Revell Science | Independent Science Consultant

 

meeting the needs of agricultural businesses & the environment

Visualising changes to our climate patterns

 

Climate change is both biophysical and political.  In the swirl of debate, the reality of changing patterns that are occurring right now and are likely in the foreseeable future can get lost.  A number of times I’ve heard people say, “we just haven’t had a proper autumn for years now”, or words to that effect.

 

I’ve also heard the comment from a pastoralist that they hadn’t had a growing season for some years. He defined a growing season as a certain number of rainfall events over a certain amount within a certain time frame.

 

I wish I could remember the detail – I think it was three rainfall events of 10mm or more within 2 months of each other. Even though my memory is fallible, the point remains clear: it’s not just how much rain we get in a year, but when it falls and how long between drinks.

 

In the south-west of Australia, a decline in winter rainfall seems a consequence of Australia slowly but steadily marching northward. Well, not exactly. It’s really the move southward of the cold fronts that bring so much of our rain.  In a sense, we are ‘running out of south’.

 

Plants, ecological systems and production systems alike will eventually be “pushed right off the south-western edge of the continent” (George Seddon, ‘The Old Country – Australian Landscapes, Plants and People’ p. 17).

 

I saw this very phenomenon a few years ago when I watched a presentation on how the isohyets the south-west of WA have been moving south and west and, with the best predictions at hand, the animated map showed the 400 mm isohyet dropping right off the landmass within the next few decades.

 

It had quite an impact with the audience, sending a murmur around the auditorium. We could ‘see’ a loss of rainfall from our landscapes to the Southern Ocean.  As far as I can tell, it’s wet enough in the Southern Ocean; we need the rain here.

 

In the meantime, let’s prepare for a future that will be different from the past. Which, of course, is the way it’s always been.