The issue of whether the world's coral reefs are dying or not shot to prominence this week, after smouldering in the scientific literature for decades. The catalyst was a New York Times opinion piece by ANU scientist Roger Bradbury, released to coincide with this week's International Coral Reef Symposium in Cairns.

In his article, Bradbury laid out a stark and depressing vision of future devastation: "Overfishing, ocean acidification and pollution are pushing coral reefs into oblivion," he wrote. "Each of those forces alone is fully capable of causing the global collapse of coral reefs; together, they assure it."

It's easy to understand over-fishing and pollution, which have been understood as threats to marine environments for decades, if not centuries. The new and alarming threat is ocean acidification, a consequence of the world's addiction to fossil fuels. The massive release of carbon dioxide into the atmosphere by the world's industries has not just led to a warming climate. It is also making the world's oceans more acidic, as the higher concentrations of CO2 interact with the water in the oceans to create carbonic acid on a global scale.

Coral is made by small organisms that secrete limestone. This makes them highly vulnerable to rising acid levels in coastal waters. The University of Queensland's Ove Hoegh-Guldberg, a world expert of reef ecology, published a review paper on the future of reefs in the prestigious journal Science in December:

"Global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems," he and his co-authors wrote. "Climate change also exacerbates local stresses from declining water quality and over-exploitation of key species, driving reefs increasingly toward the tipping point for functional collapse."

The real worry about ocean acidification is that it is so difficult to stop. The world has been singularly unsuccessful in halting the inexorable increase in global carbon emissions, even after two decades of trying. With China and India burning more coal than ever (much of it exported from Australia) there seems little prospect of a rapid turn-around in the trajectory of carbon pollution.

We don't know exactly when various reefs will reach the outside of their envelope of survivability. But accelerating damage to reefs is undeniable. There can be no doubt about the destruction that has already been visited on coral reefs around the world, particularly by over-fishing in poorer and developing countries.

The deteriorating state of reefs in the Caribbean is well-known, but just this week, the Indonesian Institute of Sciences published a new report which stated that more than 90 per cent of Indonesian coastal reefs were threatened. The study examined the health of reefs in 77 regions across the archipelago. Only 30 per cent were in good health; in the remaining 70 per cent, coral was either damaged or destroyed.

The problem is global. According to the World Resources Institute's Reefs At Risk program, roughly half of the world's reefs will experience coral bleaching by 2030 — and nearly 95 per cent by 2050.

Tropical reefs are being pushed beyond their breaking point – beyond the point where they will be able to recover. That's a problem, because tropical reefs constitute one of the ocean's most diverse ecosystems. They nurture and support many of the world's most important fisheries.

Not everyone thinks the situation is as bad as this: destruction may not be assured. The New York Times' Andrew Revkin has, as usual, some of the best coverage of the issue. (By contrast, Australian media coverage has been desultory.)

But the problems that reef destruction will cause should be clear to all. The Great Barrier Reef is a huge source of tourism and fishing employment in Australia: the Great Barrier Marine Park Authority thinks it supports over 54,000 jobs, mainly in Queensland.

But in poor countries, reefs are more than just providers of employment. They can often mean the difference between starvation and survival. According to the UN's The Economics of Environment and Biodiversity project (pdf), "some 30 million people in coastal and island communities are totally reliant on reef-based resources as their primary means of food production, income and livelihood." Reefs are the main source of protein for a greater number than this worldwide.

Reefs are especially important in our region. As the lead author of the Indonesian reef study, the World Resources Institute's Lauretta Burke was reported saying at the Cairns conference, "across the Coral Triangle region, coastal communities depend on coral reefs for food, livelihoods, and protection from waves during storms, but the threats to reefs in this region are incredibly high".

Given the importance of coral reefs to the living standards and economies of our near-neighbours, you'd think Australia would be playing a much greater role in trying to protect these areas. But our aid and conservation efforts in this area have been largely token Instead, politics being what it is, Australia is investing vast sums to try and stop asylum seekers.

Are we doing enough? No, of course not. Australia does have an excellent record at protecting the Great Barrier Reef from over-fishing, and has been active in extending marine conservation areas in recent years. But the nature of ocean acidification and global warming means that stopping over-fishing can't solve the problem. And when it comes to fossil fuel emissions, Australia's halting and agonisingly slow efforts to begin reducing our carbon emissions have been well-documented, both here and elsewhere.

Looking at long-term global problems like coral reef destruction, it's easy to become depressed about the future of our species. The power of big political lobbies and the natural human inclination for the good life mean that there is an inbuilt bias towards inertia in our economy and society. The dwindling support for action on climate change is apparent in a number of different opinion polls and community surveys; environmental fatigue seems to be on the increase.

In contrast to the scale of environmental problems, public policy reform is slow, incremental and difficult: like the "slow boring of hard boards", as the great sociologist Max Weber famously said. Just yesterday, former Treasury Secretary Ken Henry was bemoaning the lack of political leadership in this country, as he recounted the bruising battle to introduce a tax on mining super-profits. If a rich and materially comfortable society like Australia can't even agree on the desirability of spreading windfall mining profits around, what hope is there in tackling the big crises that confront our world?

And yet, despite all the gloom, there are rays of hope. Numerous studies have shown that reefs can regain health if protected vigilantly. The carbon tax debate itself is also a cause for optimism, surprisingly enough. Five years ago, Australia had no legislated mandate for emissions reduction. Now we do. We had little in the way of support for renewable energy. Now we have a situation where renewable energy might beat the 20 per cent by 2020 target. We had little hope that China or America might ever take carbon emissions seriously. Now we are seeing the introduction of emissions trading schemes in California and in several Chinese provinces.

It may not be much in the grand scheme of environmental; degradation. It may not be enough to stop runaway global warming. But it is not nothing. In the end, neither inaction nor despair are viable policies.