The storms and gale force winds which have struck the Cape over the past two days, claiming five lives and destroying property, could be as a result of climate change caused by global warming, said a top international research scientist on Tuesday.

Responding to the keynote address delivered by award-winning environmental journalist Leonie Joubert on the first day of the Climate Justice Conference being held on the Goedgedacht farm outside Malmesbury, Martin Füller said although one could not jump to the conclusion that the storms were the direct result of climate change, a long term study of the occurrences of such extreme weather events could reveal a trend toward greater frequency.

Füller, who conducts research and climate modelling with the Potsdam Institute for Climate Impact Research in Germany, said weather variability was a given, but when extreme or unusual weather events became more common over shorter periods of time, they started representing a trend toward climate change.

His modelling of global weather data collected over decades, showed an unambiguous trend toward a hotter climate, predominantly caused by human activity releasing greenhouse gases into the atmosphere.

This climate change was the "single biggest threat to human existence", he said, and it was not a threat lying in the future, he was adamant it is "a global process we're already experiencing.

An animated map of NASA data collected worldwide since the end of the 19th Century to present proved the point.

Moving from a map of blues, greens and yellows representing lower temperatures, the map becomes progressively filled with larger areas of yellow, orange and red until the present day where almost entire

continents are swathed in red and orange, representing significantly higher temperatures caused by a global mean temperature increase of 0.8 degrees Celsius over the past 100 years.

Without significantly reducing greenhouse gas emissions causing global warming, we would be entering uncharted waters by the middle of this century.

In other words, he said, most of the world would be experiencing summers that are hotter than any yet on record - including the 2003 heat wave that swept Europe.

"It's a completely new scenario," he said.

The Climate Justice Conference, funded by the German organisation Misereor, runs until Thursday and is being attended by international scientists and organisations concerned with poverty and climate change.