Category Archives: Oceans

Hotter oceans make the tropics expand polewards

The tropical climate zones are not just warmer, they now cover more of the planet. Blame it on steadily hotter oceans.

LONDON, 27 August, 2020 – The tropics are on the march and US and German scientists think they know why: hotter oceans have taken control.

The parched, arid fringes of the hot, moist conditions that nourish the equatorial forest band around the middle of the globe are moving, unevenly, further north and south in response to climate change.

And the role of the ocean is made even more dramatic in the southern hemisphere: because the ocean south of the equator is so much bigger than in the north, the southward shift of the parched zone is even more pronounced.

Across the globe, things don’t look good for places like California, which has already suffered some of its worst droughts and fires on record, and  Australia, where drought and fire if possible have been even worse.

In the past century or so, carbon dioxide levels in the atmosphere have risen from what was once a stable average of 285 parts per million to more than 400 ppm, and global average temperatures are now at least 1°C higher than they have been for most of human history.

“We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations. This is a result of global warming”

And although the fastest and most dramatic changes in the world have been in the coldest zones – and particularly the Arctic – the tropics, too, have begun to feel the heat.

Researchers have observed tropical fish moving into cooler waters; they have warned that some tropical plant species may soon find temperatures too high for germination; they have mapped tropical cyclones hitting further north and south with time, and doing more damage; and they have seen evidence that tropical diseases could soon advance even into temperate Europe.

But although satellite observations have revealed that the tropical climate zone has expanded beyond the formal limits known as the Tropics of Capricorn and Cancer, and is doing so at somewhere between a quarter and half a degree of latitude each decade, no one has been able to work out why the shift is more pronounced in the southern half of the globe.

Now a new study in the Journal of Geophysical Research: Atmospheres offers an answer. The expansion of the tropics has been driven by ocean warming.

And if that expansion is more obvious in the southern hemisphere, it is because there is more sea to have more impact.

Clear link

Researchers analysed water temperature patterns in the great ocean gyres, those giant circular currents that take warm waters to the poles and return cold water to the equatorial regions.

They matched satellite readings from 1982 – the first year in the series of measurements – with data from 2018, and compared these to measurements of tropical zone expansion.

The connection was clear: excess heat that had been building up in the subtropical oceans ever since global warming began had driven both tropical edges and ocean gyres towards the poles.

That is, the shift in the tropics wasn’t just one of those slow pulses of expansion and retraction, of cyclic change, that happen in a complex world. And more precisely, the tropics were expanding more clearly in those places where the gyres moved poleward.

“We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations,” said Hu Yang of the Alfred Wegener Institute in Bremerhaven, Germany, who led the research. “This is a result of global warming.” – Climate News Network

The tropical climate zones are not just warmer, they now cover more of the planet. Blame it on steadily hotter oceans.

LONDON, 27 August, 2020 – The tropics are on the march and US and German scientists think they know why: hotter oceans have taken control.

The parched, arid fringes of the hot, moist conditions that nourish the equatorial forest band around the middle of the globe are moving, unevenly, further north and south in response to climate change.

And the role of the ocean is made even more dramatic in the southern hemisphere: because the ocean south of the equator is so much bigger than in the north, the southward shift of the parched zone is even more pronounced.

Across the globe, things don’t look good for places like California, which has already suffered some of its worst droughts and fires on record, and  Australia, where drought and fire if possible have been even worse.

In the past century or so, carbon dioxide levels in the atmosphere have risen from what was once a stable average of 285 parts per million to more than 400 ppm, and global average temperatures are now at least 1°C higher than they have been for most of human history.

“We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations. This is a result of global warming”

And although the fastest and most dramatic changes in the world have been in the coldest zones – and particularly the Arctic – the tropics, too, have begun to feel the heat.

Researchers have observed tropical fish moving into cooler waters; they have warned that some tropical plant species may soon find temperatures too high for germination; they have mapped tropical cyclones hitting further north and south with time, and doing more damage; and they have seen evidence that tropical diseases could soon advance even into temperate Europe.

But although satellite observations have revealed that the tropical climate zone has expanded beyond the formal limits known as the Tropics of Capricorn and Cancer, and is doing so at somewhere between a quarter and half a degree of latitude each decade, no one has been able to work out why the shift is more pronounced in the southern half of the globe.

Now a new study in the Journal of Geophysical Research: Atmospheres offers an answer. The expansion of the tropics has been driven by ocean warming.

And if that expansion is more obvious in the southern hemisphere, it is because there is more sea to have more impact.

Clear link

Researchers analysed water temperature patterns in the great ocean gyres, those giant circular currents that take warm waters to the poles and return cold water to the equatorial regions.

They matched satellite readings from 1982 – the first year in the series of measurements – with data from 2018, and compared these to measurements of tropical zone expansion.

The connection was clear: excess heat that had been building up in the subtropical oceans ever since global warming began had driven both tropical edges and ocean gyres towards the poles.

That is, the shift in the tropics wasn’t just one of those slow pulses of expansion and retraction, of cyclic change, that happen in a complex world. And more precisely, the tropics were expanding more clearly in those places where the gyres moved poleward.

“We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations,” said Hu Yang of the Alfred Wegener Institute in Bremerhaven, Germany, who led the research. “This is a result of global warming.” – Climate News Network

Changing oceans reveal clear human thumbprint

Climate heating must have already begun to result in changing oceans. The next step is to confirm and monitor this change.

LONDON, 26 August, 2020 – Humankind has already begun to reshape the biggest available living space on the planet and to leave its mark in the changing oceans.

New research suggests that somewhere between 20% and 55% of the Atlantic, Pacific and Indian Oceans now have temperatures and salt levels that should be measurably different because of climate change driven by profligate human combustion of fossil fuels.

And forecasts suggest that by mid-century the scale of human impact will only have increased – to between 40% and 60%. By 2080, human impact on the oceans will have begun to change between 55% and 80% of the blue planet.

Although the researchers – they report in the journal Nature Climate Change – have based their predictions on computer models, they are confident that the thumbprint of human-induced climate change began to leave its mark on the seas of the Southern Hemisphere as long ago as the 1980s.

“We have been detecting ocean temperature change at the surface due to climate change for several decades now,” said Eric Guilyardi, of the University of Reading in the UK and the Laboratory of Oceanography and Climate in Paris, France.

“Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring persistent anthropogenic changes”

“But changes in vast areas of the ocean, particularly deeper parts, are much more challenging to detect.”

The problem of measurement is simple: the ocean is enormous. It covers 70% of the planet to an average depth of 3.7 kms. It defines the planet.

It is almost certainly where life on Earth first emerged; it was life’s only home for the first three billion years.

And it is in a state of constant change, constantly evaporating, and continually replenished with freshwater from rainfall, river flow and melting polar ice. So temperature and salinity change naturally, and with the seasons, and with much longer cyclic swings driven by the atmosphere.

Scientists have been measuring surface conditions for many decades. The ocean at depth is a bit more of a challenge. The question the researchers put was a simple one: could temperature and salinity levels in parts of the ocean have risen or fallen higher or lower than they would in normal peaks and troughs?

Beyond natural variability

It’s not an easy question: oceanography is expensive, the ocean is huge, much of it has never been studied and the ways in which the ocean layers mix is still a bit of a puzzle.

So the scientists started with two models, with and without the impact of human action. They then worked on an analysis of salt levels and temperatures to detect significant change, and then tried to predict the dates at which this change ought to declare itself.

Their readings tell them that changes beyond natural variability in the northern hemisphere – all the seas from the Arctic Ocean to the equatorial waters – could have emerged between 2010 and 2030. That is, change is already happening.

Their simulations also predicted that whatever shifts occurred at depth in the temperature and chemistry of the southern oceans, these could have been identified up to 40 years ago, had researchers had the technology, the funding, the people and the ships and submersibles to do so.

“Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring persistent anthropogenic changes,” they report. – Climate News Network

Climate heating must have already begun to result in changing oceans. The next step is to confirm and monitor this change.

LONDON, 26 August, 2020 – Humankind has already begun to reshape the biggest available living space on the planet and to leave its mark in the changing oceans.

New research suggests that somewhere between 20% and 55% of the Atlantic, Pacific and Indian Oceans now have temperatures and salt levels that should be measurably different because of climate change driven by profligate human combustion of fossil fuels.

And forecasts suggest that by mid-century the scale of human impact will only have increased – to between 40% and 60%. By 2080, human impact on the oceans will have begun to change between 55% and 80% of the blue planet.

Although the researchers – they report in the journal Nature Climate Change – have based their predictions on computer models, they are confident that the thumbprint of human-induced climate change began to leave its mark on the seas of the Southern Hemisphere as long ago as the 1980s.

“We have been detecting ocean temperature change at the surface due to climate change for several decades now,” said Eric Guilyardi, of the University of Reading in the UK and the Laboratory of Oceanography and Climate in Paris, France.

“Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring persistent anthropogenic changes”

“But changes in vast areas of the ocean, particularly deeper parts, are much more challenging to detect.”

The problem of measurement is simple: the ocean is enormous. It covers 70% of the planet to an average depth of 3.7 kms. It defines the planet.

It is almost certainly where life on Earth first emerged; it was life’s only home for the first three billion years.

And it is in a state of constant change, constantly evaporating, and continually replenished with freshwater from rainfall, river flow and melting polar ice. So temperature and salinity change naturally, and with the seasons, and with much longer cyclic swings driven by the atmosphere.

Scientists have been measuring surface conditions for many decades. The ocean at depth is a bit more of a challenge. The question the researchers put was a simple one: could temperature and salinity levels in parts of the ocean have risen or fallen higher or lower than they would in normal peaks and troughs?

Beyond natural variability

It’s not an easy question: oceanography is expensive, the ocean is huge, much of it has never been studied and the ways in which the ocean layers mix is still a bit of a puzzle.

So the scientists started with two models, with and without the impact of human action. They then worked on an analysis of salt levels and temperatures to detect significant change, and then tried to predict the dates at which this change ought to declare itself.

Their readings tell them that changes beyond natural variability in the northern hemisphere – all the seas from the Arctic Ocean to the equatorial waters – could have emerged between 2010 and 2030. That is, change is already happening.

Their simulations also predicted that whatever shifts occurred at depth in the temperature and chemistry of the southern oceans, these could have been identified up to 40 years ago, had researchers had the technology, the funding, the people and the ships and submersibles to do so.

“Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring persistent anthropogenic changes,” they report. – Climate News Network

Oceans’ plastic tide may be far larger than thought

Artificial fibres now go everywhere. The oceans’ plastic tide may reach their whole depth, entering marine life and people.

LONDON, 20 August, 2020 − The world’s seas could be home to a vast reservoir of hitherto unidentified pollution, the growing burden of the oceans’ plastic tide.

Up to 21 million tonnes of tiny and invisible plastic fibres could be floating in the first 200 metres of the Atlantic Ocean alone. And as British research exposed the scale of the problem, American chemists revealed that for the first time they had found microplastic fibres incorporated within human organ tissues.

A day or two later Dutch scientists demonstrated that plastic waste wasn’t simply a passive hazard to marine life: experiments showed that polluting plastic released chemicals into the stomachs of seabirds.

But first, the global problem. Oceanographers have known for decades that plastic waste had found its way into the sea: floating on the surface, it has reached the beaches of the remote Antarctic, been sampled in Arctic waters, been identified in the sediments on the sea floor and been ingested by marine creatures, from the smallest to the whale family.

Ominously, researchers warn that the sheer mass of plastic waste could multiply threefold in the decades to come. And, unlike all other forms of human pollution, plastic waste is here to stay, one day to form a permanent geological layer that will mark the Anthropocene era.

“Plastic is making its way into our bodies but very few studies have looked for it there. We don’t know whether this plastic is just a nuisance or whether it represents a human health hazard”

Scientists report in the journal Nature Communications that at 12 places along a 10,000 km north-south voyage in the Atlantic late in 2015, the waters were sampled for evidence of just three forms of plastic litter: polyethylene, polypropylene and polystyrene.

These samples were taken at depths of 10 metres below the surface, between 10 and 30 metres below what oceanographers call the mixed layer, and then 100 metres even deeper.

They then looked for fragments of the three plastics right down to the scale of 25 millionths of a metre, and began counting. They found up to 7,000 particles of all three types in a cubic metre of seawater.

Then they did the sums: people have been throwing plastic bags, packets, bottles, cups, nets and packaging away since 1950, and it has been getting into the Atlantic since 1950, with the estimated mass so far ranging from 17 million to 47 million tonnes.

The Atlantic has an average depth of 3000 metres. The discovery that the mass of plastic just in the upper 200 metres of one ocean lies somewhere between 12 and 21 million tonnes suggests that the flow of plastic into the seas everywhere may have been seriously under-estimated.

Missing measurement

“Previously, we couldn’t balance the mass of floating plastic we observed with the mass we thought had entered the ocean since 1950,” said Katsiaryna Pabortsava of the UK National Oceanography Centre, at Southampton, who led the study.

“This is because earlier studies hadn’t been measuring the concentrations of ‘invisible’ microplastic particles beneath the ocean surface. Our research is the first to have done this across the entire Atlantic, from the UK to the Falklands.”

Large plastic fragments disfigure the landscape and represent a direct threat to animals that mistake them for food.

Nobody yet knows how dangerous microplastic fibres might be, but if they are consumed by little animals they soon get concentrated in bigger predators, including the greatest predators of all: humans.

Scientists told the American Chemical Society – at a virtual meeting – that they had developed the techniques needed to identify microplastic fibres in 47 samples from donated lungs, liver, spleen and kidneys: that is, such fragments did more than simply pass through a gastrointestinal tract. They became part of human flesh.

Seabird vulnerability

“There’s evidence that plastic is making its way into our bodies but very few studies have looked for it there,” said Charles Rolsky of Arizona State University. “And at this point we don’t know whether this plastic is just a nuisance or whether it represents a human health hazard.”

Although plastic seems to be durable and indestructible, there may be evidence that it can react with biology. The journal Frontiers in Environmental Science reports that fragments of plastic, collected from beaches and incubated in natural oils from the stomachs of a seabird known as the northern fulmar – hunted for food in the Faroe Islands – eventually released chemicals.

These were agents that had been added in the process of making that plastic: among them flame retardants, stabilisers and plasticisers. Once again, there is no certainty that such releases would harm the birds, but some of these chemicals have been identified in other tests as hormone disruptors.

“I’ve been working on northern fulmars for almost 10 years,” said Susanne Kühn of Wageningen Marine Research in the Netherlands.

“As these seabirds ingest plastics regularly, and 93% of the fulmars from the North Sea have some plastic in their stomachs, it is important to understand the potential harm this could cause.” − Climate News Network

Artificial fibres now go everywhere. The oceans’ plastic tide may reach their whole depth, entering marine life and people.

LONDON, 20 August, 2020 − The world’s seas could be home to a vast reservoir of hitherto unidentified pollution, the growing burden of the oceans’ plastic tide.

Up to 21 million tonnes of tiny and invisible plastic fibres could be floating in the first 200 metres of the Atlantic Ocean alone. And as British research exposed the scale of the problem, American chemists revealed that for the first time they had found microplastic fibres incorporated within human organ tissues.

A day or two later Dutch scientists demonstrated that plastic waste wasn’t simply a passive hazard to marine life: experiments showed that polluting plastic released chemicals into the stomachs of seabirds.

But first, the global problem. Oceanographers have known for decades that plastic waste had found its way into the sea: floating on the surface, it has reached the beaches of the remote Antarctic, been sampled in Arctic waters, been identified in the sediments on the sea floor and been ingested by marine creatures, from the smallest to the whale family.

Ominously, researchers warn that the sheer mass of plastic waste could multiply threefold in the decades to come. And, unlike all other forms of human pollution, plastic waste is here to stay, one day to form a permanent geological layer that will mark the Anthropocene era.

“Plastic is making its way into our bodies but very few studies have looked for it there. We don’t know whether this plastic is just a nuisance or whether it represents a human health hazard”

Scientists report in the journal Nature Communications that at 12 places along a 10,000 km north-south voyage in the Atlantic late in 2015, the waters were sampled for evidence of just three forms of plastic litter: polyethylene, polypropylene and polystyrene.

These samples were taken at depths of 10 metres below the surface, between 10 and 30 metres below what oceanographers call the mixed layer, and then 100 metres even deeper.

They then looked for fragments of the three plastics right down to the scale of 25 millionths of a metre, and began counting. They found up to 7,000 particles of all three types in a cubic metre of seawater.

Then they did the sums: people have been throwing plastic bags, packets, bottles, cups, nets and packaging away since 1950, and it has been getting into the Atlantic since 1950, with the estimated mass so far ranging from 17 million to 47 million tonnes.

The Atlantic has an average depth of 3000 metres. The discovery that the mass of plastic just in the upper 200 metres of one ocean lies somewhere between 12 and 21 million tonnes suggests that the flow of plastic into the seas everywhere may have been seriously under-estimated.

Missing measurement

“Previously, we couldn’t balance the mass of floating plastic we observed with the mass we thought had entered the ocean since 1950,” said Katsiaryna Pabortsava of the UK National Oceanography Centre, at Southampton, who led the study.

“This is because earlier studies hadn’t been measuring the concentrations of ‘invisible’ microplastic particles beneath the ocean surface. Our research is the first to have done this across the entire Atlantic, from the UK to the Falklands.”

Large plastic fragments disfigure the landscape and represent a direct threat to animals that mistake them for food.

Nobody yet knows how dangerous microplastic fibres might be, but if they are consumed by little animals they soon get concentrated in bigger predators, including the greatest predators of all: humans.

Scientists told the American Chemical Society – at a virtual meeting – that they had developed the techniques needed to identify microplastic fibres in 47 samples from donated lungs, liver, spleen and kidneys: that is, such fragments did more than simply pass through a gastrointestinal tract. They became part of human flesh.

Seabird vulnerability

“There’s evidence that plastic is making its way into our bodies but very few studies have looked for it there,” said Charles Rolsky of Arizona State University. “And at this point we don’t know whether this plastic is just a nuisance or whether it represents a human health hazard.”

Although plastic seems to be durable and indestructible, there may be evidence that it can react with biology. The journal Frontiers in Environmental Science reports that fragments of plastic, collected from beaches and incubated in natural oils from the stomachs of a seabird known as the northern fulmar – hunted for food in the Faroe Islands – eventually released chemicals.

These were agents that had been added in the process of making that plastic: among them flame retardants, stabilisers and plasticisers. Once again, there is no certainty that such releases would harm the birds, but some of these chemicals have been identified in other tests as hormone disruptors.

“I’ve been working on northern fulmars for almost 10 years,” said Susanne Kühn of Wageningen Marine Research in the Netherlands.

“As these seabirds ingest plastics regularly, and 93% of the fulmars from the North Sea have some plastic in their stomachs, it is important to understand the potential harm this could cause.” − Climate News Network

End of Arctic sea ice by 2035 possible, study finds

How soon will the northern polar ocean be ice-free? New research expects the end of Arctic sea ice by 2035.

LONDON, 11 August, 2020 − The temperature of the Arctic matters to the entire world: it helps to keep the global climate fairly cool. Scientists now say that by 2035 there could be an end to Arctic sea ice.

The northern polar ocean’s sea ice is a crucial element in the Earth system: because it is highly reflective, it sends solar radiation back out into space. Once it’s melted, there’s no longer any protection for the darker water and rock beneath, and nothing to prevent them absorbing the incoming heat.

High temperatures in the Arctic during the last interglacial – the warm period around 127,000 years ago – have puzzled scientists for decades.

Now the UK Met Office’s Hadley Centre climate model has enabled an international research team to compare Arctic sea ice conditions during the last interglacial with the present day. Their findings are important for improving predictions of future sea ice change.

What is striking about the latest research is the date it suggests for a possible total melt − 2035. Many studies have thought a mid-century crisis likely, with another even carefully specifying 2044 as the year to watch. So a breathing space of only 15 years may surprise some experts.

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible”

During spring and early summer shallow pools of water form on the surface of the Arctic sea ice. These “melt ponds” help to determine how much sunlight is absorbed by the ice and how much is reflected back into space. The new Hadley Centre model is the UK’s most advanced physical representation of the Earth’s climate and a critical tool for climate research, and it incorporates sea ice and melt ponds.

The researchers report their findings in the journal Nature Climate Change. Using the model to look at Arctic sea ice during the last interglacial, they concluded that the impact of intense springtime sunshine created many melt ponds, which played a crucial role in sea ice melt. A simulation of the future using the same model indicates that the Arctic may become sea ice-free by 2035.

The joint lead author of the team is Dr Maria Vittoria Guarino, an earth system modeller at the British Antarctic Survey (BAS) in Cambridge. She says: “High temperatures in the Arctic have puzzled scientists for decades. Unravelling this mystery was technically and scientifically challenging. For the first time, we can begin to see how the Arctic became sea ice-free during the last interglacial.

“The advances made in climate modelling mean that we can create a more accurate simulation of the Earth’s past climate which, in turn, gives us greater confidence in model predictions for the future.”

Dr Louise Sime, the group head of the palaeoclimate group and joint lead author at BAS, says: “We know the Arctic is undergoing significant changes as our planet warms. By understanding what happened during Earth’s last warm period we are in a better position to understand what will happen in the future.

Melt ponds crucial

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible.”

Dr David Schroeder from the University of Reading, UK, who co-led the implementation of the melt pond scheme in the climate model, says: “This shows just how important sea ice processes like melt ponds are in the Arctic, and why it is crucial that they are incorporated into climate models.”

The extent of the areas sea ice covers varies between summer and winter. If more solar energy is absorbed at the surface, and temperatures rise further, a cycle of warming and melting occurs during summer months.

When the ice forms, the ocean water beneath becomes saltier and denser than the surrounding ocean. Saltier water sinks and moves along the ocean bottom towards the equator, while warm water from mid-depths to the surface travels from the equator towards the poles.

Scientists refer to this process as the ocean’s global “conveyor-belt”. Changes to the volume of sea ice can disrupt normal ocean circulation, with consequences for global climate. − Climate News Network

How soon will the northern polar ocean be ice-free? New research expects the end of Arctic sea ice by 2035.

LONDON, 11 August, 2020 − The temperature of the Arctic matters to the entire world: it helps to keep the global climate fairly cool. Scientists now say that by 2035 there could be an end to Arctic sea ice.

The northern polar ocean’s sea ice is a crucial element in the Earth system: because it is highly reflective, it sends solar radiation back out into space. Once it’s melted, there’s no longer any protection for the darker water and rock beneath, and nothing to prevent them absorbing the incoming heat.

High temperatures in the Arctic during the last interglacial – the warm period around 127,000 years ago – have puzzled scientists for decades.

Now the UK Met Office’s Hadley Centre climate model has enabled an international research team to compare Arctic sea ice conditions during the last interglacial with the present day. Their findings are important for improving predictions of future sea ice change.

What is striking about the latest research is the date it suggests for a possible total melt − 2035. Many studies have thought a mid-century crisis likely, with another even carefully specifying 2044 as the year to watch. So a breathing space of only 15 years may surprise some experts.

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible”

During spring and early summer shallow pools of water form on the surface of the Arctic sea ice. These “melt ponds” help to determine how much sunlight is absorbed by the ice and how much is reflected back into space. The new Hadley Centre model is the UK’s most advanced physical representation of the Earth’s climate and a critical tool for climate research, and it incorporates sea ice and melt ponds.

The researchers report their findings in the journal Nature Climate Change. Using the model to look at Arctic sea ice during the last interglacial, they concluded that the impact of intense springtime sunshine created many melt ponds, which played a crucial role in sea ice melt. A simulation of the future using the same model indicates that the Arctic may become sea ice-free by 2035.

The joint lead author of the team is Dr Maria Vittoria Guarino, an earth system modeller at the British Antarctic Survey (BAS) in Cambridge. She says: “High temperatures in the Arctic have puzzled scientists for decades. Unravelling this mystery was technically and scientifically challenging. For the first time, we can begin to see how the Arctic became sea ice-free during the last interglacial.

“The advances made in climate modelling mean that we can create a more accurate simulation of the Earth’s past climate which, in turn, gives us greater confidence in model predictions for the future.”

Dr Louise Sime, the group head of the palaeoclimate group and joint lead author at BAS, says: “We know the Arctic is undergoing significant changes as our planet warms. By understanding what happened during Earth’s last warm period we are in a better position to understand what will happen in the future.

Melt ponds crucial

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible.”

Dr David Schroeder from the University of Reading, UK, who co-led the implementation of the melt pond scheme in the climate model, says: “This shows just how important sea ice processes like melt ponds are in the Arctic, and why it is crucial that they are incorporated into climate models.”

The extent of the areas sea ice covers varies between summer and winter. If more solar energy is absorbed at the surface, and temperatures rise further, a cycle of warming and melting occurs during summer months.

When the ice forms, the ocean water beneath becomes saltier and denser than the surrounding ocean. Saltier water sinks and moves along the ocean bottom towards the equator, while warm water from mid-depths to the surface travels from the equator towards the poles.

Scientists refer to this process as the ocean’s global “conveyor-belt”. Changes to the volume of sea ice can disrupt normal ocean circulation, with consequences for global climate. − Climate News Network

250 million coastal dwellers will face rising floods

Once again, researchers confirm that coastal dwellers can expect worse floods, more often and more expensively.

LONDON, 6 August, 2020 – In the next 80 years flooding around the planet’s land masses is likely to rise by almost 50%, endangering many millions of coastal dwellers.

If humans go on burning ever greater volumes of fossil fuels, while destroying ever more natural forest, then another 77 million people could be at risk of flooding, a rise of 52%.

And these floods – increasingly frequent and extending over greater areas – will put at risk cities, homes, resorts and industries valued at more than $14 trillion (£10.7tn).

This sum alone is worth 20% of global gross domestic product, the economist’s preferred indicator of economic health and wealth, according to a new study in the journal Scientific Reports.

The researchers built their argument on historic data from 681 tide-gauge stations around the world to model the growing hazard at 10,000 coastal locations.

“Compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change”

They conclude that the land area exposed to extreme flood will increase by more than 250,000 sq kms – an increase of 48% – to 800,000 sq kms, a threat to 252 million people.

“A warming climate is driving sea level rise because water expands as it warms, and glaciers are melting. Climate change is also increasing the frequency of extreme seas, which will further increase the risk of flooding,” said Ebru Kirezci of the University of Melbourne, Australia, who led the study.

“What the data and our model are saying is that compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change.”

None of this should come as a surprise to civic authorities, governments, hydraulic engineers and oceanographers: researchers have been warning for years that coastal floods driven by global heating will end up costing colossal and seemingly ever increasing sums.

On a global scale, and on regional examination, the story remains the same, and wealthy and developed societies in Europe and the US face the same rising tide of hazard as the world’s poorest in the crowded coastal cities of Africa and Asia.

Estimate too low?

A mix of more extreme storms and storm surges, combined with ever higher sea levels, will sweep away the world’s beaches and turn millions of comfortable US citizens into climate refugees.

It is even possible that researchers have under-estimated the hazard, simply because satellite-based measurements may have misread precise land elevation: in some cases, too, coasts are sinking independently of sea level rise.

The latest study identifies a series of flood “hotspots” around the world. These include south-eastern China, Australia’s Northern Territory, Bangladesh, West Bengal and Gujarat in India, the US states of North Carolina, Virginia and Maryland, and north-west Europe including the UK, northern France and northern Germany. The new map of risks takes no account of existing flood defences, but highlights the levels of threat to come.

“This is critical research from a policy point of view, because it provides politicians with a credible estimate of the risks and costs we are facing, and a basis for taking action,” said Ian Young, an engineer at the University of Melbourne, and a co-author.

“This data should act as a wake-up call to inform policy at global and local government levels so that more flood defences can be built to safeguard coastal life and infrastructure.” – Climate News Network

Once again, researchers confirm that coastal dwellers can expect worse floods, more often and more expensively.

LONDON, 6 August, 2020 – In the next 80 years flooding around the planet’s land masses is likely to rise by almost 50%, endangering many millions of coastal dwellers.

If humans go on burning ever greater volumes of fossil fuels, while destroying ever more natural forest, then another 77 million people could be at risk of flooding, a rise of 52%.

And these floods – increasingly frequent and extending over greater areas – will put at risk cities, homes, resorts and industries valued at more than $14 trillion (£10.7tn).

This sum alone is worth 20% of global gross domestic product, the economist’s preferred indicator of economic health and wealth, according to a new study in the journal Scientific Reports.

The researchers built their argument on historic data from 681 tide-gauge stations around the world to model the growing hazard at 10,000 coastal locations.

“Compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change”

They conclude that the land area exposed to extreme flood will increase by more than 250,000 sq kms – an increase of 48% – to 800,000 sq kms, a threat to 252 million people.

“A warming climate is driving sea level rise because water expands as it warms, and glaciers are melting. Climate change is also increasing the frequency of extreme seas, which will further increase the risk of flooding,” said Ebru Kirezci of the University of Melbourne, Australia, who led the study.

“What the data and our model are saying is that compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change.”

None of this should come as a surprise to civic authorities, governments, hydraulic engineers and oceanographers: researchers have been warning for years that coastal floods driven by global heating will end up costing colossal and seemingly ever increasing sums.

On a global scale, and on regional examination, the story remains the same, and wealthy and developed societies in Europe and the US face the same rising tide of hazard as the world’s poorest in the crowded coastal cities of Africa and Asia.

Estimate too low?

A mix of more extreme storms and storm surges, combined with ever higher sea levels, will sweep away the world’s beaches and turn millions of comfortable US citizens into climate refugees.

It is even possible that researchers have under-estimated the hazard, simply because satellite-based measurements may have misread precise land elevation: in some cases, too, coasts are sinking independently of sea level rise.

The latest study identifies a series of flood “hotspots” around the world. These include south-eastern China, Australia’s Northern Territory, Bangladesh, West Bengal and Gujarat in India, the US states of North Carolina, Virginia and Maryland, and north-west Europe including the UK, northern France and northern Germany. The new map of risks takes no account of existing flood defences, but highlights the levels of threat to come.

“This is critical research from a policy point of view, because it provides politicians with a credible estimate of the risks and costs we are facing, and a basis for taking action,” said Ian Young, an engineer at the University of Melbourne, and a co-author.

“This data should act as a wake-up call to inform policy at global and local government levels so that more flood defences can be built to safeguard coastal life and infrastructure.” – Climate News Network

Waste plastic cascade could triple in 20 years

In a throwaway world, some discards are forever. New research measures the crisis of the world’s waste plastic.

LONDON, 30 July, 2020 − Without immediate, sustained and concerted action worldwide, the flow of waste plastic into the world’s oceans could triple by 2040.

Right now, 11 million tonnes of throwaway bags, cups, bottles, cables, netting, and other products made of almost indestructible polymers get into the sea each year.

And in the next 20 years, this tide of detritus could almost triple to 29 million tonnes, according to new research in the journal Science. This works out at nearly 50kg of plastic on every metre of coastline worldwide.

And because plastic may fragment but never degrade or decompose, the message is that by 2040 the measure of plastic in the oceans would equal the mass of three million blue whales.

The choice of the whale as indicator is not arbitrary. Discarded plastic has become a global hazard to ecosystems worldwide.

“The plastic crisis is solvable. It took a generation to create this challenge; we can solve it in one generation”

It has been found in all oceans, in lakes, in rivers, in soils and sediments, in the atmosphere and in the tissues of 700 marine species including whales, and in 50 freshwater species. It fouls beaches, blocks drains, and provides a substrate and breeding surface for the carriers of disease.

It is also expensive. At a very conservative estimate the economic costs of plastic pollution on tourism, fishing and shipping reach US$13bn (£10bn) a year. And plastic particles have entered the human food chain, though nobody can yet be certain of the impact of this.

The researchers modelled the flow of plastic and its accumulation in the environment and tested the consequences under six scenarios. These include one in which the world simply goes on making single-use plastic products and carelessly discarding them, and one in which the world’s plastics systems undergo complete overhaul, including every aspect of production, collection, consumption and disposal.

So far, on the evidence of government promises, the flow is likely to be reduced by only 7% by 2040.

Offering an opportunity

The scientists also identified eight things that could together reduce the flow of plastics into the sea by 80% in the next 20 years. That would still see five million tonnes each year getting into the oceans.

And the researchers warn that, even if every nation invested in concerted and immediate action, by 2040 at least 710 million tonnes of the stuff will have worked its way into the world’s wetlands, soils, estuaries, beaches and seas.

The report presents a calamity in the making, but one that could also be seen as an opportunity.

“Our results indicate that the plastic crisis is solvable. It took a generation to create this challenge; this report shows we can solve it in one generation,” said Martin Stuchtey, of the University of Innsbruck in Austria, one of the authors.

“We have today all the solutions required to stem plastic flows by more than 80%. What we now need is the industry and government resolve to do so.” − Climate News Network

In a throwaway world, some discards are forever. New research measures the crisis of the world’s waste plastic.

LONDON, 30 July, 2020 − Without immediate, sustained and concerted action worldwide, the flow of waste plastic into the world’s oceans could triple by 2040.

Right now, 11 million tonnes of throwaway bags, cups, bottles, cables, netting, and other products made of almost indestructible polymers get into the sea each year.

And in the next 20 years, this tide of detritus could almost triple to 29 million tonnes, according to new research in the journal Science. This works out at nearly 50kg of plastic on every metre of coastline worldwide.

And because plastic may fragment but never degrade or decompose, the message is that by 2040 the measure of plastic in the oceans would equal the mass of three million blue whales.

The choice of the whale as indicator is not arbitrary. Discarded plastic has become a global hazard to ecosystems worldwide.

“The plastic crisis is solvable. It took a generation to create this challenge; we can solve it in one generation”

It has been found in all oceans, in lakes, in rivers, in soils and sediments, in the atmosphere and in the tissues of 700 marine species including whales, and in 50 freshwater species. It fouls beaches, blocks drains, and provides a substrate and breeding surface for the carriers of disease.

It is also expensive. At a very conservative estimate the economic costs of plastic pollution on tourism, fishing and shipping reach US$13bn (£10bn) a year. And plastic particles have entered the human food chain, though nobody can yet be certain of the impact of this.

The researchers modelled the flow of plastic and its accumulation in the environment and tested the consequences under six scenarios. These include one in which the world simply goes on making single-use plastic products and carelessly discarding them, and one in which the world’s plastics systems undergo complete overhaul, including every aspect of production, collection, consumption and disposal.

So far, on the evidence of government promises, the flow is likely to be reduced by only 7% by 2040.

Offering an opportunity

The scientists also identified eight things that could together reduce the flow of plastics into the sea by 80% in the next 20 years. That would still see five million tonnes each year getting into the oceans.

And the researchers warn that, even if every nation invested in concerted and immediate action, by 2040 at least 710 million tonnes of the stuff will have worked its way into the world’s wetlands, soils, estuaries, beaches and seas.

The report presents a calamity in the making, but one that could also be seen as an opportunity.

“Our results indicate that the plastic crisis is solvable. It took a generation to create this challenge; this report shows we can solve it in one generation,” said Martin Stuchtey, of the University of Innsbruck in Austria, one of the authors.

“We have today all the solutions required to stem plastic flows by more than 80%. What we now need is the industry and government resolve to do so.” − Climate News Network

Arctic Ocean is set for more turbulent future

The Arctic Ocean is about to become more violent, with higher storm waves and higher frequency, across a wide region.

LONDON, 20 July, 2020 − The Arctic Ocean is changing, and changing fast. By the century’s end, the maximum height of storm waves in the polar seas could have risen by twice or even three times the present height.

According to new research, wave heights could increase by two metres and coastal floods could become four times, or even 10 times, as frequent.

And a separate study has found that even the character of the water in the ocean is changing: warm salty water from the Atlantic is weakening the ice cover at an accelerating rate, but providing more nutrients for Arctic life, while extra river water from the Pacific has made the American-Asian part of the Arctic Ocean less likely to mix, and less biologically productive.

The Arctic is warming at twice the rate of the planet as a whole: the ice cover has been thinning and retreating for decades. And temperatures keep on rising.

One Siberian town recorded a temperature of 38°C in June, and the region has been hit by devastating forest fires.

“In many respects, the Arctic Ocean now looks like a new ocean”

And as the oceans warm, winds become more powerful and the ocean waves respond, with prospects of ever-greater hazard for shipping and coastal settlements.

Extreme wave events that once occurred in the Arctic at average intervals of once every 20 years could by the end of the century happen every two to five years, according a study in the Journal of Geophysical Research: Oceans.

“It increases the risk of flooding and erosion. It increases drastically almost everywhere”, said Mercè Casas-Prat, a researcher with Environment and Climate Change Canada. “This can have a direct impact on communities that live close to the shoreline.”

She and a colleague used computer simulations and a range of climate predictions to work out what will happen to those ocean surfaces not covered by ice as the seas warm in response to greenhouse gas emissions from fossil fuel combustion.

They found that almost everywhere in the Arctic would experience greater wave height. The hardest-hit would be the Greenland Sea, bounded by the largest body of ice in the northern hemisphere, and the Svalbard Archipelago.

More salty water

Maximum annual wave heights could increase by as much as six metres.
“At the end of the century, the maximum will on average come later in the year and also be more extreme,” Dr Casas-Prat said.

The Arctic Ocean covers only about 3% of the planet’s surface, but it is vulnerable to change in ocean regions much nearer the Equator. US and Scandinavian scientists report in the journal Frontiers in Marine Science that they looked at 37 years of direct observation and measurement to find that not only are Arctic waters changing: they are changing in different ways.

Flows of increasingly warm salty water from the Atlantic have begun to mix at depth, weaken sea ice and bring deeper, nutrient-rich water to the surface. At the other entrance to the partly landlocked expanse of water, an increasing flow from rivers has begun to make the separation of surface and deep layers even more pronounced.

This limits the movement of nutrients to the surface, protentially making that part of the sea less biologically rich. Many marine creatures from low latitudes are moving north, in some cases replacing local species. The changes could affect fisheries, tourism, navigation and of course the people who live in the Arctic.

“In many respects, the Arctic Ocean now looks like a new ocean,” said Igor Polyakov, an oceanographer at the University of Fairbanks, Alaska, who led the research. − Climate News Network

The Arctic Ocean is about to become more violent, with higher storm waves and higher frequency, across a wide region.

LONDON, 20 July, 2020 − The Arctic Ocean is changing, and changing fast. By the century’s end, the maximum height of storm waves in the polar seas could have risen by twice or even three times the present height.

According to new research, wave heights could increase by two metres and coastal floods could become four times, or even 10 times, as frequent.

And a separate study has found that even the character of the water in the ocean is changing: warm salty water from the Atlantic is weakening the ice cover at an accelerating rate, but providing more nutrients for Arctic life, while extra river water from the Pacific has made the American-Asian part of the Arctic Ocean less likely to mix, and less biologically productive.

The Arctic is warming at twice the rate of the planet as a whole: the ice cover has been thinning and retreating for decades. And temperatures keep on rising.

One Siberian town recorded a temperature of 38°C in June, and the region has been hit by devastating forest fires.

“In many respects, the Arctic Ocean now looks like a new ocean”

And as the oceans warm, winds become more powerful and the ocean waves respond, with prospects of ever-greater hazard for shipping and coastal settlements.

Extreme wave events that once occurred in the Arctic at average intervals of once every 20 years could by the end of the century happen every two to five years, according a study in the Journal of Geophysical Research: Oceans.

“It increases the risk of flooding and erosion. It increases drastically almost everywhere”, said Mercè Casas-Prat, a researcher with Environment and Climate Change Canada. “This can have a direct impact on communities that live close to the shoreline.”

She and a colleague used computer simulations and a range of climate predictions to work out what will happen to those ocean surfaces not covered by ice as the seas warm in response to greenhouse gas emissions from fossil fuel combustion.

They found that almost everywhere in the Arctic would experience greater wave height. The hardest-hit would be the Greenland Sea, bounded by the largest body of ice in the northern hemisphere, and the Svalbard Archipelago.

More salty water

Maximum annual wave heights could increase by as much as six metres.
“At the end of the century, the maximum will on average come later in the year and also be more extreme,” Dr Casas-Prat said.

The Arctic Ocean covers only about 3% of the planet’s surface, but it is vulnerable to change in ocean regions much nearer the Equator. US and Scandinavian scientists report in the journal Frontiers in Marine Science that they looked at 37 years of direct observation and measurement to find that not only are Arctic waters changing: they are changing in different ways.

Flows of increasingly warm salty water from the Atlantic have begun to mix at depth, weaken sea ice and bring deeper, nutrient-rich water to the surface. At the other entrance to the partly landlocked expanse of water, an increasing flow from rivers has begun to make the separation of surface and deep layers even more pronounced.

This limits the movement of nutrients to the surface, protentially making that part of the sea less biologically rich. Many marine creatures from low latitudes are moving north, in some cases replacing local species. The changes could affect fisheries, tourism, navigation and of course the people who live in the Arctic.

“In many respects, the Arctic Ocean now looks like a new ocean,” said Igor Polyakov, an oceanographer at the University of Fairbanks, Alaska, who led the research. − Climate News Network

World wilts beneath weight of e-waste and plastic

It’s the throwaway society: e-waste outweighs Europe’s population, plastic waste often ends in the sea. Recycling rates offer little hope.

LONDON, 13 July, 2020 – Spoil heaps, landfill sites, incinerators and scrapyards of the world are bursting with a tide of e-waste, a discarded and growing sea of computers, cellphones and household appliances, according to a new international survey.

In 2019 businesses, industries and households threw away nearly 54 million tonnes of electronic waste: that is, devices – from computers and cellphones to refrigerators and vacuum cleaners – that need a power plug or a battery. And this detritus included an estimated US$57bn in gold, silver, copper, platinum and other expensive metals.

Less than 18% of this costly material went for recycling. In a separate study, Irish scientists have found that much of the plastic waste collected in Europe and exported for recycling ends up in the oceans: in 2017 the burden of polyethylene tipped into the seas off south-east Asia could have totalled more than 180,000 tonnes.

Discarded electronic gear – e-waste – is now the world’s fastest-growing waste stream, according to the latest report from a UN monitoring consortium.

Last year’s 53.6 million tonnes of it is a new record and represents a rise of more than one-fifth in the last five years. By 2030, this count of thrown-away electrically-powered hardware could hit 74 million tonnes annually.

“True recycling rates may deviate significantly from rates reported by municipalities and countries where the waste originates”

The total for 2019 alone was enough to outweigh all the adults in Europe; and its mass can be imagined as a line of 350 cruise ships, each the size of the Queen Mary 2, stretching for 125 kilometres. It amounted to 7.3 kilogrammes for every human on Earth.

This waste added directly to global warming. Greenhouse gases equivalent to an estimated 98 million tonnes of carbon dioxide were released by unwanted refrigerators and air conditioners.

E-waste also constitutes a health hazard: at least 50 tonnes of toxic mercury seeped into the environment from thrown-away monitors, printed circuit boards, fluorescent lights and so on.

Right now, only 78 nations have legislation or national policies to deal with e-waste. Electrically-powered devices are still only a small fraction of the entire human technosphere: the sum of things humans have manufactured, fashioned or simply built from minerals over the last 10,000 years has been estimated at 30 trillion tonnes.

But electronic waste is already a significant cost and possibly an important potential resource. Another – new and entirely separate – study of metal sources on the planet estimates that in the next 25 years the global demand for copper, lead, zinc and nickel is likely to exceed the total produced so far in all human history.

Recycling goes overboard

European Union members and partner countries – the UK, Switzerland and Norway – have developed the infrastructure to manage another menacing discard, plastic waste, but 46% of this is exported out of the country of origin for recycling in countries with poor records of waste management, and a high proportion ends up in the oceans.

Plastic debris has been found on the deep seabed, on the beaches of desolate Antarctic islands, in the north polar ice, and in the tissues of sea creatures from sardines to whales.

Most of this is directly and deliberately discarded. But even the waste intended for recycling gets into the oceans. Researchers report in the journal Environment International that they made estimates of the fate of Europe’s exported waste in 2017.

They think up to 7% of all exported polyethylene – the commonest plastic in Europe – found its way to the oceans: at the very least 32,115 tonnes were tipped into the sea, and at the most 180,558 tonnes.

“This study suggests that true recycling rates may deviate significantly from rates reported by municipalities and countries where the waste originates,” said one of the authors, David Styles of the University of Limerick in Eire and the National University of Ireland in Galway.

“In fact, our study found 31% of the exported plastic wasn’t actually recycled at all.” – Climate News Network

It’s the throwaway society: e-waste outweighs Europe’s population, plastic waste often ends in the sea. Recycling rates offer little hope.

LONDON, 13 July, 2020 – Spoil heaps, landfill sites, incinerators and scrapyards of the world are bursting with a tide of e-waste, a discarded and growing sea of computers, cellphones and household appliances, according to a new international survey.

In 2019 businesses, industries and households threw away nearly 54 million tonnes of electronic waste: that is, devices – from computers and cellphones to refrigerators and vacuum cleaners – that need a power plug or a battery. And this detritus included an estimated US$57bn in gold, silver, copper, platinum and other expensive metals.

Less than 18% of this costly material went for recycling. In a separate study, Irish scientists have found that much of the plastic waste collected in Europe and exported for recycling ends up in the oceans: in 2017 the burden of polyethylene tipped into the seas off south-east Asia could have totalled more than 180,000 tonnes.

Discarded electronic gear – e-waste – is now the world’s fastest-growing waste stream, according to the latest report from a UN monitoring consortium.

Last year’s 53.6 million tonnes of it is a new record and represents a rise of more than one-fifth in the last five years. By 2030, this count of thrown-away electrically-powered hardware could hit 74 million tonnes annually.

“True recycling rates may deviate significantly from rates reported by municipalities and countries where the waste originates”

The total for 2019 alone was enough to outweigh all the adults in Europe; and its mass can be imagined as a line of 350 cruise ships, each the size of the Queen Mary 2, stretching for 125 kilometres. It amounted to 7.3 kilogrammes for every human on Earth.

This waste added directly to global warming. Greenhouse gases equivalent to an estimated 98 million tonnes of carbon dioxide were released by unwanted refrigerators and air conditioners.

E-waste also constitutes a health hazard: at least 50 tonnes of toxic mercury seeped into the environment from thrown-away monitors, printed circuit boards, fluorescent lights and so on.

Right now, only 78 nations have legislation or national policies to deal with e-waste. Electrically-powered devices are still only a small fraction of the entire human technosphere: the sum of things humans have manufactured, fashioned or simply built from minerals over the last 10,000 years has been estimated at 30 trillion tonnes.

But electronic waste is already a significant cost and possibly an important potential resource. Another – new and entirely separate – study of metal sources on the planet estimates that in the next 25 years the global demand for copper, lead, zinc and nickel is likely to exceed the total produced so far in all human history.

Recycling goes overboard

European Union members and partner countries – the UK, Switzerland and Norway – have developed the infrastructure to manage another menacing discard, plastic waste, but 46% of this is exported out of the country of origin for recycling in countries with poor records of waste management, and a high proportion ends up in the oceans.

Plastic debris has been found on the deep seabed, on the beaches of desolate Antarctic islands, in the north polar ice, and in the tissues of sea creatures from sardines to whales.

Most of this is directly and deliberately discarded. But even the waste intended for recycling gets into the oceans. Researchers report in the journal Environment International that they made estimates of the fate of Europe’s exported waste in 2017.

They think up to 7% of all exported polyethylene – the commonest plastic in Europe – found its way to the oceans: at the very least 32,115 tonnes were tipped into the sea, and at the most 180,558 tonnes.

“This study suggests that true recycling rates may deviate significantly from rates reported by municipalities and countries where the waste originates,” said one of the authors, David Styles of the University of Limerick in Eire and the National University of Ireland in Galway.

“In fact, our study found 31% of the exported plastic wasn’t actually recycled at all.” – Climate News Network

Warming oceans deter more fish from spawning

When the moment to mate arrives, fish like to play it cool. So warming oceans create special problems for the generation game.

LONDON, 9 July, 2020 – German scientists now know why so many fish are so vulnerable to ever-warming oceans. Global heating imposes a harsh cost at the most critical time of all: the moment of spawning.

“Our findings show that, both as embryos in eggs and as adults ready to mate, fish are far more sensitive to heat than in their larval stage or as sexually mature adults outside the mating season,” said Flemming Dahlke, a marine biologist with the Alfred Wegener Institute at Bremerhaven.

“On the global average, for example, adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can.”

The finding – if it is confirmed by other research – should clear up some of the puzzles associated with fish numbers. There is clear evidence, established repeatedly over the decades, that fish are responding to climate change.

But almost three fourths of the planet is blue ocean, and at depth is responding far more slowly than the land surface to global heating fuelled by fossil fuel exploitation that releases greenhouse gases.

Nearing the brink

Since fish in the temperate zones already experience a wide variation in seasonal water temperatures, it hasn’t been obvious why species such as cod have shifted nearer the Arctic, and sardines have migrated to the North Sea.

But marine creatures are on the move, and although there are other factors at work, including overfishing and the increasingly alarming changes in ocean chemistry, thanks to ever-higher levels of dissolved carbon dioxide, temperature change is part of the problem.

The latest answer, Dr Dahlke and his colleagues report in the journal Science, is that many fish may already be living near the limits of their thermal tolerance.

The temperature safety margins during the moments of spawning and embryo might be very precise, and over hundreds of thousands of years of evolution, marine and freshwater species have worked out just what is best for the next generation. Rapid global warming upsets this equilibrium.

“Adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can”

The Bremerhaven scientists looked at experiments, observations and recorded data for the life cycles of 694 marine and freshwater species, to decide that oxygen supply is the key decider of reproductive success. Warmer waters carry less dissolved oxygen. Embryo fish have no gills: they cannot simply take in deeper breaths.

Fish about to mate are busy producing extra mass in the form of sperm and egg cells: this additional body mass also needs oxygen. Even at lower temperatures, piscine cardiovascular systems are under stress.

So the reasoning follows that, if global heating continues, climate change and rising water temperatures are likely to affect the reproduction of perhaps 60% of all fish species.

“Some species might successfully manage this change,” Dr Dahlke said.
“But if you consider the fact that fish have adapted their mating patterns to specific habitats over extremely long timeframes, and have tailored their mating cycles of specific ocean currents and food sources, it has to be assumed that being forced to abandon their normal spawning areas will mean major problems for them.” – Climate News Network

When the moment to mate arrives, fish like to play it cool. So warming oceans create special problems for the generation game.

LONDON, 9 July, 2020 – German scientists now know why so many fish are so vulnerable to ever-warming oceans. Global heating imposes a harsh cost at the most critical time of all: the moment of spawning.

“Our findings show that, both as embryos in eggs and as adults ready to mate, fish are far more sensitive to heat than in their larval stage or as sexually mature adults outside the mating season,” said Flemming Dahlke, a marine biologist with the Alfred Wegener Institute at Bremerhaven.

“On the global average, for example, adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can.”

The finding – if it is confirmed by other research – should clear up some of the puzzles associated with fish numbers. There is clear evidence, established repeatedly over the decades, that fish are responding to climate change.

But almost three fourths of the planet is blue ocean, and at depth is responding far more slowly than the land surface to global heating fuelled by fossil fuel exploitation that releases greenhouse gases.

Nearing the brink

Since fish in the temperate zones already experience a wide variation in seasonal water temperatures, it hasn’t been obvious why species such as cod have shifted nearer the Arctic, and sardines have migrated to the North Sea.

But marine creatures are on the move, and although there are other factors at work, including overfishing and the increasingly alarming changes in ocean chemistry, thanks to ever-higher levels of dissolved carbon dioxide, temperature change is part of the problem.

The latest answer, Dr Dahlke and his colleagues report in the journal Science, is that many fish may already be living near the limits of their thermal tolerance.

The temperature safety margins during the moments of spawning and embryo might be very precise, and over hundreds of thousands of years of evolution, marine and freshwater species have worked out just what is best for the next generation. Rapid global warming upsets this equilibrium.

“Adults outside the mating season can survive in water that’s up to 10°C warmer than adults ready to mate, or fish eggs, can”

The Bremerhaven scientists looked at experiments, observations and recorded data for the life cycles of 694 marine and freshwater species, to decide that oxygen supply is the key decider of reproductive success. Warmer waters carry less dissolved oxygen. Embryo fish have no gills: they cannot simply take in deeper breaths.

Fish about to mate are busy producing extra mass in the form of sperm and egg cells: this additional body mass also needs oxygen. Even at lower temperatures, piscine cardiovascular systems are under stress.

So the reasoning follows that, if global heating continues, climate change and rising water temperatures are likely to affect the reproduction of perhaps 60% of all fish species.

“Some species might successfully manage this change,” Dr Dahlke said.
“But if you consider the fact that fish have adapted their mating patterns to specific habitats over extremely long timeframes, and have tailored their mating cycles of specific ocean currents and food sources, it has to be assumed that being forced to abandon their normal spawning areas will mean major problems for them.” – Climate News Network

Ocean sensitivity may lower carbon emissions cuts

Ocean sensitivity to atmospheric change is well established. But just how sensitive the oceans are remains a surprise to science.

LONDON, 30 June, 2020 – As greenhouse gas emissions soar, ocean sensitivity has quietly helped humanity to slow global heating: the seas have responded by absorbing more and more carbon dioxide from the atmosphere.

But should humans come to grips with the challenge of looming climate catastrophe and start to reduce emissions, the oceans could respond again – by absorbing less and slightly slowing the fall of the mercury in the global thermometer.

And there is even an immediate chance to test this proposal: if so, then oceans that have been each year absorbing more and more carbon from the atmosphere as greenhouse gas ratios rise will go into brief reverse, because of the global economic shutdown and fall in emissions triggered by the global pandemic of Covid-19.

For the first time in decades, the oceans could take up less carbon dioxide in 2020, according to a new study by US scientists in the American Geophysical Union journal AGU Advances.

“We didn’t realise until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That’s a real surprise,” said Galen McKinley, of Columbia University’s Lamont-Doherty Earth Observatory.

Feedback in action

“As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it’s important to realise that the ocean carbon sink will respond by slowing down.”

The research should not be interpreted as an invitation to go on burning fossil fuels. It is another lesson in the intricacy of the traffic between atmosphere, rocks, oceans, and living things in an evolving world. And it is more immediately an exquisite example of what engineers call feedback.

In cases of negative feedback, the agency of change also triggers a way of slowing that change. Since 1750 – the birth of the Industrial Revolution – human economies have added 440 billion tonnes of carbon to the planetary atmosphere.

For most of human history carbon dioxide ratios in the atmosphere had hovered around 285 parts per million. They have now gone beyond 400 ppm, and global average temperatures have already risen by more than 1°C.

They’d be even higher but for the oceans, which have responded by absorbing around 39% of all that extra carbon from coal, oil and gas combustion. So the oceans are sensitive to atmospheric change, and respond.

“There will be a time when the ocean will limit the effectiveness of mitigation actions, and this should be accounted for in policymaking”

The latest study is a lesson in how sensitive: Professor McKinley and her colleagues used computer models to try to understand better why the ocean uptake of carbon varies.

In the early 1990s, the ocean absorption of carbon dioxide varied: dramatically at first, because a devastating volcanic eruption of Mt Pinatubo in the Philippines in 1991 that darkened the stratosphere also accelerated ocean uptake.

And then the ocean uptake started to slow, as the skies cleared but also as the collapse of the Soviet Union and its satellite nations changed the global pattern of fuel use. It went on declining until 2001, when fossil fuel use started to accelerate. And then the ocean sink started once again to become more absorbent.

Such research is a reminder of how much scientists still don’t know about the machinery of the planet. That greenhouse gas from fossil fuel combustion drives global heating is not now in doubt. But the precise speed, and the drivers and brakes of positive and negative feedback, remain less certain.

Many feedbacks are positive: as the Arctic warms, carbon plant remains frozen in the permafrost will start to decay, release more methane and carbon dioxide, and accelerate warming.

Forest concern

As the sea ice retreats, and the ice reflects less sunlight, the exposed blue seas will absorb ever more radiation, to turn up the planetary temperatures. A warner world will be a wetter one, which may also mean a rise in the rate of warming.

But the ocean is not the only example of negative feedback. More carbon dioxide seems to mean more vigorous plant growth, and there is clear evidence that the world’s great forests are an important carbon sink: an example of negative feedback. That is why almost all governments recognise the importance of forest conservation.

Action however is uneven, forests are still being degraded, and there is alarming evidence that at some point, as temperatures get too high, the tropical forests could start surrendering the carbon they have for millennia absorbed, and become agents of positive feedback.

Professor McKinley warns that – as global emissions are cut – there will be a phase during which ocean uptake slows. If so, then planetary temperature rise will not slow as fast as hoped: extra carbon dioxide will linger, to contribute to warming.

“We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking.” – Climate News Network

Ocean sensitivity to atmospheric change is well established. But just how sensitive the oceans are remains a surprise to science.

LONDON, 30 June, 2020 – As greenhouse gas emissions soar, ocean sensitivity has quietly helped humanity to slow global heating: the seas have responded by absorbing more and more carbon dioxide from the atmosphere.

But should humans come to grips with the challenge of looming climate catastrophe and start to reduce emissions, the oceans could respond again – by absorbing less and slightly slowing the fall of the mercury in the global thermometer.

And there is even an immediate chance to test this proposal: if so, then oceans that have been each year absorbing more and more carbon from the atmosphere as greenhouse gas ratios rise will go into brief reverse, because of the global economic shutdown and fall in emissions triggered by the global pandemic of Covid-19.

For the first time in decades, the oceans could take up less carbon dioxide in 2020, according to a new study by US scientists in the American Geophysical Union journal AGU Advances.

“We didn’t realise until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That’s a real surprise,” said Galen McKinley, of Columbia University’s Lamont-Doherty Earth Observatory.

Feedback in action

“As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it’s important to realise that the ocean carbon sink will respond by slowing down.”

The research should not be interpreted as an invitation to go on burning fossil fuels. It is another lesson in the intricacy of the traffic between atmosphere, rocks, oceans, and living things in an evolving world. And it is more immediately an exquisite example of what engineers call feedback.

In cases of negative feedback, the agency of change also triggers a way of slowing that change. Since 1750 – the birth of the Industrial Revolution – human economies have added 440 billion tonnes of carbon to the planetary atmosphere.

For most of human history carbon dioxide ratios in the atmosphere had hovered around 285 parts per million. They have now gone beyond 400 ppm, and global average temperatures have already risen by more than 1°C.

They’d be even higher but for the oceans, which have responded by absorbing around 39% of all that extra carbon from coal, oil and gas combustion. So the oceans are sensitive to atmospheric change, and respond.

“There will be a time when the ocean will limit the effectiveness of mitigation actions, and this should be accounted for in policymaking”

The latest study is a lesson in how sensitive: Professor McKinley and her colleagues used computer models to try to understand better why the ocean uptake of carbon varies.

In the early 1990s, the ocean absorption of carbon dioxide varied: dramatically at first, because a devastating volcanic eruption of Mt Pinatubo in the Philippines in 1991 that darkened the stratosphere also accelerated ocean uptake.

And then the ocean uptake started to slow, as the skies cleared but also as the collapse of the Soviet Union and its satellite nations changed the global pattern of fuel use. It went on declining until 2001, when fossil fuel use started to accelerate. And then the ocean sink started once again to become more absorbent.

Such research is a reminder of how much scientists still don’t know about the machinery of the planet. That greenhouse gas from fossil fuel combustion drives global heating is not now in doubt. But the precise speed, and the drivers and brakes of positive and negative feedback, remain less certain.

Many feedbacks are positive: as the Arctic warms, carbon plant remains frozen in the permafrost will start to decay, release more methane and carbon dioxide, and accelerate warming.

Forest concern

As the sea ice retreats, and the ice reflects less sunlight, the exposed blue seas will absorb ever more radiation, to turn up the planetary temperatures. A warner world will be a wetter one, which may also mean a rise in the rate of warming.

But the ocean is not the only example of negative feedback. More carbon dioxide seems to mean more vigorous plant growth, and there is clear evidence that the world’s great forests are an important carbon sink: an example of negative feedback. That is why almost all governments recognise the importance of forest conservation.

Action however is uneven, forests are still being degraded, and there is alarming evidence that at some point, as temperatures get too high, the tropical forests could start surrendering the carbon they have for millennia absorbed, and become agents of positive feedback.

Professor McKinley warns that – as global emissions are cut – there will be a phase during which ocean uptake slows. If so, then planetary temperature rise will not slow as fast as hoped: extra carbon dioxide will linger, to contribute to warming.

“We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking.” – Climate News Network