Back in 1999, I made an upsetting discovery.

By comparing the temperature tolerance of reef-building corals with the projected effects of rising carbon dioxide levels, I found that the oceans would soon grow too warm for corals to bear, meaning that coral-dominated systems like the Great Barrier Reef would disappear within 30-40 years.

Much as I tried to find a mistake in my reasoning and calculations, the numbers kept telling me that one of the world’s most diverse ecosystems would disappear in my lifetime.

As my study drew active discussion and debate, I desperately hoped that it was wrong and that the world had more time to solve the problem of climate change. Now, 16 years later, my conclusions have been confirmed and the message, if anything, have become even more pessimistic.

Sea surface temperatures have increased rapidly by 0.85C from 1880 to 2012. In tropical regions, these changes have driven the destabilisation of the ancient symbiosis between corals and the brown micro-algae (dinoflagellates) that live inside them – a relationship that has driven the success of coral reefs for hundreds of millions of years.

As temperatures rise, the dinoflagellates are damaged and are discarded, causing bleaching and leaving corals at increased risk of starvation, disease, and death. Meanwhile, ocean waters are acidifying at a rate that is unparallelled in at least the past 65 million years, potentially hampering the ability of coral reefs to maintain themselves through the all-important process of calcification.

The consequences of these changes threaten to ripple up through one of the most complex ecosystems on the planet, affecting thousands of organisms from sponges to seabirds.

In the process, they reduce the reef’s resilience to destructive events such as cyclones and non-climate-related human activities, fundamentally altering the food web and affecting opportunities for humans and industry.

Threat to the reef … and our hip pockets

It is important to appreciate that these concerns are not the mutterings of a few scientists. The threat of climate change to coral reefs like the Great Barrier Reef is part of a major scientific consensus set out by the Intergovernmental Panel on Climate Change (IPCC), as well as by federal government bodies such as the Great Barrier Reef Marine Park Authority (GBRMPA) and the US National Oceanic and Atmospheric Administration (NOAA).

There is no credible alternative prognosis that has survived the peer-reviewed process of science.

Without wanting to sound too dramatic, the realisation that coral reefs such as the Great Barrier Reef are about to be thumped by rapidly warming oceans should have had us on our feet. Even if you don’t like or understand coral reefs, the dollars should have spoken to you.

If we lose Great Barrier Reef, we lose a large part of the A$5 billion to A$6 billion it earns from tourism and fisheries, and with that many of the 60,000-plus jobs that this amazing ecosystem provides to Australia. If we look after the reef and don’t destroy it for short-term gains, we stand to reap those benefits, year after year, far into the future.

There is growing international concern that the World Heritage-listed Great Barrier Reef is in danger of being damaged irreparably. With 50% of the corals gone, UNESCO’s World Heritage Committee has been pressuring the Australian and Queensland governments to increase their commitment to reversing the deteriorating health of the Reef.

Later this year, the committee will decide whether to add the reef to its official ‘in danger’ list – a prospect that has already been extensively debated on The Conversation.

The situation has prompted the state and Federal governments to unveil a long-term sustainability plan for safeguarding the Great Barrier Reef until 2050, with input from reviews by the Australian Academy of Science and others.

While many elements of the plan are commendable it has also been criticised for its lack of firm, measurable targets, and adequate discussion of the implications of climate change.

Climate caution, or business as usual?

While the Reef 2050 plan does mention climate change as the predominant threat to the reef, it fails to link the problem to Australia’s plans to grow the coal trade, and to ship coal through enlarged ports on the Queensland coast. The reef plan only mentions coal in the context of local-scale impacts such as coal dust and port development.

The plan briefly mentions Australia’s intention to cut greenhouse emissions by 5% on 2000 levels by 2020. But there is no mention of the billions of tonnes (gigatonnes) of carbon dioxide that will be released when Queensland’s coal is dug up, sold, and burned by other countries.

The spectre of coal ships traversing the Great Barrier Reef couldn’t be more laden with symbolism. Coal extracted from the Queensland landscape, if burned along with other fossil fuel reserves, will ensure the destruction of the Great Barrier Reef.

With only 500-800 gigatonnes of carbon dioxide left in the global carbon budget, beyond which we will push the climate into a dangerous state, the emissions from even a single mine can play a significant role.

The Carmichael mine in the Galilee basin, for example, will pump out 4.49 gigatonnes during its lifetime. Given that the world’s reserves of fossil fuels are estimated to be capable of generating 2,500 gigatonnes of carbon dioxide, business-as-usual is easily capable of destroying the reef (pushing the added carbon dioxide well beyond the 500-800-gigatonne budget), along with many other ecosystems too.

On the other hand, the negotiations over Australia’s greenhouse emissions are clearly separate from the deliberations of the World Heritage Committee. While it is almost certainly true that continual failure to act on climate change will mean the death of the Great Barrier Reef and every other coral reef, the question of how to curb emissions is obviously best handled by the United Nations’ climate negotiations framework, which is convening this year’s crucial Paris COP21 talks.

Yet one could also argue that Australia should stand up as a nation and help lead the world away from this current dangerous climate trajectory.

After all, if we know that adding more carbon dioxide to the atmosphere is extremely dangerous for the Great Barrier Reef, why would Australia deliberately put such a national treasure and economic powerhouse at risk by helping dig up even more carbon to burn from the Queensland landscape?

If Australia is truly committed to preserving the Great Barrier Reef, it faces a tough choice: re-examine the current plans for unrestricted coal exports, taking proper account and responsibility for the resulting greenhouse emissions, or watch the reef die.

Surely we as Australians have more foresight and chutzpah than to let that happen!

Ove Hoegh-Guldberg is Director, Global Change Institute at The University of Queensland.

This article was originally published on The Conversation. Read the original article. It is the first in our series examining in depth the various threats to the Great Barrier Reef.