In 1980, I moved from California to Australia and for the past four decades have been living, working and diving the Great Barrier Reef which, in my humble opinion, is the greatest reef in the world. For most of those years, I felt that the Reef was too big, too resilient and just too incredible to fail.

Unfortunately, these past 10 years have proven me wrong. Successive mass coral bleaching events driven by marine heatwaves, and a failure of successive governments both here and abroad to effectively tackle climate change, means that the Great Barrier Reef is now on the brink of being declared in anger.

But developments over the last week have given me reason to feel hopeful for the future of our most iconic ecosystem.

The US Senate passage of the bill happened within days of the Australian House of Representatives passing Australia's first climate change legislation in more than a decade. Importantly, the climate change bill enshrines into law two national greenhouse gas emissions targets: a 43 per cent cut below 2005 levels by 2030, and a reduction to net zero by 2050.

Two great nations seen as barriers to global climate action have taken bold steps forward. It is beginning to look like global momentum is building and it's cause for hope that we can achieve real climate action in the 2020s.

Another glimmer of hope came from the Australian Institute of Marine Science's annual reef report which stated that the northern and central sectors of the Great Barrier Reef have recorded their highest level of coral cover since monitoring began 36 years ago.

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While this is certainly good news, it did come with some caveats. It was noted that the increased frequency of mass coral bleaching events was "uncharted territory" for the Reef. And while coral cover is an important indicator, it can not alone capture overall ecosystem health. These results give us reason to be cautiously optimistic, but the Reef's resilience is finite and we can't be complacent.

This decade is critical. We cannot wait until 2050. Both climate bills are excellent springboards for more action, but even more must be done to achieve the scale and speed of emissions reductions to keep global warming well below 2 degrees Celsius - a critical threshold for coral reefs.

For Australia, this means no new coal or gas projects and rapidly moving towards 100 per cent renewable energy by 2030.

And fair weather for the Great Barrier Reef.