Tag Archives: Coral

Food webs alter as warmer seas change colour

Reflected sunlight tells a story: one of deeper shading in an ever-warmer ocean. That is because climate change will also alter green growth in the high seas.

LONDON, 11 February, 2019 – The Blue Planet is to get a little bluer as the world warms and climates change. Where the seas turn green, expect an even deeper verdant tint, new research suggests.

Since humans began increasing the levels of greenhouse gases in the atmosphere – by burning the fossil fuels that have provided the energy for both economic growth and a population explosion – the oceans have warmed in ways that affect marine life. They have grown ever more acidic, in ways that affect coral growth and fish behaviour.

But when US and British scientists tested a model of ocean physics, biogeochemistry and ecosystems – intending to simulate changes in the populations of marine phytoplankton or algae – they also incorporated some of the ocean’s optical properties. Since green plants photosynthesise, they absorb sunlight, and change reflectivity.

And, as mariners have known for centuries, the blue ocean is blue because levels of marine life in the warmer mid-ocean waters are very low.

“There will be a noticeable difference in the colour of 50% of the ocean by the end of the 21st century. It could be potentially quite serious”

The researchers tweaked their simulation to see what the world would look like in 2100 if humanity carried on burning fossil fuels on the notorious business-as-usual scenario and took global average temperatures up to 3°C above historic levels.

And they found that higher temperatures would alter the global palette. More than half of the world’s oceans would intensify in colour. The subtropics would become even more blue, and the oceans that sweep around the poles would become an even deeper green, they report in the journal Nature Communications.

“The models suggest the changes won’t appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and the poles,” said Stephanie Dutkiewicz, of the Massachusetts Institute of Technology, who led the research

Wider effects.

“That basic pattern will still be there. But it will be enough different that it will affect the rest of the food web that phytoplankton supports.”

The clearer the water, the bluer the reflection of the sunlight. From space, the world looks blue. Waters rich in phytoplankton are by definition rich too in chlorophyll that absorbs blue wavelengths and reflects a green tint. But changes in chlorophyll colouring, observed over the decades from satellite monitoring, can be affected by natural climate cycles and shifts in nutrient supply.

The researchers were looking for a more complete model of the wavelengths of visible light that are absorbed, scattered or reflected by living things. They devised one, and tested their new model against satellite evidence so far. When they found agreement with the past, they had also found yet another way to read the future

Explaining ecosystem change.

They tuned their simulated planet to the 3°C warming that seems inevitable unless humans rapidly shift from fossil fuels to renewable energy sources, to discover that wavelengths of light around the blue-green spectrum shifted the fastest. The shifts in colour could tell a story of altered ecosystems.

“The nice thing about this model is that we can use it as a laboratory, a place where we can experiment, to see how our planet is going to change,” Dr Dutkiewicz said.

“There will be a noticeable difference in the colour of 50% of the ocean by the end of the 21st century. It could be potentially quite serious..

“Different types of phytoplankton absorb light differently, and if climate change shifts one community of phytoplankton to another, they will also change the types of food webs they can support.” – Climate News Network

Reflected sunlight tells a story: one of deeper shading in an ever-warmer ocean. That is because climate change will also alter green growth in the high seas.

LONDON, 11 February, 2019 – The Blue Planet is to get a little bluer as the world warms and climates change. Where the seas turn green, expect an even deeper verdant tint, new research suggests.

Since humans began increasing the levels of greenhouse gases in the atmosphere – by burning the fossil fuels that have provided the energy for both economic growth and a population explosion – the oceans have warmed in ways that affect marine life. They have grown ever more acidic, in ways that affect coral growth and fish behaviour.

But when US and British scientists tested a model of ocean physics, biogeochemistry and ecosystems – intending to simulate changes in the populations of marine phytoplankton or algae – they also incorporated some of the ocean’s optical properties. Since green plants photosynthesise, they absorb sunlight, and change reflectivity.

And, as mariners have known for centuries, the blue ocean is blue because levels of marine life in the warmer mid-ocean waters are very low.

“There will be a noticeable difference in the colour of 50% of the ocean by the end of the 21st century. It could be potentially quite serious”

The researchers tweaked their simulation to see what the world would look like in 2100 if humanity carried on burning fossil fuels on the notorious business-as-usual scenario and took global average temperatures up to 3°C above historic levels.

And they found that higher temperatures would alter the global palette. More than half of the world’s oceans would intensify in colour. The subtropics would become even more blue, and the oceans that sweep around the poles would become an even deeper green, they report in the journal Nature Communications.

“The models suggest the changes won’t appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and the poles,” said Stephanie Dutkiewicz, of the Massachusetts Institute of Technology, who led the research

Wider effects.

“That basic pattern will still be there. But it will be enough different that it will affect the rest of the food web that phytoplankton supports.”

The clearer the water, the bluer the reflection of the sunlight. From space, the world looks blue. Waters rich in phytoplankton are by definition rich too in chlorophyll that absorbs blue wavelengths and reflects a green tint. But changes in chlorophyll colouring, observed over the decades from satellite monitoring, can be affected by natural climate cycles and shifts in nutrient supply.

The researchers were looking for a more complete model of the wavelengths of visible light that are absorbed, scattered or reflected by living things. They devised one, and tested their new model against satellite evidence so far. When they found agreement with the past, they had also found yet another way to read the future

Explaining ecosystem change.

They tuned their simulated planet to the 3°C warming that seems inevitable unless humans rapidly shift from fossil fuels to renewable energy sources, to discover that wavelengths of light around the blue-green spectrum shifted the fastest. The shifts in colour could tell a story of altered ecosystems.

“The nice thing about this model is that we can use it as a laboratory, a place where we can experiment, to see how our planet is going to change,” Dr Dutkiewicz said.

“There will be a noticeable difference in the colour of 50% of the ocean by the end of the 21st century. It could be potentially quite serious..

“Different types of phytoplankton absorb light differently, and if climate change shifts one community of phytoplankton to another, they will also change the types of food webs they can support.” – Climate News Network

Scientists differ on climate’s CO2 sensitivity

There is another enigma in the warming puzzle: the climate’s CO2 sensitivity. How will life respond as carbon dioxide levels rise and heat soars?

LONDON, 11 July, 2018 – Scientists have yet to settle one of the biggest questions of warming: the climate’s CO2 sensitivity. How much more carbon dioxide can the atmosphere absorb – and how will life on Earth respond – before the global temperature ticks past the political milestones of 1.5°C and 2°C above the average levels for most of human history?

These were set in 2015 when 195 nations agreed in Paris to contain global warming to “well below” 2°C by 2100 and spoke openly of holding to no more than a 1.5°C average rise as the ambition.

But that means doing the sums all over again. In the last century the ratio of the greenhouse gas in the atmosphere has risen from its historic average of around 280 parts per million to more than 400 ppm. And global average temperatures have risen by around 1°C already: the world has just half a degree of leeway before the Paris target becomes impossible.

But one of the longest-running arguments in climate science is a simple uncertainty known to the professionals as “climate sensitivity.” That is: how much emitted carbon dioxide – emitted from the combustion of fossil fuels – makes a half a degree rise?

And it is a difficult question because forests, grasslands, wetlands, rivers, animals, microbes, rocks and oceans all release and absorb carbon dioxide from the atmosphere, sometimes storing it as hardwood, or peat, or carbonate rocks, sometimes releasing it as organisms decay.

“As well as being a major cause of global warming, CO2 also affects life directly”

Global temperature and carbon dioxide ratios have varied many times in pre-human history. So the human use of fossil fuels is only one component in a truly global calculation. Another factor is the area of healthy mixed forest and wetland, mangrove and prairie available to absorb that extra carbon, not to mention the algae in the warming oceans.

British scientists report in the journal Nature Climate Change that they asked the big question: how high could carbon levels get while temperatures stayed at no more than 1.5°C? They calculate that – as long as warming happens slowly – the carbon count could get as high as 765ppm. Right now, most climate researchers think that this mark will be reached or surpassed at between 425 ppm and 520 ppm.

And what makes the difference is the unresolved question of how the green things respond to all that extra carbon dioxide in the atmosphere. What difference will this make to crop yields (it is, in effect, a fertiliser), to the mix of species in the forests, and to the acidity of the oceans?

Other researchers have already asked the same question: what difference, for instance, will it make just to the tropics? And how will clouds – another factor in temperature control – respond?

Winners and losers

“As well as being a major cause of global warming, CO2 also affects life directly,” said Richard Betts, of the UK Met Office, based at the Hadley Centre in Exeter.

“Higher CO2 concentrations cause increased growth in many plant species. This causes a general ‘greening’ of vegetation, but also changes the make-up of ecosystems – some species do better than others. Slower-growing large tree species can lose out to faster-growing competitors,” he said.

“It can also reduce the effects of drought to some extent, because many plants use less water when CO2 is higher. Both of these factors can potentially enhance crop yields, possibly helping to offset some of the negative impacts of climate change – although even if that happens, the nutritional value of the crops can be reduced as a result of the extra CO2.”

But, Professor Betts warned, the same extra carbon dioxide changed the chemistry of the oceans, making sea water more acidic and potentially more damaging to corals, and to plankton.

No quick answers

The message of such research is that there are a lot more questions to be answered. Nature’s response might buy the world more time to act. But there is no guarantee.

And the Exeter reasoning has its limitations: that is because it considered only the case of carbon dioxide, and although this is the big driver of climate change, it is not the only greenhouse gas. In a warming world, the permafrost is expected to melt to release potentially colossal quantities of buried methane.

The researchers arrived at their estimates by reversing the normal reasoning. They did not try to calculate the probability of so much warming for a stipulated rise in CO2 ratios. Instead, they started with what the carbon dioxide count might look like at a particular temperature.

“This lets us estimate what the range of CO2 concentrations would be when global warming passes those levels, if CO2 were the only thing in the atmosphere that we are changing,” Professor Betts said. – Climate News Network

There is another enigma in the warming puzzle: the climate’s CO2 sensitivity. How will life respond as carbon dioxide levels rise and heat soars?

LONDON, 11 July, 2018 – Scientists have yet to settle one of the biggest questions of warming: the climate’s CO2 sensitivity. How much more carbon dioxide can the atmosphere absorb – and how will life on Earth respond – before the global temperature ticks past the political milestones of 1.5°C and 2°C above the average levels for most of human history?

These were set in 2015 when 195 nations agreed in Paris to contain global warming to “well below” 2°C by 2100 and spoke openly of holding to no more than a 1.5°C average rise as the ambition.

But that means doing the sums all over again. In the last century the ratio of the greenhouse gas in the atmosphere has risen from its historic average of around 280 parts per million to more than 400 ppm. And global average temperatures have risen by around 1°C already: the world has just half a degree of leeway before the Paris target becomes impossible.

But one of the longest-running arguments in climate science is a simple uncertainty known to the professionals as “climate sensitivity.” That is: how much emitted carbon dioxide – emitted from the combustion of fossil fuels – makes a half a degree rise?

And it is a difficult question because forests, grasslands, wetlands, rivers, animals, microbes, rocks and oceans all release and absorb carbon dioxide from the atmosphere, sometimes storing it as hardwood, or peat, or carbonate rocks, sometimes releasing it as organisms decay.

“As well as being a major cause of global warming, CO2 also affects life directly”

Global temperature and carbon dioxide ratios have varied many times in pre-human history. So the human use of fossil fuels is only one component in a truly global calculation. Another factor is the area of healthy mixed forest and wetland, mangrove and prairie available to absorb that extra carbon, not to mention the algae in the warming oceans.

British scientists report in the journal Nature Climate Change that they asked the big question: how high could carbon levels get while temperatures stayed at no more than 1.5°C? They calculate that – as long as warming happens slowly – the carbon count could get as high as 765ppm. Right now, most climate researchers think that this mark will be reached or surpassed at between 425 ppm and 520 ppm.

And what makes the difference is the unresolved question of how the green things respond to all that extra carbon dioxide in the atmosphere. What difference will this make to crop yields (it is, in effect, a fertiliser), to the mix of species in the forests, and to the acidity of the oceans?

Other researchers have already asked the same question: what difference, for instance, will it make just to the tropics? And how will clouds – another factor in temperature control – respond?

Winners and losers

“As well as being a major cause of global warming, CO2 also affects life directly,” said Richard Betts, of the UK Met Office, based at the Hadley Centre in Exeter.

“Higher CO2 concentrations cause increased growth in many plant species. This causes a general ‘greening’ of vegetation, but also changes the make-up of ecosystems – some species do better than others. Slower-growing large tree species can lose out to faster-growing competitors,” he said.

“It can also reduce the effects of drought to some extent, because many plants use less water when CO2 is higher. Both of these factors can potentially enhance crop yields, possibly helping to offset some of the negative impacts of climate change – although even if that happens, the nutritional value of the crops can be reduced as a result of the extra CO2.”

But, Professor Betts warned, the same extra carbon dioxide changed the chemistry of the oceans, making sea water more acidic and potentially more damaging to corals, and to plankton.

No quick answers

The message of such research is that there are a lot more questions to be answered. Nature’s response might buy the world more time to act. But there is no guarantee.

And the Exeter reasoning has its limitations: that is because it considered only the case of carbon dioxide, and although this is the big driver of climate change, it is not the only greenhouse gas. In a warming world, the permafrost is expected to melt to release potentially colossal quantities of buried methane.

The researchers arrived at their estimates by reversing the normal reasoning. They did not try to calculate the probability of so much warming for a stipulated rise in CO2 ratios. Instead, they started with what the carbon dioxide count might look like at a particular temperature.

“This lets us estimate what the range of CO2 concentrations would be when global warming passes those levels, if CO2 were the only thing in the atmosphere that we are changing,” Professor Betts said. – Climate News Network

Coral island freshwater faces pollution risk

People on low-lying coral atolls need not wait until the rising seas lap at their feet. It’s the island freshwater that is first at risk.

LONDON, 10 May, 2018 – For atoll dwellers across much of the world, the island freshwater on which they depend may be in jeopardy within a couple of decades.

The combination of sea level rise and ever more extreme storm conditions – each a consequence of global warming and climate change – could make many of the world’s coral atolls uninhabitable  within one human generation.

Although many of the low-lying islands of the Indian and Pacific Oceans are two metres above sea level, and although in the gloomier scenarios sea levels will rise a metre by 2100, the freshwater resources of such islands are likely to be polluted by the invading seas by about 2050, according to new research.

Worldwide, there are thousands of inhabited atolls and cays, with reaches of coral above the reef waterline long colonised by vegetation, to provide shelter for birds, small animals and people.

“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century”

But as the icecaps and glaciers melt, in response to ever greater greenhouse gas emissions from factory chimneys, power stations and vehicle exhausts, to drive up the planetary thermometer, more freshwater will flow into the oceans, which will anyway expand as temperatures rise.

And since global warming is likely to be accompanied by greater extremes of tropical cyclone and windstorm, islanders everywhere will become increasingly vulnerable.

US scientists report in the journal Science Advances that they decided to look in fine detail at the consequences for one group of atoll-dwellers on Roi-Namur, in the Kwajalein atoll in the Republic of the Marshall Islands.

There are around 1,100 low-lying islands in 29 atolls in the group, and these are home to hundreds of thousands of people. But not, possibly, for much longer.

Dual risk

The researchers considered the projections for gradual sea level rise but focused also on the dynamics of waves as the seas continue to rise, and as ever higher waves driven by ever more energetic storms wash over the low coral structures.

And as these waves batter the coral above the high tide line, so does the likelihood grow that brine will get into the bedrock and poison the natural bedrock aquifers filled with rainwater on which the islanders rely.

Coast-dwellers and people of the lowest-lying islands have the most to lose from climate change, starting with the ground on which they live. Sea level rise has already been identified as a threat for one small settlement off the coast of the US mainland, and future sea level rise could threaten many in the wider Pacific and sweep away tourist investments in the Indian Ocean.

Such findings matter not just for the Marshall Islanders: there are settled atolls in the Caroline, Cook, Line and Society Islands, in the Maldives, the Seychelles and the Hawaiian Islands. All could be vulnerable.

Little choice

“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century,” said Curt Storlazzi, of the US Geological Survey, who led the research.

The damage from flooding to the islands’ homes, stores and workshops, combined with the loss of freshwater, will start to make human habitation difficult in many such islands by between 2030 and 2060, and go on doing so.

Either the islanders must find the money to secure their water supply and protect their homes, or they must abandon their homelands. What oceanographers call overwash – the great waves that occasionally splash right across the narrow atolls – will become more frequent, and more damaging.

“The overwash events generally result in salty ocean water seeping into the ground and contaminating the freshwater aquifer. Rainfall later in the year is not enough to flush out the saltwater and refresh the island’s water supply before the next year’s storms arrive, repeating the overwash events,” said Stephen Gingerich of the USGS, a co-author. – Climate News Network

People on low-lying coral atolls need not wait until the rising seas lap at their feet. It’s the island freshwater that is first at risk.

LONDON, 10 May, 2018 – For atoll dwellers across much of the world, the island freshwater on which they depend may be in jeopardy within a couple of decades.

The combination of sea level rise and ever more extreme storm conditions – each a consequence of global warming and climate change – could make many of the world’s coral atolls uninhabitable  within one human generation.

Although many of the low-lying islands of the Indian and Pacific Oceans are two metres above sea level, and although in the gloomier scenarios sea levels will rise a metre by 2100, the freshwater resources of such islands are likely to be polluted by the invading seas by about 2050, according to new research.

Worldwide, there are thousands of inhabited atolls and cays, with reaches of coral above the reef waterline long colonised by vegetation, to provide shelter for birds, small animals and people.

“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century”

But as the icecaps and glaciers melt, in response to ever greater greenhouse gas emissions from factory chimneys, power stations and vehicle exhausts, to drive up the planetary thermometer, more freshwater will flow into the oceans, which will anyway expand as temperatures rise.

And since global warming is likely to be accompanied by greater extremes of tropical cyclone and windstorm, islanders everywhere will become increasingly vulnerable.

US scientists report in the journal Science Advances that they decided to look in fine detail at the consequences for one group of atoll-dwellers on Roi-Namur, in the Kwajalein atoll in the Republic of the Marshall Islands.

There are around 1,100 low-lying islands in 29 atolls in the group, and these are home to hundreds of thousands of people. But not, possibly, for much longer.

Dual risk

The researchers considered the projections for gradual sea level rise but focused also on the dynamics of waves as the seas continue to rise, and as ever higher waves driven by ever more energetic storms wash over the low coral structures.

And as these waves batter the coral above the high tide line, so does the likelihood grow that brine will get into the bedrock and poison the natural bedrock aquifers filled with rainwater on which the islanders rely.

Coast-dwellers and people of the lowest-lying islands have the most to lose from climate change, starting with the ground on which they live. Sea level rise has already been identified as a threat for one small settlement off the coast of the US mainland, and future sea level rise could threaten many in the wider Pacific and sweep away tourist investments in the Indian Ocean.

Such findings matter not just for the Marshall Islanders: there are settled atolls in the Caroline, Cook, Line and Society Islands, in the Maldives, the Seychelles and the Hawaiian Islands. All could be vulnerable.

Little choice

“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century,” said Curt Storlazzi, of the US Geological Survey, who led the research.

The damage from flooding to the islands’ homes, stores and workshops, combined with the loss of freshwater, will start to make human habitation difficult in many such islands by between 2030 and 2060, and go on doing so.

Either the islanders must find the money to secure their water supply and protect their homes, or they must abandon their homelands. What oceanographers call overwash – the great waves that occasionally splash right across the narrow atolls – will become more frequent, and more damaging.

“The overwash events generally result in salty ocean water seeping into the ground and contaminating the freshwater aquifer. Rainfall later in the year is not enough to flush out the saltwater and refresh the island’s water supply before the next year’s storms arrive, repeating the overwash events,” said Stephen Gingerich of the USGS, a co-author. – Climate News Network

Hopes rise for some coral survival

US scientists have good news about prospects for coral survival on one of the world’s great reefs, threatened by climate change.

LONDON, 25 April, 2018 – Researchers have raised hopes that limited coral survival may be possible, allowing one of the world’s best-known reefs to survive a little longer.

Although corals are highly sensitive to ocean warming, and notoriously bleach when temperatures exceed a certain limit, a new study has shown that at least one coral can evolve tolerance to excessive temperatures.

The implication is that even though other teams have repeatedly warned that the world’s reefs are in peril as the world warms because of ever-greater ratios of greenhouse gases in the atmosphere, as a consequence of human combustion of fossil fuels at a profligate rate, the world’s great reefs may survive for perhaps another century, rather than perish within the next 50 years.

“It means these corals will still go extinct if we do nothing,” said Misha Matz, of the University of Texas at Austin, who led the study. “But it also means we have a chance to save them. It buys us time to actually do something about global warming, which is the main problem.”

The argument is based on Darwinian logic: coral colonies produce colossal numbers of larvae each year, set adrift on ocean currents to colonise new reefs. As conditions change, those corals that by an accident of genetic inheritance have the traits needed to cope with environmental challenge will get a foothold, and flourish. Those that don’t will fade out. Natural selection will respond.

”While the fact that one species may do well is good news, there are many other reef organisms that may fare far worse, so it is easy to envisage a future with a few winners but many losers”

And this is hopeful news, if only because the world’s reefs are under threat as never before. Bleaching – the response to heat in which coral rejects the algae with which it normally lives in symbiosis – has always happened: research earlier this year suggests it could become five times more frequent, and reefs such as Australia’s Great Barrier would have no time to recover.

Some reefs have already been pronounced too damaged ever to be restored. This is bad news not just for the coral animals: the tropical reefs are just about the richest habitats on the planet, and of profound economic importance to humans too.

A partnership of US and Australian scientists reports in the Public Library of Science journal PLOS Genetics that computer simulation models and genetic evidence of variation from one species of staghorn coral, called Acropora millepora, together show that the coral could in theory adapt over a stretch of 20 to 50 generations.

“This genetic variation is like fuel for natural selection,” Dr Matz said. “If there is enough of it, evolution can be remarkably fast, because all it needs to do is reshuffle the existing variants between the populations.

“It doesn’t have to wait for a new mutation to appear; it’s already there. The problem is, when the genetic variation is exhausted, it is over and the future is unclear.”

Tentative conclusions

There are problems with such studies. This one is based on genetic evidence from one species of coral. But the 2,300 km Great Barrier Reef of Australia is home to at least 411 species of hard coral. It is based on a mathematical model, not on observed change in the reefs.

And global warming is not the only challenge to coral reefs, which are also threatened by human exploitation, pollution and increasing acidification  of the surrounding seas, again as a consequence of ever higher levels of carbon dioxide in the atmosphere.

“Corals live in a symbiotic relationship with zooxanthellae, which are plant-like cells hosted in surface tissues that provide up to 90% of the energy to the colony,” said Stephen Simpson, a marine biologist at the University of Exeter in the UK, commenting on the study.

“Whether there is also sufficient genotypic variation in the zooxanthellae to tolerate further warming remains to be seen. While the fact that one species may do well is good news, there are many other reef organisms that may fare far worse, so it is easy to envisage a future with a few winners but many losers, threatening the functional integrity of reef ecosystems.” – Climate News Network

US scientists have good news about prospects for coral survival on one of the world’s great reefs, threatened by climate change.

LONDON, 25 April, 2018 – Researchers have raised hopes that limited coral survival may be possible, allowing one of the world’s best-known reefs to survive a little longer.

Although corals are highly sensitive to ocean warming, and notoriously bleach when temperatures exceed a certain limit, a new study has shown that at least one coral can evolve tolerance to excessive temperatures.

The implication is that even though other teams have repeatedly warned that the world’s reefs are in peril as the world warms because of ever-greater ratios of greenhouse gases in the atmosphere, as a consequence of human combustion of fossil fuels at a profligate rate, the world’s great reefs may survive for perhaps another century, rather than perish within the next 50 years.

“It means these corals will still go extinct if we do nothing,” said Misha Matz, of the University of Texas at Austin, who led the study. “But it also means we have a chance to save them. It buys us time to actually do something about global warming, which is the main problem.”

The argument is based on Darwinian logic: coral colonies produce colossal numbers of larvae each year, set adrift on ocean currents to colonise new reefs. As conditions change, those corals that by an accident of genetic inheritance have the traits needed to cope with environmental challenge will get a foothold, and flourish. Those that don’t will fade out. Natural selection will respond.

”While the fact that one species may do well is good news, there are many other reef organisms that may fare far worse, so it is easy to envisage a future with a few winners but many losers”

And this is hopeful news, if only because the world’s reefs are under threat as never before. Bleaching – the response to heat in which coral rejects the algae with which it normally lives in symbiosis – has always happened: research earlier this year suggests it could become five times more frequent, and reefs such as Australia’s Great Barrier would have no time to recover.

Some reefs have already been pronounced too damaged ever to be restored. This is bad news not just for the coral animals: the tropical reefs are just about the richest habitats on the planet, and of profound economic importance to humans too.

A partnership of US and Australian scientists reports in the Public Library of Science journal PLOS Genetics that computer simulation models and genetic evidence of variation from one species of staghorn coral, called Acropora millepora, together show that the coral could in theory adapt over a stretch of 20 to 50 generations.

“This genetic variation is like fuel for natural selection,” Dr Matz said. “If there is enough of it, evolution can be remarkably fast, because all it needs to do is reshuffle the existing variants between the populations.

“It doesn’t have to wait for a new mutation to appear; it’s already there. The problem is, when the genetic variation is exhausted, it is over and the future is unclear.”

Tentative conclusions

There are problems with such studies. This one is based on genetic evidence from one species of coral. But the 2,300 km Great Barrier Reef of Australia is home to at least 411 species of hard coral. It is based on a mathematical model, not on observed change in the reefs.

And global warming is not the only challenge to coral reefs, which are also threatened by human exploitation, pollution and increasing acidification  of the surrounding seas, again as a consequence of ever higher levels of carbon dioxide in the atmosphere.

“Corals live in a symbiotic relationship with zooxanthellae, which are plant-like cells hosted in surface tissues that provide up to 90% of the energy to the colony,” said Stephen Simpson, a marine biologist at the University of Exeter in the UK, commenting on the study.

“Whether there is also sufficient genotypic variation in the zooxanthellae to tolerate further warming remains to be seen. While the fact that one species may do well is good news, there are many other reef organisms that may fare far worse, so it is easy to envisage a future with a few winners but many losers, threatening the functional integrity of reef ecosystems.” – Climate News Network

Coral reefs face infection risk from plastic

Plastic flotsam provides a liferaft for deadly bacteria – and a way of colonising coral reefs with killer infections.

LONDON, 29 January, 2018 – Scientists have established yet another hazard from the millions of tons of plastic waste that tip into the sea: it delivers microbial infection to the world’s coral reefs.

When plastic pollutants snag on coral reefs, the likelihood of disease rises from 4% to 89%, they calculate. That is an increase in risk of more than twentyfold.

And the impact on the world’s reefs – already under increasing hazard from ocean acidification and from bleaching in extremes of heat – could be devastating.

“Plastic debris acts like a marine motor home for microbes,” said Joleah Lamb, a researcher at Cornell University in the US. She began gathering data while at James Cook University in Australia.

“Plastics make ideal vessels for colonising microscopic organisms that could trigger disease if they come into contact with corals.

“Our work shows that plastic pollution is killing corals. Our goal is to focus less on measuring things dying and more on finding solutions”

“Plastic items – commonly made of polypropylene, such as bottle caps and toothbrushes – have been shown to become heavily inhabited by bacteria. This is associated with the globally devastating group of coral diseases known as white syndromes.”

She and colleagues from the US, Canada, Australia, Myanmar, Thailand and Indonesia report in the journal Science that between 2011 and 2014 they surveyed 124,000 reef-building corals from 159 reefs in the Asia-Pacific region.

One third of the reefs surveyed were polluted with plastic waste, the highest in Indonesian waters, the lowest off the Australian coast.

They calculate that, right now, the number of plastic bags, cups, bottles, toothbrushes and bits of packaging snagged on the reefs in the region could be 11.1 billion. By 2025, there could be 15.7 bn plastic objects stuck on the same reefs.

No return

And, they report, the presence of plastic was associated with a 20-fold increase in risk of disease, and in particular infections know to marine biologists as skeletal eroding band disease, white syndrome and black band disease.

The items snagged on the corals deprived them of sunlight and oxygen, and weakened the coral to the point at which invasive pathogens could gain a hold.

“What’s troubling about coral disease is that once the coral tissue loss occurs, it’s not coming back,” Dr Lamb said. “It’s like getting gangrene on your foot and there is nothing you can do to stop it from affecting your whole body.”

The Asia-Pacific region is home to more than 55% of the world’s coral reefs. Complex reef structures – reefs with branching corals, for instance – were eight times more likely to trap floating plastic waste.

An estimated 12 billion metric tons of indestructible plastic waste is in the world’s landfills. Somewhere between 4.8 million and 12.7 million metric tons of plastic waste gets into the oceans in a single year.

Rich resource

Coral reefs are among the richest habitats on the planet: a diseased or dying reef can no longer provide food and shelter for a vast range of sea creatures.

Pollution and disease also put at risk much of the estimated $375bn value that reefs offer to 275 million people as sources of fisheries, tourism and coastal protection.

“Our work shows that plastic pollution is killing corals. Our goal is to focus less on measuring things dying and more on finding solutions,” said Drew Harvell, professor of ecology and evolutionary biology at Cornell, and one of the authors.

“While we can’t stop the huge impact of global warming on coral health in the short term, this new work should drive policy toward reducing plastic pollution.” – Climate News Network

Plastic flotsam provides a liferaft for deadly bacteria – and a way of colonising coral reefs with killer infections.

LONDON, 29 January, 2018 – Scientists have established yet another hazard from the millions of tons of plastic waste that tip into the sea: it delivers microbial infection to the world’s coral reefs.

When plastic pollutants snag on coral reefs, the likelihood of disease rises from 4% to 89%, they calculate. That is an increase in risk of more than twentyfold.

And the impact on the world’s reefs – already under increasing hazard from ocean acidification and from bleaching in extremes of heat – could be devastating.

“Plastic debris acts like a marine motor home for microbes,” said Joleah Lamb, a researcher at Cornell University in the US. She began gathering data while at James Cook University in Australia.

“Plastics make ideal vessels for colonising microscopic organisms that could trigger disease if they come into contact with corals.

“Our work shows that plastic pollution is killing corals. Our goal is to focus less on measuring things dying and more on finding solutions”

“Plastic items – commonly made of polypropylene, such as bottle caps and toothbrushes – have been shown to become heavily inhabited by bacteria. This is associated with the globally devastating group of coral diseases known as white syndromes.”

She and colleagues from the US, Canada, Australia, Myanmar, Thailand and Indonesia report in the journal Science that between 2011 and 2014 they surveyed 124,000 reef-building corals from 159 reefs in the Asia-Pacific region.

One third of the reefs surveyed were polluted with plastic waste, the highest in Indonesian waters, the lowest off the Australian coast.

They calculate that, right now, the number of plastic bags, cups, bottles, toothbrushes and bits of packaging snagged on the reefs in the region could be 11.1 billion. By 2025, there could be 15.7 bn plastic objects stuck on the same reefs.

No return

And, they report, the presence of plastic was associated with a 20-fold increase in risk of disease, and in particular infections know to marine biologists as skeletal eroding band disease, white syndrome and black band disease.

The items snagged on the corals deprived them of sunlight and oxygen, and weakened the coral to the point at which invasive pathogens could gain a hold.

“What’s troubling about coral disease is that once the coral tissue loss occurs, it’s not coming back,” Dr Lamb said. “It’s like getting gangrene on your foot and there is nothing you can do to stop it from affecting your whole body.”

The Asia-Pacific region is home to more than 55% of the world’s coral reefs. Complex reef structures – reefs with branching corals, for instance – were eight times more likely to trap floating plastic waste.

An estimated 12 billion metric tons of indestructible plastic waste is in the world’s landfills. Somewhere between 4.8 million and 12.7 million metric tons of plastic waste gets into the oceans in a single year.

Rich resource

Coral reefs are among the richest habitats on the planet: a diseased or dying reef can no longer provide food and shelter for a vast range of sea creatures.

Pollution and disease also put at risk much of the estimated $375bn value that reefs offer to 275 million people as sources of fisheries, tourism and coastal protection.

“Our work shows that plastic pollution is killing corals. Our goal is to focus less on measuring things dying and more on finding solutions,” said Drew Harvell, professor of ecology and evolutionary biology at Cornell, and one of the authors.

“While we can’t stop the huge impact of global warming on coral health in the short term, this new work should drive policy toward reducing plastic pollution.” – Climate News Network

Bleaching hits coral reefs faster

Coral reefs have always lived near the edge. Now, thanks to global warming, life there is five times more precarious.

LONDON, 16 January, 2018 – Forty years ago, the world’s coral reefs faced a known risk: every 25 or 30 years, ocean temperatures would rise to intolerable levels.

Corals would minimise the risk of death by everting the algae with which they lived in symbiotic partnership: that is, the reef animals would avoid death by getting rid of the algae, deliberately weakening themselves.

This response is known as bleaching, and it can have a catastrophic effect on other life on the reef. In the Pacific such episodes were sometimes linked to cycles of ocean warming known as an El Niño event.

By 2018 the odds had altered. Coral reefs now face this hazard every six years. That is, in four decades of global warming and climate change, the risks have multiplied fivefold.

Bleaching breaks out

“Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise,” said Terry Hughes, who directs Australia’s Centre of Excellence for Coral Reef Studies at James Cook University.

He and colleagues report in the journal Science that they analysed data from bleaching events at 100 locations around the planet between 1980 and 2016. Bleaching events are a fact of life for corals: these little creatures tend to live best in temperatures near the upper limit of their tolerance levels, and respond to extreme events by rejecting the algae that normally provide the nutrients they need.

But as global air temperatures have increased, in response to profligate burning of fossil fuels that increase greenhouse gas levels in the atmosphere, so have sea temperatures. And Professor Hughes and his team report that in the last two years more than a third of all bleaching events have been “severe,” extending over hundreds of kilometres.

When they measured the growth of risk over the decades, they found that the bleaching hazard had increased by 4% per year since 1980.

“Repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world”

The finding should be no surprise. In 2015, during a severe El Niño event, scientists began to record cases of coral death. In 2016, they observed that 93% of Australia’s Great Barrier reef had been affected. In 2017 they found that reefs in the western Pacific and off the Indian Ocean had been damaged beyond repair, and a separate set of calculations has warned that by 2100, up to 99% of the world’s coral colonies could be at risk of bleaching every year.

Reefs can recover, but this recovery can take as long as a decade. Coral reefs are among the planet’s richest habitats, and the death of a reef puts many ocean species at risk: it also damages local commercial fish catches and local tourist industries.

“Reefs have entered a distinctive human-dominated era – the Anthropocene,” said Mark Eakin of the US National Oceanic and Atmospheric Administration, a co-author. “The climate has warmed rapidly in the past 50 years, first making El Niños dangerous for corals, and now we’re seeing the emergence of bleaching in every hot summer.”

And Professor Hughes said: “We hope our stark results will help spur on the stronger action needed to reduce greenhouse gases in Australia, the United States and elsewhere.” – Climate News Network

Coral reefs have always lived near the edge. Now, thanks to global warming, life there is five times more precarious.

LONDON, 16 January, 2018 – Forty years ago, the world’s coral reefs faced a known risk: every 25 or 30 years, ocean temperatures would rise to intolerable levels.

Corals would minimise the risk of death by everting the algae with which they lived in symbiotic partnership: that is, the reef animals would avoid death by getting rid of the algae, deliberately weakening themselves.

This response is known as bleaching, and it can have a catastrophic effect on other life on the reef. In the Pacific such episodes were sometimes linked to cycles of ocean warming known as an El Niño event.

By 2018 the odds had altered. Coral reefs now face this hazard every six years. That is, in four decades of global warming and climate change, the risks have multiplied fivefold.

Bleaching breaks out

“Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise,” said Terry Hughes, who directs Australia’s Centre of Excellence for Coral Reef Studies at James Cook University.

He and colleagues report in the journal Science that they analysed data from bleaching events at 100 locations around the planet between 1980 and 2016. Bleaching events are a fact of life for corals: these little creatures tend to live best in temperatures near the upper limit of their tolerance levels, and respond to extreme events by rejecting the algae that normally provide the nutrients they need.

But as global air temperatures have increased, in response to profligate burning of fossil fuels that increase greenhouse gas levels in the atmosphere, so have sea temperatures. And Professor Hughes and his team report that in the last two years more than a third of all bleaching events have been “severe,” extending over hundreds of kilometres.

When they measured the growth of risk over the decades, they found that the bleaching hazard had increased by 4% per year since 1980.

“Repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world”

The finding should be no surprise. In 2015, during a severe El Niño event, scientists began to record cases of coral death. In 2016, they observed that 93% of Australia’s Great Barrier reef had been affected. In 2017 they found that reefs in the western Pacific and off the Indian Ocean had been damaged beyond repair, and a separate set of calculations has warned that by 2100, up to 99% of the world’s coral colonies could be at risk of bleaching every year.

Reefs can recover, but this recovery can take as long as a decade. Coral reefs are among the planet’s richest habitats, and the death of a reef puts many ocean species at risk: it also damages local commercial fish catches and local tourist industries.

“Reefs have entered a distinctive human-dominated era – the Anthropocene,” said Mark Eakin of the US National Oceanic and Atmospheric Administration, a co-author. “The climate has warmed rapidly in the past 50 years, first making El Niños dangerous for corals, and now we’re seeing the emergence of bleaching in every hot summer.”

And Professor Hughes said: “We hope our stark results will help spur on the stronger action needed to reduce greenhouse gases in Australia, the United States and elsewhere.” – Climate News Network

High marine extinction risk by 2100

If marine extinction is not a reality for many species by the end of this century, scientists say, it will certainly be a strong probability.

LONDON, 9 October, 2017 – Mass marine extinction may be inevitable. If humans go on burning fossil fuels under the notorious “business as usual” scenario, then by 2100 they will have added so much carbon to the world’s oceans that a sixth mass extinction of marine species will follow, inexorably.

And even if the 197 nations that agreed in Paris in 2015 to take steps to limit global warming in fact do so, then by 2100 humans will have added 300 billion tons of carbon to the seas. And a US scientist has calculated that the critical threshold for mass extinction stands at 310 billion tons.

So in either case, the world will be condemned to, or at imminent risk of, a “great dying” of the kind that characterised the end of the geological period called the Permian, in which 95% of marine species vanished, or the Cretaceous era that witnessed the last of the dinosaurs.

Daniel Rothman, a geophysicist at the Massachusetts Institute of Technology, reports in the journal Science Advances that he worked through hundreds of scientific studies to identify 31 occasions of significant change in 542 million years in the planet’s carbon cycle – in which plants draw down carbon from the atmosphere and cycle it through the animal community and back into the atmosphere.

Happening now

For each event, including the five great mass extinctions in the geological record, he estimated the record of carbon preserved in the rocks, to find a predictable threshold at which catastrophe might be an outcome. Four of the five great extinction events lay beyond this threshold. He then considered the timescales of such extinction events to arrive at his modern-day danger zone figure of 310 billion tons.

And by 2100, unconstrained fossil fuel combustion may have tipped the planet into “unknown territory,” he says.

“This is not saying that disaster occurs the next day. It’s saying that, if left unchecked, the carbon cycle would move into a realm which would no longer be stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behaviour is associated with mass extinction.”

In effect, Professor Rothman has used a mathematical technique to predict an event many biologists believe is already happening. Pollution, the clearing of the wilderness and the disruption of habitat have already placed many species at risk. Global warming as a consequence of the combustion of fossil fuels will, they have repeatedly said, make a bad situation worse.

“Our activities as humans are pushing species to the brink so fast that it’s impossible for conservationists to assess the declines in real time. Even those species that we thought were abundant and safe now face an imminent threat of extinction”

Researchers have already begun to record local extinctions – the disappearance of once-familiar creatures from local landscapes – and climate change that will follow global warming could heighten the hazard for animals and plants already under stress.

And Professor Rothman’s warning came hard on the heels of several studies that indicate the dangerous impact of climate change.

Scientists from the University of Washington in Seattle warn that as the world’s waters warm, fish will have to migrate to surviveand those that cannot – the ones in lakes and river systems – could be at risk.

They report in the journal Nature Climate Change that they looked at available physiological data and climate predictions to see how 3,000 species in oceans and rivers would respond to warmer waters and to judge what the “breaking point” temperatures for any species would be.

Many losers

“Nowhere on Earth are fish spared from having to cope with climate change”, said senior author Julian Olden, professor of aquatic and fishery sciences. “Fish have unique challenges – they either have to make rapid movements to track their temperature requirements, or they will be forced to adapt quickly.”

But other creatures in the most extreme environments are affected too. British Antarctic Survey scientists report in Nature Climate Change that they used computer models to test a warming scenario for 900 species of marine invertebrates that live in the south polar seas.

Even a small warming of 0.4°C will cause unique local animals to change their distribution, and although some will fare well, overall there will be more losers than winners.

“While a few species might thrive at least during the early decades of warming, the future for a whole range of invertebrates from starfish to corals is bleak, and there’s nowhere to swim to, nowhere to hide when you’re sitting on the bottom of the world’s coldest and most southerly ocean and it’s getting warmer by the decade”, said Huw Griffiths, the Survey scientist who led the research.

Africa in jeopardy

As if to hammer home the message, the International Union for the Conservation of Nature has just issued its latest warnings on imminent extinction. This international body has now rated 25,062 species as in danger of extinction out of a list of more than 87,000.

The latest list includes five of the six species of ash tree native to North America, some of them threatened by an invasive beetle infestation, helped by global warming, and five species of African antelope.

“Our activities as humans are pushing species to the brink so fast that it’s impossible for conservationists to assess the declines in real time,” says Inger Andersen, director general of the IUCN.

“Even those species that we thought were abundant and safe – such as antelopes in Africa or ash trees in the US – now face an imminent threat of extinction.” – Climate News Network

If marine extinction is not a reality for many species by the end of this century, scientists say, it will certainly be a strong probability.

LONDON, 9 October, 2017 – Mass marine extinction may be inevitable. If humans go on burning fossil fuels under the notorious “business as usual” scenario, then by 2100 they will have added so much carbon to the world’s oceans that a sixth mass extinction of marine species will follow, inexorably.

And even if the 197 nations that agreed in Paris in 2015 to take steps to limit global warming in fact do so, then by 2100 humans will have added 300 billion tons of carbon to the seas. And a US scientist has calculated that the critical threshold for mass extinction stands at 310 billion tons.

So in either case, the world will be condemned to, or at imminent risk of, a “great dying” of the kind that characterised the end of the geological period called the Permian, in which 95% of marine species vanished, or the Cretaceous era that witnessed the last of the dinosaurs.

Daniel Rothman, a geophysicist at the Massachusetts Institute of Technology, reports in the journal Science Advances that he worked through hundreds of scientific studies to identify 31 occasions of significant change in 542 million years in the planet’s carbon cycle – in which plants draw down carbon from the atmosphere and cycle it through the animal community and back into the atmosphere.

Happening now

For each event, including the five great mass extinctions in the geological record, he estimated the record of carbon preserved in the rocks, to find a predictable threshold at which catastrophe might be an outcome. Four of the five great extinction events lay beyond this threshold. He then considered the timescales of such extinction events to arrive at his modern-day danger zone figure of 310 billion tons.

And by 2100, unconstrained fossil fuel combustion may have tipped the planet into “unknown territory,” he says.

“This is not saying that disaster occurs the next day. It’s saying that, if left unchecked, the carbon cycle would move into a realm which would no longer be stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behaviour is associated with mass extinction.”

In effect, Professor Rothman has used a mathematical technique to predict an event many biologists believe is already happening. Pollution, the clearing of the wilderness and the disruption of habitat have already placed many species at risk. Global warming as a consequence of the combustion of fossil fuels will, they have repeatedly said, make a bad situation worse.

“Our activities as humans are pushing species to the brink so fast that it’s impossible for conservationists to assess the declines in real time. Even those species that we thought were abundant and safe now face an imminent threat of extinction”

Researchers have already begun to record local extinctions – the disappearance of once-familiar creatures from local landscapes – and climate change that will follow global warming could heighten the hazard for animals and plants already under stress.

And Professor Rothman’s warning came hard on the heels of several studies that indicate the dangerous impact of climate change.

Scientists from the University of Washington in Seattle warn that as the world’s waters warm, fish will have to migrate to surviveand those that cannot – the ones in lakes and river systems – could be at risk.

They report in the journal Nature Climate Change that they looked at available physiological data and climate predictions to see how 3,000 species in oceans and rivers would respond to warmer waters and to judge what the “breaking point” temperatures for any species would be.

Many losers

“Nowhere on Earth are fish spared from having to cope with climate change”, said senior author Julian Olden, professor of aquatic and fishery sciences. “Fish have unique challenges – they either have to make rapid movements to track their temperature requirements, or they will be forced to adapt quickly.”

But other creatures in the most extreme environments are affected too. British Antarctic Survey scientists report in Nature Climate Change that they used computer models to test a warming scenario for 900 species of marine invertebrates that live in the south polar seas.

Even a small warming of 0.4°C will cause unique local animals to change their distribution, and although some will fare well, overall there will be more losers than winners.

“While a few species might thrive at least during the early decades of warming, the future for a whole range of invertebrates from starfish to corals is bleak, and there’s nowhere to swim to, nowhere to hide when you’re sitting on the bottom of the world’s coldest and most southerly ocean and it’s getting warmer by the decade”, said Huw Griffiths, the Survey scientist who led the research.

Africa in jeopardy

As if to hammer home the message, the International Union for the Conservation of Nature has just issued its latest warnings on imminent extinction. This international body has now rated 25,062 species as in danger of extinction out of a list of more than 87,000.

The latest list includes five of the six species of ash tree native to North America, some of them threatened by an invasive beetle infestation, helped by global warming, and five species of African antelope.

“Our activities as humans are pushing species to the brink so fast that it’s impossible for conservationists to assess the declines in real time,” says Inger Andersen, director general of the IUCN.

“Even those species that we thought were abundant and safe – such as antelopes in Africa or ash trees in the US – now face an imminent threat of extinction.” – Climate News Network

Marine reserves protect against warming climate

Marine reserves can give protection against the impacts of climate change to both sea life and land-dwelling species, including humans.

LONDON, 7 June, 2017 – Protecting more of the world’s seas offers a double benefit, scientists say. Marine reserves protect fish and other sea creatures against exploitation and pollution. They can also help life both in the oceans and on land to cope with the growing impacts of a warmer climate.

Matt Rand, director of the Pew Bertarelli Ocean Legacy project, which supported part of the research, said: “Marine reserves are climate reserves.” 

An international study has found that reserves help marine ecosystems and people adapt to five harmful consequences of climate change: ocean acidification; sea-level rise; the increased intensity of storms; shifts in species distribution, and decreased productivity and availability of oxygen.

Reserves also can also help to increase the long-term storage of carbon from greenhouse gas emissions, especially in coastal wetlands, which helps to reduce the rate of climate change, the study found.

Published in the Proceedings of the National Academy of Sciences, it evaluated existing peer reviewed studies on the impact of marine reserves around the world.

Climate lens

The lead author, Professor Callum Roberts of the University of York, UK, said: “Many studies show that well-managed marine reserves can protect wildlife and support productive fisheries, but we wanted to explore this body of research through the lens of climate change to see whether these benefits could help ameliorate or slow its impacts.

“It was soon quite clear that they can offer the ocean ecosystem and people critical resilience benefits to rapid climate change.”

Only 3.5 % of the world’s oceans has so far been set aside for protection, with just 1.6 % given full protection from exploitation. International groups are working to raise the total to 10% by 2020.

Delegates to the International Union for the Conservation of Nature’s 2016 World Conservation Congress agreed that at least 30% of the oceans should be protected by 2030.

Stock recovery 

Scientists say marine reserves and marine protected areas (MPAs) protect coasts from sea-level rise and can help to sustain coastal wetlands, mudflats and coral reefs that can act to absorb the impact of storms and extreme weather.

They also help to offset declines in ocean and fisheries productivity caused by climate change, for example through the growing acidification of seawater and the reduction in plankton abundance.  

The reserves protect key coastal systems – mangroves, salt marshes and seagrasses – creating localised reductions in carbon dioxide concentrations and water acidity. And they can provide refuges for fish as they adjust their ranges to changing conditions. 

Previously published research revealed that marine reserves can promote the rapid recovery of exploited species and damaged habitats while safeguarding intact ecosystems. With fishing outlawed and other human activity limited, they can create very productive areas which allow exploited stocks and degraded habitats to recover.

“This study should be proof positive to decision makers that creating effectively managed marine reserves can deliver a multitude of benefits”

These benefits are greater in large, long-established, well-managed reserves that have full protection from activities such as fishing and oil and mineral extraction. Relative isolation from damaging human activities adds further conservation benefits.

The research shows that protecting more of the ocean will also improve the outlook for environmental recovery after greenhouse gas emissions have been brought under control.

It reinforces the IUCN’s argument that the UN ocean protection target should be raised from 10% to 30% of the oceans, which will require many more large-scale MPAs and protected areas beyond national jurisdiction.

Beth O’Leary, a co-author and a research fellow at the University of York, said: “We were keenly aware that marine reserves can increase species’ abundance and help alleviate food scarcity, but our evaluation showed reserves are a viable low-tech, cost-effective adaptation strategy.”

Matt Rand of Ocean Legacy said: “This study should be proof positive to decision makers that creating effectively managed marine reserves can deliver a multitude of benefits.” – Climate News Network 

Marine reserves can give protection against the impacts of climate change to both sea life and land-dwelling species, including humans.

LONDON, 7 June, 2017 – Protecting more of the world’s seas offers a double benefit, scientists say. Marine reserves protect fish and other sea creatures against exploitation and pollution. They can also help life both in the oceans and on land to cope with the growing impacts of a warmer climate.

Matt Rand, director of the Pew Bertarelli Ocean Legacy project, which supported part of the research, said: “Marine reserves are climate reserves.” 

An international study has found that reserves help marine ecosystems and people adapt to five harmful consequences of climate change: ocean acidification; sea-level rise; the increased intensity of storms; shifts in species distribution, and decreased productivity and availability of oxygen.

Reserves also can also help to increase the long-term storage of carbon from greenhouse gas emissions, especially in coastal wetlands, which helps to reduce the rate of climate change, the study found.

Published in the Proceedings of the National Academy of Sciences, it evaluated existing peer reviewed studies on the impact of marine reserves around the world.

Climate lens

The lead author, Professor Callum Roberts of the University of York, UK, said: “Many studies show that well-managed marine reserves can protect wildlife and support productive fisheries, but we wanted to explore this body of research through the lens of climate change to see whether these benefits could help ameliorate or slow its impacts.

“It was soon quite clear that they can offer the ocean ecosystem and people critical resilience benefits to rapid climate change.”

Only 3.5 % of the world’s oceans has so far been set aside for protection, with just 1.6 % given full protection from exploitation. International groups are working to raise the total to 10% by 2020.

Delegates to the International Union for the Conservation of Nature’s 2016 World Conservation Congress agreed that at least 30% of the oceans should be protected by 2030.

Stock recovery 

Scientists say marine reserves and marine protected areas (MPAs) protect coasts from sea-level rise and can help to sustain coastal wetlands, mudflats and coral reefs that can act to absorb the impact of storms and extreme weather.

They also help to offset declines in ocean and fisheries productivity caused by climate change, for example through the growing acidification of seawater and the reduction in plankton abundance.  

The reserves protect key coastal systems – mangroves, salt marshes and seagrasses – creating localised reductions in carbon dioxide concentrations and water acidity. And they can provide refuges for fish as they adjust their ranges to changing conditions. 

Previously published research revealed that marine reserves can promote the rapid recovery of exploited species and damaged habitats while safeguarding intact ecosystems. With fishing outlawed and other human activity limited, they can create very productive areas which allow exploited stocks and degraded habitats to recover.

“This study should be proof positive to decision makers that creating effectively managed marine reserves can deliver a multitude of benefits”

These benefits are greater in large, long-established, well-managed reserves that have full protection from activities such as fishing and oil and mineral extraction. Relative isolation from damaging human activities adds further conservation benefits.

The research shows that protecting more of the ocean will also improve the outlook for environmental recovery after greenhouse gas emissions have been brought under control.

It reinforces the IUCN’s argument that the UN ocean protection target should be raised from 10% to 30% of the oceans, which will require many more large-scale MPAs and protected areas beyond national jurisdiction.

Beth O’Leary, a co-author and a research fellow at the University of York, said: “We were keenly aware that marine reserves can increase species’ abundance and help alleviate food scarcity, but our evaluation showed reserves are a viable low-tech, cost-effective adaptation strategy.”

Matt Rand of Ocean Legacy said: “This study should be proof positive to decision makers that creating effectively managed marine reserves can deliver a multitude of benefits.” – Climate News Network 

Sea floor erosion causes coral reefs to sink

Coral reefs Molokini crater near Maui
Coral reefs Molokini crater near Maui

Five US coral reefs are sinking beneath the waves due to the erosion of the sea floor, robbing coastal communities of their natural storm barrier.

LONDON, 28 April, 2017 – The world’s coral reefs are not just in hot water and under threat from acid attack; they may even be getting out of their depth. New research around five US coral reefs shows that even as sea levels rise, the sea floor around the reefs is being eroded.

And coral growth simply may not be fast enough to keep up, which means that coastal communities in Florida, the Caribbean and Hawaii could become increasingly at risk from storms, waves and erosion.

The news comes close after revelations that great tracts of Australia’s Great Barrier Reef, like other coral colonies, have been devastated by bleaching, as ocean temperatures rise above the levels that corals – animals that live in symbiosis with algae – can tolerate, and researchers have warned that this could soon be happening to reefs almost everywhere, every year.

Coral under threat

There is already widespread alarm among marine scientists as the seas become measurably more acidic due to an increase in levels of carbon dioxide in the atmosphere, and this too poses a threat to corals everywhere.

But while researchers in the tropics had monitored the living reefs of the surface waters, hardly anybody had paid attention to the sea floor around the reefs.

Now, scientists of the US Geological Survey report in Biogeosciences that – possibly as a consequence of the degradation of the reefs of the Florida Keys, the US Virgin Islands and the Hawaiian island of Maui – the sea floor is being scoured of sand and sediments, just as sea levels continue to creep to a predicted rise of up to a metre by 2100.

Around Maui, they report, they measured the loss enough sand, rock and shell to fill the Empire State Building in New York 81 times over.

At current rates, by 2100 sea floor erosion could
increase water depths by two to eight times more than
what has been predicted from sea level rise alone”

This means that the seas along those coasts have become unexpectedly deep. Since tropical corals depend for nourishment on light photosynthesised by their algal partners at the surface, this raises yet another hazard: if the sea floor is falling at the same time as the seawater ceiling is going up, can corals grow fast enough to keep up?

Our measurements show that seafloor erosion has already caused water depths to increase to levels not predicted to occur until near the year 2100,” says Kimberly Yates, a biogeochemist at the USGS’s St Petersburg Coastal and Marine Science Centre, who led the research.

At current rates, by 2100 sea floor erosion could increase water depths by two to eight times more than what has been predicted from sea level rise alone.”

Healthy coral reefs are among the richest and most diverse habitats on the planet. They represent an immediate asset to human communities: they underwrite tourism and fisheries, and they deliver protection against storm surge and tsunami for around 200 million people in low-lying coastal communities.

Sea level rise presents a threat to communities along the coasts of all the inhabited continents, and coastal flooding could by 2100 be costing the world $100 trillion a year.

One group has calculated that money spent on protecting and restoring reefs would represent a bargain, at about one-twentieth the cost of artificial breakwaters.

Reefs in decline

The USGS team identify no specific cause for erosion around the reefs, but they point out that reefs worldwide are in decline because of coastal development, pollution, coral bleaching, disease and acidification.

They worked from seafloor measurements taken by the US government’s own National Oceanic and Atmospheric Administration between 1934 and 1982, and more recent surveys by the US Army Corps of Engineers and LIDAR data gathered by remote sensing. Across all five sites they examined, they found that the sea floor had become lower, in some cases by as much as 0.8 metres.

We saw lower rates of erosion – and even some localised increases in seafloor elevation – in areas that were protected, near refuges or distant from human population centres,” Dr Yates says. “But these were not significant enough to offset the ecosystem-wide pattern of erosion at each of our study sites.”
Climate News Network

Five US coral reefs are sinking beneath the waves due to the erosion of the sea floor, robbing coastal communities of their natural storm barrier.

LONDON, 28 April, 2017 – The world’s coral reefs are not just in hot water and under threat from acid attack; they may even be getting out of their depth. New research around five US coral reefs shows that even as sea levels rise, the sea floor around the reefs is being eroded.

And coral growth simply may not be fast enough to keep up, which means that coastal communities in Florida, the Caribbean and Hawaii could become increasingly at risk from storms, waves and erosion.

The news comes close after revelations that great tracts of Australia’s Great Barrier Reef, like other coral colonies, have been devastated by bleaching, as ocean temperatures rise above the levels that corals – animals that live in symbiosis with algae – can tolerate, and researchers have warned that this could soon be happening to reefs almost everywhere, every year.

Coral under threat

There is already widespread alarm among marine scientists as the seas become measurably more acidic due to an increase in levels of carbon dioxide in the atmosphere, and this too poses a threat to corals everywhere.

But while researchers in the tropics had monitored the living reefs of the surface waters, hardly anybody had paid attention to the sea floor around the reefs.

Now, scientists of the US Geological Survey report in Biogeosciences that – possibly as a consequence of the degradation of the reefs of the Florida Keys, the US Virgin Islands and the Hawaiian island of Maui – the sea floor is being scoured of sand and sediments, just as sea levels continue to creep to a predicted rise of up to a metre by 2100.

Around Maui, they report, they measured the loss enough sand, rock and shell to fill the Empire State Building in New York 81 times over.

At current rates, by 2100 sea floor erosion could
increase water depths by two to eight times more than
what has been predicted from sea level rise alone”

This means that the seas along those coasts have become unexpectedly deep. Since tropical corals depend for nourishment on light photosynthesised by their algal partners at the surface, this raises yet another hazard: if the sea floor is falling at the same time as the seawater ceiling is going up, can corals grow fast enough to keep up?

Our measurements show that seafloor erosion has already caused water depths to increase to levels not predicted to occur until near the year 2100,” says Kimberly Yates, a biogeochemist at the USGS’s St Petersburg Coastal and Marine Science Centre, who led the research.

At current rates, by 2100 sea floor erosion could increase water depths by two to eight times more than what has been predicted from sea level rise alone.”

Healthy coral reefs are among the richest and most diverse habitats on the planet. They represent an immediate asset to human communities: they underwrite tourism and fisheries, and they deliver protection against storm surge and tsunami for around 200 million people in low-lying coastal communities.

Sea level rise presents a threat to communities along the coasts of all the inhabited continents, and coastal flooding could by 2100 be costing the world $100 trillion a year.

One group has calculated that money spent on protecting and restoring reefs would represent a bargain, at about one-twentieth the cost of artificial breakwaters.

Reefs in decline

The USGS team identify no specific cause for erosion around the reefs, but they point out that reefs worldwide are in decline because of coastal development, pollution, coral bleaching, disease and acidification.

They worked from seafloor measurements taken by the US government’s own National Oceanic and Atmospheric Administration between 1934 and 1982, and more recent surveys by the US Army Corps of Engineers and LIDAR data gathered by remote sensing. Across all five sites they examined, they found that the sea floor had become lower, in some cases by as much as 0.8 metres.

We saw lower rates of erosion – and even some localised increases in seafloor elevation – in areas that were protected, near refuges or distant from human population centres,” Dr Yates says. “But these were not significant enough to offset the ecosystem-wide pattern of erosion at each of our study sites.”
Climate News Network

World’s reefs damaged beyond repair

reefs great barrier reef
reefs great barrier reef

Australia’s Great Barrier Reef and reefs in the Maldives have been dangerously weakened by coral bleaching caused by global warming and El Niño events.

LONDON, 24 March, 2017 The Great Barrier Reef, one of the wonders of the Pacific Ocean, may never fully recover from the combined effects of global warming and an El Niño year, according to a new study in one of the world’s leading science journals.

And a second study, in a second journal, warns that increased sea surface temperatures have also caused both a major die-off of corals and the collapse of reef growth rates in the Maldives, in the Indian Ocean.

Corals are very sensitive to ocean temperatures, and in unusually hot years and these have recurred naturally and cyclically since long before humans started burning coal, oil and gas, to accelerate the build-up of greenhouse gases in the atmosphere – the corals react to stress by bleaching. That is, they eject the photosynthesising algae that live with them in symbiosis, to the advantage of both creatures.

Hotter oceans

But the world’s oceans are becoming hotter anyway, because of global warming driven by greenhouse gas concentrations in the atmosphere. The seas are becoming ever more acidic as atmospheric carbon dioxide reacts with the water.

And the periodic return of a blister of oceanic heat in the eastern Pacific called El Niño – Spanish for “The Child”, because it becomes most visible around Christmastime – has begun to put the world’s reefs at risk. The El Niño of 2015-16 triggered a massive episode of bleaching throughout the tropics. And, Australian researchers say in Nature, the bleaching continues.

We’re hoping that the next two to three weeks will cool off quickly, and this year’s bleaching won’t be anything like last year. The severity of the 2016 bleaching was off the chart,” says Terry Hughes, of Australia’s Centre of Excellence for Coral Reef Studies, at James Cook University in Queensland.

It was the third major bleaching to affect the Great Barrier Reef, following earlier heatwaves in 1998 and 2002. Now we’re gearing up to study a potential number four.

We have now assessed whether past exposure to bleaching in 1998 and 2002 made reefs any more tolerant in 2016. Sadly, we found no evidence that past bleaching makes the corals any tougher.”

Recovery from similar past disturbances
in the Maldives has taken 10-15 years, but major
bleaching events are predicted to become
far more frequent than this”

Researchers have already warned that, unless there is urgent action to limit global warming by drastically reducing dependence on fossil fuel as an energy source, severe bleaching could damage 99% of the world’s coral reefs.

The reefs are among the richest ecosystems on the planet, and they provide vital coastal protection for human settlements as well as a source of sustainable protein for human economies.

It broke my heart to see so many corals dying on northern reefs on the Great Barrier Reef in 2016,” says Professor Hughes. “With rising temperatures due to global warming, it’s only a matter of time before we see more of these events. A fourth event after only one year is a major blow to the Reef.”

British scientists saw much the same devastation from the same El Niño bleaching around the Maldives in the Indian Ocean, they write in Scientific Reports journal. And the big question now is: how quickly can the Indian Ocean reefs recover?

Growth rate of reefs

Recovery from similar past disturbances in the Maldives has taken 10-15 years, but major bleaching events are predicted to become far more frequent than this. If this is the case it could lead to long-term loss of reef growth and so limit the coastal protection and habitat services these reefs presently provide,” says Chris Perry, professor of physical geography at the University of Exeter, UK.

The most alarming aspect of this coral die-off event is that it has led to a rapid and very large decline in the growth rate of the reefs.

This in turn has major implications not only for the capacity of these reefs to match any increases in sea-level, but because it is also likely to lead to a loss of the surface structure of the reefs that is so critical for supporting fish species diversity and abundance.” Climate News Network

Australia’s Great Barrier Reef and reefs in the Maldives have been dangerously weakened by coral bleaching caused by global warming and El Niño events.

LONDON, 24 March, 2017 The Great Barrier Reef, one of the wonders of the Pacific Ocean, may never fully recover from the combined effects of global warming and an El Niño year, according to a new study in one of the world’s leading science journals.

And a second study, in a second journal, warns that increased sea surface temperatures have also caused both a major die-off of corals and the collapse of reef growth rates in the Maldives, in the Indian Ocean.

Corals are very sensitive to ocean temperatures, and in unusually hot years and these have recurred naturally and cyclically since long before humans started burning coal, oil and gas, to accelerate the build-up of greenhouse gases in the atmosphere – the corals react to stress by bleaching. That is, they eject the photosynthesising algae that live with them in symbiosis, to the advantage of both creatures.

Hotter oceans

But the world’s oceans are becoming hotter anyway, because of global warming driven by greenhouse gas concentrations in the atmosphere. The seas are becoming ever more acidic as atmospheric carbon dioxide reacts with the water.

And the periodic return of a blister of oceanic heat in the eastern Pacific called El Niño – Spanish for “The Child”, because it becomes most visible around Christmastime – has begun to put the world’s reefs at risk. The El Niño of 2015-16 triggered a massive episode of bleaching throughout the tropics. And, Australian researchers say in Nature, the bleaching continues.

We’re hoping that the next two to three weeks will cool off quickly, and this year’s bleaching won’t be anything like last year. The severity of the 2016 bleaching was off the chart,” says Terry Hughes, of Australia’s Centre of Excellence for Coral Reef Studies, at James Cook University in Queensland.

It was the third major bleaching to affect the Great Barrier Reef, following earlier heatwaves in 1998 and 2002. Now we’re gearing up to study a potential number four.

We have now assessed whether past exposure to bleaching in 1998 and 2002 made reefs any more tolerant in 2016. Sadly, we found no evidence that past bleaching makes the corals any tougher.”

Recovery from similar past disturbances
in the Maldives has taken 10-15 years, but major
bleaching events are predicted to become
far more frequent than this”

Researchers have already warned that, unless there is urgent action to limit global warming by drastically reducing dependence on fossil fuel as an energy source, severe bleaching could damage 99% of the world’s coral reefs.

The reefs are among the richest ecosystems on the planet, and they provide vital coastal protection for human settlements as well as a source of sustainable protein for human economies.

It broke my heart to see so many corals dying on northern reefs on the Great Barrier Reef in 2016,” says Professor Hughes. “With rising temperatures due to global warming, it’s only a matter of time before we see more of these events. A fourth event after only one year is a major blow to the Reef.”

British scientists saw much the same devastation from the same El Niño bleaching around the Maldives in the Indian Ocean, they write in Scientific Reports journal. And the big question now is: how quickly can the Indian Ocean reefs recover?

Growth rate of reefs

Recovery from similar past disturbances in the Maldives has taken 10-15 years, but major bleaching events are predicted to become far more frequent than this. If this is the case it could lead to long-term loss of reef growth and so limit the coastal protection and habitat services these reefs presently provide,” says Chris Perry, professor of physical geography at the University of Exeter, UK.

The most alarming aspect of this coral die-off event is that it has led to a rapid and very large decline in the growth rate of the reefs.

This in turn has major implications not only for the capacity of these reefs to match any increases in sea-level, but because it is also likely to lead to a loss of the surface structure of the reefs that is so critical for supporting fish species diversity and abundance.” Climate News Network