Five years ago I stood in the Mural Hall of Parliament House to speak at a bipartisan event hosted by MPs pushing for a national system of marine parks. Most of those present believed it was an idea whose time had finally come. Polling supported it. But with Julia Gillard's minority government just barely clinging to power, it was a tough time to be asking parliamentarians for an act of courage.

Yet that was basically my line. Because back when the nation was younger and poorer, it took great vision and mettle for our forebears to reserve country for the first national parks. It was that sort of gumption I sought to foster. I believed we still had it in us. Australians have always loved the ocean, but now, more importantly, we understand how vital the sea's health is to the future of our island home.

In the corridors of Parliament House that day, as I met MPs of every stripe, I felt a great sense of promise, even pride. And it seemed for a while such hope was not misplaced. In 2012, after an exhaustive scientific process and wide community consultation, Tony Burke declared a system of marine national parks, one of the biggest and best in the world, the most significant conservation gain in Australian history.

That took courage. Because it put science before politics, prudence ahead of expediency. And it was popular. But as soon as he came to power in 2013 Tony Abbott announced an immediate moratorium on these parks and instigated a review. The purpose was purely political. To delay implementation, corrode consensus and deny the science. A move straight out of the culture warrior's playbook.