Tropical cyclones feed off the energy provided by hot ocean waters. In recent summers there has been “unusually warmer water” in the Tasman Sea; the ongoing warming trend from human-induced climate change is playing a big role.
In New Zealand, the result is “moist, rainy conditions” in the north and east of the country and warmer-than-average sea and air temperatures. And there could be more like Gabrielle on the way, sooner than you might expect.
A basic rule of climate science is that the atmosphere can hold more moisture as it warms; the Clausius-Clapeyron relationship.
The main driver of climate change is the greenhouse effect. Today’s atmospheric CO2 levels are over 422.21 ppm, the highest in more than 14 million years.
The best we can do is, worldwide, all must stop using fossil fuels right now.
Bob Hughes