Wind and waves getting stronger and bigger

The team on Camper may have to endure bigger waves and stronger winds than predecessors Grant Dalton and Kevin Shoebridge. Photo / Supplied

A study of the ocean shows it is getting to be a tougher place.

It has long been something of a truism that the older we get the better things used to be.

Summers were always long, fine and warm; everything was much cheaper and life was simpler, better and more fun. It is, of course, a lot of rubbish.

Well, mostly. It appears when it comes to the conditions we experience when we head offshore, things really were better 20-odd years ago.

According to a major study undertaken by researchers at Swinburne University of Technology in Melbourne, oceanic wind speeds and wave heights have increased significantly over the last quarter of a century.

The results of the research programme, believed to be the most comprehensive of its kind undertaken, were recently published in the journal Science.

It was conducted by former Swinburne University Vice-Chancellor Professor Ian Young, who this year became Vice-Chancellor of the Australian National University, and Swinburne oceanographers Professor Alex Babanin and Dr Stefan Zieger.

Most climate-change studies focus on measurements or predictions of temperature over long periods of time. However, this study examined global changes of oceanic wind speed and wave height, both also important environmental indicators.

This is because, as Professor Young explains, winds and waves control "the flux of energy" from the atmosphere to the ocean. "Therefore, understanding whether their parameters are changing on a global scale is very important."

The researchers analysed satellite data over a 23-year period from 1985 to 2008.

"We found a general global trend of increasing values of wind speed and, to a lesser degree, wave height over this period.

"The rate of increase for extreme events was most significant."

The data showed that wind speeds over the majority of the world's oceans increased by 0.25 to 0.5 per cent every year.

However, when it came to extremely high winds, the speed increased by a yearly average of 0.75 per cent.

The global increase in wave height was also most significant for extreme waves. The largest 1 per cent increased by an average of 0.5 per cent every year.

But in some parts of the ocean, extreme waves increased by up to 1 per cent per annum.

To put that in perspective, Professor Babanin uses the example of wave heights studied off one of Australia's roughest coasts.

"Today, the average height of the top 1 per cent of waves off south-west Australia's coastline is around six metres. That's over one metre higher than in 1985."

It was, according to Professor Young, the researchers' access to satellite data that allowed them to conduct such a comprehensive study.

"Previous attempts to investigate global trends in oceanic wind speed and wave height have relied on visual observations, point measurements or numerical modelling. Due to these limitations, researchers have only been able to examine changes to wind speed and wave height on a regional basis.

"However, our study used recently developed satellite altimeter data sets, which enabled us to investigate trends on a global scale.

"This has really given us a much clearer picture of what is happening in the world's oceans."

While older sailors love telling their younger counterparts how easy they have it, they may now have to eat their words.

When the crew on Emirates Team New Zealand's Volvo 70, Camper, sets off around the world this year, the young guns on board will, it appears, have all the boasting rights.

One can just imagine the scene as they turn their gazes on the older Whitbread campaigners such as Grant Dalton and Kevin Shoebridge.

"You guys had it so easy: the ocean was a millpond compared with what we'll have to endure ..."