I was asked by the Adelaide Advertiser newspaper to write a short piece last week which addressed the question “Does all the recent rain across the country prove man made climate change is real?“, in less than 500 words. My response, given below, appeared in the print edition on Thursday 9 September 2010:
Does all the recent rain across the country prove man made climate change is real? No.
As Dorothea Mackellar wrote over a century ago, Australia is naturally “A land… Of droughts and flooding rains”.
Putting the impossible issue of ‘proof’ aside, scientists certainly do expect climate change to lead to an increase the frequency and intensity of extreme weather events. After all, a warmer planet holds extra energy, making today’s climate system more dynamic than when Mackellar penned her poem.
In short, as the Earth’s atmosphere traps more heat due to an increase in greenhouse gases, it triggers more evaporation of water from the oceans. Average global humidity and precipitation rise in response.
As such, climate scientists predict increasingly energetic storms, heavier bursts of rain, and more intense flooding. In many parts of the world, deeper droughts and longer, hotter heat waves are also forecast.
So, while it is impossible to attribute any one event solely to human-caused warming, a useful analogy is that “weather throws the punches, but climate trains the boxer”. Another way to look at it is that human impacts are “loading the climate dice” towards more unfavourable (and previously unlikely) outcomes.