New research out of Australia has shown that oceanic wind speeds and wave heights have increased dramatically over the last twenty-five years. The results stem from the most comprehensive study of its kind ever undertaken, which looked at satellite data dating from 1985 to 2008.
The study is published in the journal Science and was authored by former Swinburne University Vice-Chancellor Professor Ian Young, who earlier this month became Vice-Chancellor of the Australian National University and Swinburne oceanographers Professor Alex Babanin and Dr Stefan Zieger.
“Winds and waves control the flux of energy from the atmosphere to the ocean,” Professor Young said. “So an understanding of whether their parameters are changing on a global scale is very important.”
“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,” Young added.
The statistics showed that oceanic wind speeds increased by 0.25 to 0.5 percent each year, while extremely high wind speeds increased by 0.75 percent each year.
The most significant increase for wave height occurred in extreme waves, with the largest one percent of waves increasing by an average of 0.5 percent every year, while in some parts of the ocean these waves increased by up to one percent per year.
“For example, today the average height of the top one per cent of waves off south-west Australia’s coastline is around six metres. That’s over one metre higher than in 1985,” Professor Babanin said.
According to Professor Young, it was the researchers’ access to satellite data that enabled 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 modeling. 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.”