How La Niña causes higher tides and lower global sea levels (but only temporarily)

We’re officially in for a La Niña summer, which means eastern Australia can expect higher-than-average rainfall, plus more tropical cyclones and flooding in Queensland.

But La Niña doesn’t only increase the amount of water falling from the sky. People living on the coast may notice tides are higher than predicted too.

That’s because even though we can accurately forecast when tides will peak and dip, based on the celestial dance between Earth, our Moon and the Sun, calculating their height to that same level of precision is a different kettle of fish.

Take a look at tide data from Sydney Harbour over the past week.

The difference between the predicted water level and actual measurements was out by around 10 centimetres — and this isn’t…