Scientists call for global action on coral reefs

Scientists call for global action on coral reefs

Urgent cuts in carbon emissions are needed if Caribbean coral reefs are to survive past the end of the century, scientists have warned.

A new paper, published in the journal Current Biology, says Caribbean reef growth is already much slower than it was 30 years ago. Its authors say that without serious action on , the reefs may stop growing and begin to break down within the next 20-30 years.

'The balance between reef growth and reef erosion is changing as we alter the environment,' says Dr Emma Kennedy of the University of Exeter, who led the study.

'This means that increasingly, some reefs are breaking down faster than they can replace themselves – essentially they're being worn away.'

As corals grow they produce limestone skeletons which build up over time into vast reefs. They provide a natural breakwater and a complex three-dimensional habitat, making an ideal home for a vast array of .

'Healthy reefs are the rainforests of the sea,' says Kennedy. 'They provide habitat for over a quarter of all marine species, including many colourful fish and corals.'

'They also provide a range of vital benefits to humanity, like food, jobs and protection from the sea. Globally, over half a billion people rely on reef services to some extent.'

Scientists call for global action on coral reefs
Healthy coral on a bleached neighbour.

In the Caribbean alone, are thought to be worth US$3.1-4.6 billion every year. But serious local and global pressures are causing corals around the world to fall into ill health.

Locally, they're suffering from , and an influx of reef-smothering sediments from coastal developments.

Pacific reefs have also fallen victim to plagues of coral-eating , whose thrive in nitrogen washed into the sea from farms on land. Australian authorities estimate that 35 per cent of the Great Barrier Reef's coral cover has been lost to crown-of-thorns starfish in the past 25 years. They're warning that a new outbreak could be on the way this year.

Carbon emissions pose a variety of dangers to corals. Rising sea levels threaten to leave them stranded in darker waters, starving them of the light they need to survive.

As the oceans absorb more carbon from the atmosphere, they are also becoming slightly more acidic, and less favourable to corals.

Perhaps most seriously, warming ocean temperatures are causing a breakdown in the vital give-and-take relationship between corals and the algae that live in their tissues. This leads to coral bleaching, where whole coral colonies become lighter in colour or completely white, and many go on to die.

Kennedy and her team used their own observations and information from more than 300 academic papers to build computer simulations of Caribbean reef growth and erosion.

Scientists call for global action on coral reefs
Reef health under different policies.

Taking over 116 different factors into account, they were able to predict the effect of various conservation measures and climate scenarios on reef health.

They found that local policies and conservation measures, like protecting key species and preventing agricultural run-off, could buy reefs an extra decade or so. But the study suggests that it's going to take global action if Caribbean reefs are to survive beyond the end of the century.

'We're all responsible for looking after our planet to a certain extent, and as individuals we can help out by trying to reduce our carbon footprint in any way we can,' says Kennedy.

'But unless governments can work together at an international level, then our research suggests that the future looks grim for reefs.'

'Under business-as-usual climate scenarios we found Caribbean reefs eventually all degraded well before the end of the century. At the moment, we're still following this trajectory.'

Explore further

Could coral reefs become sponge reefs in the future?

More information: Kennedy EV, Perry CT, Halloran PR, Preito-Iglesias R, Schonberg CHL, Wisshak M, Form AU, Carricart-Ganivet JP, Fine M, Eakin CM, Mumby PJ, Avoiding Coral Reef Functional Collapse Requires Local and Global Action, 2013, Current Biology. DOI:
Journal information: Current Biology

Provided by PlanetEarth Online

This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).

Citation: Scientists call for global action on coral reefs (2013, August 14) retrieved 23 October 2019 from
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User comments

Aug 14, 2013
Translation: "G̸l̸o̸b̸a̸l̸ W̸a̸r̸m̸i̸n̸g̸."

Crack in the dam: Google mainstream climatologist Hans von Storch.

Corals evolved when CO2 was 10X that of today!

Aug 14, 2013
"Taking over 116 different factors into account...."

"With four parameters I can fit an elephant, and with five I can make him wiggle his trunk." - John von Neumann (via Enrico Fermi, as quoted by Freeman Dyson in 2004).

"We're all responsible for looking after our planet to a certain extent, and as individuals we can help out by trying to reduce our carbon footprint in any way we can."

Translation: "We" = Africans / "carbon footprint" = breathing / "any way" = dying.

Coral experts whose emergency level boost in funding pivots on climate alarm are suddenly energy policy advisors?

Aug 14, 2013
Their sophisticated (translation: perverted, corrupted) "analysis" even features poor little Nemo:


"As the oceans absorb more carbon from the atmosphere, they are also becoming slightly more acidic...."

Translation: less basic and more neutral.

Aug 20, 2013
If you ever get a chance to skin dive into a reef it is worth your best efforts to do so. They are amazing collections of natural beauty. You can not find anything even closely comparable to the stunning diversity of Life, color, interaction and activity you find in these underwater forests. The Reefs, they are the canaries of Ocean health. If they die, you know the ocean is not far from collapse itself. The reefs are mostly formed by the corals which form shells of calcium cabonate, silicon, some minerals. Calcium carbonate is extremely sensitive to the PH of the water.
CO2 when it is absorbed into water, tends to form carbolic acid which makes water more acid. Especially in shallow areas where natural mixing doesn't dilute the acid as much as the larger oceans. The result is coral bleaching and dead reefs.

Since almost all the CO2 in the last 200 years is man-made, it is our pollution that is killing off these reefs. Give our industrial scale output; ... extinction!

Aug 20, 2013
Again, Change is not the issue. Rate of change is. Given enough time, corals that were able to extract and sequester calcium easily in a more acidic ocean would develop.

The issue is rate of change.

Life will survive, just not much variety. It's really a decision about whether we want to retain some of that variety, and how.

A world after rapid climate change is boring, culled of efficient specialists and larger creatures more sensitive to a quickly changing environment and the reduced common resources that result.

Aug 21, 2013
SPIEGEL: Just since the turn of the millennium, humanity has emitted another 400 billion metric tons of CO2 into the atmosphere, yet temperatures haven't risen in nearly 15 years. What can explain this?
I explain it as someone feeding you a line that you bit hook-line-and sinker (if you will excuse the pun). If you look at global average temperatures, the past twenty years have all been way above the statistical normal. The correlations between modern human industrialism, fossil fuel use, CO2 levels and temperature rise are all to uncanny to dismiss as you do.

The disaster that appears to be coming are the first stages of the collapse of diatoms in nears surface ocean at reef locations. Nature, Science and other prominent science magazines have numerous papers on the subject. It's all related and as obvious as the nose on a bull.

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