one of the most complete studies that actually show that we can see in the observational record there is an increase in extreme rainfall," he said.

"There have been a few observational studies, but this is really starting to strengthen the evidence pool that people can use to say 'yes, we are seeing an increase in extremes because of this change in average temperature around the world'."


- ABC

© ABC 2013

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