Global warming slows weed invasion

Important native grasslands are threatened by climate change. (ABC News: David Hudspeth)

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Tasmanian scientists have discovered a possible benefit to global warming.

In 50 years, it is expected our climate will be two degrees warmer with elevated levels of carbon dioxide.

The School of Plant Science at the University of Tasmania has simulated those conditions so they can see how global warming will affect important biosystems.

The seven-year study by the University of Tasmania has found climate change can slow the invasion of some types of weeds threatening native grasslands.

Dr Mark Hovenden from the School of Plant Science says it has been predicted that increasing levels of carbon dioxide will promote the growth of weeds.

But he says higher temperatures could change that.

"When you add warming to an experiment as well, the warming actually knocks the weeds out very strongly," he said.

"The type of weeds that we're talking about are the big problem weeds for grasslands across the country and these are the introduced flat weeds like dandelions and plantagos."

But it is not all good news.

A carbon dioxide-rich environment increases productivity, but only if there is substantial summer rain, and predictions point towards worsening summer droughts.

"It's highly unlikely that carbon dioxide's goinf to be the panacea that people see it," says Dr Hovenden.

Some of the findings are being applied to dairy pastures in Tasmania's north.

Mark Smith from DairyTas says adapting to climate change is a high priority for the industry.

"The scientific evidence is fairly clear, there are going to be some impacts through temperature and rainfall changes in the next 20 to 30 years," he said.

But Mr Smith says the industry is remaining optomistic.

"There's no panic in this, from a dairy industry point of view, but it's making sure that we're at the forefront with the scientists, knowing what the likely impacts are going to be," he said.

The research team is seeking funding to continue its studies for another five years.