Posts Tagged coral

The Climate Show #26: All the news that fits Gareth Renowden May 04

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Aafter a busy month of harvesting (Gareth) and breakfast broadcasting (Glenn), the Climate Show returns with all the latest climate news: from the thinning of Antarctic ice shelves and the intensification of hydrological cycle (floods and drought, that is) to satellites capturing solar energy and beaming it down to earth, we’ve got it all. And if that weren’t enough, John Cook looks at a new paper that explains the apparent lag between warming and CO2 increase at the end of the last ice age, and tips us off about an excellent outtake from ABC’s recent I Can Change Your Mind about Climate documentary, featuring Naomi Oreskes.

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The Climate Show

News & commentary: [0:02:30]

WMO confirms 2011 as 11th warmest in long term record

’It was the warmest decade ever recorded for global land surface, sea surface and for every continent.’


Warm ocean currents cause majority of ice loss from Antarctica: Scripps, British Antarctic Survey.

“What’s really interesting is just how sensitive these glaciers seem to be,” added Pritchard. “Some ice shelves are thinning by a few metres a year and, in response, the glaciers drain billions of tons of ice into the sea. This supports the idea that ice shelves are important in slowing down the glaciers that feed them, controlling the loss of ice from the Antarctic ice sheet. It means that we can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt – the oceans can do all the work from below.”

Climate Progress coverage.

Dry parts of the planet to get drier, wet parts wetter: The Conversation, Science Magazine.

Kiribati as a refuge for corals: Pacific Islands May Become Refuge for Corals in a Warming Climate, Study Finds

World needs to stabilise population and cut consumption, says Royal Society

Key recommendations include:

  • The international community must bring the 1.3 billion people living on less than $1.25 per day out of absolute poverty, and reduce the inequality that persists in the world today. This will require focused efforts in key policy areas including economic development, education, family planning and health.
  • The most developed and the emerging economies must stabilise and then reduce material consumption levels through: dramatic improvements in resource use efficiency, including: reducing waste; investment in sustainable resources, technologies and infrastructures; and systematically decoupling economic activity from environmental impact.
  • Reproductive health and voluntary family planning programmes urgently require political leadership and financial commitment, both nationally and internationally. This is needed to continue the downward trajectory of fertility rates, especially in countries where the unmet need for contraception is high.
  • Population and the environment should not be considered as two separate issues. Demographic changes, and the influences on them, should be factored into economic and environmental debate and planning at international meetings, such as the Rio+20 Conference on Sustainable Development and subsequent meetings.

Guardian coverage.

Debunking the sceptic [37:15]

John Cook from talks about I Can Change Your Mind About Climate.

The telling outtake: Naomi Oreskes with Nick Minchin:

Dealing with the “lag”:

Solutions [1:00:00]

Tinted Windows that Generate Electricity: A German company borrows the materials and manufacturing process of OLED displays to make a new kind of solar panel.

NASA Funding Satellite That Would Beam Solar Power Down to Earth

Blimp with a blower:

Solar Thermal Heating Could Eliminate CO2 Emissions from Cement Production

Thanks to our media partners: Idealog Sustain, Sciblogs, Scoop and KiwiFM.

Theme music: A Drop In The Ocean by The Bads.

Every little bit hurts Bryan Walker Dec 08

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Coral reefs… once survived in a world where CO2 from volcanoes and methane was much higher than anything predicted today.’  That sounds like good news from John Veron, a world authority on coral. Not if you read on: ’But that was over 40 million years ago, and the increase took place over millions of years, not just a few decades, time enough for ocean equilibration to take place and marine life to adapt.

Veron is writing in an article recently published at Yale Environment 360.  He is deeply alarmed at the prospect for coral reefs and wants to communicate why as clearly and accurately as he can. He begins by acknowledging that warnings of dire threats to coral reefs have been common over past decades; in his 40 years of working on reefs he has often been concerned at the impacts of sediments, nutrients and habitat loss. But the devastation which global warming threatens is of a different order.

Veron is frank about the depth of his anxiety. He writes of the ’long period of deep personal anguish’ he felt when he realised the big picture that was emerging from his widespread research into the effect of global temperature changes on reefs. He speaks of turning in his dismay to specialists in many different fields of science to find ’anything that might suggest a fault’ in his conclusions. But without success.  The bottom line remains that coral reefs can be utterly trashed in the lifetime of today’s children.

He realises that such a conclusion will be treated as an exaggeration by many. People may think that while there may be something to worry about it won’t be as bad as doomsayers like him are predicting.

’This view is understandable given that only a few decades ago I, myself, would have thought it ridiculous to imagine that reefs might have a limited lifespan on Earth as a consequence of human actions. It would have seemed preposterous that, for example, the Great Barrier Reef – the biggest structure ever made by life on Earth – could be mortally threatened by any present or foreseeable environmental change.

’Yet here I am today, humbled to have spent the most productive scientific years of my life around the rich wonders of the underwater world, and utterly convinced that they will not be there for our children’s children to enjoy unless we drastically change our priorities and the way we live.’

He goes on to explain the issues with helpful clarity. Single-celled algae live in coral cells and provide the photosynthetic fuel for them to grow and reefs to form. High light conditions at the same time as above-normal water temperatures cause the algae to produce toxic levels of oxygen.

’Under these conditions, corals must expel the zooxanthellae, bleach, and probably die or succumb to the toxin and definitely die. A tough choice, one they have not had to make at any time in their long genetic history.’

They can recover from bleaching, but not if further events continue to occur while the ecosystem is re-establishing. Increasing ocean heat, which affects surface layers most, will mean increasing severity and frequency of bleaching events.

’Scientists don’t need a pocket calculator to conclude that compressing the time periods between events in this way will prevent recovery: If we do not take action, the only corals not affected by mass bleaching by 2050 will be those hiding in refuges away from strong sunlight.’

However, serious though bleaching is, the effects of ocean acidification will be much more serious, affecting coral reefs badly and also impacting on all marine ecosystems. He considers that ocean acidification has played a major part in each of the five major extinctions in Earth’s history. In the last four extinctions reefs disappeared for millions of years. Reversal of acidification is a long process which can take place only through the immensely slow weathering and dissolution processes of geological time, processes that take hundreds of thousands to millions of years.

Veron asks his readers to consider two facts:

’The atmospheric levels of CO2 we are already committed to reach, no matter what mitigation is now implemented, have no equal over the entire longevity of the Great Barrier Reef, perhaps 25 million years. And most significantly, the rate of CO2 increase we are now experiencing has no precedent in all known geological history.’

He concludes with a solemn reminder:

’Reefs are the ocean’s canaries and we must hear their call. This call is not just for themselves, for the other great ecosystems of the ocean stand behind reefs like a row of dominoes. If coral reefs fail, the rest will follow in rapid succession, and the Sixth Mass Extinction will be upon us – and will be of our making.’

I realise it’s only a week since I last wrote on the effect of global warming on corals. Veron is not saying anything that others aren’t also pointing to, or that he hasn’t himself said before. But he’s saying it with great lucidity and there’s an urgency and poignancy to the article which impressed me and made me want to draw attention to it. Scientific reticence is not permitted to mute the expression of his profound concern. The issue is too fundamental for that.

We cannot afford to wait until the predictions of science can be totally verified, because by that time it will be too late.’

[Brenda Holloway]

Warm oceans killing coral Bryan Walker Dec 01

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This has not only been a bad year for the Amazon rainforest, it has also been a year in which coral reefs, the rainforests of the ocean as they are sometimes called, have suffered severe bleaching because of raised ocean temperatures. Not a matter likely to strike the public consciousness. A recent Yale University survey found 75 percent of Americans have not heard of coral bleaching. But the reefs are one of the world’s great ecosystems and they matter enormously.

Mark Eakin, who coordinates the National Oceanic and Atmospheric Administration’s Coral Reef Watch and is frequently quoted in reports on this year’s bleaching events, explains that coral bleaching happens when ocean temperatures get too warm and stay warm for too long, and the relationship between the coral and the algae gets stressed. This thermal stress to corals, he said, is the highest it’s been since 1998, when 15% of the world’s coral reefs died.

’When you have high temperatures, in conjunction with normal high light conditions, the photosynthetic apparatus in the algae starts to poison the coral. They’ll spit them out into the water. When they do this, they lose their colour, look white, which is why they’re called bleached. If that persists for a long time, it can cause the corals to die.’

In July an article in the Telegraph on the coral bleaching events becoming apparent quoted Eakin:

“The bleaching is very strong throughout south east Asia and the central Indian Ocean. The reports are that it is the worst since 1997/1998. This is a really huge event and we are going to see a lot of corals dying.”

Indonesian reefs were badly affected. Some detail is provided in a report from the International Coral Reef Initiative which indicated the extent and severity of bleaching in different areas, and commented on the high rate of coral mortality following the bleaching.

In September Pierre Fidenci, president of Endangered Species International, wrote in a Mongabay article of severe wide-scale bleaching in the Philippines. The bleaching has been observed at many sites around the Philippines featuring mass mortality of corals including the coral triangle outside the Philippines. He considers this environmental catastrophe will probably be considered the most damaging bleaching event ever recorded in the Philippines, surpassing the big one of 1998.

’Prior to this year’s bleaching, it was estimated that about 85 percent of the reefs have been damaged or destroyed in the Philippines, now the current estimate is likely to be close to 95 percent.’

The Telegraph article noted scientists in Thailand have reported reefs suffering 90% of their corals being bleached and up to 20% of the corals dead. Olivia Durkin, who is leading the bleaching monitoring at the Centre for Biodiversity in Peninsular Thailand, said: ’This year’s severe coral bleaching has the potential to be the worst on record.’

In June The Maldives reported the most serious incidence of coral bleaching since the major 1998 El Niño-event that destroyed most of the country’s shallow reef coral. Since then there has been gradual reef recovery but the 2010 event will be at least a major setback.

Eakin warned in September that this year had the potential to be also one of the worst bleaching seasons for some reefs in the Caribbean. It follows hard on the heels of the 2005 bleaching which caused record losses to Caribbean reefs, according to a collaborative study published a couple of weeks ago.  More than 80 percent of surveyed corals bleached and over 40 percent of the total surveyed died as a result of the 2005 event. It will be a while before the effects of this year’s bleaching can be measured, but it is already apparent that in some locations this year’s event is worse than the event in 2005. Not only are temperatures causing further damage to reefs hit hard during the 2005 event, but new locations have also been impacted.

Eakin’s comment on the release of the study of the 2005 impacts:

’This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems, and events like this are likely to become more common as the climate warms.’

Bleaching is a consequence of a warming ocean, but it’s not the only adverse effect of global warming on corals. The other major impact is from the increase in ocean acidification as carbon dioxide emissions continue to rise. The double whammy is very clearly explained by Australian scientist and coral reef expert John Veron in his 2009 lecture to the Royal Society. I summarised his content in this post last year, and suggest any readers who’d like a longer explanation of what bleaching and acidification mean for the future of coral reefs take a look at it. The link to the video of the lecture provided in the post is outdated, but this link will get you there if you want to hear him in person. He is sombre about the outlook for coral reefs if greenhouse gas concentrations continue to rise, and nothing that has happened this year suggests he is getting it wrong.

Polar warming, Amazon drought, coral reefs bleaching and dying: I’ve gathered material for posts on all three of them within the past week. They are all sending out danger signals. They all threaten massive effects which cannot but have drastic consequences for humanity if they continue. And they’re only part of what threatens from climate change. They ought to have us scurrying to do what we are still able to do to prevent them developing further. The Cancún conference should be charged with a sense of high urgency.

I found myself applauding our Prime Minister when he said on Sunday that nothing less than the future of underground coal mining in New Zealand rests on the investigation into the Pike River tragedy. ’We can’t put people into mines that are dangerous.’ I also found myself wondering how that sentiment would go down with some of our economic interests. I thought John Key was absolutely right, and I presume in saying it he was not unaware of the economic implications. I guess I needn’t spell out the obvious parallel with the dangers from climate change and the perspective they put on the protests that economic interests mustn’t be harmed by climate change measures.

Johann Hari, in the eloquent article Gareth has already drawn attention to, wrote, ’At Cancún, the real question will be carefully ignored by delegates keen to preserve big business as usual.’  It’s the wrong choice, Hari points out. But as he also says it’s not too late to change.

The Climate Show #1 (Astral Express) Gareth Renowden Nov 04

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The Climate Show comes out of beta testing today, with the release of the first full show, code-named Astral Express after the yacht that kiwi yachtsman Graeme Kendall sailed through the North West Passage in record time a couple of months ago. Graeme’s our star guest, but we’re also pleased to welcome to the programme John Cook, the creator of that superb climate science resource Skeptical Science. John will be joining us on a regular basis to look at favourite climate sceptic arguments, but for his first appearance we talk about the so-called Climategate emails. Also covered: what may be the worst ever coral bleaching event, narwhals as oceanographers, geoengineering, and GM’s EV with a petrol engine, the Chevy Volt, aka Vauxhall/Opel Ampera.

The Climate Show is also available as a podcast via iTunes, or listen direct/download here:

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Show notes below the fold.

Coral bleaching in the Caribbean and SE Asia: Maribo and Climate Shifts.

Next IPCC report will consider geo-engineering schemes: Reuters

Narwhals measure sea temps off Greenland: Nature News.

Feature interview – Graeme Kendall’s Astral Express web site (with lots of nice pics).

Debunking the skeptic with John Cook from Skeptical Science. This week: Climategate.

Solutions: This week: electric cars with two motors — the Chevy Volt (etc) at The Economist’s Intelligent Life.

New climate computer game Fate Of The World released: Guardian coverage.

Not forgetting our media partners: and KiwiFM.

The Weather of the Future Bryan Walker Sep 16

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Weather of the Future: Heat Waves, Extreme Storms, and Other Scenes from a Climate-Changed PlanetHeidi Cullen takes readers forty years forward in her survey of what is likely to happen in several areas of the world if we continue to burn fossil fuels. Her book is The Weather of the Future: Heat Waves, Extreme Storms, and Other Scenes from a Climate-Changed Planet. It is a highly effective communication to the lay person of what climate science predicts for the specific areas she has chosen to explore. Cullen, a climatologist, works as a senior research scientist for Climate Central, an organisation set up in 2008 to act as a central authoritative source for climate change information.

Before moving to the selected areas for closer examination she offers some lucid general introductory chapters, including a very useful explanation of the use of modelling in climate prediction. In response to the question of when the weather will start to reflect predictions about the climate she answers that it already has in extreme weather events. If greenhouse gases continue to rise, the way weather affects life on Earth will be far worse than anything we’ve ever seen before. ’Can we rally around this forty-year forecast for the good of the world, or will we wait until the levees break before we decide to act?

The first area Cullen surveys is the Sahel region of Africa.  She talks with climatologists who work on understanding the rainfall patterns and outlook for the region.  The picture is complex, but there is no doubt that the region is going to get warmer. All the models agree on that. They show some variation on the expected amount of rainfall, but it seems likely that the rainy season will start later and become shorter, with storms that will possibly become more intense. Pockets of resilience offer some hope from farmers who have turned to tree planting with considerable benefits to their crops and welcome extra income from the trees. But as Cullen takes her projections forward she remarks that there is only so much the trees can do against the increasing reality of climate change. Socially, climate change will become a threat multiplier as conflict spreads across the African continent in lockstep with temperature.

The next selected area is the Great Barrier Reef. Cullen talks with Joanie Kleypas, a marine ecologist and geologist who uses climate models to study the health of coral reefs. ’I work on coral reefs, for God’s sake. The entire coral science community is depressed.’ The chapter provides very clear accounts of the bleaching effect of warming oceans (’Bleached corals aren’t dead; they’re just starving.’) and the deleterious effect on coral growth from ocean acidification. The speed of both warming and acidification is likely to quickly outpace the conditions under which coral reefs have adapted and flourished through past changes. They are unlikely to be able to adapt fast enough. It’s not a good outlook. Cullen allows herself a detour to point to other and more dramatic effects of climate change that Australia is set to encounter – ferocious wildfires, pervasive drought, and unbreathable air. The lucky country looks anything but in coming decades.

The US is a leading per capita contributor to global emissions. It has not yet accepted the level of responsibility it carries. Other places, far less responsible and much poorer, are bearing the early consequences of global warming. But that doesn’t mean the US will remain exempt from any serious consequences, and it was good to see Cullen turning to her own country for two of her chapters, and driving home that message.  One of the places she selects is Central Valley, California.  The Sacramento-San Joaquin Delta is a focus of her attention here. It’s the hub of California’s water supply system. The Hollywood-style dream is that the Delta will be able to supply enough clean fresh water to help cities and crops increase ’forever’, all without harm to the natural environment, she notes dryly. She speaks with a multidisciplinary team studying the Delta, which in reality has far more in common with New Orleans than with Hollywood. The details of the problems and threats are canvassed and the extreme vulnerability of California to coming water shortage exposed. Her other US focus is New York city. Here it will be energy blackouts which threaten as the average temperature increases over coming decades. The power grid is unsuited to climate extremes. The other major area not ready for what lies ahead is flood protection.  However planning is going on in New York to develop resilience to what the changed climate will deliver, and also to mitigate the city’s emissions.  Cullen imagines a time four years from now in which, following damage from a storm, a co-ordinated plan is finally adopted by an alarmed population and New York becomes a city obsessed with adapting to climate change. It clearly needs to.

Her other chapters look at more obviously and immediately vulnerable places. In the Arctic she examines the current experience of the Inuit in an area of Canada and in Greenland. Change is well under way as sea ice diminishes and permafrost melts. It brings with it not only the physical challenges to the Inuit ways but also severe cultural threats. In Greenland as the ice melts there’s the promise of wealth from resource extraction, and the ambiguities that come with it. Bangladesh is skilled in adaptation to change and experienced in flood management, but by 2050 with almost 25 per cent of the country under water as a result of rising seas and increasing tropical cyclones, accompanied by the slow and deadly seepage of saline water into wells and fields, Bangladesh will be in serious trouble. Millions of villagers will have to move to the city, and many are likely to cross illegally into India hoping to find work.

The value of Cullen’s book is that by focusing on specific places, and by talking with scientists who are devoting full attention to the problems climate change poses for those places, she brings the reader close up to inescapable realities. The details are spelt out. Moreover she does this by a lively narrative of her discussions with the scientists closely involved. Her book is not a dry account of scientific papers but a picture of the people working to understand, predict and prepare for what is in waiting for the populations in the areas she discusses. It’s a reminder too of the number and variety of people who now work on climate change-related issues.

The book recognises the adaptation capabilities being shown by some of the populations already affected by climate changes. It is with some reluctance that it acknowledges the possibility of defeat if high emission levels continue. They don’t need to continue, of course, but that is in the hands of policy makers. Cullen in conclusion examines two words in use in the science. One is unequivocal, used to describe the warming of the climate system. The other is irreversible, used to describe uncertain but all too possible eventualities. She uses the cutting down of the last tree on Easter Island, as imagined so vividly by Jared Diamond in his book Collapse, as an analogy for irreversibility. Unfortunately as yet the two words are not powerful enough in policy circles to shift the forecast for the future.

[More at: Fishpond (NZ),, Book Depository (UK, free shipping worldwide).]

You don’t know what you’ve got ’til it’s gone Bryan Walker May 01

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Biodiversity continues its steady decline. A team of scientists have this week published a study in Science confirming that fact.  Governments in 2002 at a summit on the Convention on Biological Diversity agreed to aim to halt biodiversity loss by the year 2010. When experts meet in Nairobi on May 10 it will be to face the news that they have failed.  For example, since 1970  the world’s animal population has decreased by 30%, mangroves and sea grasses have shrunk in area by 20%, and live-coral coverage has fallen by 40%. “The state of biodiversity is definitely showing a rapid decline,” says Matt Foster, one of the lead authors on the Science paper. “And the pressure just keeps increasing.”

It’s not that governments have made no efforts. The amount of protected land has steadily increased around the world, as has the area of sustainably managed forests. Increased money is being spent on biodiversity aid. But we’re still shouldering other species out of our way. And in doing so we’re attacking our own well-being. “We all benefit from biodiversity and we all hurt when it’s lost,” says Foster.

Climate change is only one of the ways in which humankind is contributing to biodiversity loss.  But it’s worth reminding ourselves that it is seriously exacerbating the process. I’ve been re-reading a fine book by Michael Novacek, Terra, published in 2007. He’s a distinguished paleontologist, Provost of Science at the American Museum of Natural History.  He was involved in the splendid Darwin exhibition put together by the Museum of Natural History which I was fortunate to be able to see when it was brought to the Auckland Museum in 2007.  That’s when I bought his book.  It’s subtitled Our 100-Million-Year-Old Ecosystem —- and the Threats That Now Put It at Risk. I think some points from his chapter on how the current warming is contributing to biodiversity loss are worth recounting here.

He notes changes in the activity of 694 species whose life history data between 1951 and 2001 has been studied.  A 2003 review found on average the species were either breeding, blooming, or doing other seasonally related activities 5.3 days earlier each decade.

The warming trend has also set species in motion. Some move poleward. Other species have moved upslope. Some have simply contracted and their surviving, marginalised populations have been reduced to precariously low levels.

Novacek is interesting on the evolutionary processes at work in the organisms affected by rapid alteration of range. The hardy colonisers which often establish at the leading edge of the shift may have a very low level of gene diversity, leaving them susceptible to further environmental changes. The populations at the trailing edge of the migration may have more genetic diversity, but they will start to fragment as the environmental conditions break up their preferred habitats.  The rate of environmental challenge may determine how a population’s genetic makeup and evolution are transformed. Slow change may be easier for the species to maintain genetic diversity at levels that allow it to persist. Drastic and rapid change make it more vulnerable. Simply moving to a cooler habitat does not guarantee that the genetic composition of the migrating populations will be robust enough to sustain them.

It’s made more complex by the bewildering diversity of examples in nature. Some species, especially in tropical and mountainous regions, may be buffered by the amount of genetic variation already resident in their populations. Other genetic studies suggest that climate change has easily outrun the rate at which a given population can adjust.

Novacek  sees contemporary evidence that climate change in combination with other factors is killing off certain species.  It seems to be the coup de grace for some coral species.  Increasing ocean acidification also plays a part in the demise of coral and threatens the most abundant and ecologically important sea organisms, the coccolithophorids, foraminifera and pteropods which are vitally important food for many fish.

On land, organisms that live in lakes, streams, rivers, and other bodies of freshwater are highly endangered and are especially susceptible to climate change because they cannot escape its effects, being captive in their habitat.

Most threatened are the habitats and species at high latitudes, the northern tundra and polar deserts such as those on the Arctic islands and Antarctica as well as species inhabiting high Alpine or montane habitats at middle to low latitudes.

I liked the last sentence of his chapter. In the preceding sentences he noted what he regarded as encouraging signs of acceptance of the science of global warming.  He recorded, however, still encountering individuals normally open to the discoveries of science who find it beyond belief that humans could disrupt the balance of the planet in such an enormous way. The final sentence: ’But science has eventually convinced us before of the unbelievable.’

The cost of losing coral: no drop in the ocean Bryan Walker Oct 21

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Climatechallenge Perhaps it will register if it’s expressed in money terms. The latest issue of the New Scientist carries an article reporting an estimate of  the loss of the world’s coral reefs at $172 billion per year. The estimate comes from the work of Pavan Sukhdev and colleagues. He’s an economist with the United Nations Environment Programme, and head of a European Commission study called The Economics of Ecosystems and Biodiversity (TEEB). It’s an international project to raise awareness about the economic benefits of biodiversity. I hadn’t come across its work before, but last month it produced a report TEEB Climate Issues Update. It’s a subset of early conclusions relating to climate change and a fuller report will follow next month.

The report addresses what it sees as three critical issues for the Copenhagen negotiations. First, the imminent loss of coral reefs. Second, an early and appropriate agreement on forest carbon.  Third, the compelling cost-benefit case for public investment in ecological infrastructure (especially restoring and conserving forests, mangroves, river basins, wetlands, etc.)

I might examine issues two and three another time, but for this post I’ll stay with coral reefs. Hot Topic covered John Veron’s lecture to the Royal Society a couple of months ago on the parlous state of coral reefs and the worse dangers ahead as ocean acidification worsens. The TEEB report confirms that outlook, quoting the Royal Society statement. But it goes further in indicating what the effects on human welfare will be.

Coral reefs are an integral part of an extensive and vital landscape of coastal ecosystems which includes estuaries, marshes, mangrove forests, dunes, seagrass beds and lagoons. These ecosystems are  biologically highly productive.

Estimates of the total number of people reliant on coral reefs for their food resources range from 500 million to over one billion. Some 30 million of the world’s poorest and most vulnerable people in coastal and island communities are totally reliant on reef-based resources as their primary means of food production, sources of income and livelihoods.

Coral reefs are often likened to ‘oases’ within marine nutrient deserts. Productivity of coral reefs may be many thousands of times higher than in the surrounding open sea. This high productivity makes the reefs critical to the survival of both marine and coastal ecosystems. It is also the underlying reason why they contribute so significantly to human welfare.

The benefits which analyses have so far attempted to quantify include fisheries, shoreline protection, tourism, recreation, and aesthetic value.  But the report says when an ecosystem is close to a critical threshold, it may become impossible to value because of uncertainty or even ignorance about the potential consequences of nonlinear behaviour.

The reported science suggests that anthropogenic emissions have brought the coral reef ecosystem to the brink of potential irreversible collapse. Thus we may have encountered our first major global ecosystem ‘threshold’. At such a point we need to consider the ethical and social dimensions of value as well as the economic. Right now it can be said:

’The imminent demise of tropical coral reefs is predicted to be an extinction event of proportions never before witnessed by humankind. The loss of this critical ecological infrastructure will damage the productivity of global fisheries and the chances of stock survival. It could thus lead to future food crises. It will impoverish over 500 million people who depend on coral reefs for their livelihoods.’

 This section of the report concludes with the rather forlorn urging that global political leaders and their climate negotiators recognize and address the risks of irreversible loss of most of the world’s tropical coral reefs by:

• providing explicitly for coral reefs in measures for coherent climate change adaptation solutions for coastal areas when establishing climate adaptation strategies and agreeing adaptation funds

• working towards agreeing on more ambitious CO2 reduction, that will improve the chances of survival and recovery of coral reefs.

It can be added that less than 350 ppm CO2 concentration is the level that the Royal Society scientists saw as needed to ensure the long-term viability of coral reefs.

A solemn warning on coral reefs Bryan Walker Aug 29

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Australian scientist and coral reef expert John Veron reckons there’s a ’great big gorilla in the cupboard’ — advancing ocean acidification. It cleans out reefs, leaving them ’horrible places — dead, empty, slime-covered.’ He paints this grim picture in a lecture given to the Royal Society in London last month. It’s available on line and I have just watched it - twice. His seriousness and the weight of his concern are deeply impressive.  Veron warned that his talk would not be a happy one. Usually his talks on coral are fun. This one wouldn’t be, but ’I’ve never given a more important talk in my life.’ It was highly focused and informative, accompanied throughout by a range of illuminating pictures and graphs. I watched it carefully, anxious to fully understand its import, and have pulled out a rough summary of some of his major points.   

But first a little background to the occasion. The Royal Society is concerned that the  coral reef crisis doesn’t receive the attention it warrants as one of the major indications of threatening climate change disaster.  It has been attempting to remedy that. In July, in combination with the Zoological Society of London and the International Programme on the State of the Ocean, it facilitated a Coral Reef Crisis meeting to identify key thresholds of atmospheric carbon dioxide needed for coral reefs to remain viable.  I’ll reproduce the summary of its findings at the end of this post.  Veron’s lecture was hosted as part of the event.

David Attenborough introduced Veron with some general remarks on the key role of coral reefs in ocean ecosystems, their complexity but also their fragility and the ease with which they can be damaged. He observed that deterioration is under way and continuing. The question is whether we can prevent it getting even worse. Veron he described as one of the great authorities of the world on coral and stressed that his knowledge was first-hand and authoritative.

Veron began with some general background on coral reefs. Their uniqueness is defined by several factors: they live at the interface of atmosphere and ocean, which is physically and chemically stressful; they are geological structures yet they are alive; they are closely attuned to the hostile environment in which they exist, dependent on light as trees are, sensitive to optimum temperature (31 degrees in Great Barrier), and dependent on the carbonate chemistry of the oceans.

Coral reefs are nature’s historians. Whether in fossil form or living their growth layers not only indicate rate of growth but also contain information about the environment in which they grew. Ancient reefs uplifted in land, of which he had some great pictures, preserve this information for us to read.

 He went on to talk about the great mass extinction events, in which corals were always deeply affected, in the Permian to the point of total extinction and in others to near extinction. 

The precariousness of their habitat makes them extremely sensitive to climate change. The mass extinctions are closely related to the carbon cycle, particularly to carbon dioxide and ocean acidification, with methane sometimes playing a part. In the present he pointed to current levels of carbon dioxide as indicating that we have broken out of the ice age fluctuation patterns in a big way.

He explained the mass bleaching phenomenon. Coral is dependent on the algae which live in its tissues. Overheating — just a little — causes the algae to produce too much oxygen which kills corals. This is something which hasn’t happened for millions of years. It started only in the 1980s.  Mass bleaching events can turn coral to rubble, though if the ocean conditions are right it will start to grow again.  He looks at carbon dioxide concentrations and what they have meant for the Great Barrier Reef (GBR) as representative of all reefs. At 320 parts per million there was some mass bleaching, but only in patches.  At 350 ppm there was a lot of mass bleaching all over the GBR and many other reefs as well. Today at 387 ppm there is compounding long-term degradation on the GBR.  Held at this level indefinitely the GBR would slowly decline.  The upper 20 or 30 metres would gradually become more or less rubble. At 400 ppm there will be more severe weather events affecting the reef and severe bleaching will occur, mainly during El Nino cycles. 450 ppm will cause severe bleaching most years, irrespective of the natural cycles. At 500 ppm there won’t be anything left to bleach.  

Ocean acidification, is a ’very, very serious thing indeed’ not only for corals but for anything that forms a carbonate skeleton. We have every reason to worry about it. He showed a picture of what a reef looks like when acidification takes hold. Horrible is certainly the word.

 ’I hate doing this job,’ he inserted here. 

The future is all about synergies, the way various factors combine to produce the effect on coral reefs. In 25 years at 450 ppm, plus acidification, plus warmer temperature, there will be mass bleaching most years, which will mean very extensive habitat destruction which in turn will mean extinctions start.

In 50 years time at 600 ppm, plus further acidification, plus even warmer temperatures, plus sea level rise of 400 mms, we get the following:  no coral will occur shallower than 10 metres, calcification of anything will be marginal, extinctions will be extensive, reefs will be highly erosional, there will be no shallow water habitats, coralline algae which hold the reefs together won’t exist, there will be major impacts from sea-level rise and super-cyclones.  At that point we are heading for a mid-Eocene climate and accompanying extinctions. Certainly our carbon dioxide levels will not be as high as then, but we are increasing them so fast that the carbon dioxide is remaining in the surface skin of the oceans; it is not getting injected down into deep water where it can be buffered by the carbonates which will de-acidify water. 

In 75 years from now at 800 ppm, plus further acidification effects, plus 5 degrees warming: some corals may survive in askeletal form, but there will be no reefs, molluscs will be in sharp decline and there will be huge biodiversity loss.

100 years ahead it will be runaway climate change which is producing the carbon dioxide. Corals will be extinct or askeletal, all other taxa will be going extinct, reefs will be wave-washed geological structures.  The sixth mass extinction, such as we had in KT will be under way. “How can it not be?”  One ecosystem after another will tumble, an extinction not just of corals but led by corals.

’However much we want to talk about the economic problems associated with climate change they pale, they’re trivial compared to the problems created if we start up a runaway carbon dioxide climate change explosion.’ (Take note John Key and Nick Smith and all the others who cheer them on.)

A reminder towards the end: 450 ppm will bring on the demise of the GBR.  ’Not a skerrick of doubt about it.’

It’s a solemn warning from a scientist who clearly wishes he didn’t have to deliver it but can do no other.  It’s not surprising that the document produced by a working group in association with the occasion should be plain spoken in its conclusion:  

Coral reefs speak unambiguously about climate change. Abrupt carbonising of the environment will destroy carbonate-based ecosystems. Changes to water chemistry will flow on to all marine ecosystems as the oceans turn hostile to a high proportion of marine life. This is the path of mass extinctions, the most destructive events in all Earth history.

 The Earth’s atmospheric CO2 level must be returned to <350ppm to reverse this escalating ecological crisis and to 320ppm to ensure permanent planetary health. Actions to achieve this must be taken urgently. The commonly mooted best case target of 450ppm and a time frame reaching to 2050 will plunge the Earth into an environmental state that has not occurred in millions of years and from which there will be no recovery for coral reefs and for many other natural systems on which humanity depends.


PS  I might be able to save our denialist commenters a bit of time if I report here Veron’s comments on Ian Plimer’s book: “Every original statement Plimer makes in the book on coral and coral reefs is incorrect…[he] serve[s] up diagrams from no acknowledged source, diagrams known to be obsolete and diagrams that combine bits of science with bits of fiction.”

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