Rainy days do not long-term climate make.

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We must not be lulled a false sense of security. Think long term.

Rainy days do not long-term climate make

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AFTER a decade of record-breaking drought in southeastern Australia where our water supplies for our capital cities were perilously low, it’s raining.

Over the past couple of years our dams have been filling up and some are now overflowing.

So it seems counter-intuitive to talk about water security.

Despite our wet summer, the long-term trend shows that southeastern Australia is getting drier. This is the difference between weather and climate. Weather is about what’s happening day-to-day and year-to-year. But climate refers to weather trends over the long term.

Sorry, Tim, but weather’s just not your forte

Think about that diet started as a New Year’s resolution. You might eat too much chocolate cake one weekend, and find you’re slightly heavier. But if you stick to the diet, over time, the trend will be clear as you shed the kilos.

Records over the past 40 years indicate that rainfall has been steadily declining in southern and eastern Australia and studies by the CSIRO show that it’s likely to continue.

Southeastern Australia is likely to get drier and droughts more frequent and intense. Also, as the Earth heats, the frequency and intensity of heavy rainfall events is likely to increase.

Of course there are wet years like this one and there is likely to be wet years in the future. Wet years may come and go, but overall, scientists are concerned we are facing a drier future.

Why? There are likely to be more dry years than wet years. Looking at the long-term trend, average rainfall is still expected to decline.

Reductions in water supply in southern and eastern Australia are of particular concern. This is where our major population centres are located. If the long-term trend continues as expected, our cities may again face water challenges.

That is why, even in a wet year it is responsible to think about our long-term water security. After the last decade Australians well remember the harrowing consequences of long, severe droughts. The National Water Commission, the CSIRO and many other public bodies and scientists were warning of the future challenges to water security.

Today those warnings remain relevant. We can ill afford complacency. It is worth remembering that the situation in Perth remains severe.

Some commentators jump on any cold spell or rainy period to claim climate change is not happening.

This cherry picking is irresponsible and misleading.

All of the major scientific bodies around the world paint an unequivocal picture that the climate is changing rapidly. It is now beyond reasonable doubt that humans are the primary cause.

Professor Tim Flannery is Chief Climate Commissioner

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