Tag Archives: Ocean acidification

Oceanic carbon uptake could falter

What does oceanic carbon uptake achieve? Greenhouse gas that sinks below the waves slows global warming a little and makes the water more acidic.

LONDON, 20 March, 2019 − Scientists can now put a measure to the role of the waves as a climate shock absorber: they estimate that oceanic carbon uptake by the deep blue seas has consumed 34 billion tonnes of man-made carbon from the atmosphere between the years 1994 and 2007.

This is just about 31% of all the carbon emitted in that time by car exhausts, power station chimneys, aircraft, ships, tractors and scorched forest, as human economies expand and ever more fossil fuel is consumed.

This confident figure is based on a global survey of the chemistry and other physical properties of the ocean by scientists from seven nations on more than 50 research cruises, taking measurements of the ocean from the surface to a depth of six kilometres.

The researchers report in the journal Science that they already had the results of a global carbon survey of the oceans conducted at the close of the last century, and had calculated that from the dawn of the Industrial Revolution – when humans started using coal, and then oil and gas – to 1994, the oceans had already absorbed 118 billion tonnes.

“The marine sink does not just respond to the increase in atmospheric CO2. Its substantial sensitivity to climate variations suggests a significant potential for feedbacks”

For the latest exercise, they developed a statistical tool that helped them make the distinction between the man-made and the natural atmospheric carbon dioxide always found dissolved in water.

The good news is that the ocean remains for the moment a stable component of the planet’s carbon budget: overall, as more man-made carbon is emitted from exhausts and chimneys, the ocean takes up proportionally more.

The bad news is that this may not go on for ever. At some point, the planet’s seas could become saturated with carbon, leaving ever more in the atmosphere to accelerate global warming to ever more alarming temperatures.

And there is a second unhappy consequence: the more carbon dioxide absorbed by the oceans, the more the sea shifts towards a weak solution of carbonic acid, with potentially calamitous consequences both for marine life and for commercial fisheries.

Research like this is essentially of academic interest: it adds precision to the big picture of a vast ocean that absorbs carbon dioxide, and overturning currents that take it to great depths, and out of atmospheric circulation.

An active moderator

But it is also a reminder that the ocean plays an active role in moderating planetary temperatures, absorbing ever greater quantities of heat and responding with fiercer levels of energy.

It also confirms that although, on average, the high seas are responding to atmospheric change as expected, different ocean basins can vary: the North Atlantic actually absorbed 20% less CO2 than expected between 1994 and 2007, probably thanks to the slowing of the North Atlantic Meridional Overturning Circulation at the time.

And, the researchers say, the acidification of the oceans is on the increase, to depths of 3000 metres. The next step is to understand a little better the interplay between ocean, atmosphere and human emissions of greenhouse gases.

“We learned that the marine sink does not just respond to the increase in atmospheric CO2,” said Nicolas Gruber of the Swiss Federal Institute of Technology, always known as ETH Zurich, who led the study.

“Its substantial sensitivity to climate variations suggests a significant potential for feedbacks with the ongoing change in climate.” − Climate News Network

What does oceanic carbon uptake achieve? Greenhouse gas that sinks below the waves slows global warming a little and makes the water more acidic.

LONDON, 20 March, 2019 − Scientists can now put a measure to the role of the waves as a climate shock absorber: they estimate that oceanic carbon uptake by the deep blue seas has consumed 34 billion tonnes of man-made carbon from the atmosphere between the years 1994 and 2007.

This is just about 31% of all the carbon emitted in that time by car exhausts, power station chimneys, aircraft, ships, tractors and scorched forest, as human economies expand and ever more fossil fuel is consumed.

This confident figure is based on a global survey of the chemistry and other physical properties of the ocean by scientists from seven nations on more than 50 research cruises, taking measurements of the ocean from the surface to a depth of six kilometres.

The researchers report in the journal Science that they already had the results of a global carbon survey of the oceans conducted at the close of the last century, and had calculated that from the dawn of the Industrial Revolution – when humans started using coal, and then oil and gas – to 1994, the oceans had already absorbed 118 billion tonnes.

“The marine sink does not just respond to the increase in atmospheric CO2. Its substantial sensitivity to climate variations suggests a significant potential for feedbacks”

For the latest exercise, they developed a statistical tool that helped them make the distinction between the man-made and the natural atmospheric carbon dioxide always found dissolved in water.

The good news is that the ocean remains for the moment a stable component of the planet’s carbon budget: overall, as more man-made carbon is emitted from exhausts and chimneys, the ocean takes up proportionally more.

The bad news is that this may not go on for ever. At some point, the planet’s seas could become saturated with carbon, leaving ever more in the atmosphere to accelerate global warming to ever more alarming temperatures.

And there is a second unhappy consequence: the more carbon dioxide absorbed by the oceans, the more the sea shifts towards a weak solution of carbonic acid, with potentially calamitous consequences both for marine life and for commercial fisheries.

Research like this is essentially of academic interest: it adds precision to the big picture of a vast ocean that absorbs carbon dioxide, and overturning currents that take it to great depths, and out of atmospheric circulation.

An active moderator

But it is also a reminder that the ocean plays an active role in moderating planetary temperatures, absorbing ever greater quantities of heat and responding with fiercer levels of energy.

It also confirms that although, on average, the high seas are responding to atmospheric change as expected, different ocean basins can vary: the North Atlantic actually absorbed 20% less CO2 than expected between 1994 and 2007, probably thanks to the slowing of the North Atlantic Meridional Overturning Circulation at the time.

And, the researchers say, the acidification of the oceans is on the increase, to depths of 3000 metres. The next step is to understand a little better the interplay between ocean, atmosphere and human emissions of greenhouse gases.

“We learned that the marine sink does not just respond to the increase in atmospheric CO2,” said Nicolas Gruber of the Swiss Federal Institute of Technology, always known as ETH Zurich, who led the study.

“Its substantial sensitivity to climate variations suggests a significant potential for feedbacks with the ongoing change in climate.” − Climate News Network

North Atlantic doubles carbon intake

The North Atlantic is gulping down twice as much human-caused carbon and becoming increasingly acidic, intensifying alarm for marine creatures.

LONDON, 12 February, 2016  – The North Atlantic Ocean is responding rapidly to climate change: it has absorbed 50% more carbon from human activities in the last 10 years,than in the previous decade, a new study shows.

In effect, it has become both a sink for the byproduct of the fossil fuel combustion that is driving global warming, and at the same time an index of the impact humans are now having on the ocean and atmosphere.

Scientists from the University of Miami’s school of marine and atmospheric science established the Atlantic’s hunger for carbon dioxide by simply looking at data samples taken a decade apart.

They report in the journal Global Biogeochemical Cycles that the data were collected in two international ship-based studies. One was CLIVAR, short for Climate Variability CO2 Repeat Hydrography, the other GO-SHIP, or the Global Ocean Ship-based Hydrographic Investigations Program’

Unprecedented rate

The extra CO2 absorbed means a change in ocean chemistry: the oceans are becoming increasingly acidic at an unprecedented rate, with unknown consequences for corals, shellfish and juvenile fish.

“This study shows the impact all of us are having on the environment and that our use of fossil fuels isn’t only causing climate to change, but also affects the oceans by decreasing the pH,” said Ryan Woosley, of the University of Miami, one of the authors.

But that is not the only change in the region. Jon Hawkings, of the University of Bristol, UK,  and colleagues report in the same journal that they spent three months in 2012 and 2013 sampling the flow of water from two glaciers in Greenland and calculated that the overall melt from the northern hemisphere’s biggest ice sheet is now delivering the nutrient phosphorus into the Arctic at about the same level as the Mississippi, or the Amazon.

“It could stimulate growth of plankton at the base of the food web, which could impact birds, fish and marine mammals higher up the food chain”

Since, once again, the Greenland ice sheet is melting as a response to global warming, humans are as a consequence altering ocean productivity. By how much is less certain: the researchers still have to establish how much of the nutrient crushed from the rocks by the moving glaciers is getting to the open ocean.

“It could stimulate growth of plankton at the base of the food web, which could impact birds, fish and marine mammals higher up the food chain,” said Dr Hawkings. “The research also suggests ice sheet-derived phosphorus could eventually reach the northern Pacific and Atlantic Oceans, which are connected to the Arctic Ocean.”

Underestimated consequences

Both studies indicate a warming ocean. And research by German scientists now suggests that humans have underestimated one important consequence of this rate of warming; the rise in global sea levels.

They report in the Proceedings of the National Academy of Sciences that the expansion of the oceans as a consequence of raised temperature could lift sea levels by an average of 1.4mm a year. Until now, oceanographers have assumed that the calculated expansion would add up to perhaps 0.7mm a year. The new study doubles that estimate.

“This height difference corresponds to roughly twice the volume from the melting ice sheets of Greenland,” said one of the authors, Roelof Rietbroek of the University of Bonn. – Climate News Network

The North Atlantic is gulping down twice as much human-caused carbon and becoming increasingly acidic, intensifying alarm for marine creatures.

LONDON, 12 February, 2016  – The North Atlantic Ocean is responding rapidly to climate change: it has absorbed 50% more carbon from human activities in the last 10 years,than in the previous decade, a new study shows.

In effect, it has become both a sink for the byproduct of the fossil fuel combustion that is driving global warming, and at the same time an index of the impact humans are now having on the ocean and atmosphere.

Scientists from the University of Miami’s school of marine and atmospheric science established the Atlantic’s hunger for carbon dioxide by simply looking at data samples taken a decade apart.

They report in the journal Global Biogeochemical Cycles that the data were collected in two international ship-based studies. One was CLIVAR, short for Climate Variability CO2 Repeat Hydrography, the other GO-SHIP, or the Global Ocean Ship-based Hydrographic Investigations Program’

Unprecedented rate

The extra CO2 absorbed means a change in ocean chemistry: the oceans are becoming increasingly acidic at an unprecedented rate, with unknown consequences for corals, shellfish and juvenile fish.

“This study shows the impact all of us are having on the environment and that our use of fossil fuels isn’t only causing climate to change, but also affects the oceans by decreasing the pH,” said Ryan Woosley, of the University of Miami, one of the authors.

But that is not the only change in the region. Jon Hawkings, of the University of Bristol, UK,  and colleagues report in the same journal that they spent three months in 2012 and 2013 sampling the flow of water from two glaciers in Greenland and calculated that the overall melt from the northern hemisphere’s biggest ice sheet is now delivering the nutrient phosphorus into the Arctic at about the same level as the Mississippi, or the Amazon.

“It could stimulate growth of plankton at the base of the food web, which could impact birds, fish and marine mammals higher up the food chain”

Since, once again, the Greenland ice sheet is melting as a response to global warming, humans are as a consequence altering ocean productivity. By how much is less certain: the researchers still have to establish how much of the nutrient crushed from the rocks by the moving glaciers is getting to the open ocean.

“It could stimulate growth of plankton at the base of the food web, which could impact birds, fish and marine mammals higher up the food chain,” said Dr Hawkings. “The research also suggests ice sheet-derived phosphorus could eventually reach the northern Pacific and Atlantic Oceans, which are connected to the Arctic Ocean.”

Underestimated consequences

Both studies indicate a warming ocean. And research by German scientists now suggests that humans have underestimated one important consequence of this rate of warming; the rise in global sea levels.

They report in the Proceedings of the National Academy of Sciences that the expansion of the oceans as a consequence of raised temperature could lift sea levels by an average of 1.4mm a year. Until now, oceanographers have assumed that the calculated expansion would add up to perhaps 0.7mm a year. The new study doubles that estimate.

“This height difference corresponds to roughly twice the volume from the melting ice sheets of Greenland,” said one of the authors, Roelof Rietbroek of the University of Bonn. – Climate News Network

Acid oceans harm more species

FOR IMMEDIATE RELEASE As climate change warms the world’s oceans, they are becoming more acidic. Researchers in Europe and the US have found the rising acidity is bad news for several species. LONDON, 3 December – The chemistry of the oceans is changing. And it isn’t just the corals and the baby oysters that are unhappy. It makes juvenile rockfish really anxious, and it upsets the digestion of sea urchins. The pH (a measure of acidity – the lower the pH, the more acid the water) of the planet’s oceans is dropping rapidly, largely because the carbon dioxide levels in the atmosphere are increasing. Since carbon dioxide dissolves in water to form carbonic acid, the seas are responding to global change. The first and clearest victims are likely to be the corals, which are adapted to a specific value of pH in the oceans, but there have also been problems reported by oyster farmers. Now Martin Tresguerres of the University of California, San Diego reports in the Proceedings of the Royal Society B that at least one species of juvenile fish responds badly to the changes in ocean chemistry. There is a natural aspect to ocean acidification – submarine volcanoes discharge carbon dioxide and turn the deep seas around them to a kind of fizzing champagne, and upwelling ocean currents can occasionally deliver a stressful level of lower pH sea water to blight fishing waters. But Tresguerres reports that he and colleagues subjected young Californian rockfish to the kind of water chemistry predicted as atmospheric carbon levels rise, and then measured their behaviour in response to changes of light in the aquarium, and to an unfamiliar object in the tank.

Stomach problems

What the researchers found was that the lower pH had a pronounced effect on one of the fish neuroreceptors linked to anxiety, and this effect lasted for at least seven days after the little creatures were returned to normal sea water. The change was not permanent: normal responses seemed to return after 12 days. Meanwhile, across the Atlantic, Meike Stumpp of the University of Gothenburg in Sweden has been looking at how sea urchin larvae respond to altered pH in the seas. She and colleagues report in Nature Climate Change that they too tweaked the seawater chemistry, to discover that digestion took longer and was less effective, a bit of a problem for any young creature – especially one hardly a fifth of a millimeter in length – in the competitive world of the oceans. “My measurements demonstrated a very strong pH dependency”, she said. “The enzymes in the sea urchins’ stomachs are optimised to function at very high pH – which is different from the situation in mammals, where stomach pH is acidic and enzymes work best at low pH.” The implications are that as pH levels fall, life will become a great deal more problematic for at least some key marine species. And the likelihood of change is increasing. Scientists of the International Geosphere-Biosphere Programme  recently allotted a “very high” confidence level to a set of simple findings. One was that humans were indeed making the seas more acidic, another was that the capacity of the oceans to absorb carbon dioxide would fall with increasing acidity, and a third was that the impact of this change in water chemistry would be felt for centuries. They also had “high confidence” that cold water corals and mollusc communities would be affected. – Climate News Network

FOR IMMEDIATE RELEASE As climate change warms the world’s oceans, they are becoming more acidic. Researchers in Europe and the US have found the rising acidity is bad news for several species. LONDON, 3 December – The chemistry of the oceans is changing. And it isn’t just the corals and the baby oysters that are unhappy. It makes juvenile rockfish really anxious, and it upsets the digestion of sea urchins. The pH (a measure of acidity – the lower the pH, the more acid the water) of the planet’s oceans is dropping rapidly, largely because the carbon dioxide levels in the atmosphere are increasing. Since carbon dioxide dissolves in water to form carbonic acid, the seas are responding to global change. The first and clearest victims are likely to be the corals, which are adapted to a specific value of pH in the oceans, but there have also been problems reported by oyster farmers. Now Martin Tresguerres of the University of California, San Diego reports in the Proceedings of the Royal Society B that at least one species of juvenile fish responds badly to the changes in ocean chemistry. There is a natural aspect to ocean acidification – submarine volcanoes discharge carbon dioxide and turn the deep seas around them to a kind of fizzing champagne, and upwelling ocean currents can occasionally deliver a stressful level of lower pH sea water to blight fishing waters. But Tresguerres reports that he and colleagues subjected young Californian rockfish to the kind of water chemistry predicted as atmospheric carbon levels rise, and then measured their behaviour in response to changes of light in the aquarium, and to an unfamiliar object in the tank.

Stomach problems

What the researchers found was that the lower pH had a pronounced effect on one of the fish neuroreceptors linked to anxiety, and this effect lasted for at least seven days after the little creatures were returned to normal sea water. The change was not permanent: normal responses seemed to return after 12 days. Meanwhile, across the Atlantic, Meike Stumpp of the University of Gothenburg in Sweden has been looking at how sea urchin larvae respond to altered pH in the seas. She and colleagues report in Nature Climate Change that they too tweaked the seawater chemistry, to discover that digestion took longer and was less effective, a bit of a problem for any young creature – especially one hardly a fifth of a millimeter in length – in the competitive world of the oceans. “My measurements demonstrated a very strong pH dependency”, she said. “The enzymes in the sea urchins’ stomachs are optimised to function at very high pH – which is different from the situation in mammals, where stomach pH is acidic and enzymes work best at low pH.” The implications are that as pH levels fall, life will become a great deal more problematic for at least some key marine species. And the likelihood of change is increasing. Scientists of the International Geosphere-Biosphere Programme  recently allotted a “very high” confidence level to a set of simple findings. One was that humans were indeed making the seas more acidic, another was that the capacity of the oceans to absorb carbon dioxide would fall with increasing acidity, and a third was that the impact of this change in water chemistry would be felt for centuries. They also had “high confidence” that cold water corals and mollusc communities would be affected. – Climate News Network

Ocean damage 'is worse than thought'

FOR IMMEDIATE RELEASE
A new report says the world’s oceans are changing faster than previously thought, which could have dire consequences for both human and marine life.

LONDON, 3 October – Marine scientists say the state of the world’s oceans is deteriorating more rapidly than anyone had realised, and is worse than that described in last month’s UN climate report from the Intergovernmental Panel on Climate Change.

They say the rate, speed and impacts of ocean change are greater, faster and more imminent than previously thought – and they expect summertime Arctic sea ice cover will have disappeared in around 25 years.

Their review, produced by the International Programme on the State of the Ocean (IPSO)  and the International Union for the Conservation of Nature (IUCN) and published in the journal Marine Pollution Bulletin, agrees with the IPCC that the oceans are absorbing much of the warming caused by carbon dioxide and other greenhouse gases.

But it says the impact of this warming, when combined with other stresses, is far graver than previous estimates. The stresses include decreasing oxygen levels caused by climate change and nitrogen run-off, other forms of chemical pollution, and serious overfishing.

Professor Alex Rogers of the University of Oxford, IPSO’s scientific director, says: “The health of the ocean is spiralling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated.”

The IUCN’s Professor Dan Laffoley says: “What these latest reports make absolutely clear is that deferring action will increase costs in the future and lead to even greater, perhaps irreversible, losses.”

Damaged molluscs found

The review says there is growing evidence that the oceans are losing oxygen. Predictions for ocean oxygen content suggest a decline of between 1% and 7% by 2100.

The loss is occurring in two ways: through the broad trend of decreasing oxygen levels in tropical oceans and areas of the North Pacific over the last 50 years, and because of the “dramatic” increase in coastal hypoxia (low oxygen) associated with eutrophication, when excessive nutrient levels cause blooms of algae and plankton.

The first is caused by global warming, the second by increased nutrient runoff from agriculture and sewage.

The authors are also concerned about the growing acidity of the oceans, which means “extremely serious consequences for ocean life, and in turn for food and coastal protection”. The Global Ocean Commission reported recently that acidification would make up to half of the Arctic Ocean uninhabitable for shelled animals by 2050.

Professor Rogers told the Climate News Network: “At high latitudes pH levels are decreasing faster than anywhere else because water temperatures are lower, and the water is becoming more acidic. Last year, for the first time, molluscs called sea butterflies were caught with corroded shells.”

When atmospheric CO2 concentrations reach 450-500 parts per million (ppm) coral reefs will be eroded faster than they can grow, and some species will become extinct. Projections are for concentrations to reach that level by 2030-2050: in May they passed 400 ppm for the first time since measurements began in 1958.

Methane a concern

With the ocean bearing the brunt of warming in the climate system, the review says, the impacts of continued warming until 2050 include reduced seasonal ice zones and increasing stratification of ocean layers, leading to oxygen depletion.

It also expects increased releases from the Arctic seabed of methane, a greenhouse gas at least 20 times more effective than carbon dioxide in trapping heat in the atmosphere (the releases were not not considered by the IPCC); and more low oxygen problems.

Another stress identified is overfishing. Contrary to claims, the review says, and despite some improvements, fisheries management is still failing to halt the decline of key species and damage to ecosystems. In 2012 the UN’s Food and Agriculture Organisation said 70% of world fish populations were unsustainably exploited.

The scientists say world governments must urgently reduce global CO2 emissions to limit temperature rise to under 2°C – something which would mean limiting all greenhouse gas emissions to 450 ppm.

They say current targets for carbon emission reductions are not enough to ensure coral reef survival and to counter other biological effects of acidification, especially as there is a time lag of several decades between atmospheric CO2 emissions and the detection of dissolved oceanic CO2.

Potential knock-on effects of climate change, such as methane release from melting permafrost, and coral dieback, mean the consequences for human and ocean life could be even worse than presently calculated. The scientists also urge better fisheries management and an effective global infrastructure for high seas governance. – Climate News Network

FOR IMMEDIATE RELEASE
A new report says the world’s oceans are changing faster than previously thought, which could have dire consequences for both human and marine life.

LONDON, 3 October – Marine scientists say the state of the world’s oceans is deteriorating more rapidly than anyone had realised, and is worse than that described in last month’s UN climate report from the Intergovernmental Panel on Climate Change.

They say the rate, speed and impacts of ocean change are greater, faster and more imminent than previously thought – and they expect summertime Arctic sea ice cover will have disappeared in around 25 years.

Their review, produced by the International Programme on the State of the Ocean (IPSO)  and the International Union for the Conservation of Nature (IUCN) and published in the journal Marine Pollution Bulletin, agrees with the IPCC that the oceans are absorbing much of the warming caused by carbon dioxide and other greenhouse gases.

But it says the impact of this warming, when combined with other stresses, is far graver than previous estimates. The stresses include decreasing oxygen levels caused by climate change and nitrogen run-off, other forms of chemical pollution, and serious overfishing.

Professor Alex Rogers of the University of Oxford, IPSO’s scientific director, says: “The health of the ocean is spiralling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated.”

The IUCN’s Professor Dan Laffoley says: “What these latest reports make absolutely clear is that deferring action will increase costs in the future and lead to even greater, perhaps irreversible, losses.”

Damaged molluscs found

The review says there is growing evidence that the oceans are losing oxygen. Predictions for ocean oxygen content suggest a decline of between 1% and 7% by 2100.

The loss is occurring in two ways: through the broad trend of decreasing oxygen levels in tropical oceans and areas of the North Pacific over the last 50 years, and because of the “dramatic” increase in coastal hypoxia (low oxygen) associated with eutrophication, when excessive nutrient levels cause blooms of algae and plankton.

The first is caused by global warming, the second by increased nutrient runoff from agriculture and sewage.

The authors are also concerned about the growing acidity of the oceans, which means “extremely serious consequences for ocean life, and in turn for food and coastal protection”. The Global Ocean Commission reported recently that acidification would make up to half of the Arctic Ocean uninhabitable for shelled animals by 2050.

Professor Rogers told the Climate News Network: “At high latitudes pH levels are decreasing faster than anywhere else because water temperatures are lower, and the water is becoming more acidic. Last year, for the first time, molluscs called sea butterflies were caught with corroded shells.”

When atmospheric CO2 concentrations reach 450-500 parts per million (ppm) coral reefs will be eroded faster than they can grow, and some species will become extinct. Projections are for concentrations to reach that level by 2030-2050: in May they passed 400 ppm for the first time since measurements began in 1958.

Methane a concern

With the ocean bearing the brunt of warming in the climate system, the review says, the impacts of continued warming until 2050 include reduced seasonal ice zones and increasing stratification of ocean layers, leading to oxygen depletion.

It also expects increased releases from the Arctic seabed of methane, a greenhouse gas at least 20 times more effective than carbon dioxide in trapping heat in the atmosphere (the releases were not not considered by the IPCC); and more low oxygen problems.

Another stress identified is overfishing. Contrary to claims, the review says, and despite some improvements, fisheries management is still failing to halt the decline of key species and damage to ecosystems. In 2012 the UN’s Food and Agriculture Organisation said 70% of world fish populations were unsustainably exploited.

The scientists say world governments must urgently reduce global CO2 emissions to limit temperature rise to under 2°C – something which would mean limiting all greenhouse gas emissions to 450 ppm.

They say current targets for carbon emission reductions are not enough to ensure coral reef survival and to counter other biological effects of acidification, especially as there is a time lag of several decades between atmospheric CO2 emissions and the detection of dissolved oceanic CO2.

Potential knock-on effects of climate change, such as methane release from melting permafrost, and coral dieback, mean the consequences for human and ocean life could be even worse than presently calculated. The scientists also urge better fisheries management and an effective global infrastructure for high seas governance. – Climate News Network

Ocean damage ‘is worse than thought’

FOR IMMEDIATE RELEASE A new report says the world’s oceans are changing faster than previously thought, which could have dire consequences for both human and marine life. LONDON, 3 October – Marine scientists say the state of the world’s oceans is deteriorating more rapidly than anyone had realised, and is worse than that described in last month’s UN climate report from the Intergovernmental Panel on Climate Change. They say the rate, speed and impacts of ocean change are greater, faster and more imminent than previously thought – and they expect summertime Arctic sea ice cover will have disappeared in around 25 years. Their review, produced by the International Programme on the State of the Ocean (IPSO)  and the International Union for the Conservation of Nature (IUCN) and published in the journal Marine Pollution Bulletin, agrees with the IPCC that the oceans are absorbing much of the warming caused by carbon dioxide and other greenhouse gases. But it says the impact of this warming, when combined with other stresses, is far graver than previous estimates. The stresses include decreasing oxygen levels caused by climate change and nitrogen run-off, other forms of chemical pollution, and serious overfishing. Professor Alex Rogers of the University of Oxford, IPSO’s scientific director, says: “The health of the ocean is spiralling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated.” The IUCN’s Professor Dan Laffoley says: “What these latest reports make absolutely clear is that deferring action will increase costs in the future and lead to even greater, perhaps irreversible, losses.”

Damaged molluscs found

The review says there is growing evidence that the oceans are losing oxygen. Predictions for ocean oxygen content suggest a decline of between 1% and 7% by 2100. The loss is occurring in two ways: through the broad trend of decreasing oxygen levels in tropical oceans and areas of the North Pacific over the last 50 years, and because of the “dramatic” increase in coastal hypoxia (low oxygen) associated with eutrophication, when excessive nutrient levels cause blooms of algae and plankton. The first is caused by global warming, the second by increased nutrient runoff from agriculture and sewage. The authors are also concerned about the growing acidity of the oceans, which means “extremely serious consequences for ocean life, and in turn for food and coastal protection”. The Global Ocean Commission reported recently that acidification would make up to half of the Arctic Ocean uninhabitable for shelled animals by 2050. Professor Rogers told the Climate News Network: “At high latitudes pH levels are decreasing faster than anywhere else because water temperatures are lower, and the water is becoming more acidic. Last year, for the first time, molluscs called sea butterflies were caught with corroded shells.” When atmospheric CO2 concentrations reach 450-500 parts per million (ppm) coral reefs will be eroded faster than they can grow, and some species will become extinct. Projections are for concentrations to reach that level by 2030-2050: in May they passed 400 ppm for the first time since measurements began in 1958.

Methane a concern

With the ocean bearing the brunt of warming in the climate system, the review says, the impacts of continued warming until 2050 include reduced seasonal ice zones and increasing stratification of ocean layers, leading to oxygen depletion. It also expects increased releases from the Arctic seabed of methane, a greenhouse gas at least 20 times more effective than carbon dioxide in trapping heat in the atmosphere (the releases were not not considered by the IPCC); and more low oxygen problems. Another stress identified is overfishing. Contrary to claims, the review says, and despite some improvements, fisheries management is still failing to halt the decline of key species and damage to ecosystems. In 2012 the UN’s Food and Agriculture Organisation said 70% of world fish populations were unsustainably exploited. The scientists say world governments must urgently reduce global CO2 emissions to limit temperature rise to under 2°C – something which would mean limiting all greenhouse gas emissions to 450 ppm. They say current targets for carbon emission reductions are not enough to ensure coral reef survival and to counter other biological effects of acidification, especially as there is a time lag of several decades between atmospheric CO2 emissions and the detection of dissolved oceanic CO2. Potential knock-on effects of climate change, such as methane release from melting permafrost, and coral dieback, mean the consequences for human and ocean life could be even worse than presently calculated. The scientists also urge better fisheries management and an effective global infrastructure for high seas governance. – Climate News Network

FOR IMMEDIATE RELEASE A new report says the world’s oceans are changing faster than previously thought, which could have dire consequences for both human and marine life. LONDON, 3 October – Marine scientists say the state of the world’s oceans is deteriorating more rapidly than anyone had realised, and is worse than that described in last month’s UN climate report from the Intergovernmental Panel on Climate Change. They say the rate, speed and impacts of ocean change are greater, faster and more imminent than previously thought – and they expect summertime Arctic sea ice cover will have disappeared in around 25 years. Their review, produced by the International Programme on the State of the Ocean (IPSO)  and the International Union for the Conservation of Nature (IUCN) and published in the journal Marine Pollution Bulletin, agrees with the IPCC that the oceans are absorbing much of the warming caused by carbon dioxide and other greenhouse gases. But it says the impact of this warming, when combined with other stresses, is far graver than previous estimates. The stresses include decreasing oxygen levels caused by climate change and nitrogen run-off, other forms of chemical pollution, and serious overfishing. Professor Alex Rogers of the University of Oxford, IPSO’s scientific director, says: “The health of the ocean is spiralling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated.” The IUCN’s Professor Dan Laffoley says: “What these latest reports make absolutely clear is that deferring action will increase costs in the future and lead to even greater, perhaps irreversible, losses.”

Damaged molluscs found

The review says there is growing evidence that the oceans are losing oxygen. Predictions for ocean oxygen content suggest a decline of between 1% and 7% by 2100. The loss is occurring in two ways: through the broad trend of decreasing oxygen levels in tropical oceans and areas of the North Pacific over the last 50 years, and because of the “dramatic” increase in coastal hypoxia (low oxygen) associated with eutrophication, when excessive nutrient levels cause blooms of algae and plankton. The first is caused by global warming, the second by increased nutrient runoff from agriculture and sewage. The authors are also concerned about the growing acidity of the oceans, which means “extremely serious consequences for ocean life, and in turn for food and coastal protection”. The Global Ocean Commission reported recently that acidification would make up to half of the Arctic Ocean uninhabitable for shelled animals by 2050. Professor Rogers told the Climate News Network: “At high latitudes pH levels are decreasing faster than anywhere else because water temperatures are lower, and the water is becoming more acidic. Last year, for the first time, molluscs called sea butterflies were caught with corroded shells.” When atmospheric CO2 concentrations reach 450-500 parts per million (ppm) coral reefs will be eroded faster than they can grow, and some species will become extinct. Projections are for concentrations to reach that level by 2030-2050: in May they passed 400 ppm for the first time since measurements began in 1958.

Methane a concern

With the ocean bearing the brunt of warming in the climate system, the review says, the impacts of continued warming until 2050 include reduced seasonal ice zones and increasing stratification of ocean layers, leading to oxygen depletion. It also expects increased releases from the Arctic seabed of methane, a greenhouse gas at least 20 times more effective than carbon dioxide in trapping heat in the atmosphere (the releases were not not considered by the IPCC); and more low oxygen problems. Another stress identified is overfishing. Contrary to claims, the review says, and despite some improvements, fisheries management is still failing to halt the decline of key species and damage to ecosystems. In 2012 the UN’s Food and Agriculture Organisation said 70% of world fish populations were unsustainably exploited. The scientists say world governments must urgently reduce global CO2 emissions to limit temperature rise to under 2°C – something which would mean limiting all greenhouse gas emissions to 450 ppm. They say current targets for carbon emission reductions are not enough to ensure coral reef survival and to counter other biological effects of acidification, especially as there is a time lag of several decades between atmospheric CO2 emissions and the detection of dissolved oceanic CO2. Potential knock-on effects of climate change, such as methane release from melting permafrost, and coral dieback, mean the consequences for human and ocean life could be even worse than presently calculated. The scientists also urge better fisheries management and an effective global infrastructure for high seas governance. – Climate News Network

Acid oceans threaten billion-dollar oyster business

FOR IMMEDIATE RELEASE Scientists have identified the problem that commercial hatcheries must overcome to keep baby oysters alive in increasingly acid seas − but wild oysters are still under threat LONDON, 22 June − Bad news for American gourmets: the commercial oyster industry in the Pacific Northwest has been failing for several years, and may go on failing as increasingly acid oceans put the larvae of the bivalve Crassostrea gigas seriously at risk. The good news is that US scientists now know exactly why things are going wrong in the oyster beds, which opens up the possibility of commercial hatcheries finding ways to get round the problem. First, the facts: as carbon dioxide levels in the atmosphere rise inexorably, so the gas dissolves in water and falls as a very weak carbonic acid rain, with a subtle but measurable change in the pH values of the planet’s oceans. There have always been dissolved gases in rainwater, but as long as pH levels remain stable, the ocean’s corals and molluscs not only adapt, they subtly exploit the water chemistry to build stronger bones and shells.

Sensitive to change

Oysters seem unusually sensitive to changes in pH, but marine biologist George Waldbusser and research colleagues at Oregon State University report in Geophysical Research Letters that the failure of the oyster harvest isn’t a simple case of acid waters dissolving calcium carbonate shells. Instead, water high in dissolved carbon dioxide tends to alter the shell formation rates, the energy usage and, ultimately, the growth and survival of young oysters. Females tend to produce eggs by the million as water temperatures reach around 20°C. Once fertilised and hatched, the embryos have about two days to start building a shell. Raised carbon dioxide levels in the water impose an extra energy cost for the little shell-builders. Mature oysters can take their time and assemble calcium carbonate production more slowly, but larvae don’t have the time. Their only energy supply is the nourishment in the egg. “From the time eggs are fertilised, Pacific oyster larvae precipitate roughly 90% of their bodyweight as calcium carbonate shell within 48 hours,” Dr Waldbusser says. “They must build their first shell quickly on a limited amount of energy – and, along with the shell, comes the organ to capture external food.

Death race

“It becomes a death race of sorts. Can the oyster build its shell quickly enough to allow its feeding mechanism to develop before it runs out of energy from the egg?” Armed with this insight into oyster bed ecology, the scientists say, there are interventions that can be introduced at hatcheries that may offset some of the effects of ocean acidification. Some hatcheries have started to “buffer” the water supplies in commercial hatcheries that supply the marine and estuary oyster beds − essentially, adding antacids to incoming waters. However, what may be hopeful news for fish farmers may not be such good news for the wild oyster, which will no doubt experience more stress in its native waters as carbon dioxide levels go on rising. The research matters at one level because Pacific oyster farming is now a billion-dollar business, and at another because it exposes something of the intricate connection between sea-dwelling creatures and the chemistry of the sea. It is also a reminder that any creature faces different hazards at every stage of its life cycle. The report’s authors say: “We suggest that the predictions of winners and losers in a high CO² world may be better informed by calcium carbonate kinetics, bioenergetics, ontogeny, and life-history characteristics than by shell mineralogy alone.” − Climate News Network  

FOR IMMEDIATE RELEASE Scientists have identified the problem that commercial hatcheries must overcome to keep baby oysters alive in increasingly acid seas − but wild oysters are still under threat LONDON, 22 June − Bad news for American gourmets: the commercial oyster industry in the Pacific Northwest has been failing for several years, and may go on failing as increasingly acid oceans put the larvae of the bivalve Crassostrea gigas seriously at risk. The good news is that US scientists now know exactly why things are going wrong in the oyster beds, which opens up the possibility of commercial hatcheries finding ways to get round the problem. First, the facts: as carbon dioxide levels in the atmosphere rise inexorably, so the gas dissolves in water and falls as a very weak carbonic acid rain, with a subtle but measurable change in the pH values of the planet’s oceans. There have always been dissolved gases in rainwater, but as long as pH levels remain stable, the ocean’s corals and molluscs not only adapt, they subtly exploit the water chemistry to build stronger bones and shells.

Sensitive to change

Oysters seem unusually sensitive to changes in pH, but marine biologist George Waldbusser and research colleagues at Oregon State University report in Geophysical Research Letters that the failure of the oyster harvest isn’t a simple case of acid waters dissolving calcium carbonate shells. Instead, water high in dissolved carbon dioxide tends to alter the shell formation rates, the energy usage and, ultimately, the growth and survival of young oysters. Females tend to produce eggs by the million as water temperatures reach around 20°C. Once fertilised and hatched, the embryos have about two days to start building a shell. Raised carbon dioxide levels in the water impose an extra energy cost for the little shell-builders. Mature oysters can take their time and assemble calcium carbonate production more slowly, but larvae don’t have the time. Their only energy supply is the nourishment in the egg. “From the time eggs are fertilised, Pacific oyster larvae precipitate roughly 90% of their bodyweight as calcium carbonate shell within 48 hours,” Dr Waldbusser says. “They must build their first shell quickly on a limited amount of energy – and, along with the shell, comes the organ to capture external food.

Death race

“It becomes a death race of sorts. Can the oyster build its shell quickly enough to allow its feeding mechanism to develop before it runs out of energy from the egg?” Armed with this insight into oyster bed ecology, the scientists say, there are interventions that can be introduced at hatcheries that may offset some of the effects of ocean acidification. Some hatcheries have started to “buffer” the water supplies in commercial hatcheries that supply the marine and estuary oyster beds − essentially, adding antacids to incoming waters. However, what may be hopeful news for fish farmers may not be such good news for the wild oyster, which will no doubt experience more stress in its native waters as carbon dioxide levels go on rising. The research matters at one level because Pacific oyster farming is now a billion-dollar business, and at another because it exposes something of the intricate connection between sea-dwelling creatures and the chemistry of the sea. It is also a reminder that any creature faces different hazards at every stage of its life cycle. The report’s authors say: “We suggest that the predictions of winners and losers in a high CO² world may be better informed by calcium carbonate kinetics, bioenergetics, ontogeny, and life-history characteristics than by shell mineralogy alone.” − Climate News Network  

Acid seas make corals feeble but they survive

FOR IMMEDIATE RELEASE Two important habitats for marine life, coral reefs and eelgrass meadows, will survive climate change but it will make them vulnerable. LONDON 17 June – Ocean acidification will make coral skeletons more feeble and coral reefs more vulnerable to battering by the seas – but it may not kill the corals, according to new research from the University of California, Santa Cruz. The Californian scientists report in the Proceedings of the National Academy of Sciences (PNAS) that they tested coral’s response to changes in future ocean chemistry not by experiments in a tank in a laboratory, but under real conditions – off Mexico’s Yucatan Peninsula where submarine springs naturally alter the chemistry of the surrounding sea water. “People have seen similar effects in laboratory experiments,” said Adina Paytan, of the university’s Institute of Marine Sciences. “We looked in places where corals are exposed to lower pH for their entire lifespan. The good news is that they don’t just die. They are able to grow and calcify, but they are not producing robust structures.” As carbon dioxide levels rise, falling rain becomes even more weakly acidic, and all rain eventually makes its way into the oceans, changing the water chemistry subtly. Storm waves By monitoring seawater chemistry near natural submarine springs, and by examining cores from colonies of an important Caribbean reef-building coral called Porites astreoides, the scientists were able to show that predicted future changes in water chemistry did have consequences for creatures that exploit that chemistry: it became more demanding for the coral animals to build up the blocks of calcium carbonate skeletons. As the skeletons become less dense, so they become more vulnerable to storm waves, and to coral predators. Corals are also vulnerable to temperature rise, and recent research has shown that corals can recover slowly from devastating spells of heat. Now it seems they can survive changes in ocean acidity. The question of course is whether reefs can survive both at the same time – and other stresses such as pollution and overfishing. Eelgrass meadows Meanwhile, far away to the north and across the Atlantic, Swedish researchers at the University of Gothenburg have been testing the effect of both rising temperatures and changes in sea chemistry on another important marine ecosystem: the eelgrass meadows. Christian Alsterberg reports in the PNAS that they raised the temperature in laboratory tanks containing eelgrass, while at the same time bubbling extra carbon dioxide through the water, to simulate the real changes predicted in the decades to come. The aim was to see how the plants, and the animals for which the plants form a natural habitat, responded. As water temperatures increased, for instance, so did the metabolism of many of the crustaceans that live in the eelgrass meadows. As a consequence, the animals consumed more algae, and grazed the meadows more efficiently. Benthic microalgae on the sediment of the meadows responded more vigorously. Overall, there seemed to be no great effect on the meadows. But that depended on the presence of crustaceans: without these small, algae-eating animals, the outcome could have been much worse. The research is just another piece in the vast jigsaw puzzle of climate science, in which small changes can have complex outcomes. “The experiment also taught us the importance of investigating climate change using several different approaches, in order to fully understand its effects and to predict future impacts,” said Alsterberg. – Climate News Network

FOR IMMEDIATE RELEASE Two important habitats for marine life, coral reefs and eelgrass meadows, will survive climate change but it will make them vulnerable. LONDON 17 June – Ocean acidification will make coral skeletons more feeble and coral reefs more vulnerable to battering by the seas – but it may not kill the corals, according to new research from the University of California, Santa Cruz. The Californian scientists report in the Proceedings of the National Academy of Sciences (PNAS) that they tested coral’s response to changes in future ocean chemistry not by experiments in a tank in a laboratory, but under real conditions – off Mexico’s Yucatan Peninsula where submarine springs naturally alter the chemistry of the surrounding sea water. “People have seen similar effects in laboratory experiments,” said Adina Paytan, of the university’s Institute of Marine Sciences. “We looked in places where corals are exposed to lower pH for their entire lifespan. The good news is that they don’t just die. They are able to grow and calcify, but they are not producing robust structures.” As carbon dioxide levels rise, falling rain becomes even more weakly acidic, and all rain eventually makes its way into the oceans, changing the water chemistry subtly. Storm waves By monitoring seawater chemistry near natural submarine springs, and by examining cores from colonies of an important Caribbean reef-building coral called Porites astreoides, the scientists were able to show that predicted future changes in water chemistry did have consequences for creatures that exploit that chemistry: it became more demanding for the coral animals to build up the blocks of calcium carbonate skeletons. As the skeletons become less dense, so they become more vulnerable to storm waves, and to coral predators. Corals are also vulnerable to temperature rise, and recent research has shown that corals can recover slowly from devastating spells of heat. Now it seems they can survive changes in ocean acidity. The question of course is whether reefs can survive both at the same time – and other stresses such as pollution and overfishing. Eelgrass meadows Meanwhile, far away to the north and across the Atlantic, Swedish researchers at the University of Gothenburg have been testing the effect of both rising temperatures and changes in sea chemistry on another important marine ecosystem: the eelgrass meadows. Christian Alsterberg reports in the PNAS that they raised the temperature in laboratory tanks containing eelgrass, while at the same time bubbling extra carbon dioxide through the water, to simulate the real changes predicted in the decades to come. The aim was to see how the plants, and the animals for which the plants form a natural habitat, responded. As water temperatures increased, for instance, so did the metabolism of many of the crustaceans that live in the eelgrass meadows. As a consequence, the animals consumed more algae, and grazed the meadows more efficiently. Benthic microalgae on the sediment of the meadows responded more vigorously. Overall, there seemed to be no great effect on the meadows. But that depended on the presence of crustaceans: without these small, algae-eating animals, the outcome could have been much worse. The research is just another piece in the vast jigsaw puzzle of climate science, in which small changes can have complex outcomes. “The experiment also taught us the importance of investigating climate change using several different approaches, in order to fully understand its effects and to predict future impacts,” said Alsterberg. – Climate News Network