Extreme weather events will be more frequent in a warming world.

Anyone reading the news about recent extreme weather events will understandably be confused by the varied statements regarding the attribution of these events to climate change. This debate seems to intensify each year but there is a danger that it is simply going round in circles -- pondering the same short-term questions at each occurrence without paying attention to the ultimate warning signs.

Australia’s floods in particular have inspired a range of media coverage including claims about the link between La Niña and climate change. La Niña is the name given to the extensive cooling of the central and eastern Pacific Ocean. In Australia (particularly eastern Australia), La Niña events are associated with wetter conditions. And scientists have attributed the Queensland floods to this year’s La Niña, which is the strongest such episode since 1974.

What we’re not certain about yet is the strength of any link between the intensity of La Niña events and climate change. Similarly, direct links between individual extreme weather events have yet to be found. But this doesn’t mean we should wait around to make decisions on climate action until we can identify and fully characterise such links. Direct cause and effect will remain hard to establish in any one case, but the overall pattern of extreme weather events we’re witnessing year after year is completely consistent with the widely accepted predictions of climate change impacts. If we wait for more proof of the link with climate change, it won’t be long before we are past the point of no return - if in fact we have not passed it already. It’s best to assume that, since climate change is with us here and now, the impacts will only get more severe, more costly and more damaging to society. It makes sense to act in ways which have a chance of reducing the frequency of such catastrophic events, even if we don’t know for sure.

Thai Buddhist monks escape flood waters

Thai Buddhist monks wade through rising flood waters from the Chao Phraya River as they collect food alms at Koh Kred a tiny island situated in the Chao Phraya River, located in Nonthaburi Province on the outskirts of Bangkok. Earlier in the year, scientists warned that Thailand would experience more frequent extreme weather events due to the impacts of climate change.

In 2002, we featured a story about extreme weather events including floods in Eastern Europe, giant smog clouds in Asia, floods and droughts in India and China, heatwaves in Canada, the US and Australia. This story included the following statement by Pier Vellinga, a climatologist at Amsterdam University:

"Warmer weather fuels natural disasters. Few places in the world will be spared from climatic disruptions. We can say with reasonable confidence that human-induced climate change is now affecting the frequency and intensity of extreme weather events."

In 2003, we said “while no one weather event can be directly linked to climate change, a warmer climate means more storms, floods and droughts”. The heatwaves and droughts in Europe that year were consistent with predictions made by scientists a few years earlier:

"Climate change will bring warm, wet weather, which will encourage plants to grow, followed by long periods of drought, during which they will burn," -- Meinrat Andreae, Max Planck Institute for Chemistry, August 2001.

In 2004, we were writing about extreme weather events becoming more common due to climate change.  And in 2007, we documented  the  computer models predicting extreme and shifting weather patterns --  more heavy rain in some areas, crippling drought in others. And there was even a scientific study, published in the journal Nature, which compared recorded precipitation to predicted precipitation under climate change scenarios. This suggested that weather patterns were already changing.

It seems to me that time is running out. We can debate the issue endlessly. But each extreme weather event, whatever the strength of its underlying link to climate change, only serves to emphasise the consequences of such phenomena in terms of structural damage and human suffering. It also highlights our limited ability, despite technological advancement, to predict, mitigate and recover from them. They are yet another painful reminder of the urgent necessity for the deep cuts in greenhouse gas emissions, cuts that the Energy Revolution could deliver.

So, enough is enough! It’s time to act.

Dr. Paul Johnston is principal scientist at the Greenpeace Research Laboratories at the University of Exeter and Head of the Greenpeace International Science Unit.