Category Archives: Oceans

Weakening Gulf Stream may disrupt world weather

The Gulf Stream is growing feebler, the Arctic seas are gaining fresh water. Together they could affect the world’s weather.

LONDON, 2 March, 2021 − The Atlantic Conveyer, otherwise the Gulf Stream − that great flow of surface water pouring northwards that overturns in the Arctic and heads south again at great depth − is now weaker than at any point in the last 1,000 years, European scientists report.

And in a second, separate but related study, researchers have found that the Beaufort Sea, in the Arctic, has gained two-fifths more fresh water in the last 20 years: water that could flow into the Atlantic to affect the Conveyor, and with it, climatic conditions.

Scientists call it the Atlantic Meridional Overturning Circulation or just AMOC. Europeans know it as the Gulf Stream: the current that conveys tropic warmth to their coasts and keeps Britain and Western Europe at a temperature several degrees higher than latitude alone might dictate.

And for years, oceanographers and climate scientists have been observing a slowing of the flow, by as much as 15%. But direct measurement of the great current began only relatively recently in 2004: researchers needed to know whether the slowdown was part of a natural cycle, or a consequence of climate change driven by global heating.

Now they know a little more. European researchers report in Nature Geoscience that they looked for evidence of ocean circulation shifts in what they call “proxy evidence”: the story of climate change told by tree growth rings, ice cores, ocean sediments, corals and historical records, including naval logbooks.

The combined evidence of temperature patterns, the sizes of particles of ocean floor sediment and the salinity and density of sub-surface water helps build up a picture of the Atlantic current for the last 1,600 years.

“The Gulf Stream System moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow”

The verdict? Up to the 19th century, ocean currents were stable. The flow is now more sluggish than at any time in the last millennium.

This is roughly what climate models have predicted: the warm salty water moves north, cools, becomes more dense, sinks to the deep and flows back south. But the Arctic has begun to warm, Greenland to melt, and the flow of fresh water into the northern seas to intensify.

Since the flow is driven by the difference in temperatures, any change in the regional thermometer will play back into the rate of flow. And any extra arrival of fresh water could further slow the overturning circulation.

“The Gulf Stream system works like a giant conveyor belt, carrying warm surface water from the equator up north, and sending cold, low-salinity deep water back down south. It moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow,” said Stefan Rahmstorf, of the Potsdam Institute for Climate Impact Research, in Germany, one of the authors.

“For the first time, we have combined a range of previous studies and found they provide a consistent picture of the AMOC evolution over the past 1600 years. The study results suggest that it has been relatively stable until the late 19th century.

“With the end of the Little Ice Age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century.”

Outcome awaited

The change could have ominous consequences for European weather systems: it could also deliver more intense coastal flooding to the US eastern seaboard. If the current continues to weaken, the consequences could be catastrophic.

Which is why a new study in Nature Communications matters so much. US researchers tracked the flow of fresh water from the Beaufort Sea − melt water from glaciers, rivers and disappearing Arctic sea ice − through the Canadian Archipelago and into the Labrador Sea.

Arctic water is fresher than Atlantic water, and richer in nutrients. But this extra volume, measured at a total of 23,300 cubic kilometres, could also affect the rate of flow of the overturning circulation. That is because relatively fresh water is less dense than saline water, and tends to float on top.

Quite what role it could play is uncertain: the message is that, sooner or later, it will escape into the North Atlantic. Then the world will find out.

“People have already spent a lot of time studying why the Beaufort Sea fresh water has gotten so high in the past few decades,” said Jiaxu Zhang,  of the Los Alamos National Laboratory, first author. “But they rarely care where the freshwater goes, and we think that’s a much more important problem.” − Climate News Network

The Gulf Stream is growing feebler, the Arctic seas are gaining fresh water. Together they could affect the world’s weather.

LONDON, 2 March, 2021 − The Atlantic Conveyer, otherwise the Gulf Stream − that great flow of surface water pouring northwards that overturns in the Arctic and heads south again at great depth − is now weaker than at any point in the last 1,000 years, European scientists report.

And in a second, separate but related study, researchers have found that the Beaufort Sea, in the Arctic, has gained two-fifths more fresh water in the last 20 years: water that could flow into the Atlantic to affect the Conveyor, and with it, climatic conditions.

Scientists call it the Atlantic Meridional Overturning Circulation or just AMOC. Europeans know it as the Gulf Stream: the current that conveys tropic warmth to their coasts and keeps Britain and Western Europe at a temperature several degrees higher than latitude alone might dictate.

And for years, oceanographers and climate scientists have been observing a slowing of the flow, by as much as 15%. But direct measurement of the great current began only relatively recently in 2004: researchers needed to know whether the slowdown was part of a natural cycle, or a consequence of climate change driven by global heating.

Now they know a little more. European researchers report in Nature Geoscience that they looked for evidence of ocean circulation shifts in what they call “proxy evidence”: the story of climate change told by tree growth rings, ice cores, ocean sediments, corals and historical records, including naval logbooks.

The combined evidence of temperature patterns, the sizes of particles of ocean floor sediment and the salinity and density of sub-surface water helps build up a picture of the Atlantic current for the last 1,600 years.

“The Gulf Stream System moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow”

The verdict? Up to the 19th century, ocean currents were stable. The flow is now more sluggish than at any time in the last millennium.

This is roughly what climate models have predicted: the warm salty water moves north, cools, becomes more dense, sinks to the deep and flows back south. But the Arctic has begun to warm, Greenland to melt, and the flow of fresh water into the northern seas to intensify.

Since the flow is driven by the difference in temperatures, any change in the regional thermometer will play back into the rate of flow. And any extra arrival of fresh water could further slow the overturning circulation.

“The Gulf Stream system works like a giant conveyor belt, carrying warm surface water from the equator up north, and sending cold, low-salinity deep water back down south. It moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow,” said Stefan Rahmstorf, of the Potsdam Institute for Climate Impact Research, in Germany, one of the authors.

“For the first time, we have combined a range of previous studies and found they provide a consistent picture of the AMOC evolution over the past 1600 years. The study results suggest that it has been relatively stable until the late 19th century.

“With the end of the Little Ice Age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century.”

Outcome awaited

The change could have ominous consequences for European weather systems: it could also deliver more intense coastal flooding to the US eastern seaboard. If the current continues to weaken, the consequences could be catastrophic.

Which is why a new study in Nature Communications matters so much. US researchers tracked the flow of fresh water from the Beaufort Sea − melt water from glaciers, rivers and disappearing Arctic sea ice − through the Canadian Archipelago and into the Labrador Sea.

Arctic water is fresher than Atlantic water, and richer in nutrients. But this extra volume, measured at a total of 23,300 cubic kilometres, could also affect the rate of flow of the overturning circulation. That is because relatively fresh water is less dense than saline water, and tends to float on top.

Quite what role it could play is uncertain: the message is that, sooner or later, it will escape into the North Atlantic. Then the world will find out.

“People have already spent a lot of time studying why the Beaufort Sea fresh water has gotten so high in the past few decades,” said Jiaxu Zhang,  of the Los Alamos National Laboratory, first author. “But they rarely care where the freshwater goes, and we think that’s a much more important problem.” − Climate News Network

Rising sea levels may make some airports unusable

High flyers could soon have a problem with high water. Rising sea levels could one day shut down airports.

LONDON, 3 February, 2021 − Passengers, prepare for splashdown. Take-off may have to wait for low tide. By 2100, thanks to rising sea levels, around 100 of the world’s airports could be below mean sea level and at least 364 will be vulnerable to flooding.

And that’s assuming the world’s nations keep a promise made in 2015 and confine global heating to no more than 2°C above the average maintained for most of human history. If humans go on burning fossil fuels and clearing forests at the present rate, then at least 572 of the world’s airports could be at risk of flooding from extreme tides, according to a new study in the journal Climate Risk Management.

These things have already happened: in 2018 a typhoon storm surge inundated Kansai International Airport in Osaka Bay, Japan. Superstorm Sandy in 2012 closed New York City’s La Guardia Airport for three days. One-tenth of the planet’s population lives on coastlines less than 10 metres above sea level.

Airports grow up around the great cities: they require flat land and a clear flight path. Coastal flood plains, wetlands and reclaimed land provide exactly that.

Serious risk

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption,” said Richard Dawson, an engineer at Newcastle University in the United Kingdom. “Sea level rise therefore poses a serious risk to global passenger and freight movements, with considerable cost of damage and disruption.”

He and a colleague looked at the world’s 14,000 airports and helicopter pads to identify 1,238 airports in what geographers call low elevation coastal zones: that is, down by the seaside. Of these, 199, serving 3,436 routes, were in the US; China had 30 airports serving 2,333 routes.

They found that just 20 airports at risk handled more than 800 million passengers in 2018 − approaching a fifth of the world’s passenger traffic that year − and nearly 16 million tonnes of cargo: one-fourth of all the world’s air freight that year. They then started looking at what climate change could do to all that business.

Even before the shutdown of traffic because of the global pandemic, the world’s airlines had been feeling the heat. Research teams have confirmed that ever higher global temperatures mean more atmospheric turbulence at altitude; that wind speed changes will slow flights and raise costs; that extremes of heat could even close airport runways and delay flights for extended periods.

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption”

Now Professor Dawson and his colleague have compiled a table of hazard rankings for flooded airstrips under a range of climate change scenarios.

Right now, 269 of the world’s airports are at some risk of coastal flooding. This number must rise: by how much, and at what cost, depends on what actions the world takes. But the researchers calculate that by 2100 the risk of disruption could increase 17-fold, or even 69-fold. And because so many important airports are already at or near sea level, up to a fifth of all the world’s routes will be at risk.

And that means higher costs for flood protection, or action to raise airport sites, or relocation. The choice is to adapt or, quite literally, to go under.

“The cost of adaptation will be modest in the context of global infrastructure expenditure,” Professor Dawson said. “However, in some locations the rate of sea level rise, limited economic resources or space for alternative locations will make some airports unviable.” − Climate News Network

High flyers could soon have a problem with high water. Rising sea levels could one day shut down airports.

LONDON, 3 February, 2021 − Passengers, prepare for splashdown. Take-off may have to wait for low tide. By 2100, thanks to rising sea levels, around 100 of the world’s airports could be below mean sea level and at least 364 will be vulnerable to flooding.

And that’s assuming the world’s nations keep a promise made in 2015 and confine global heating to no more than 2°C above the average maintained for most of human history. If humans go on burning fossil fuels and clearing forests at the present rate, then at least 572 of the world’s airports could be at risk of flooding from extreme tides, according to a new study in the journal Climate Risk Management.

These things have already happened: in 2018 a typhoon storm surge inundated Kansai International Airport in Osaka Bay, Japan. Superstorm Sandy in 2012 closed New York City’s La Guardia Airport for three days. One-tenth of the planet’s population lives on coastlines less than 10 metres above sea level.

Airports grow up around the great cities: they require flat land and a clear flight path. Coastal flood plains, wetlands and reclaimed land provide exactly that.

Serious risk

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption,” said Richard Dawson, an engineer at Newcastle University in the United Kingdom. “Sea level rise therefore poses a serious risk to global passenger and freight movements, with considerable cost of damage and disruption.”

He and a colleague looked at the world’s 14,000 airports and helicopter pads to identify 1,238 airports in what geographers call low elevation coastal zones: that is, down by the seaside. Of these, 199, serving 3,436 routes, were in the US; China had 30 airports serving 2,333 routes.

They found that just 20 airports at risk handled more than 800 million passengers in 2018 − approaching a fifth of the world’s passenger traffic that year − and nearly 16 million tonnes of cargo: one-fourth of all the world’s air freight that year. They then started looking at what climate change could do to all that business.

Even before the shutdown of traffic because of the global pandemic, the world’s airlines had been feeling the heat. Research teams have confirmed that ever higher global temperatures mean more atmospheric turbulence at altitude; that wind speed changes will slow flights and raise costs; that extremes of heat could even close airport runways and delay flights for extended periods.

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption”

Now Professor Dawson and his colleague have compiled a table of hazard rankings for flooded airstrips under a range of climate change scenarios.

Right now, 269 of the world’s airports are at some risk of coastal flooding. This number must rise: by how much, and at what cost, depends on what actions the world takes. But the researchers calculate that by 2100 the risk of disruption could increase 17-fold, or even 69-fold. And because so many important airports are already at or near sea level, up to a fifth of all the world’s routes will be at risk.

And that means higher costs for flood protection, or action to raise airport sites, or relocation. The choice is to adapt or, quite literally, to go under.

“The cost of adaptation will be modest in the context of global infrastructure expenditure,” Professor Dawson said. “However, in some locations the rate of sea level rise, limited economic resources or space for alternative locations will make some airports unviable.” − Climate News Network

Human rubbish is smothering the planet’s oceans

In a throwaway world garbage may be unseen, but not gone. Human rubbish is everywhere, from ocean abyss to coastal mud.

LONDON, 29 January, 2021 − In the next 30 years, an estimated three billion metric tonnes of human rubbish − everything from abandoned trawl nets to plastic bottles, from broken teacups to tins of toxin − could find its way into the sea, to defile the ocean floor.

One recent survey in the Strait of Messina, the seaway that separates Italy and Sicily, measured this detritus at concentrations of between 121,000 and 1.3 million items per square kilometre trapped in submarine canyons.

In seabed fissures off Portugal, bits of human litter large enough to identify have been counted at rates of 11,000 per sq km. Off the Ryukyu Islands far from mainland Japan, divers and remotely operated vehicles have made estimates of up to 71,000 items per sq km.

There is more and worse lying on other parts of the seabed. An estimated one million tonnes of chemical weaponry could be scattered about the planet’s oceans. The North Sea floor could be host to 1.3 million tonnes of conventional and chemical weapons; the Baltic enfolds and flows over 385,00 tonnes of dropped bombs, grenades, torpedoes, landmines and other weaponry.

“As humans, we have little or no care at all to prevent litter from accumulating everywhere”

And, says a new study in the journal Environmental Research Letters, this conversion of sea floor to careless landfill site creates problems for at least 693 marine species that so far have been observed to “interact” with marine debris: eat it, get caught in it, grow on it. Of these species, around one in six are in some degree endangered.

This list of sea creatures includes 93 kinds of invertebrate, 89 fish, 83 birds, 38 mammals and all species of sea turtle. So many fish now become ensnared in abandoned and derelict fishing gear that they are known as “ghost catches.”

Across the Asia-Pacific region, an estimated 11.1 billion bits of plastic bigger than 25mm could be entangled in the coral reefs. This problem of marine pollution goes far beyond the concern over plastic pollution of the planet’s seas and shores, from pole to pole, and is now found even in marine tissues.

Much of the previous concern has been about the presence of microfibres and small particles of polymer material now found everywhere. But the new study by European scientists tries to address the more obvious problem of these larger items − generally larger than 25mms − of all kinds of detritus, including plastic denser than water and ultimately destined to reach the seabed.

Poor management

The researchers want to try to find standard ways to measure the levels of waste, map its concentrations accurately, identify all the sources of refuse and classify the most problematic kinds: the toxic waste, the heavy metals and radioactive substances, the pharmaceuticals. They also urge international co-operation, and policies designed to discourage marine discharges and to clear up stretches of the sea floor.

“Marine litter has reached the most remote places in the ocean, even the least − or never − frequented by our species and not yet mapped by science,” said Miquel Canals of the University of Barcelona, who led the study.

“In order to correct something bad, we must attack its cause. And the cause of the accumulation of waste on the coasts, seas and oceans , and all over the planet, is the excess waste generation and spillage in the environment, and poor or insufficient management practices.

“As humans, we have little or no care at all to prevent litter from accumulating everywhere.” − Climate News Network

In a throwaway world garbage may be unseen, but not gone. Human rubbish is everywhere, from ocean abyss to coastal mud.

LONDON, 29 January, 2021 − In the next 30 years, an estimated three billion metric tonnes of human rubbish − everything from abandoned trawl nets to plastic bottles, from broken teacups to tins of toxin − could find its way into the sea, to defile the ocean floor.

One recent survey in the Strait of Messina, the seaway that separates Italy and Sicily, measured this detritus at concentrations of between 121,000 and 1.3 million items per square kilometre trapped in submarine canyons.

In seabed fissures off Portugal, bits of human litter large enough to identify have been counted at rates of 11,000 per sq km. Off the Ryukyu Islands far from mainland Japan, divers and remotely operated vehicles have made estimates of up to 71,000 items per sq km.

There is more and worse lying on other parts of the seabed. An estimated one million tonnes of chemical weaponry could be scattered about the planet’s oceans. The North Sea floor could be host to 1.3 million tonnes of conventional and chemical weapons; the Baltic enfolds and flows over 385,00 tonnes of dropped bombs, grenades, torpedoes, landmines and other weaponry.

“As humans, we have little or no care at all to prevent litter from accumulating everywhere”

And, says a new study in the journal Environmental Research Letters, this conversion of sea floor to careless landfill site creates problems for at least 693 marine species that so far have been observed to “interact” with marine debris: eat it, get caught in it, grow on it. Of these species, around one in six are in some degree endangered.

This list of sea creatures includes 93 kinds of invertebrate, 89 fish, 83 birds, 38 mammals and all species of sea turtle. So many fish now become ensnared in abandoned and derelict fishing gear that they are known as “ghost catches.”

Across the Asia-Pacific region, an estimated 11.1 billion bits of plastic bigger than 25mm could be entangled in the coral reefs. This problem of marine pollution goes far beyond the concern over plastic pollution of the planet’s seas and shores, from pole to pole, and is now found even in marine tissues.

Much of the previous concern has been about the presence of microfibres and small particles of polymer material now found everywhere. But the new study by European scientists tries to address the more obvious problem of these larger items − generally larger than 25mms − of all kinds of detritus, including plastic denser than water and ultimately destined to reach the seabed.

Poor management

The researchers want to try to find standard ways to measure the levels of waste, map its concentrations accurately, identify all the sources of refuse and classify the most problematic kinds: the toxic waste, the heavy metals and radioactive substances, the pharmaceuticals. They also urge international co-operation, and policies designed to discourage marine discharges and to clear up stretches of the sea floor.

“Marine litter has reached the most remote places in the ocean, even the least − or never − frequented by our species and not yet mapped by science,” said Miquel Canals of the University of Barcelona, who led the study.

“In order to correct something bad, we must attack its cause. And the cause of the accumulation of waste on the coasts, seas and oceans , and all over the planet, is the excess waste generation and spillage in the environment, and poor or insufficient management practices.

“As humans, we have little or no care at all to prevent litter from accumulating everywhere.” − Climate News Network

Ocean research plan seeks to preserve seas’ wealth

A decade of ocean research is about to begin to try to save the planet’s richest habitat from human destruction.

LONDON, 9 December, 2020 − Humans need urgently to invest in ocean research and protection. In return, the ocean could repay them handsomely, by soaking up atmospheric carbon, delivering huge amounts of renewable energy, providing six times more sustainable seafood, creating millions of jobs and generating trillions in economic benefits.

The oceans cover 70% of the planet but, a trio of scientists warn in the journal Nature, “for much too long, the ocean has been out of sight, out of mind and out of luck.”

From the margins of the coast to the deepest seas, the oceans’ habitats and the living creatures in them have been threatened by excessive and destructive fishing, they say.

“Unsustainable development along coastlines is destroying coral reefs, seagrass beds, salt marshes and mangrove forests. These house biodiversity, sequester carbon, provide nurseries for fish and buffer coasts against storm surges.

Separate approaches inadequate

Plastics and nutrients washed from the land are also killing wildlife. All of these threats erode the capacity of the ocean to provide nutritious food, jobs, medicines and pharmaceuticals as well as regulate the climate.”

But something can be done. A new report − commissioned by Norway, Palau, 12 other nations and a UN envoy, collectively responsible for two-fifths of the world’s coastlines, almost a third of the exclusive economic zones and a fifth of the world’s shipping − argues that it is not enough for individual nations to manage their sectors or confront challenging issues separately. The largest and deepest continuous living space on the planet demands something more.

The report finds that − if the world co-operated in an holistic approach to care for the oceans, and protected at least 30% of them − then by 2050 the deep blue sea could account for 20% of the carbon emission reductions needed to match the Paris climate agreement target of no more than 1.5°C warming above pre-industrial levels.

Such an initiative could exploit the ocean to provide 40 times the renewable energy generated worldwide in 2018. It could provide six times the sustainable seafood, create 12 million jobs and generate US$15.5 trillion in net economic benefits.

“Managing these resources sustainably requires first that we understand deep-sea ecosystems and their role on the planet”

But to make all this happen, the nations of the world would have to co-operate to manage fishing and seafood farming in sustainable ways; and they would have to take steps to mitigate climate change.

The world would have to invest in a variety of ways of generating renewable energy. It would have to clean up the shipping business − 90% of global goods move across the sea’s surface − to reduce emissions and pollution.

And it would have to halt the decline of, and restore, salt marshes, seagrass beds and mangroves: these cover areas more than 50 times smaller than the world’s forests, but they can store carbon at 10 times the rate of land-based ecosystems.

The world would also have to seriously protect great tracts of the seas: at least 30%. Right now, only 2.6% is fully protected from fishing and other disturbance. The researchers argue that political action to deliver a healthy ocean has been lacking − until now. But, they add, “Our knowledge of the ocean is deep.”

Ten-year study

It may not be deep enough, though, which explains the emphasis on more ocean research. Right on cue, another team of scientists reminds the world that the deepest parts of the ocean cover 60% of the globe and most of this has yet to be properly explored.

So, 150 years after the history-making British research ship HMS Challenger began its first systematic measurement of the deep sea, a consortium of scientists from 45 laboratories and universities in 17 countries has called for a dedicated decade of systematic and detailed study of a saltwater habitat that begins at 200 metres and extends as far in a few places as 11,000 metres in depth.

This initiative, they argue in the journal Nature Ecology and Evolution, should happen during the United Nations Decade of Ocean Science for Sustainable Development, from 2021 to 2030.

“The deep seas and seabed are increasingly being used by society, and they are seen as a potential future asset for the resources they possess,” said Kerry Howell, an ecologist at the University of Plymouth in the UK, lead author. “But managing these resources sustainably requires first that we understand deep-sea ecosystems, and their role on the planet, its people and its atmosphere.” − Climate News Network

A decade of ocean research is about to begin to try to save the planet’s richest habitat from human destruction.

LONDON, 9 December, 2020 − Humans need urgently to invest in ocean research and protection. In return, the ocean could repay them handsomely, by soaking up atmospheric carbon, delivering huge amounts of renewable energy, providing six times more sustainable seafood, creating millions of jobs and generating trillions in economic benefits.

The oceans cover 70% of the planet but, a trio of scientists warn in the journal Nature, “for much too long, the ocean has been out of sight, out of mind and out of luck.”

From the margins of the coast to the deepest seas, the oceans’ habitats and the living creatures in them have been threatened by excessive and destructive fishing, they say.

“Unsustainable development along coastlines is destroying coral reefs, seagrass beds, salt marshes and mangrove forests. These house biodiversity, sequester carbon, provide nurseries for fish and buffer coasts against storm surges.

Separate approaches inadequate

Plastics and nutrients washed from the land are also killing wildlife. All of these threats erode the capacity of the ocean to provide nutritious food, jobs, medicines and pharmaceuticals as well as regulate the climate.”

But something can be done. A new report − commissioned by Norway, Palau, 12 other nations and a UN envoy, collectively responsible for two-fifths of the world’s coastlines, almost a third of the exclusive economic zones and a fifth of the world’s shipping − argues that it is not enough for individual nations to manage their sectors or confront challenging issues separately. The largest and deepest continuous living space on the planet demands something more.

The report finds that − if the world co-operated in an holistic approach to care for the oceans, and protected at least 30% of them − then by 2050 the deep blue sea could account for 20% of the carbon emission reductions needed to match the Paris climate agreement target of no more than 1.5°C warming above pre-industrial levels.

Such an initiative could exploit the ocean to provide 40 times the renewable energy generated worldwide in 2018. It could provide six times the sustainable seafood, create 12 million jobs and generate US$15.5 trillion in net economic benefits.

“Managing these resources sustainably requires first that we understand deep-sea ecosystems and their role on the planet”

But to make all this happen, the nations of the world would have to co-operate to manage fishing and seafood farming in sustainable ways; and they would have to take steps to mitigate climate change.

The world would have to invest in a variety of ways of generating renewable energy. It would have to clean up the shipping business − 90% of global goods move across the sea’s surface − to reduce emissions and pollution.

And it would have to halt the decline of, and restore, salt marshes, seagrass beds and mangroves: these cover areas more than 50 times smaller than the world’s forests, but they can store carbon at 10 times the rate of land-based ecosystems.

The world would also have to seriously protect great tracts of the seas: at least 30%. Right now, only 2.6% is fully protected from fishing and other disturbance. The researchers argue that political action to deliver a healthy ocean has been lacking − until now. But, they add, “Our knowledge of the ocean is deep.”

Ten-year study

It may not be deep enough, though, which explains the emphasis on more ocean research. Right on cue, another team of scientists reminds the world that the deepest parts of the ocean cover 60% of the globe and most of this has yet to be properly explored.

So, 150 years after the history-making British research ship HMS Challenger began its first systematic measurement of the deep sea, a consortium of scientists from 45 laboratories and universities in 17 countries has called for a dedicated decade of systematic and detailed study of a saltwater habitat that begins at 200 metres and extends as far in a few places as 11,000 metres in depth.

This initiative, they argue in the journal Nature Ecology and Evolution, should happen during the United Nations Decade of Ocean Science for Sustainable Development, from 2021 to 2030.

“The deep seas and seabed are increasingly being used by society, and they are seen as a potential future asset for the resources they possess,” said Kerry Howell, an ecologist at the University of Plymouth in the UK, lead author. “But managing these resources sustainably requires first that we understand deep-sea ecosystems, and their role on the planet, its people and its atmosphere.” − Climate News Network

Rising ocean heat leaves fish gasping for oxygen

Lack of oxygen will leave some fish gasping as the thermometer rises. Deep time offers a guide to those at greatest risk.

LONDON, 2 December, 2020 − As global temperatures soar, the planetary menu could start to dwindle. Cod, sea bass and haddock will move to cooler and more distant waters. Tropical species relying on the shelter of coral reefs could simply disappear. Fish gasping for oxygen will struggle to survive.

And although the world’s marine catch is already under pressure from pollution, ocean acidification and overfishing, the real threat is now clear. As ocean temperatures rise, oxygen levels in the world’s seas will fall, and the most active fish could start to stifle.

Some sea creatures will survive: sharks, rays and other cartilaginous fish will do better than the bony ones. Bivalves that cling to rocks will also cling on to life.

But some types of fish could be pushed to their tolerance limits, says a new study in the journal Global Change Biology, and global heating driven by ever-higher carbon dioxide levels in the atmosphere will be the primary cause.

“Warm water contains less oxygen than cool water. This tends to affect organisms that consume the most oxygen, which can mean that actively mobile animals are particularly affected,” said Carl Reddin of the Museum of Natural History in Berlin, who headed the research.

Heading for 3°C

He and his colleagues set themselves a simple challenge: why do some groups of marine creatures go extinct more often than others? The steady decline in fish catches on traditional grounds already has one obvious explanation: humans have overfished, and polluted. So the scientists decided to take a long cool look at the past.

“The deep time fossil record, conversely, is free from human impacts, and documents extinctions during ancient episodes of rapid climate warming, or hyperthermals,” they write.

They looked back across the evidence preserved in the rocks over the last 300 million years and identified what they call “six global hyperthermal events that shared a rapid increase in tropical sea surface temperatures, generally greater than 2°C, with an onset duration less than 100,000 years.”

In effect, they were looking for global conditions that matched those now happening. In the last 100 years, planetary average temperatures have risen by 1°C, and although almost all the world’s nations met in 2015 and vowed to try to contain global heating by 2100 to “well below” 2°C, the planet is heading towards a rise of more than 3°C above the long-term average in the next eight decades.

The Berlin team found that those groups of marine animals that − on the evidence of the fossil record − were most vulnerable to global warming in the deep past looked very like those that seem most in trouble today, among them the bony fishes.

“The deep time fossil record documents extinctions during ancient episodes of rapid climate warming”

The idea is not new. Other marine biologists have repeatedly warned of oxygen depletion in and beyond the fishing grounds.

Separately, there has been evidence that higher temperatures have begun to change the nature of the oceans, and fishermen have begun to count the cost as their catch migrates to waters that are cooler.

What this latest study does is clear up the uncertainty. Overfishing remains a problem. Ocean acidification will certainly affect some shellfish and possibly also fish behaviour. Pollution has already increased the number of marine dead zones.

But beyond that, the problem is simply one of temperature, and the latest study identifies those groups or classes of marine creature most at risk from another rise in the planetary thermometer: those sensitive to “warming-induced seawater de-oxygenation,” the researchers report.

And they add: “In anticipation of modern warming-driven marine extinctions, the trends illustrated in the fossil record offer an expedient preview.” − Climate News Network

Lack of oxygen will leave some fish gasping as the thermometer rises. Deep time offers a guide to those at greatest risk.

LONDON, 2 December, 2020 − As global temperatures soar, the planetary menu could start to dwindle. Cod, sea bass and haddock will move to cooler and more distant waters. Tropical species relying on the shelter of coral reefs could simply disappear. Fish gasping for oxygen will struggle to survive.

And although the world’s marine catch is already under pressure from pollution, ocean acidification and overfishing, the real threat is now clear. As ocean temperatures rise, oxygen levels in the world’s seas will fall, and the most active fish could start to stifle.

Some sea creatures will survive: sharks, rays and other cartilaginous fish will do better than the bony ones. Bivalves that cling to rocks will also cling on to life.

But some types of fish could be pushed to their tolerance limits, says a new study in the journal Global Change Biology, and global heating driven by ever-higher carbon dioxide levels in the atmosphere will be the primary cause.

“Warm water contains less oxygen than cool water. This tends to affect organisms that consume the most oxygen, which can mean that actively mobile animals are particularly affected,” said Carl Reddin of the Museum of Natural History in Berlin, who headed the research.

Heading for 3°C

He and his colleagues set themselves a simple challenge: why do some groups of marine creatures go extinct more often than others? The steady decline in fish catches on traditional grounds already has one obvious explanation: humans have overfished, and polluted. So the scientists decided to take a long cool look at the past.

“The deep time fossil record, conversely, is free from human impacts, and documents extinctions during ancient episodes of rapid climate warming, or hyperthermals,” they write.

They looked back across the evidence preserved in the rocks over the last 300 million years and identified what they call “six global hyperthermal events that shared a rapid increase in tropical sea surface temperatures, generally greater than 2°C, with an onset duration less than 100,000 years.”

In effect, they were looking for global conditions that matched those now happening. In the last 100 years, planetary average temperatures have risen by 1°C, and although almost all the world’s nations met in 2015 and vowed to try to contain global heating by 2100 to “well below” 2°C, the planet is heading towards a rise of more than 3°C above the long-term average in the next eight decades.

The Berlin team found that those groups of marine animals that − on the evidence of the fossil record − were most vulnerable to global warming in the deep past looked very like those that seem most in trouble today, among them the bony fishes.

“The deep time fossil record documents extinctions during ancient episodes of rapid climate warming”

The idea is not new. Other marine biologists have repeatedly warned of oxygen depletion in and beyond the fishing grounds.

Separately, there has been evidence that higher temperatures have begun to change the nature of the oceans, and fishermen have begun to count the cost as their catch migrates to waters that are cooler.

What this latest study does is clear up the uncertainty. Overfishing remains a problem. Ocean acidification will certainly affect some shellfish and possibly also fish behaviour. Pollution has already increased the number of marine dead zones.

But beyond that, the problem is simply one of temperature, and the latest study identifies those groups or classes of marine creature most at risk from another rise in the planetary thermometer: those sensitive to “warming-induced seawater de-oxygenation,” the researchers report.

And they add: “In anticipation of modern warming-driven marine extinctions, the trends illustrated in the fossil record offer an expedient preview.” − Climate News Network

Antarctic depths warm far beyond oceanic average

Heat from factories and car exhausts must go somewhere. A surprising amount is now sunk in the remote Antarctic depths.

LONDON, 28 October, 2020 − Thanks to global heating, a vital part of the Southern Ocean is warming at a rate five times faster than the average for the Blue Planet as a whole, in the far Antarctic depths: 2000 metres or more below the surface of the Weddell Sea.

It is happening because at that depth the Weddell Sea has absorbed five times as much atmospheric heat − fuelled by greenhouse gas emissions from human fossil fuel combustion − as the average for the rest of the ocean. But what happens out of sight and far below the surface may not stay invisible. The Weddell Sea is where vast volumes of water circulate.

The fear is that such dramatic warming at depth could end up weakening a powerful current that encircles Antarctica, according to a new study in the Journal of Climate.

The evidence comes from 30 years of temperature and salinity samples, taken at the same spot and through the entire water column, with exquisite accuracy, by scientists aboard the German research icebreaker Polarstern.

“Our time series confirms the pivotal role of the Southern Ocean and especially the Weddell Sea in terms of storing heat in the depths of the world’s oceans”

“Our data shows a clear division in the water column of the Weddell Sea. While the water in the upper 700 metres has hardly warmed at all, in the deeper regions we’re seeing a consistent temperature rise of 0.0021 to 0.0024 degrees Celsius per year,” said Volker Strass, of the Alfred Wegener Institute in Bremerhaven in Germany.

“Since the ocean has roughly 1,000 times the heat capacity of the atmosphere, these numbers represent an enormous scale of heat absorption. By using the temperature rise to calculate the warming rate in watts per square metre, you can see that over the past 30 years, at depths of over 2,000 metres, the Weddell Sea has absorbed five times as much heat as the rest of the ocean on average.”

The global ocean is the great absorber of atmospheric shock. The deep blue sea has so far absorbed more than nine-tenths of the heat trapped by greenhouse gas emissions in the atmosphere.

The Weddell Sea begins at the extreme south of the Atlantic Ocean: it is roughly 10 times the size of Europe’s North Sea. Here tremendous volumes of water cool down. As sea ice forms on the surface the remaining waters become more salty, and because they have become colder, and denser, sink to the bottom, to spread at depth to drive deep sea flow into the oceans.

Ocean circulation risk

This act of overturning − the sinking of surface waters for thousands of metres into the Antarctic depths − is part of the machinery of ocean circulation that drives and modifies the world’s weather systems, and the climate.

The problem is that if the bottom waters are warming − and are therefore less dense − then this could weaken or stall the mechanism for ocean circulation. In the past 30 years the prevailing winds have shifted and intensified, and the flow speed of ocean water has increased to deliver more heat to the Weddell Sea with each decade.

Warming ocean waters have already been implicated in the loss of sea ice  cover that normally slows the flow of Antarctica’s continental glaciers. And warming in the Arctic has already triggered worries about the future of the “Atlantic Conveyer,” that enormous circulation of water that distributes heat from the Equator to the Poles and keeps northern Europe much warmer than its latitudes would dictate.

“Our time series confirms the pivotal role of the Southern Ocean and especially the Weddell Sea in terms of storing heat in the depths of the world’s oceans,” said Dr Strass. − Climate News Network

Heat from factories and car exhausts must go somewhere. A surprising amount is now sunk in the remote Antarctic depths.

LONDON, 28 October, 2020 − Thanks to global heating, a vital part of the Southern Ocean is warming at a rate five times faster than the average for the Blue Planet as a whole, in the far Antarctic depths: 2000 metres or more below the surface of the Weddell Sea.

It is happening because at that depth the Weddell Sea has absorbed five times as much atmospheric heat − fuelled by greenhouse gas emissions from human fossil fuel combustion − as the average for the rest of the ocean. But what happens out of sight and far below the surface may not stay invisible. The Weddell Sea is where vast volumes of water circulate.

The fear is that such dramatic warming at depth could end up weakening a powerful current that encircles Antarctica, according to a new study in the Journal of Climate.

The evidence comes from 30 years of temperature and salinity samples, taken at the same spot and through the entire water column, with exquisite accuracy, by scientists aboard the German research icebreaker Polarstern.

“Our time series confirms the pivotal role of the Southern Ocean and especially the Weddell Sea in terms of storing heat in the depths of the world’s oceans”

“Our data shows a clear division in the water column of the Weddell Sea. While the water in the upper 700 metres has hardly warmed at all, in the deeper regions we’re seeing a consistent temperature rise of 0.0021 to 0.0024 degrees Celsius per year,” said Volker Strass, of the Alfred Wegener Institute in Bremerhaven in Germany.

“Since the ocean has roughly 1,000 times the heat capacity of the atmosphere, these numbers represent an enormous scale of heat absorption. By using the temperature rise to calculate the warming rate in watts per square metre, you can see that over the past 30 years, at depths of over 2,000 metres, the Weddell Sea has absorbed five times as much heat as the rest of the ocean on average.”

The global ocean is the great absorber of atmospheric shock. The deep blue sea has so far absorbed more than nine-tenths of the heat trapped by greenhouse gas emissions in the atmosphere.

The Weddell Sea begins at the extreme south of the Atlantic Ocean: it is roughly 10 times the size of Europe’s North Sea. Here tremendous volumes of water cool down. As sea ice forms on the surface the remaining waters become more salty, and because they have become colder, and denser, sink to the bottom, to spread at depth to drive deep sea flow into the oceans.

Ocean circulation risk

This act of overturning − the sinking of surface waters for thousands of metres into the Antarctic depths − is part of the machinery of ocean circulation that drives and modifies the world’s weather systems, and the climate.

The problem is that if the bottom waters are warming − and are therefore less dense − then this could weaken or stall the mechanism for ocean circulation. In the past 30 years the prevailing winds have shifted and intensified, and the flow speed of ocean water has increased to deliver more heat to the Weddell Sea with each decade.

Warming ocean waters have already been implicated in the loss of sea ice  cover that normally slows the flow of Antarctica’s continental glaciers. And warming in the Arctic has already triggered worries about the future of the “Atlantic Conveyer,” that enormous circulation of water that distributes heat from the Equator to the Poles and keeps northern Europe much warmer than its latitudes would dictate.

“Our time series confirms the pivotal role of the Southern Ocean and especially the Weddell Sea in terms of storing heat in the depths of the world’s oceans,” said Dr Strass. − Climate News Network

Hotter seas imperil both human and marine life

Climate warming brings hotter seas. The waters mix less. And conditions for some creatures could grow increasingly stifling.

LONDON, 9 October, 2020 − Climate change has led to hotter seas across the world: in 2018 European water temperatures reached record levels, and a marine heatwave in the north-east Pacific devastated marine life.

Less predictably, global heating has made the oceans more stable, with discrete, stratified layers that resist mixing. And that could be very bad news, because it could make the blue water that covers 70% of the planet less effective at absorbing atmospheric heat and thus mitigating climate change.

And ever-warmer sea temperatures could have another unwelcome impact: as temperatures rise, levels of dissolved oxygen fall. And that could make it difficult for some sea creatures to breathe.

The oceans play a vital role in the water, energy and carbon cycles upon which all life depends. In 2010, demographers counted 1.9 billion people living within 100kms of the sea and less than 100 metres above sea level: that is 28% of all humanity. Many of them are crowded into 17 megacities with populations of more than 5 million people each. For many, the sea is the neighbourhood.

European researchers warn, in a new and detailed report on the state of the oceans from 1993 to 2010, that the rise in sea temperatures in the Mediterranean is without precedent, and the largest rise of all has been measured in the Arctic Ocean.

“Human society has always been dependent on the seas. Failure to reach good environmental status for our seas and oceans is not an option”

They also call as a matter of urgency for comprehensive and systematic monitoring of the ocean. “Human society has always been dependent on the seas,” they warn. “Failure to reach good environmental status for our seas and oceans is not an option.”

Chinese and US scientists report in the journal Nature Climate Change that − beyond reports of stronger winds and waves and ever more intense tropical cyclones − the rise in atmospheric temperatures has fundamentally altered oceanic temperatures and salinity, with a paradoxical effect: the seas have become more stable. Warm and therefore less dense surface water lies upon colder, more saline and denser waters at depth, to limit overall mixing.

Since 1960, the upper 2000 metres of the oceans have become 5% more stratified, and the top 150 metres 18% more stratified.

“The same process, global warming, is both making the atmosphere less stable and the oceans more stable. Water near the ocean’s surface is warming faster than the water below. That makes the oceans become more stable,” said Michael Mann of Penn State University in Pennsylvania, one of the team.

“The ability of the oceans to bury heat from the atmosphere and mitigate global warming is made more difficult when the ocean becomes more stratified and there is less mixing. Less downward mixing of warming waters means the ocean surface warms even faster, leading, for example, to more powerful hurricanes. Global climate models underestimate these trends.”

Struggle for survival

Warmer temperatures don’t just make the oceans more stable, they may make living conditions more uncomfortable or even impossible for some of the sea’s citizenry.

US researchers report in the journal Nature that they looked at the physiological challenge of oxygen and energy demands faced by 145 marine species − including shrimps, catsharks and sea squirts − to find that many are already under pressure.

“Organisms today are living right up to the warmest temperatures possible that will supply them with adequate oxygen for their activity level – so higher temperatures are immediately going to affect their ability to get enough oxygen,” said Curtis Deutsch of the University of Washington.

“In response to warming, their activity level is going to be restricted or their habitat is going to start shrinking. It’s not like they are going to be fine and carry on.” − Climate News Network

Climate warming brings hotter seas. The waters mix less. And conditions for some creatures could grow increasingly stifling.

LONDON, 9 October, 2020 − Climate change has led to hotter seas across the world: in 2018 European water temperatures reached record levels, and a marine heatwave in the north-east Pacific devastated marine life.

Less predictably, global heating has made the oceans more stable, with discrete, stratified layers that resist mixing. And that could be very bad news, because it could make the blue water that covers 70% of the planet less effective at absorbing atmospheric heat and thus mitigating climate change.

And ever-warmer sea temperatures could have another unwelcome impact: as temperatures rise, levels of dissolved oxygen fall. And that could make it difficult for some sea creatures to breathe.

The oceans play a vital role in the water, energy and carbon cycles upon which all life depends. In 2010, demographers counted 1.9 billion people living within 100kms of the sea and less than 100 metres above sea level: that is 28% of all humanity. Many of them are crowded into 17 megacities with populations of more than 5 million people each. For many, the sea is the neighbourhood.

European researchers warn, in a new and detailed report on the state of the oceans from 1993 to 2010, that the rise in sea temperatures in the Mediterranean is without precedent, and the largest rise of all has been measured in the Arctic Ocean.

“Human society has always been dependent on the seas. Failure to reach good environmental status for our seas and oceans is not an option”

They also call as a matter of urgency for comprehensive and systematic monitoring of the ocean. “Human society has always been dependent on the seas,” they warn. “Failure to reach good environmental status for our seas and oceans is not an option.”

Chinese and US scientists report in the journal Nature Climate Change that − beyond reports of stronger winds and waves and ever more intense tropical cyclones − the rise in atmospheric temperatures has fundamentally altered oceanic temperatures and salinity, with a paradoxical effect: the seas have become more stable. Warm and therefore less dense surface water lies upon colder, more saline and denser waters at depth, to limit overall mixing.

Since 1960, the upper 2000 metres of the oceans have become 5% more stratified, and the top 150 metres 18% more stratified.

“The same process, global warming, is both making the atmosphere less stable and the oceans more stable. Water near the ocean’s surface is warming faster than the water below. That makes the oceans become more stable,” said Michael Mann of Penn State University in Pennsylvania, one of the team.

“The ability of the oceans to bury heat from the atmosphere and mitigate global warming is made more difficult when the ocean becomes more stratified and there is less mixing. Less downward mixing of warming waters means the ocean surface warms even faster, leading, for example, to more powerful hurricanes. Global climate models underestimate these trends.”

Struggle for survival

Warmer temperatures don’t just make the oceans more stable, they may make living conditions more uncomfortable or even impossible for some of the sea’s citizenry.

US researchers report in the journal Nature that they looked at the physiological challenge of oxygen and energy demands faced by 145 marine species − including shrimps, catsharks and sea squirts − to find that many are already under pressure.

“Organisms today are living right up to the warmest temperatures possible that will supply them with adequate oxygen for their activity level – so higher temperatures are immediately going to affect their ability to get enough oxygen,” said Curtis Deutsch of the University of Washington.

“In response to warming, their activity level is going to be restricted or their habitat is going to start shrinking. It’s not like they are going to be fine and carry on.” − Climate News Network

Wilder shores of science yield new ideas on climate

New ideas on climate mean earthquake scientists know more about global heating and astronomers worry over rising warmth.

LONDON, 22 September, 2020 – Science has extended research into the global heating crisis, thanks to new ideas on climate. And, conversely, climate change has extended science in unexpected ways.

Seismologists believe they may have a new way to take the temperature of the world’s oceans. And astronomers focused on distant galaxies have unwittingly amassed a 30-year record of climate change in the Earth’s own atmosphere.

Both discoveries, in the same week, start with the simple physics of sight and sound. US and Chinese researchers report in the journal Science that records from submarine earthquakes could now deliver an unexpected way of measuring the warmth of the water.

Submarine earthquakes create a pattern of sound that can be transmitted immense distances through the ocean without much weakening. And, since the speed of sound in water increases as the temperature of the water rises, the length of time the sound takes to reach detector equipment is itself an indicator of ocean temperature.

Seismologists know – from waves travelling through the Earth’s crust and its deep interior – when and where the earthquakes happen. Seismic waves sprint through rock at rates measured in kilometres per second. Sound waves propagate through oceans at rates measured in kilometres per hour.

“It is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B”

Just as the differences between the speed of lightning and the speed of thunder can establish the distance of an electrical storm, so if researchers know the time and distance of the sea floor event, they have a way of taking the temperature of the water. The constant rumbling of a living planet could offer a new set of easily assembled readings.

“The key is that we use repeating earthquakes – earthquakes that happen again and again in the same place,” said Wenbo Wu, of the California Institute of Technology, who led the Science study.

“We’re looking at earthquakes that occur off Sumatra in Indonesia, and we measure when they arrive in the central Indian Ocean. It takes about half an hour for them to travel that distance, with water temperature causing about one tenth of a second difference. It’s a very small fractional change, but we can measure it.”

The finding matters because – although humans have been recording local ground and air temperatures for at least 300 years, and worldwide for more than a century – it is much harder to be sure about ocean temperatures: the seas cover 70% of the planet, to an average depth of more than 3 kms, and the temperatures vary with both depth and latitude.

Sound goes deep

Oceanographic research is costly, technically challenging, and uneven. Researchers know that the oceans are responding to climate change driven by global heating as a consequence of greenhouse gas emissions: they do not, however, yet have an assured measure of how much heat the oceans have absorbed, and will go on absorbing.

“The ocean plays a role in the rate that the climate is changing,” said Jörn Callies of Caltech, a co-author. “The ocean is the main reservoir of energy in the climate system, and the deep ocean in particular is important to monitor. One advantage of our method is that the sound waves sample depths below 2,000 metres where there are very few conventional measurements.”

Paradoxically, astronomers need to know a great deal about the first few thousand metres of planet Earth as they peer into the furthest reaches of the universe: what they see and how well they see it is affected by atmospheric temperature, turbulence and moisture.

As ground-based telescopes become bigger and more sensitive – the Extremely Large Telescope now under construction at Paranal in northern Chile will collect light with a mirror 39 metres across – so do the challenges of eliminating the atmospheric turbulence that puts the twinkle in the stars of the night sky: cold air and warm air refract light differently, to create a blur. The bigger the telescope, the greater will be the problem of blur.

For three decades, scientists in the highest and driest part of Chile have been recording subtle and not so subtle atmospheric change. And according to the journal Nature Astronomy, climate change is already beginning to affect astronomical research, and will go on creating problems.

Terrestrial disturbances

“The data showed a 1.5°C increase in near-ground temperature over the last four decades at the Paranal Observatory,” said Susanne Crewell of the University of Cologne. “This is slightly higher than the worldwide average of 1°C since the pre-industrial age.”

Average wind speeds – wind also affects the precision of observations – have increased by 3 or 4 metres per second in the same period. Humidity, too, is expected to change as the world moves to what could be a 4°C average rise in temperature by the century’s end.

The message is that conditions on Earth can disturb the observations and mask the understanding of events billions of light years away and billions of years ago. Astronomers, too, need to sound the alarm about climate change, she and her colleagues write.

“To do so, a massive cultural shift is needed,” they conclude, “and it is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B.” – Climate News Network

New ideas on climate mean earthquake scientists know more about global heating and astronomers worry over rising warmth.

LONDON, 22 September, 2020 – Science has extended research into the global heating crisis, thanks to new ideas on climate. And, conversely, climate change has extended science in unexpected ways.

Seismologists believe they may have a new way to take the temperature of the world’s oceans. And astronomers focused on distant galaxies have unwittingly amassed a 30-year record of climate change in the Earth’s own atmosphere.

Both discoveries, in the same week, start with the simple physics of sight and sound. US and Chinese researchers report in the journal Science that records from submarine earthquakes could now deliver an unexpected way of measuring the warmth of the water.

Submarine earthquakes create a pattern of sound that can be transmitted immense distances through the ocean without much weakening. And, since the speed of sound in water increases as the temperature of the water rises, the length of time the sound takes to reach detector equipment is itself an indicator of ocean temperature.

Seismologists know – from waves travelling through the Earth’s crust and its deep interior – when and where the earthquakes happen. Seismic waves sprint through rock at rates measured in kilometres per second. Sound waves propagate through oceans at rates measured in kilometres per hour.

“It is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B”

Just as the differences between the speed of lightning and the speed of thunder can establish the distance of an electrical storm, so if researchers know the time and distance of the sea floor event, they have a way of taking the temperature of the water. The constant rumbling of a living planet could offer a new set of easily assembled readings.

“The key is that we use repeating earthquakes – earthquakes that happen again and again in the same place,” said Wenbo Wu, of the California Institute of Technology, who led the Science study.

“We’re looking at earthquakes that occur off Sumatra in Indonesia, and we measure when they arrive in the central Indian Ocean. It takes about half an hour for them to travel that distance, with water temperature causing about one tenth of a second difference. It’s a very small fractional change, but we can measure it.”

The finding matters because – although humans have been recording local ground and air temperatures for at least 300 years, and worldwide for more than a century – it is much harder to be sure about ocean temperatures: the seas cover 70% of the planet, to an average depth of more than 3 kms, and the temperatures vary with both depth and latitude.

Sound goes deep

Oceanographic research is costly, technically challenging, and uneven. Researchers know that the oceans are responding to climate change driven by global heating as a consequence of greenhouse gas emissions: they do not, however, yet have an assured measure of how much heat the oceans have absorbed, and will go on absorbing.

“The ocean plays a role in the rate that the climate is changing,” said Jörn Callies of Caltech, a co-author. “The ocean is the main reservoir of energy in the climate system, and the deep ocean in particular is important to monitor. One advantage of our method is that the sound waves sample depths below 2,000 metres where there are very few conventional measurements.”

Paradoxically, astronomers need to know a great deal about the first few thousand metres of planet Earth as they peer into the furthest reaches of the universe: what they see and how well they see it is affected by atmospheric temperature, turbulence and moisture.

As ground-based telescopes become bigger and more sensitive – the Extremely Large Telescope now under construction at Paranal in northern Chile will collect light with a mirror 39 metres across – so do the challenges of eliminating the atmospheric turbulence that puts the twinkle in the stars of the night sky: cold air and warm air refract light differently, to create a blur. The bigger the telescope, the greater will be the problem of blur.

For three decades, scientists in the highest and driest part of Chile have been recording subtle and not so subtle atmospheric change. And according to the journal Nature Astronomy, climate change is already beginning to affect astronomical research, and will go on creating problems.

Terrestrial disturbances

“The data showed a 1.5°C increase in near-ground temperature over the last four decades at the Paranal Observatory,” said Susanne Crewell of the University of Cologne. “This is slightly higher than the worldwide average of 1°C since the pre-industrial age.”

Average wind speeds – wind also affects the precision of observations – have increased by 3 or 4 metres per second in the same period. Humidity, too, is expected to change as the world moves to what could be a 4°C average rise in temperature by the century’s end.

The message is that conditions on Earth can disturb the observations and mask the understanding of events billions of light years away and billions of years ago. Astronomers, too, need to sound the alarm about climate change, she and her colleagues write.

“To do so, a massive cultural shift is needed,” they conclude, “and it is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B.” – Climate News Network

Seas and forests are muddying the carbon budget

As climates change, forests may not absorb more carbon as expected. But a new carbon budget could appeal to the oceans.

LONDON, 18 September 2020 – Two new studies could throw long-term climate forecasts into confusion. The planetary carbon budget – the all-important traffic of life’s first element between rocks, water, atmosphere and living things – that underpins planetary temperatures and maintains a stable climate needs a rethink.

A warming climate makes trees grow faster. The awkward finding is that  faster-growing trees die younger. Therefore they must surrender their carbon back to the atmosphere quicker.

So tomorrow’s forests may not be quite such reliable long-term banks of carbon pumped into the atmosphere as a consequence of profligate fossil fuel use by human economies.

The more reassuring news is that the ocean – that’s almost three fourths of the planet’s surface – may absorb and store a lot more atmospheric carbon than previous estimates suggest.

All calculations about the future rate of global heating, and the potential consequences of climate change, rest upon the carbon budget.

Forest doubts

This is the intricate accounting of the mass of carbon in continuous circulation from air to plant to animal and then to shell, skeleton and sediment, and the expected flow of carbon emissions from the combustion of fossil fuels stored hundreds of millions of years ago, and exhumed in the last two centuries.

To make sense of the factors at work, climate scientists have to make calculations about all the carbon stored in the permafrost, in the soils, in the forests, dissolved in the oceans, free in the atmosphere and being released from power station chimneys, vehicle exhausts and ploughed or scorched land.

But for decades, one component of the equation has been automatically accepted: more forests must mean more carbon absorbed, and better protected natural forests would store the most carbon, the most efficiently.

Now a new report in the journal Nature Communications introduces some doubt into this cornerstone of the carbon budget. In an already warming world, much more of the carbon stored in tomorrow’s forests might find its way back into the atmosphere.

Researchers looked at 200,000 tree ring records from 82 tree species from sites around the planet. They found what they describe as trade-offs that are near universal: faster-growing trees have shorter lives.

“There is likely to be a timelag before we see the worst of the potential loss of carbon stocks from increases in tree mortality”

This was true in cool climates and warm ones, and in all species. So the hope that natural vegetation will respond to warmer temperatures by absorbing even more carbon becomes insecure, especially if it means that the more vigorous growth means simply swifter death and decay.

“Our modeling suggests that there is likely to be a timelag before we see the worst of the potential loss of carbon stocks from increases in tree mortality,” said Roel Brienen of the University of Leeds in the UK, who led the research. “They estimate that global increases in tree death don’t kick in until after sites show accelerated growth.”

All such research is provisional: the findings gain currency only when supported by other teams using different approaches. So it has yet to be confirmed.

But recent studies have suggested that climate change has already begun to complicate calculations. Just in recent months, research teams have found that forest trees are growing shorter and dying younger; that higher temperatures may affect plant germination; and that forests already hit by drought may start surrendering carbon more swiftly than they absorb it. Planting more trees is not an alternative to reducing greenhouse gas emissions.

On the other hand, the carbon budget may still make sense: the oceans may be responding to ever-higher concentrations of carbon dioxide by absorbing more from the atmosphere, which also makes the oceans more acidic, which is not necessarily helpful.

Oceans’ effect

All such calculations are based on sea surface temperatures. Gases such as carbon dioxide and oxygen dissolve well in colder water, not so well in warm lagoons and tropical tides.

But a British group reports in the same journal that calculations so far may have been under-estimates. This is because, on balance, researchers have tended to ignore the small difference between the temperatures at the surface, and a few metres down, where the measurements of dissolved greenhouse gas were actually made.

A team from the University of Exeter worked from a global database to make new estimates of the oceans’ appetite for carbon between 1992 and 2018.

“We used satellite data to correct for these temperature differences, and when we do that, it makes a big difference – we get a substantially larger flux going into the ocean,” said Andrew Watson, who led the study.

“The difference in ocean uptake we calculate amounts to 10% of global fossil fuel emissions.” – Climate News Network

As climates change, forests may not absorb more carbon as expected. But a new carbon budget could appeal to the oceans.

LONDON, 18 September 2020 – Two new studies could throw long-term climate forecasts into confusion. The planetary carbon budget – the all-important traffic of life’s first element between rocks, water, atmosphere and living things – that underpins planetary temperatures and maintains a stable climate needs a rethink.

A warming climate makes trees grow faster. The awkward finding is that  faster-growing trees die younger. Therefore they must surrender their carbon back to the atmosphere quicker.

So tomorrow’s forests may not be quite such reliable long-term banks of carbon pumped into the atmosphere as a consequence of profligate fossil fuel use by human economies.

The more reassuring news is that the ocean – that’s almost three fourths of the planet’s surface – may absorb and store a lot more atmospheric carbon than previous estimates suggest.

All calculations about the future rate of global heating, and the potential consequences of climate change, rest upon the carbon budget.

Forest doubts

This is the intricate accounting of the mass of carbon in continuous circulation from air to plant to animal and then to shell, skeleton and sediment, and the expected flow of carbon emissions from the combustion of fossil fuels stored hundreds of millions of years ago, and exhumed in the last two centuries.

To make sense of the factors at work, climate scientists have to make calculations about all the carbon stored in the permafrost, in the soils, in the forests, dissolved in the oceans, free in the atmosphere and being released from power station chimneys, vehicle exhausts and ploughed or scorched land.

But for decades, one component of the equation has been automatically accepted: more forests must mean more carbon absorbed, and better protected natural forests would store the most carbon, the most efficiently.

Now a new report in the journal Nature Communications introduces some doubt into this cornerstone of the carbon budget. In an already warming world, much more of the carbon stored in tomorrow’s forests might find its way back into the atmosphere.

Researchers looked at 200,000 tree ring records from 82 tree species from sites around the planet. They found what they describe as trade-offs that are near universal: faster-growing trees have shorter lives.

“There is likely to be a timelag before we see the worst of the potential loss of carbon stocks from increases in tree mortality”

This was true in cool climates and warm ones, and in all species. So the hope that natural vegetation will respond to warmer temperatures by absorbing even more carbon becomes insecure, especially if it means that the more vigorous growth means simply swifter death and decay.

“Our modeling suggests that there is likely to be a timelag before we see the worst of the potential loss of carbon stocks from increases in tree mortality,” said Roel Brienen of the University of Leeds in the UK, who led the research. “They estimate that global increases in tree death don’t kick in until after sites show accelerated growth.”

All such research is provisional: the findings gain currency only when supported by other teams using different approaches. So it has yet to be confirmed.

But recent studies have suggested that climate change has already begun to complicate calculations. Just in recent months, research teams have found that forest trees are growing shorter and dying younger; that higher temperatures may affect plant germination; and that forests already hit by drought may start surrendering carbon more swiftly than they absorb it. Planting more trees is not an alternative to reducing greenhouse gas emissions.

On the other hand, the carbon budget may still make sense: the oceans may be responding to ever-higher concentrations of carbon dioxide by absorbing more from the atmosphere, which also makes the oceans more acidic, which is not necessarily helpful.

Oceans’ effect

All such calculations are based on sea surface temperatures. Gases such as carbon dioxide and oxygen dissolve well in colder water, not so well in warm lagoons and tropical tides.

But a British group reports in the same journal that calculations so far may have been under-estimates. This is because, on balance, researchers have tended to ignore the small difference between the temperatures at the surface, and a few metres down, where the measurements of dissolved greenhouse gas were actually made.

A team from the University of Exeter worked from a global database to make new estimates of the oceans’ appetite for carbon between 1992 and 2018.

“We used satellite data to correct for these temperature differences, and when we do that, it makes a big difference – we get a substantially larger flux going into the ocean,” said Andrew Watson, who led the study.

“The difference in ocean uptake we calculate amounts to 10% of global fossil fuel emissions.” – Climate News Network

Hotter oceans harm seabed life survival prospects

Seabed life is tough: only the young can migrate. But climate change is taking many of them the wrong way.

LONDON, 14 September, 2020 – It can be hard being a junior part of seabed life – a young starfish, say, or an adolescent worm. Down in the ocean depths, the environment is conspiring against you.

Marine biologists have just identified – and explained – a climate change paradox: while most fish are migrating towards the poles as the world’s oceans warm, one part of a potentially valuable commercial fishery is heading in the wrong direction – and perhaps to extinction.

Why? Once again, the finger of suspicion points to global climate change, and its impact on ocean tides and currents.

Throughout this century, researchers have repeatedly confirmed a pattern of ocean warming – and acidification – driven by ever-rising ratios of carbon dioxide in the atmosphere; a pattern that could affect both established commercial fishing industries and ocean life as a whole.

Tropical fish have been shifting away from the equator; further north and south, pelagic (open-ocean) and demersal (seabed-dwelling) fish have been seeking more suitable grounds. Warmer seas can affect spawning patterns.

“As the seas continue to warm, spawning times will get ever earlier and the currents will sweep many of the next generation to oblivion”

But the ocean is a vast living space, and the speed at which it warms tends to vary with depth.

US researchers report in the journal Nature Climate Change that they worked through 60 years of data on 50 species of benthic invertebrates – creatures without backbones that dwell on the sea floor – to find that the populations of four-fifths of these had begun to disappear from the shelves and fishing grounds of the Georges Bank and the outer shelf that runs from New Jersey and east of the Delmarva Peninsula occupied by the states of Delaware, Maryland and Virginia.

More to the point, they identified the mechanism that had begun to limit life on the submarine sediments. Bottom-dwellers – shellfish, snails, starfish, worms and so on – can’t migrate: they are stuck where they are. But their larvae can, and at spawning time the infant shellfish are at the mercy of the ocean currents.

The waters of the north-east Atlantic coast are warming at three times the global average rate. Warming has affected the time at which benthic invertebrates spawn. Because the larvae appear earlier in spring and summer, they are swept away by currents they would not encounter in a cooler, more stable world.

And these currents, driven by river discharge and seasonal winds, tend to bring them south-west and inshore, where waters are warmer and the larvae are even less likely to survive.

Nowhere to go

Those adults that remain are stuck where they are: as the seas continue to warm, spawning times will get ever earlier and the currents will sweep many of the next generation to oblivion.

These bottom-dwelling denizens could survive, if they could colonise cooler waters. Instead they are condemned to a submarine version of what terrestrial biologists call the elevator to extinction: on land, hotter temperatures drive birds and butterflies and plants ever further uphill: in the end, nearer the summit, there’s nowhere to go.

The researchers, from Rutgers University in New Brunswick, call it the downwelling effect, and identify a paradox: as the area habitable by bottom-dwellers gets bigger, their ranges dwindle.

The finding so far is true only for the north-east Atlantic waters, and some species seem less affected. Scallops could flourish, because they spawn at a wider range of temperatures. But clams and mussels are adapted to low temperatures, and their ranges have warmed and contracted.

And, the scientists warn, as global heating reduces yields from traditional fisheries, the seafood industry is likely to rely increasingly on shellfish. But this industry, too, is vulnerable to ocean change. – Climate News Network

Seabed life is tough: only the young can migrate. But climate change is taking many of them the wrong way.

LONDON, 14 September, 2020 – It can be hard being a junior part of seabed life – a young starfish, say, or an adolescent worm. Down in the ocean depths, the environment is conspiring against you.

Marine biologists have just identified – and explained – a climate change paradox: while most fish are migrating towards the poles as the world’s oceans warm, one part of a potentially valuable commercial fishery is heading in the wrong direction – and perhaps to extinction.

Why? Once again, the finger of suspicion points to global climate change, and its impact on ocean tides and currents.

Throughout this century, researchers have repeatedly confirmed a pattern of ocean warming – and acidification – driven by ever-rising ratios of carbon dioxide in the atmosphere; a pattern that could affect both established commercial fishing industries and ocean life as a whole.

Tropical fish have been shifting away from the equator; further north and south, pelagic (open-ocean) and demersal (seabed-dwelling) fish have been seeking more suitable grounds. Warmer seas can affect spawning patterns.

“As the seas continue to warm, spawning times will get ever earlier and the currents will sweep many of the next generation to oblivion”

But the ocean is a vast living space, and the speed at which it warms tends to vary with depth.

US researchers report in the journal Nature Climate Change that they worked through 60 years of data on 50 species of benthic invertebrates – creatures without backbones that dwell on the sea floor – to find that the populations of four-fifths of these had begun to disappear from the shelves and fishing grounds of the Georges Bank and the outer shelf that runs from New Jersey and east of the Delmarva Peninsula occupied by the states of Delaware, Maryland and Virginia.

More to the point, they identified the mechanism that had begun to limit life on the submarine sediments. Bottom-dwellers – shellfish, snails, starfish, worms and so on – can’t migrate: they are stuck where they are. But their larvae can, and at spawning time the infant shellfish are at the mercy of the ocean currents.

The waters of the north-east Atlantic coast are warming at three times the global average rate. Warming has affected the time at which benthic invertebrates spawn. Because the larvae appear earlier in spring and summer, they are swept away by currents they would not encounter in a cooler, more stable world.

And these currents, driven by river discharge and seasonal winds, tend to bring them south-west and inshore, where waters are warmer and the larvae are even less likely to survive.

Nowhere to go

Those adults that remain are stuck where they are: as the seas continue to warm, spawning times will get ever earlier and the currents will sweep many of the next generation to oblivion.

These bottom-dwelling denizens could survive, if they could colonise cooler waters. Instead they are condemned to a submarine version of what terrestrial biologists call the elevator to extinction: on land, hotter temperatures drive birds and butterflies and plants ever further uphill: in the end, nearer the summit, there’s nowhere to go.

The researchers, from Rutgers University in New Brunswick, call it the downwelling effect, and identify a paradox: as the area habitable by bottom-dwellers gets bigger, their ranges dwindle.

The finding so far is true only for the north-east Atlantic waters, and some species seem less affected. Scallops could flourish, because they spawn at a wider range of temperatures. But clams and mussels are adapted to low temperatures, and their ranges have warmed and contracted.

And, the scientists warn, as global heating reduces yields from traditional fisheries, the seafood industry is likely to rely increasingly on shellfish. But this industry, too, is vulnerable to ocean change. – Climate News Network