Cloud seeding, ocean fertilisation and firing sulphur into the stratosphere are all risky and controversial ways of manipulating the Earth's environment.

But experts say these drastic measures need to be part of a global emergency response if all else fails when tackling climate change.

Dr Graeme Pearman, senior research fellow at Monash University, addressed an Australian-first conference on geo-engineering in Canberra today.

He says there needs to be a global approach to putting geo-engineering on the table as a back-up option.

"We should not consider this as an option to mitigating [climate change]. It's an insurance," Dr Pearman said.

Some techniques - like plating deserts with mirrors to reflect the sun back up into the atmosphere - sound more like science fiction.

But scientists at the conference say there are many techniques governments could introduce immediately.

Dr Greg Bodeker says firing sulphate aerosols into the stratosphere is one option; the technique would create a semi-transparent umbrella that would shade the planet from the sun, thereby reducing global temperatures.

"It's very effective but the risk associated with that is very high," he said.

Dr Bodeker says the technique is relatively cheap - some tens of billions of dollars to start off with - and it could begin within the next decade.

But it would reduce solar power generation and the effects on the environment could be catastrophic if the technique were to be suddenly stopped.

"There would be a steep increase in temperature if you try and stop it," he said.

Potential danger

Dr Pearman agrees there is a risk associated with geo-engineering and techniques like this could have a devastating impact on parts of the world.

"Putting the sulphate into the atmosphere produces a climate change of its own," he said.

"It's possible that geo-engineering would be potentially dangerous."

He says a range of factors need to be addressed when looking at the techniques.

"When you actually consider one option versus another, you want to know whether it's feasible; you want to know whether it's equitable," he said.

"There's a whole series of issues. There are issues around timing, particularly if you suddenly find that we've underestimated the rate of change."

Dr Pearman says the Australian conference is the first step towards forming geo-engineering regulation for the the scientific community and governments.

Roger Beale, from PriceWaterhouseCoopers' Climate Commission, says a G20-style group is needed to develop protocols surrounding the issue.

Geo-engineering methods are already being used in Australia in the form of various carbon capture techniques.

Mr Beale says that is all the more reason for further discussion on regulating the sector.

"There's entrepreneurs that see an opportunity here and that's fine, but at the moment they're doing that in a situation where there's no agreement," he said.