Tag Archives: Coral

Ocean heat waves damage reefs and kill coral

Heat extremes on land can kill. Ocean heat waves can devastate coral reefs and other ecosystems – and these too are on the increase.

LONDON, 12 August, 2019 − Heat extremes on the high seas are on the increase, with ocean heat waves disturbing ecosystems in two hemispheres and two great oceans, US scientists report.

And these same sudden rises in sea temperatures don’t just damage coral reefs, they kill the corals and start the process of reef decay, according to a separate study by Australian researchers.

Andrew Pershing of the Gulf of Maine Research Institute and colleagues report in the Proceedings of the National Academy of Sciences that they examined data from 65 marine ecosystems over the years 1854 to 2018 to work out how frequently ocean temperatures suddenly rose to unexpected levels.

They found such deviations from the average in the Arctic, North Atlantic, eastern Pacific and off the Australian coasts. They expected to find evidence of occasional hot flushes. But they did not expect to find quite so many.

“Severe marine heatwave events can have a far more severe impact than coral bleaching – the animal dies and its underlying skeleton is all that remains”

“Across the 65 ecosystems we examined, we expected about six or seven of them would experience these ‘surprises’ each year,” Dr Pershing said. “Instead, we’ve seen an average of 12 ecosystems experiencing these warming events each year over the past seven years, including a high of 23 ‘surprises’ in 2016.”

Intense and sudden changes in sea temperatures affect crustaceans, algae, corals, molluscs and many millions of humans who depend on the oceans for income. And a new study by researchers from Australian universities reports that even a rise of 0.5°C is reflected in deaths during an outbreak of coral bleaching.

Corals live in symbiosis with algae: ocean warming periodically disturbs this normally beneficial relationship. The coral animals evert (turn out) the algae and once-lurid reefs will bleach, and become more vulnerable to disease.

Corals support the world’s richest ocean ecosystems so such changes are a challenge, both to the survival of biodiversity and to local incomes from the tourism linked to the beauty of the reefs.

Very warm water

“What we are seeing is that severe marine heatwave events can have a far more severe impact than coral bleaching: the water temperatures are so warm that that the coral animal doesn’t bleach – in terms of a loss of its symbiosis – the animal dies and its underlying skeleton is all that remains,” said Tracy Ainsworth of the University of New South Wales.

The researchers report in the journal Current Biology that they used computer tomography scanning techniques to explore the marine destruction. In 2016, more than 30% of the northern part of Australia’s Great Barrier Reef experienced temperatures higher than those in which corals can survive.

“We find that the skeleton is immediately overgrown by rapid growth of algae and bacteria,” said Bill Leggat of the University of Newcastle, a co-author.

“We show that this process is devastating not just for the animal tissue but also for the skeleton that is left behind, which is rapidly eroded and weakened.” − Climate News Network

Heat extremes on land can kill. Ocean heat waves can devastate coral reefs and other ecosystems – and these too are on the increase.

LONDON, 12 August, 2019 − Heat extremes on the high seas are on the increase, with ocean heat waves disturbing ecosystems in two hemispheres and two great oceans, US scientists report.

And these same sudden rises in sea temperatures don’t just damage coral reefs, they kill the corals and start the process of reef decay, according to a separate study by Australian researchers.

Andrew Pershing of the Gulf of Maine Research Institute and colleagues report in the Proceedings of the National Academy of Sciences that they examined data from 65 marine ecosystems over the years 1854 to 2018 to work out how frequently ocean temperatures suddenly rose to unexpected levels.

They found such deviations from the average in the Arctic, North Atlantic, eastern Pacific and off the Australian coasts. They expected to find evidence of occasional hot flushes. But they did not expect to find quite so many.

“Severe marine heatwave events can have a far more severe impact than coral bleaching – the animal dies and its underlying skeleton is all that remains”

“Across the 65 ecosystems we examined, we expected about six or seven of them would experience these ‘surprises’ each year,” Dr Pershing said. “Instead, we’ve seen an average of 12 ecosystems experiencing these warming events each year over the past seven years, including a high of 23 ‘surprises’ in 2016.”

Intense and sudden changes in sea temperatures affect crustaceans, algae, corals, molluscs and many millions of humans who depend on the oceans for income. And a new study by researchers from Australian universities reports that even a rise of 0.5°C is reflected in deaths during an outbreak of coral bleaching.

Corals live in symbiosis with algae: ocean warming periodically disturbs this normally beneficial relationship. The coral animals evert (turn out) the algae and once-lurid reefs will bleach, and become more vulnerable to disease.

Corals support the world’s richest ocean ecosystems so such changes are a challenge, both to the survival of biodiversity and to local incomes from the tourism linked to the beauty of the reefs.

Very warm water

“What we are seeing is that severe marine heatwave events can have a far more severe impact than coral bleaching: the water temperatures are so warm that that the coral animal doesn’t bleach – in terms of a loss of its symbiosis – the animal dies and its underlying skeleton is all that remains,” said Tracy Ainsworth of the University of New South Wales.

The researchers report in the journal Current Biology that they used computer tomography scanning techniques to explore the marine destruction. In 2016, more than 30% of the northern part of Australia’s Great Barrier Reef experienced temperatures higher than those in which corals can survive.

“We find that the skeleton is immediately overgrown by rapid growth of algae and bacteria,” said Bill Leggat of the University of Newcastle, a co-author.

“We show that this process is devastating not just for the animal tissue but also for the skeleton that is left behind, which is rapidly eroded and weakened.” − Climate News Network

Desert dust cools vulnerable Red Sea corals

Desert dust whipped up by strong winds and volcanic aerosols alter the climate as the world warms.

LONDON, 20 May, 2019 − Located between two of the hottest and driest places on earth, the Red Sea is being protected by the desert dust that the winds whip up in the lands that surround it.

The dust so effectively blocks out the sun that the Red Sea is kept cool, saving its coral reefs from dangerous overheating and providing nutrients that keep its waters healthy.

The sea lies between North Africa and the Arabian Peninsula, the world’s largest region for generating dust, which strong summer winds pump down a narrowing mountain-fringed passage that forces it into the air over the widest southern portion of the sea.

The research, carried out by the King Abdullah University of Science and Technology (KAUST, the first mixed-gender university in Saudi Arabia), is part of a wider programme to discover the effect of dust in the atmosphere in changing the weather and climate.

Cooling influence

Volcanic eruptions can have a significant effect by ejecting aerosol particles into the upper atmosphere where they block out some of the sun’s rays, radiating heat back into space, a process known as radiative forcing. Dust blown from deserts also has a strong regional effect.

Sergey Osipov, postdoctoral fellow and co-author with his supervisor Georgiy Stenchikov of the Red Sea study, said: “We show that summer conditions over the Red Sea produce the world’s largest aerosol radiative forcing, and yet the impact of dust on the Red Sea was never studied − it was simply unknown.”

A surprising finding relates to biological productivity. “Dust deposition adds nutrients,” he said. “However, we find that dust radiative forcing slows down the Red Sea circulation and reduces the main nutrient supply to the Red Sea through the Bab-el Mandeb strait. The net effect on overall bioproductivity remains to be established.”

Volcanoes’ impact

Large volcanic eruptions, such as the 1991 eruption of Mount Pinatubo in the Philippines, inject vast amounts of sulphur dioxide into the upper atmosphere, where it is converted into tiny sulphate aerosol droplets.

These sulphate aerosols spread around the globe, exerting a strong radiative forcing effect, and reducing global temperature for nearly two years by 0.6°C before the dust finally settled back to earth.

The university is using its supercomputer to look at the effects of dust on the whole of the region, which is extremely arid and hurls large quantities of dust into the atmosphere, potentially changing weather patterns. It is important for future climate projections to predict droughts and famines that might cause mass migrations of the region’s peoples.

Another KAUST climate modelling study reveals potential changes in the West African monsoon caused by global warming and the dust it creates.

African monsoon

Home to more than 300 million people, West Africa has an agriculture-based economy: its food security is affected by the monsoon, making it important to understand present and future variability.

A KAUST doctoral student, Jerry Raj, simulated the monsoon under present and future climates. The results show that West Africa will become generally hotter as a result of climate change – with higher areas of the Sahel and Western Sahara projected to have increased temperatures of 4°C or more by the century’s end.

The simulations also indicate precipitation increases over the equatorial Atlantic and the Guinean coast, yet the southern Sahel appears drier. At the same time, Western Sahara experiences a moderate increase of rain.

Finally, and crucially for farmers sowing crops, the onset of the monsoon occurs earlier over the eastern part of the region, but is delayed over the western part.

“Strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood”

“Climate projection is the first and the most important step toward adaptation policies aimed at avoiding damaging environmental and socio-economic consequences,” Raj said.

Another doctoral student, Evgeniya Predybaylo, is looking further afield at the impact of large volcanic eruptions on a major natural climate variation, the El Niño‐Southern Oscillation.

This periodic warm water flush in the Pacific drives extreme weather events like hurricane and tornado activity as well as coral bleaching. It also causes floods and droughts and disrupts fish populations.

Forecasting El Niño events would help people prepare for possible collapses of fish stocks and agricultural crises, says Predybaylo. However, El Niño is notoriously difficult to predict, but volcanic eruptions may play a role.

El Niño link?

“Interestingly, strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood,” says Predybaylo.

She says the response to volcanoes partly depends on the eruption’s seasonal timing: summer eruptions induce stronger El Niños than winter or spring eruptions.
Ocean conditions prevailing at the time of the eruption also play a role.

“Radiative forcing following large eruptions generally results in surface cooling,” explains Predybaylo. “However, the tropical Pacific often shows a warming response. We show that this is due to uneven equatorial ocean cooling and changes in trade winds.”

“A Pinatubo-size eruption may partially determine the phase, magnitude and duration of El Niño, but it is crucial to account for the eruption season and ocean conditions just before the eruption,” she says. − Climate News Network

Desert dust whipped up by strong winds and volcanic aerosols alter the climate as the world warms.

LONDON, 20 May, 2019 − Located between two of the hottest and driest places on earth, the Red Sea is being protected by the desert dust that the winds whip up in the lands that surround it.

The dust so effectively blocks out the sun that the Red Sea is kept cool, saving its coral reefs from dangerous overheating and providing nutrients that keep its waters healthy.

The sea lies between North Africa and the Arabian Peninsula, the world’s largest region for generating dust, which strong summer winds pump down a narrowing mountain-fringed passage that forces it into the air over the widest southern portion of the sea.

The research, carried out by the King Abdullah University of Science and Technology (KAUST, the first mixed-gender university in Saudi Arabia), is part of a wider programme to discover the effect of dust in the atmosphere in changing the weather and climate.

Cooling influence

Volcanic eruptions can have a significant effect by ejecting aerosol particles into the upper atmosphere where they block out some of the sun’s rays, radiating heat back into space, a process known as radiative forcing. Dust blown from deserts also has a strong regional effect.

Sergey Osipov, postdoctoral fellow and co-author with his supervisor Georgiy Stenchikov of the Red Sea study, said: “We show that summer conditions over the Red Sea produce the world’s largest aerosol radiative forcing, and yet the impact of dust on the Red Sea was never studied − it was simply unknown.”

A surprising finding relates to biological productivity. “Dust deposition adds nutrients,” he said. “However, we find that dust radiative forcing slows down the Red Sea circulation and reduces the main nutrient supply to the Red Sea through the Bab-el Mandeb strait. The net effect on overall bioproductivity remains to be established.”

Volcanoes’ impact

Large volcanic eruptions, such as the 1991 eruption of Mount Pinatubo in the Philippines, inject vast amounts of sulphur dioxide into the upper atmosphere, where it is converted into tiny sulphate aerosol droplets.

These sulphate aerosols spread around the globe, exerting a strong radiative forcing effect, and reducing global temperature for nearly two years by 0.6°C before the dust finally settled back to earth.

The university is using its supercomputer to look at the effects of dust on the whole of the region, which is extremely arid and hurls large quantities of dust into the atmosphere, potentially changing weather patterns. It is important for future climate projections to predict droughts and famines that might cause mass migrations of the region’s peoples.

Another KAUST climate modelling study reveals potential changes in the West African monsoon caused by global warming and the dust it creates.

African monsoon

Home to more than 300 million people, West Africa has an agriculture-based economy: its food security is affected by the monsoon, making it important to understand present and future variability.

A KAUST doctoral student, Jerry Raj, simulated the monsoon under present and future climates. The results show that West Africa will become generally hotter as a result of climate change – with higher areas of the Sahel and Western Sahara projected to have increased temperatures of 4°C or more by the century’s end.

The simulations also indicate precipitation increases over the equatorial Atlantic and the Guinean coast, yet the southern Sahel appears drier. At the same time, Western Sahara experiences a moderate increase of rain.

Finally, and crucially for farmers sowing crops, the onset of the monsoon occurs earlier over the eastern part of the region, but is delayed over the western part.

“Strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood”

“Climate projection is the first and the most important step toward adaptation policies aimed at avoiding damaging environmental and socio-economic consequences,” Raj said.

Another doctoral student, Evgeniya Predybaylo, is looking further afield at the impact of large volcanic eruptions on a major natural climate variation, the El Niño‐Southern Oscillation.

This periodic warm water flush in the Pacific drives extreme weather events like hurricane and tornado activity as well as coral bleaching. It also causes floods and droughts and disrupts fish populations.

Forecasting El Niño events would help people prepare for possible collapses of fish stocks and agricultural crises, says Predybaylo. However, El Niño is notoriously difficult to predict, but volcanic eruptions may play a role.

El Niño link?

“Interestingly, strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood,” says Predybaylo.

She says the response to volcanoes partly depends on the eruption’s seasonal timing: summer eruptions induce stronger El Niños than winter or spring eruptions.
Ocean conditions prevailing at the time of the eruption also play a role.

“Radiative forcing following large eruptions generally results in surface cooling,” explains Predybaylo. “However, the tropical Pacific often shows a warming response. We show that this is due to uneven equatorial ocean cooling and changes in trade winds.”

“A Pinatubo-size eruption may partially determine the phase, magnitude and duration of El Niño, but it is crucial to account for the eruption season and ocean conditions just before the eruption,” she says. − Climate News Network

Paris climate pledge would help world fishing

Honouring the Paris climate pledge would provide a fair catch for the world’s fishing fleets. Warm up the oceans, though, and everyone loses.

LONDON, 12 March, 2019 – Canadian scientists have worked out the way to make the most of the world’s fish stocks: by honouring the Paris climate pledge.

Seagoing nations could raise revenues for their fishing fleets, put more seafood on the table and protect the most valuable commercial fish stocks simply by doing what they had promised in 2015 to do anyway.

The key is the historic agreement reached then in Paris by 195 nations, to take steps to limit average global warming to “well below” a total of 2°C above the long-term average for most of human history, and to do this by 2100.

In the last century or so the global temperature has already risen by around 1°C, as a consequence of ever-increasing combustion of fossil fuels that emit greenhouse gases into the atmosphere.

“The largest gains will occur in developing country waters … which are at the greatest risk due to warming temperatures”

But although the world agreed its ideal target, the action so far leaves it on course for a potentially catastrophic rise of 3.5°C by the end of the century.

“Achieving the Agreement’s target could increase global fisheries revenues by $4.6 billion annually, seafood workers’ income by $3.7 bn and reduce household seafood expenditures by $5.4 bn,” said Rashid Sumaila, of the University of British Columbia’s Institute for Oceans and Fisheries.

“The largest gains will occur in developing country waters, such as Kiribati, the Maldives and Indonesia, which are at the greatest risk due to warming temperatures and rely the most on fish for food security, incomes and employment.”

What the researchers did – they explain their approach in the journal Science Advances – was to match what the computer forecasts said the Paris target would deliver, with what might happen if the world went on burning oil, coal and gas under the notorious business-as-usual scenario.

Impacts on ecosystems

They looked at the impact of less or more warming on 381 marine species, including the 10 that generate the most money, and they included ecosystem consequences as well as the economic payoff promised by the Paris target.

Their conclusion is that three-fourths of maritime countries would benefit, with the largest gains to be made by the developing nations.

Under the Paris scenario, the total mass of the fish species that generate the highest revenues would increase globally by 6.5%, with an 8.4% increase in the waters of developing countries. Overall, developed countries would see a marginal fall of 0.4%.

The Paris option would see an additional 3.3 million tonnes landed sustainably every year, compared with the business-as-usual scenario.

Conservation also needed

The British Columbia scientists are not the first to make the case for Paris in terms of fishery revenues: US and Japanese scientists looked at the same problem last year and concluded that the Paris option – matched by careful conservation approaches – could yield more fish for the hungry, and more revenues for the fishermen, if the ocean temperatures were kept from rising too dangerously.

But all the signals so far are ominous. A warmer world means a stormier one and greater danger for fishing fleets. More carbon dioxide in the atmosphere means ever more acidic seas, which seems to affect fish behaviour and threaten marine habitats such as coral reefs and kelp forests.

The same rise in carbon dioxide will warm the oceans and drive fish to migrate. Overall, humans have already left the seas diminished, and worse could be on the way. Fishing and seafood support an estimated 260 million full-time and part-time jobs worldwide.

Many to benefit

The Science Advances study is a reminder that while change is inexorable, the worst need not be inevitable. All continents except Europe would benefit from implementation of the Paris Agreement.

But as fish move towards the poles, countries in northern Europe might benefit from greater choice in their waters, and losses in the overall catch might be buffered by hjgher prices for those fish actually landed.

Russia could see catches reduced by as much as 25% under the 1.5°C target rather than the 3.5°C forecast. “However a projected 19% increase in fish prices, known as the price effect, should result in a negligible loss of less than 2% in fisheries revenues in Russia,” said William Cheung, one of the co-authors, of the University of British Columbia.

“Conversely, for the US fishing revenues are expected to decrease by 8% due to price effects but will be offset by a 21% increase in catch potential.” – Climate News Network

Honouring the Paris climate pledge would provide a fair catch for the world’s fishing fleets. Warm up the oceans, though, and everyone loses.

LONDON, 12 March, 2019 – Canadian scientists have worked out the way to make the most of the world’s fish stocks: by honouring the Paris climate pledge.

Seagoing nations could raise revenues for their fishing fleets, put more seafood on the table and protect the most valuable commercial fish stocks simply by doing what they had promised in 2015 to do anyway.

The key is the historic agreement reached then in Paris by 195 nations, to take steps to limit average global warming to “well below” a total of 2°C above the long-term average for most of human history, and to do this by 2100.

In the last century or so the global temperature has already risen by around 1°C, as a consequence of ever-increasing combustion of fossil fuels that emit greenhouse gases into the atmosphere.

“The largest gains will occur in developing country waters … which are at the greatest risk due to warming temperatures”

But although the world agreed its ideal target, the action so far leaves it on course for a potentially catastrophic rise of 3.5°C by the end of the century.

“Achieving the Agreement’s target could increase global fisheries revenues by $4.6 billion annually, seafood workers’ income by $3.7 bn and reduce household seafood expenditures by $5.4 bn,” said Rashid Sumaila, of the University of British Columbia’s Institute for Oceans and Fisheries.

“The largest gains will occur in developing country waters, such as Kiribati, the Maldives and Indonesia, which are at the greatest risk due to warming temperatures and rely the most on fish for food security, incomes and employment.”

What the researchers did – they explain their approach in the journal Science Advances – was to match what the computer forecasts said the Paris target would deliver, with what might happen if the world went on burning oil, coal and gas under the notorious business-as-usual scenario.

Impacts on ecosystems

They looked at the impact of less or more warming on 381 marine species, including the 10 that generate the most money, and they included ecosystem consequences as well as the economic payoff promised by the Paris target.

Their conclusion is that three-fourths of maritime countries would benefit, with the largest gains to be made by the developing nations.

Under the Paris scenario, the total mass of the fish species that generate the highest revenues would increase globally by 6.5%, with an 8.4% increase in the waters of developing countries. Overall, developed countries would see a marginal fall of 0.4%.

The Paris option would see an additional 3.3 million tonnes landed sustainably every year, compared with the business-as-usual scenario.

Conservation also needed

The British Columbia scientists are not the first to make the case for Paris in terms of fishery revenues: US and Japanese scientists looked at the same problem last year and concluded that the Paris option – matched by careful conservation approaches – could yield more fish for the hungry, and more revenues for the fishermen, if the ocean temperatures were kept from rising too dangerously.

But all the signals so far are ominous. A warmer world means a stormier one and greater danger for fishing fleets. More carbon dioxide in the atmosphere means ever more acidic seas, which seems to affect fish behaviour and threaten marine habitats such as coral reefs and kelp forests.

The same rise in carbon dioxide will warm the oceans and drive fish to migrate. Overall, humans have already left the seas diminished, and worse could be on the way. Fishing and seafood support an estimated 260 million full-time and part-time jobs worldwide.

Many to benefit

The Science Advances study is a reminder that while change is inexorable, the worst need not be inevitable. All continents except Europe would benefit from implementation of the Paris Agreement.

But as fish move towards the poles, countries in northern Europe might benefit from greater choice in their waters, and losses in the overall catch might be buffered by hjgher prices for those fish actually landed.

Russia could see catches reduced by as much as 25% under the 1.5°C target rather than the 3.5°C forecast. “However a projected 19% increase in fish prices, known as the price effect, should result in a negligible loss of less than 2% in fisheries revenues in Russia,” said William Cheung, one of the co-authors, of the University of British Columbia.

“Conversely, for the US fishing revenues are expected to decrease by 8% due to price effects but will be offset by a 21% increase in catch potential.” – Climate News Network

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