Category Archives: Oceans

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

Antarctic melting could bring a much hotter future

Antarctic melting can force sea ice retreat of 50 metres daily. CO2 levels are at their highest for 23 million years. Learn from the past.

LONDON, 23 June, 2020 – Antarctic melting starts with dramatic speed. Ice shelves during the sudden warm spell at the close of the last Ice Age retreated at up to 50 metres a day.

This finding is not based on climate simulations generated by computer algorithms. It is based on direct evidence left 12,000 years ago on the Antarctic sea floor by retreating ice.

The finding is an indirect indicator of how warm things could get – and how high sea levels could rise – as humans burn ever more fossil fuels and raise atmospheric greenhouse gas levels to ever higher ratios.

And as if to highlight the approaching climate catastrophe, a second and separate study finds that the measure of carbon dioxide in the atmosphere now is not just higher than at any time in human history or at any interval in the Ice Ages. It is the highest for at least 23 million years.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise”

British scientists report in the journal Science that they used an autonomous underwater vehicle (AUV), cruising at depth in the Weddell Sea, to read the pattern of the past preserved in ridges of the Antarctic seabed.

The original push for the expedition had been to search for the ship Endurance, commanded by the polar explorer Ernest Shackleton on his doomed voyage in 1914. The loss of the ship, crushed in the polar ice, and the rescue of his crew became one of the epic stories of maritime history.

The researchers did not find Endurance. But they did find an enduring record of past ice retreat.

Sea ice skirts about 75% of the continent’s coastline: when it melts it makes no difference to sea levels, but while it remains frozen it does serve the purpose of buttressing glacial flow from the high Antarctic interior. Brushed by increasingly warm air each summer, and swept by slowly warming ocean currents all year round, the ice shelves are thinning and retreating.

Tell-tale line

Underneath the ice, the research team’s robot submarine spotted wave-like ridges, each about a metre high and 20 to 25 metres apart: ridges formed at what had once been the grounding line – the point at which a grounded ice sheet starts to float, and evidence of ice rising and falling with the tides.

There are twelve hours between high tide and low, so by measuring the distance between the ridges, scientists could measure the pace of retreat at the end of the last Ice Age. It is estimated at 40 to 50 metres a day.

Right now, the fastest retreat measured from grounding lines in Antarctica is only about 1.6 kms a year. The implication is that it could get a lot faster.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise,” said Julian Dowdeswell, director of the Scott Polar Research Institute in Cambridge, who led the research.

Faster change ahead

Past warm periods are associated only with relatively modest rises in atmospheric carbon dioxide. Right now, researchers have repeatedly confirmed that the present increasingly rapid rise is the highest in the last 800,000 years.

Now a team from the US and Norway report in the journal Geology that they have measured past atmospheric carbon levels in fossil plants to establish that present day carbon levels are higher currently than at any time in the last 23 million years.

This means that – unless there are drastic steps to contain global warming – the retreat will become increasingly more rapid, and the rate of glacial flow towards the sea ever faster.

Were all the ice in Antarctica to melt, sea levels would rise by about 60 metres, completely submerging many of the world’s great cities. – Climate News Network

Antarctic melting can force sea ice retreat of 50 metres daily. CO2 levels are at their highest for 23 million years. Learn from the past.

LONDON, 23 June, 2020 – Antarctic melting starts with dramatic speed. Ice shelves during the sudden warm spell at the close of the last Ice Age retreated at up to 50 metres a day.

This finding is not based on climate simulations generated by computer algorithms. It is based on direct evidence left 12,000 years ago on the Antarctic sea floor by retreating ice.

The finding is an indirect indicator of how warm things could get – and how high sea levels could rise – as humans burn ever more fossil fuels and raise atmospheric greenhouse gas levels to ever higher ratios.

And as if to highlight the approaching climate catastrophe, a second and separate study finds that the measure of carbon dioxide in the atmosphere now is not just higher than at any time in human history or at any interval in the Ice Ages. It is the highest for at least 23 million years.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise”

British scientists report in the journal Science that they used an autonomous underwater vehicle (AUV), cruising at depth in the Weddell Sea, to read the pattern of the past preserved in ridges of the Antarctic seabed.

The original push for the expedition had been to search for the ship Endurance, commanded by the polar explorer Ernest Shackleton on his doomed voyage in 1914. The loss of the ship, crushed in the polar ice, and the rescue of his crew became one of the epic stories of maritime history.

The researchers did not find Endurance. But they did find an enduring record of past ice retreat.

Sea ice skirts about 75% of the continent’s coastline: when it melts it makes no difference to sea levels, but while it remains frozen it does serve the purpose of buttressing glacial flow from the high Antarctic interior. Brushed by increasingly warm air each summer, and swept by slowly warming ocean currents all year round, the ice shelves are thinning and retreating.

Tell-tale line

Underneath the ice, the research team’s robot submarine spotted wave-like ridges, each about a metre high and 20 to 25 metres apart: ridges formed at what had once been the grounding line – the point at which a grounded ice sheet starts to float, and evidence of ice rising and falling with the tides.

There are twelve hours between high tide and low, so by measuring the distance between the ridges, scientists could measure the pace of retreat at the end of the last Ice Age. It is estimated at 40 to 50 metres a day.

Right now, the fastest retreat measured from grounding lines in Antarctica is only about 1.6 kms a year. The implication is that it could get a lot faster.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise,” said Julian Dowdeswell, director of the Scott Polar Research Institute in Cambridge, who led the research.

Faster change ahead

Past warm periods are associated only with relatively modest rises in atmospheric carbon dioxide. Right now, researchers have repeatedly confirmed that the present increasingly rapid rise is the highest in the last 800,000 years.

Now a team from the US and Norway report in the journal Geology that they have measured past atmospheric carbon levels in fossil plants to establish that present day carbon levels are higher currently than at any time in the last 23 million years.

This means that – unless there are drastic steps to contain global warming – the retreat will become increasingly more rapid, and the rate of glacial flow towards the sea ever faster.

Were all the ice in Antarctica to melt, sea levels would rise by about 60 metres, completely submerging many of the world’s great cities. – Climate News Network

Threatened mangrove forests won’t protect coasts

Rising tides driven by global heating could swamp the mangrove forests – bad news for the natural world, and for humans.

LONDON, 17 June, 2020 – If sea levels go on rising at ever higher rates, then by 2050 the world’s mangrove forests could be obliterated, drowned by rising tides.

Mangrove forests cover between 140,000 and 200,000 square kilometres of the intertidal zones that fringe more than 100 tropical and subtropical countries, and have become among the richest ecosystems of the planet.

They are estimated to store at least 30 million tonnes of atmospheric carbon each year, and a couple of sq kms of this saltwater forest can harbour nursery space for what could become 100 tonnes of commercial fish catch every year.

They also provide shelter for a huge range of creatures, including an estimated 500 Bengal tigers in the vast Sundarbans mangrove forests along the Ganges-Brahmaputra delta.

And while most of the 80 or so species of mangrove tree can keep up with an annual sea level rise of around 5mm a year, they seem unlikely, on evidence from the past, to be able to survive a 10mm rise. Right now, the world is heading for the higher end of the scale.

Sheltering people

A second and separate study finds that, importantly for humans, along with coral reefs, the mangrove forests provide vital natural protection from tropical storms for 31 million very vulnerable people in North and Central America and the crowded archipelagos of Indonesia and the Philippines.

Researchers from Australia, China, Singapore and the US report in the journal Science that they looked at the evidence locked in the sediments in 78 locations from the last 10,000 years, to work out how mangrove forests have – through the millennia – responded to changes in sea level.

At the close of the last ice age, sea levels rose at 10mm a year and slowed to nearly stable conditions 4000 years ago.

In a high emissions scenario, by 2050 sea level rise would exceed 6mm: the scientists found a 90% probability that mangroves would not be able to grow fast enough to keep up. Nor – because of the development of coastal settlements worldwide – would the forests be able to shift inland.

“Simply put, it’s much cheaper to conserve a mangrove than build a sea wall”

“This research therefore highlights yet another compelling reason why countries must take urgent action to reduce carbon emissions,” said Benjamin Horton of Nanyang Technical University in Singapore., one of the researchers.

“Mangroves are among the most valuable of natural ecosystems, supporting coastal fisheries and biodiversity, while protecting shorelines from wave and storm attack across the tropics.”

As so often happens in research, confirmatory evidence of the importance of mangroves had been published only days earlier, in the Public Library of Science journal PLOS One.

US researchers found that – in the Gulf of Mexico and the Caribbean, off the coasts of east Africa and in the Indo-Pacific – a total of 30.9 million people lived in regions vulnerable to powerful tropical storms such as Typhoon Haiyan and Hurricane Harvey.

Of these, more than 8 million people were offered severe weather protection by shoreline mangrove forests and coral reefs, both of which absorb wave energy, reduce wave heights and keep coastal settlements safer.

Not enough protection

But only 38% of mangroves and 11% of coral reefs along the vulnerable coastlines are protected, they found.

A 100-metre screen of shoreline mangrove forest can reduce wave heights by as much as two-thirds. By 2100, coastal floods could be costing the world’s nations US$1 trillion a year in economic damage.

Geographers have argued for decades that natural protection is the most efficient way of saving lives and settlements from the storm surges and flooding associated with tropical cyclone extremes.

“Simply put”, said Holly Jones of Northern Illinois University, who led the research, “it’s much cheaper to conserve a mangrove than build a sea wall.” – Climate News Network

Rising tides driven by global heating could swamp the mangrove forests – bad news for the natural world, and for humans.

LONDON, 17 June, 2020 – If sea levels go on rising at ever higher rates, then by 2050 the world’s mangrove forests could be obliterated, drowned by rising tides.

Mangrove forests cover between 140,000 and 200,000 square kilometres of the intertidal zones that fringe more than 100 tropical and subtropical countries, and have become among the richest ecosystems of the planet.

They are estimated to store at least 30 million tonnes of atmospheric carbon each year, and a couple of sq kms of this saltwater forest can harbour nursery space for what could become 100 tonnes of commercial fish catch every year.

They also provide shelter for a huge range of creatures, including an estimated 500 Bengal tigers in the vast Sundarbans mangrove forests along the Ganges-Brahmaputra delta.

And while most of the 80 or so species of mangrove tree can keep up with an annual sea level rise of around 5mm a year, they seem unlikely, on evidence from the past, to be able to survive a 10mm rise. Right now, the world is heading for the higher end of the scale.

Sheltering people

A second and separate study finds that, importantly for humans, along with coral reefs, the mangrove forests provide vital natural protection from tropical storms for 31 million very vulnerable people in North and Central America and the crowded archipelagos of Indonesia and the Philippines.

Researchers from Australia, China, Singapore and the US report in the journal Science that they looked at the evidence locked in the sediments in 78 locations from the last 10,000 years, to work out how mangrove forests have – through the millennia – responded to changes in sea level.

At the close of the last ice age, sea levels rose at 10mm a year and slowed to nearly stable conditions 4000 years ago.

In a high emissions scenario, by 2050 sea level rise would exceed 6mm: the scientists found a 90% probability that mangroves would not be able to grow fast enough to keep up. Nor – because of the development of coastal settlements worldwide – would the forests be able to shift inland.

“Simply put, it’s much cheaper to conserve a mangrove than build a sea wall”

“This research therefore highlights yet another compelling reason why countries must take urgent action to reduce carbon emissions,” said Benjamin Horton of Nanyang Technical University in Singapore., one of the researchers.

“Mangroves are among the most valuable of natural ecosystems, supporting coastal fisheries and biodiversity, while protecting shorelines from wave and storm attack across the tropics.”

As so often happens in research, confirmatory evidence of the importance of mangroves had been published only days earlier, in the Public Library of Science journal PLOS One.

US researchers found that – in the Gulf of Mexico and the Caribbean, off the coasts of east Africa and in the Indo-Pacific – a total of 30.9 million people lived in regions vulnerable to powerful tropical storms such as Typhoon Haiyan and Hurricane Harvey.

Of these, more than 8 million people were offered severe weather protection by shoreline mangrove forests and coral reefs, both of which absorb wave energy, reduce wave heights and keep coastal settlements safer.

Not enough protection

But only 38% of mangroves and 11% of coral reefs along the vulnerable coastlines are protected, they found.

A 100-metre screen of shoreline mangrove forest can reduce wave heights by as much as two-thirds. By 2100, coastal floods could be costing the world’s nations US$1 trillion a year in economic damage.

Geographers have argued for decades that natural protection is the most efficient way of saving lives and settlements from the storm surges and flooding associated with tropical cyclone extremes.

“Simply put”, said Holly Jones of Northern Illinois University, who led the research, “it’s much cheaper to conserve a mangrove than build a sea wall.” – Climate News Network

Ocean warming spurs marine life to rapid migration

Far from the sunlight and even at the lowest temperatures, ocean warming is making marine life uncomfortable.

LONDON, 15 June, 2020 – Scientists have taken the temperature of the deep seas and found alarming signs of change: ocean warming is prompting many creatures to migrate fast.

The species that live in the deep and the dark are moving towards the poles at twice to almost four times the speed of surface creatures.

The implication is that – even though conditions in the abyssal plain are far more stable than surface currents – the creatures of the abyss are feeling the heat.

The oceans of the world cover almost three-fourths of the globe and, from surface to seafloor, provide at least 90% of the planet’s living space.

And although there has been repeated attention to the health of the waters that define the Blue Planet, it remains immensely difficult to arrive at a consistent, global figure for rates of change in temperature of the planet’s largest habitat.

“Marine life in the deep ocean will face escalating threats from ocean warming until the end of the century, no matter what we do now”

Oceanographers are fond of complaining that humankind knows more about the surface of Mars and Venus than it does about the bedrock and marine sediments at depth.

This may still be true, but repeated studies have confirmed that the ocean floor ecosystem is surprisingly rich, varied and potentially at risk.

Now researchers from Australia, Europe, Japan, South Africa and the Philippines report in the journal Nature Climate Change that although they could not deliver thermometer readings, they had found an indirect measure: the rate at which marine creatures move on because they don’t care for their local temperature shifts.

They call this “climate velocity”. They had data for 20,000 marine species. And they found that overall, at depths greater than 1000 metres, marine creatures have been on the move much faster than their fellow citizens near the surface, over the second half of the 20th century.

Computer simulations tell an even more alarming story: by the end of this century, creatures in the mesopelagic layer – from 200 metres down to 1000 metres – will be moving away between four and 11 times faster than those at the surface do now.

Faster migrants

The finding is indirectly supported by a second and unrelated study on the same day in the journal Nature Ecology & Evolution. French scientists looked at studies of more than 12,000 kinds of the migrations of bacteria, plant, fungus and animal to find that sea creatures are already floating, swimming or crawling towards the poles six times faster than those on land, as a response to global heating driven by profligate human use of fossil fuels.

So shifts in range can be interpreted as an indicator of the stress on the ocean habitats. This creates complications for conservationists arguing for internationally protected zones – protected from fishing trawl nets, and from submarine mining operations – because, if for no other reason, not only are ocean creatures moving at different speeds at different depths; some of the shifts are in different directions.

“Significantly reducing carbon emissions is vital to control warming and help take control of climate velocities in the surface layers of the ocean by 2100”, said Anthony Richardson of the University of Queensland in Australia, one of the authors.

“But because of the immense size and depth of the ocean, warming already observed at the ocean surface will mix into deeper waters. This means that marine life in the deep ocean will face escalating threats from ocean warming until the end of the century, no matter what we do now.

“This leaves only one option – act urgently to alleviate other human-generated threats to deep sea life, including seabed mining and deep-sea bottom-fishing.” – Climate News Network

Far from the sunlight and even at the lowest temperatures, ocean warming is making marine life uncomfortable.

LONDON, 15 June, 2020 – Scientists have taken the temperature of the deep seas and found alarming signs of change: ocean warming is prompting many creatures to migrate fast.

The species that live in the deep and the dark are moving towards the poles at twice to almost four times the speed of surface creatures.

The implication is that – even though conditions in the abyssal plain are far more stable than surface currents – the creatures of the abyss are feeling the heat.

The oceans of the world cover almost three-fourths of the globe and, from surface to seafloor, provide at least 90% of the planet’s living space.

And although there has been repeated attention to the health of the waters that define the Blue Planet, it remains immensely difficult to arrive at a consistent, global figure for rates of change in temperature of the planet’s largest habitat.

“Marine life in the deep ocean will face escalating threats from ocean warming until the end of the century, no matter what we do now”

Oceanographers are fond of complaining that humankind knows more about the surface of Mars and Venus than it does about the bedrock and marine sediments at depth.

This may still be true, but repeated studies have confirmed that the ocean floor ecosystem is surprisingly rich, varied and potentially at risk.

Now researchers from Australia, Europe, Japan, South Africa and the Philippines report in the journal Nature Climate Change that although they could not deliver thermometer readings, they had found an indirect measure: the rate at which marine creatures move on because they don’t care for their local temperature shifts.

They call this “climate velocity”. They had data for 20,000 marine species. And they found that overall, at depths greater than 1000 metres, marine creatures have been on the move much faster than their fellow citizens near the surface, over the second half of the 20th century.

Computer simulations tell an even more alarming story: by the end of this century, creatures in the mesopelagic layer – from 200 metres down to 1000 metres – will be moving away between four and 11 times faster than those at the surface do now.

Faster migrants

The finding is indirectly supported by a second and unrelated study on the same day in the journal Nature Ecology & Evolution. French scientists looked at studies of more than 12,000 kinds of the migrations of bacteria, plant, fungus and animal to find that sea creatures are already floating, swimming or crawling towards the poles six times faster than those on land, as a response to global heating driven by profligate human use of fossil fuels.

So shifts in range can be interpreted as an indicator of the stress on the ocean habitats. This creates complications for conservationists arguing for internationally protected zones – protected from fishing trawl nets, and from submarine mining operations – because, if for no other reason, not only are ocean creatures moving at different speeds at different depths; some of the shifts are in different directions.

“Significantly reducing carbon emissions is vital to control warming and help take control of climate velocities in the surface layers of the ocean by 2100”, said Anthony Richardson of the University of Queensland in Australia, one of the authors.

“But because of the immense size and depth of the ocean, warming already observed at the ocean surface will mix into deeper waters. This means that marine life in the deep ocean will face escalating threats from ocean warming until the end of the century, no matter what we do now.

“This leaves only one option – act urgently to alleviate other human-generated threats to deep sea life, including seabed mining and deep-sea bottom-fishing.” – Climate News Network

Human action will decide how much sea levels rise

Sea levels will go on rising, because of human action. By how much, though, depends on what humans do next.

LONDON, 21 May 2020 – It’s a racing certainty that sea levels everywhere will go on climbing. Unless the world’s nations act to contain global warming, by 2100 the tides around the world will be one metre higher. And by 2300, they could be five metres higher.

Humans will not be able to blame natural causes: if beaches wash away and coastal towns flood, it will be because of deliberate human inaction.

And even if the 195 nations that met in Paris in 2015 and vowed to limit global warming to “well below” a maximum of 2°C by 2100 actually keep their promise, sea levels around the world will almost certainly rise by at least half a metre, as ever warmer oceans expand, and mountain glaciers and polar icecaps continue to melt.

The predicted levels are not new – individual research teams and the Intergovernmental Panel on Climate Change have said as much many times – but they represent a second and closer look, by 106 experts, at the forecasts for the future.

The charge of human complicity in sea level rise, too, is not new, but science has a way of continuously re-examining its own conclusions to see if they could be wrong. And the message is: they are not wrong.

“This provides a great deal of hope for the future, as well as strong motivation to act now”

Researchers from Hong Kong, Ireland, the UK, the US and Germany joined scientists from Singapore to consider, once again, what could happen to the world’s oceans under two scenarios: one in which global warming – already at least 1°C higher now than for most of human history – rose by no more than 2°C altogether, and one in which humankind went on burning fossil fuels and destroying tropical rainforests at ever greater rates.

The conclusion? They report in the journal Climate and Atmospheric Science that at the 2°C limit, seas will rise by 0.5 metres by 2100 and two metres by 2300.

If temperatures by 2100 reach 4.5°C, then by the century’s end the tides could reach anywhere between 0.6 and 1.3 metres above present levels. Two centuries on, the high tide mark could be anywhere between 1.7 and 5.6 metres above the present.

And these are the judgments of 106 scientists, each of whom has published at least six peer-reviewed scientific studies of future sea level rise in the last six years.

“We know that the planet will see additional sea level rise in the future. But there are stark differences in the amount of sea level rise experts project for low emissions compared to high emissions,” said one of the scientists, Andra Garner of Rowan University in the US.

Lessons from prehistory

“This provides a great deal of hope for the future, as well as strong motivation to act now to avoid the more severe impacts of rising sea levels.”

Quite separately, researchers in the US report in the journal Science Advances that they too, took a closer look at puzzles posed by past sea level change. Long before humans ever started burning coal, oil and natural gas, the ice caps retreated, and the seas rose.

The scientists reconstructed the history of sea levels and glaciation since the end of the Cretaceous era 60 million or so years ago, and matched them to estimated carbon dioxide levels long before the emergence of any human ancestry.

They concluded that all the changes in the past had natural explanations, but not the changes happening now.

Kenneth Miller of Rutgers University who led the study said: “Although carbon dioxide levels had an important influence on ice-free periods, minor variations in the Earth’s orbit were the dominant factor in terms of ice volume and sea level changes – until modern times.” – Climate News Network

Sea levels will go on rising, because of human action. By how much, though, depends on what humans do next.

LONDON, 21 May 2020 – It’s a racing certainty that sea levels everywhere will go on climbing. Unless the world’s nations act to contain global warming, by 2100 the tides around the world will be one metre higher. And by 2300, they could be five metres higher.

Humans will not be able to blame natural causes: if beaches wash away and coastal towns flood, it will be because of deliberate human inaction.

And even if the 195 nations that met in Paris in 2015 and vowed to limit global warming to “well below” a maximum of 2°C by 2100 actually keep their promise, sea levels around the world will almost certainly rise by at least half a metre, as ever warmer oceans expand, and mountain glaciers and polar icecaps continue to melt.

The predicted levels are not new – individual research teams and the Intergovernmental Panel on Climate Change have said as much many times – but they represent a second and closer look, by 106 experts, at the forecasts for the future.

The charge of human complicity in sea level rise, too, is not new, but science has a way of continuously re-examining its own conclusions to see if they could be wrong. And the message is: they are not wrong.

“This provides a great deal of hope for the future, as well as strong motivation to act now”

Researchers from Hong Kong, Ireland, the UK, the US and Germany joined scientists from Singapore to consider, once again, what could happen to the world’s oceans under two scenarios: one in which global warming – already at least 1°C higher now than for most of human history – rose by no more than 2°C altogether, and one in which humankind went on burning fossil fuels and destroying tropical rainforests at ever greater rates.

The conclusion? They report in the journal Climate and Atmospheric Science that at the 2°C limit, seas will rise by 0.5 metres by 2100 and two metres by 2300.

If temperatures by 2100 reach 4.5°C, then by the century’s end the tides could reach anywhere between 0.6 and 1.3 metres above present levels. Two centuries on, the high tide mark could be anywhere between 1.7 and 5.6 metres above the present.

And these are the judgments of 106 scientists, each of whom has published at least six peer-reviewed scientific studies of future sea level rise in the last six years.

“We know that the planet will see additional sea level rise in the future. But there are stark differences in the amount of sea level rise experts project for low emissions compared to high emissions,” said one of the scientists, Andra Garner of Rowan University in the US.

Lessons from prehistory

“This provides a great deal of hope for the future, as well as strong motivation to act now to avoid the more severe impacts of rising sea levels.”

Quite separately, researchers in the US report in the journal Science Advances that they too, took a closer look at puzzles posed by past sea level change. Long before humans ever started burning coal, oil and natural gas, the ice caps retreated, and the seas rose.

The scientists reconstructed the history of sea levels and glaciation since the end of the Cretaceous era 60 million or so years ago, and matched them to estimated carbon dioxide levels long before the emergence of any human ancestry.

They concluded that all the changes in the past had natural explanations, but not the changes happening now.

Kenneth Miller of Rutgers University who led the study said: “Although carbon dioxide levels had an important influence on ice-free periods, minor variations in the Earth’s orbit were the dominant factor in terms of ice volume and sea level changes – until modern times.” – Climate News Network

Plastic waste now litters Antarctic shore

From the deep Mediterranean marine mud to the desolate beaches of the Southern Ocean, plastic waste now gets everywhere.

LONDON, 12 May, 2020 – The throwaway society now has a global reach. British and German scientists have found astonishing concentrations of plastic waste in the form of tiny fibres on the sea floor. In just one square metre of marine ooze, they have counted as many as 1.9 million fragments less than a millimetre in length.

And two studies have identified sickening levels of plastic waste in the Southern Ocean that washes around Antarctica. One team reports ever greater counts of debris on the beaches of islands in South Georgia and South Orkney; the other on the increasing quantities ingested by the wandering albatross and the giant petrel, two iconic birds of the south polar seas.

An estimated 10 million tonnes of discarded food wrapping, drinking straws, disposable cups, bottles, carrier bags and fishing gear are tipped into the sea each year: plastic waste has now been found in all the world’s oceans, and even in the polar ice, an indestructible reminder of human impact on the natural world.

Tiny textile particles or microfibres of plastic have been found in every sampled litre of sea water, in the stomachs of seabirds and in the bellies of whales.

In fact the visible debris – the polystyrene cups and drinking straws and carrier bags floating on or near the surface – is thought to account for a tiny proportion of the total. Around 99% is thought to be in the deep oceans.

“Microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents that concentrate them in certain areas”

And researchers now report in the journal Science that they have found an indicator as to the final fate of most of it. They collected sediment at depths of up to 900 metres from the floor of the Tyrrhenian Sea to the west of the Italian peninsula and began counting the particles of indestructible polymer material in the marine mud, carried there by deep ocean currents.

“Almost everybody has heard of the infamous ‘garbage patches’ of floating plastic, but we were shocked at the high concentrations of microplastics we found on the sea floor,” said Ian Kane of the University of Manchester, in the UK, one of the authors.

“We discovered that microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents that concentrate them in certain areas.”

These same deep currents also carry oxygen-rich water and nutrients, which suggests that toxic microplastics are being carried into vital deep ecosystems. But the surface-borne debris has far-reaching consequences too.

Remedial efforts

British and Australian scientists who made surveys over three decades of beached plastic, metal, glass, paper and rubber at locations in the Southern Ocean report in the journal Environment International that between 1989 and March 2019, they recovered 10,112 items of waste weighing in total more than 100kg from Bird Island off South Georgia, and 1,304 items weighing in all 268 kg from the remote shores of Signy Island in the South Orkney archipelago.

Almost 90% of the total was plastic. The peak of the debris count was in the 1990s, which suggests that some attempts have been made to reduce the levels discarded from shipping and other sources.

And a second study in the same journal reports that in the same 30 years, levels of plastic pollution had been consumed in increasing quantities by two out of three species of albatross, and another sea bird.

Annual intake in Diomedea exulans, the wandering albatross, had increased 14-fold, and in the giant petrel Macronectes giganteus the intake had increased six-fold.

“Our study adds to the growing body of evidence that fishing and other vessels make a major contribution to plastic pollution,” said Richard Phillips of the British Antarctic Survey. “It’s clear that marine plastics are a threat to seabirds and other wildlife, and more needs to be done.” – Climate News Network

From the deep Mediterranean marine mud to the desolate beaches of the Southern Ocean, plastic waste now gets everywhere.

LONDON, 12 May, 2020 – The throwaway society now has a global reach. British and German scientists have found astonishing concentrations of plastic waste in the form of tiny fibres on the sea floor. In just one square metre of marine ooze, they have counted as many as 1.9 million fragments less than a millimetre in length.

And two studies have identified sickening levels of plastic waste in the Southern Ocean that washes around Antarctica. One team reports ever greater counts of debris on the beaches of islands in South Georgia and South Orkney; the other on the increasing quantities ingested by the wandering albatross and the giant petrel, two iconic birds of the south polar seas.

An estimated 10 million tonnes of discarded food wrapping, drinking straws, disposable cups, bottles, carrier bags and fishing gear are tipped into the sea each year: plastic waste has now been found in all the world’s oceans, and even in the polar ice, an indestructible reminder of human impact on the natural world.

Tiny textile particles or microfibres of plastic have been found in every sampled litre of sea water, in the stomachs of seabirds and in the bellies of whales.

In fact the visible debris – the polystyrene cups and drinking straws and carrier bags floating on or near the surface – is thought to account for a tiny proportion of the total. Around 99% is thought to be in the deep oceans.

“Microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents that concentrate them in certain areas”

And researchers now report in the journal Science that they have found an indicator as to the final fate of most of it. They collected sediment at depths of up to 900 metres from the floor of the Tyrrhenian Sea to the west of the Italian peninsula and began counting the particles of indestructible polymer material in the marine mud, carried there by deep ocean currents.

“Almost everybody has heard of the infamous ‘garbage patches’ of floating plastic, but we were shocked at the high concentrations of microplastics we found on the sea floor,” said Ian Kane of the University of Manchester, in the UK, one of the authors.

“We discovered that microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents that concentrate them in certain areas.”

These same deep currents also carry oxygen-rich water and nutrients, which suggests that toxic microplastics are being carried into vital deep ecosystems. But the surface-borne debris has far-reaching consequences too.

Remedial efforts

British and Australian scientists who made surveys over three decades of beached plastic, metal, glass, paper and rubber at locations in the Southern Ocean report in the journal Environment International that between 1989 and March 2019, they recovered 10,112 items of waste weighing in total more than 100kg from Bird Island off South Georgia, and 1,304 items weighing in all 268 kg from the remote shores of Signy Island in the South Orkney archipelago.

Almost 90% of the total was plastic. The peak of the debris count was in the 1990s, which suggests that some attempts have been made to reduce the levels discarded from shipping and other sources.

And a second study in the same journal reports that in the same 30 years, levels of plastic pollution had been consumed in increasing quantities by two out of three species of albatross, and another sea bird.

Annual intake in Diomedea exulans, the wandering albatross, had increased 14-fold, and in the giant petrel Macronectes giganteus the intake had increased six-fold.

“Our study adds to the growing body of evidence that fishing and other vessels make a major contribution to plastic pollution,” said Richard Phillips of the British Antarctic Survey. “It’s clear that marine plastics are a threat to seabirds and other wildlife, and more needs to be done.” – Climate News Network

US coasts face far more frequent severe floods

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

For US coasts, high-water hazards have just become more hazardous: a lot more hazardous, say scientists.

LONDON, 24 April, 2020 − A new study of high-water levels on US coasts in 200 regions brings ominous news for those who live in vulnerable towns and cities.

By 2050, floods expected perhaps once every 50 years will happen almost every year in nearly three fourths of all the coasts under study.

And by 2100, the kind of extreme high tides that now happen once in a lifetime could wash over the streets and gardens of 93% of these communities, almost every day.

The message, from researchers led by the US Geological Survey, is that sea levels will go on rising steadily by millimetres every year, but the number of extreme flooding events could double every five years.

Researchers outline their argument in the journal Scientific Reports. They looked at the data routinely collected from 202 tide gauges distributed around the US coasts and then extended the tidal levels forward in time in line with predictions based on global sea level rise that will inevitably accompany ever-increasing global average temperatures, driven by greenhouse gas emissions from fossil fuel use.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100”

Other scientists have warned that the damage from coastal flooding, storm surges and marine invasion will rise to colossal levels by the century’s end, that routine high-tide floods will become increasingly common, and that up to 13 million US citizens now in coastal settlements could become climate refugees.

But researchers based in Chicago, Santa Cruz and Hawaii wanted more than that: they wanted to know what sea level rise will do, as the waters lap ever higher, from year to year.

“Sea level rise is slow, yet consequential and accelerating,” they point out. “Upper end sea level rise scenarios could displace hundreds of millions of people by the end of the 21st century. However, even small amounts of sea level rise can disproportionately increase coastal flood frequency.”

The researchers selected 202 sites, most of them in sheltered harbours or bays, for their tide data: that way their record reflected the highest tides and storm surges, but not the haphazard readings of waves.

They concentrated on what they called “extreme water-level events” of the kind that happened once every 50 years, because most US coastal engineering work is based on that kind of hazard frequency. And then they started doing the calculations.

Exponential hazard growth

For nine out of 10 locations, the difference between the kind of flood that happened every 50 years and the sort that occurred maybe once a year was about half a metre. For 73% of their chosen tide gauges, the difference between the daily highest tide and the once-every-50-years event was less than a metre. Most projections for sea level rise worldwide by the end of the century are higher than a metre.

Once the researchers had set their algorithms to work, they found that even in median sea-level rise scenarios, the hazards grew exponentially. They found that all tidal stations would by 2050 be recording what remain for the moment 50-year events, every year. When they set the timetable to 2100, 93% of their locations would be recording a once-in-50-years flood every day.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100,” they warn.

This would have profound consequences for what they call extreme events. And even in ordinary circumstances, beaches are increasingly likely to be washed away, and cliffs eroded.

The researchers conclude: “Our society has yet to fully comprehend the imminence of the projected regime shifts in coastal hazards and the consequences thereof.” − Climate News Network

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

For US coasts, high-water hazards have just become more hazardous: a lot more hazardous, say scientists.

LONDON, 24 April, 2020 − A new study of high-water levels on US coasts in 200 regions brings ominous news for those who live in vulnerable towns and cities.

By 2050, floods expected perhaps once every 50 years will happen almost every year in nearly three fourths of all the coasts under study.

And by 2100, the kind of extreme high tides that now happen once in a lifetime could wash over the streets and gardens of 93% of these communities, almost every day.

The message, from researchers led by the US Geological Survey, is that sea levels will go on rising steadily by millimetres every year, but the number of extreme flooding events could double every five years.

Researchers outline their argument in the journal Scientific Reports. They looked at the data routinely collected from 202 tide gauges distributed around the US coasts and then extended the tidal levels forward in time in line with predictions based on global sea level rise that will inevitably accompany ever-increasing global average temperatures, driven by greenhouse gas emissions from fossil fuel use.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100”

Other scientists have warned that the damage from coastal flooding, storm surges and marine invasion will rise to colossal levels by the century’s end, that routine high-tide floods will become increasingly common, and that up to 13 million US citizens now in coastal settlements could become climate refugees.

But researchers based in Chicago, Santa Cruz and Hawaii wanted more than that: they wanted to know what sea level rise will do, as the waters lap ever higher, from year to year.

“Sea level rise is slow, yet consequential and accelerating,” they point out. “Upper end sea level rise scenarios could displace hundreds of millions of people by the end of the 21st century. However, even small amounts of sea level rise can disproportionately increase coastal flood frequency.”

The researchers selected 202 sites, most of them in sheltered harbours or bays, for their tide data: that way their record reflected the highest tides and storm surges, but not the haphazard readings of waves.

They concentrated on what they called “extreme water-level events” of the kind that happened once every 50 years, because most US coastal engineering work is based on that kind of hazard frequency. And then they started doing the calculations.

Exponential hazard growth

For nine out of 10 locations, the difference between the kind of flood that happened every 50 years and the sort that occurred maybe once a year was about half a metre. For 73% of their chosen tide gauges, the difference between the daily highest tide and the once-every-50-years event was less than a metre. Most projections for sea level rise worldwide by the end of the century are higher than a metre.

Once the researchers had set their algorithms to work, they found that even in median sea-level rise scenarios, the hazards grew exponentially. They found that all tidal stations would by 2050 be recording what remain for the moment 50-year events, every year. When they set the timetable to 2100, 93% of their locations would be recording a once-in-50-years flood every day.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100,” they warn.

This would have profound consequences for what they call extreme events. And even in ordinary circumstances, beaches are increasingly likely to be washed away, and cliffs eroded.

The researchers conclude: “Our society has yet to fully comprehend the imminence of the projected regime shifts in coastal hazards and the consequences thereof.” − Climate News Network

Entire wild systems at risk from rising global heat

Rising global heat raises risks to the creatures and ecosystems that sustain human society. Collapse could be sudden and near-total.

LONDON, 14 April, 2020 – Worldwide, entire ecosystems could collapse as the planetary thermometer soars: rising global heat could see the Earth’s average temperature rise by 4°C (right now the world is heading for a rise of more than three degrees).

And then one in six of the complex communities of plants and animals in wetlands, grasslands, forests or oceans could drastically alter or fail.

That is because at such temperatures more than one in five of the creatures in that network of co-dependencies would in the same decade experience temperatures beyond their normal tolerance levels.

The prediction is based on data that pinpoint the geographical ranges of 30,652 birds, mammals, reptiles, amphibians, fish and plants, and climate data from 1850 to 2005.

“We found that climate change risks to biodiversity don’t increase gradually,” said Alex Pigot of Imperial College London, in the UK, who led the research.

Abrupt change

“Instead, as the climate warms, within a certain area most species will be able to cope for a while, before crossing a temperature threshold, when a large proportion of the species will suddenly face conditions they’ve never experienced before.

“It’s not a slippery slope, but a series of cliff edges, hitting different areas at different times.”

The finding – published in the journal Nature – should come as no great surprise to the world’s zoologists, botanists, ecologists, foresters, marine scientists and conservationists.

They have repeatedly warned that as global temperatures rise, and climate patterns become increasingly unstable, in response to ever-higher greenhouse gas emissions from power stations and car exhausts, and forest destruction, both individual species and even whole habitats could be exposed to loss and species extinction.

Such threats can be prefigured even in subtle changes in species behaviour. Within this month, Spanish ornithologists who have studied the nightingale Luscinia megarhynchos since 1995 report in the journal The Auk: Ornithological Advances that in two decades, as Spanish summers became hotter and more parched, the wings of each new generation of birds have become progressively shorter.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction”

A shorter wingspan in proportion to body length creates potential survival problems for a species that breeds in Europe but prefers to fly to sub-Saharan Africa for the winter.

And across the Atlantic, another species, the American robin Turdus migratorius now takes wing 12 days earlier each spring in Mexico and the US to fly to its summer breeding grounds in Canada and Alaska.

The ornithologists report in the journal Environmental Research Letters that GPS tracking of 55 individual birds confirms that the bird may be timing its migration to the snow melt and the first arrival of insects in the high latitudes nearer the fast-warming Arctic.

So far, the planet on average has warmed around only 1°C above the long-term average for most of human history. But Dr Pigot and colleagues in the US and South Africa wanted to look at the big picture of potential change in species everywhere as global heating reaches 2°C – the upper limits that the world’s nations promised in a key international agreement reached in Paris in 2015 – and then goes on soaring.

So they took their species data, and mapped it onto a global grid divided into 100-km-square cells, and then fine-tuned the temperature predicted by climate scientists to see where species and their habitats would experience ever-rising heat beyond their comfort zone.

Unprecedented ocean heat

Any ecosystem is a network of interdependencies: insects pollinate flowers, animals disperse seed and prey upon pests and each other in an intricate set of arrangements that have evolved over tens of thousands of years in a particular pattern of temperature and precipitation. Any disturbance ripples through the entire habitat.

The scientists’ atlas of potential ecological disruption included isolated bits of the world such as the Cayman Islands in the Caribbean and the Gobi Desert in Mongolia as well as the Amazon basin and the forests and clearings in the Congo, and one of the world’s richest marine habitats, the so-called Coral Triangle bounded by the Philippines, Malaysia, Papua New Guinea and the islands of the Western Pacific.

They found that if warming could be contained to 2°C or less, only about one community in 50 would be faced with exposure to such disruption: they warn however that even this 2% includes some of the richest habitats on the planet.

They also warn that by 2030, the tropical oceans will start to experience temperature regimes that have no precedent in human history. The tropical forests could be at risk by 2050. Ominously, almost three-fourths of all the species to face unprecedented temperatures before the end of this century will all do so more or less at the same time.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction,” Dr Pigot said. – Climate News Network

Rising global heat raises risks to the creatures and ecosystems that sustain human society. Collapse could be sudden and near-total.

LONDON, 14 April, 2020 – Worldwide, entire ecosystems could collapse as the planetary thermometer soars: rising global heat could see the Earth’s average temperature rise by 4°C (right now the world is heading for a rise of more than three degrees).

And then one in six of the complex communities of plants and animals in wetlands, grasslands, forests or oceans could drastically alter or fail.

That is because at such temperatures more than one in five of the creatures in that network of co-dependencies would in the same decade experience temperatures beyond their normal tolerance levels.

The prediction is based on data that pinpoint the geographical ranges of 30,652 birds, mammals, reptiles, amphibians, fish and plants, and climate data from 1850 to 2005.

“We found that climate change risks to biodiversity don’t increase gradually,” said Alex Pigot of Imperial College London, in the UK, who led the research.

Abrupt change

“Instead, as the climate warms, within a certain area most species will be able to cope for a while, before crossing a temperature threshold, when a large proportion of the species will suddenly face conditions they’ve never experienced before.

“It’s not a slippery slope, but a series of cliff edges, hitting different areas at different times.”

The finding – published in the journal Nature – should come as no great surprise to the world’s zoologists, botanists, ecologists, foresters, marine scientists and conservationists.

They have repeatedly warned that as global temperatures rise, and climate patterns become increasingly unstable, in response to ever-higher greenhouse gas emissions from power stations and car exhausts, and forest destruction, both individual species and even whole habitats could be exposed to loss and species extinction.

Such threats can be prefigured even in subtle changes in species behaviour. Within this month, Spanish ornithologists who have studied the nightingale Luscinia megarhynchos since 1995 report in the journal The Auk: Ornithological Advances that in two decades, as Spanish summers became hotter and more parched, the wings of each new generation of birds have become progressively shorter.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction”

A shorter wingspan in proportion to body length creates potential survival problems for a species that breeds in Europe but prefers to fly to sub-Saharan Africa for the winter.

And across the Atlantic, another species, the American robin Turdus migratorius now takes wing 12 days earlier each spring in Mexico and the US to fly to its summer breeding grounds in Canada and Alaska.

The ornithologists report in the journal Environmental Research Letters that GPS tracking of 55 individual birds confirms that the bird may be timing its migration to the snow melt and the first arrival of insects in the high latitudes nearer the fast-warming Arctic.

So far, the planet on average has warmed around only 1°C above the long-term average for most of human history. But Dr Pigot and colleagues in the US and South Africa wanted to look at the big picture of potential change in species everywhere as global heating reaches 2°C – the upper limits that the world’s nations promised in a key international agreement reached in Paris in 2015 – and then goes on soaring.

So they took their species data, and mapped it onto a global grid divided into 100-km-square cells, and then fine-tuned the temperature predicted by climate scientists to see where species and their habitats would experience ever-rising heat beyond their comfort zone.

Unprecedented ocean heat

Any ecosystem is a network of interdependencies: insects pollinate flowers, animals disperse seed and prey upon pests and each other in an intricate set of arrangements that have evolved over tens of thousands of years in a particular pattern of temperature and precipitation. Any disturbance ripples through the entire habitat.

The scientists’ atlas of potential ecological disruption included isolated bits of the world such as the Cayman Islands in the Caribbean and the Gobi Desert in Mongolia as well as the Amazon basin and the forests and clearings in the Congo, and one of the world’s richest marine habitats, the so-called Coral Triangle bounded by the Philippines, Malaysia, Papua New Guinea and the islands of the Western Pacific.

They found that if warming could be contained to 2°C or less, only about one community in 50 would be faced with exposure to such disruption: they warn however that even this 2% includes some of the richest habitats on the planet.

They also warn that by 2030, the tropical oceans will start to experience temperature regimes that have no precedent in human history. The tropical forests could be at risk by 2050. Ominously, almost three-fourths of all the species to face unprecedented temperatures before the end of this century will all do so more or less at the same time.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction,” Dr Pigot said. – Climate News Network

Fossil fuels add to world’s marine dead zones

Air pollution from burning fossil fuels is adding to fertiliser run-off and sewage to kill marine life in global dead zones.

LONDON, 6 April, 2020 − Cutting out coal-burning and other sources of nitrogen oxides (NOx) from heavy industry, electricity production and traffic will reduce the size of the world’s dead zones along coasts where all fish life is vanishing because of a lack of oxygen.

Researchers in Hong Kong report in the journal Environmental Science & Technology that cutting fossil fuel use in China would benefit not only the climate but also the fisheries along all the country’s coasts.

The finding is significant because many countries concerned about the loss of their coastal and lake fisheries caused by dead zones have been concentrating only on reducing agricultural fertiliser run-off from fields and sewage discharges, which are known to load the rivers with nutrients.

When the nutrients reach lakes or the open sea they feed algae, which rapidly grow into huge green masses. When these so-called algal blooms die they sink to the bottom and decompose, using up nearly all the oxygen in the water.

This process, known as eutrophication, leads to hypoxia, a level of oxygen that is too low for most organisms to survive. Fish usually swim away to healthier waters, but life forms which cannot easily move simply die.

“I hope our study brings more attention to the potential benefit of reducing fossil fuel burning on human and ecosystem health, but also on local economic activities like fisheries”

NOx emissions from fossil fuel burning and fertiliser manufacture lead to the formation of ground-level ozone, smog and acid rain, and contribute to global warming through the greenhouse effect.

What the new research shows is that while fertiliser and sewage are very important in creating dead zones, the aerial input of NOx makes a bad situation far worse.

The report’s lead author, Yu Yan Yau, an MPhil student at the University of Hong Kong’s Swire Institute of Marine Science (SWIMS), and her colleagues studied the South China, East China, Yellow and Bohai Seas.

They found that the atmospheric deposition of nutrients from fossil fuel burning on the mainland increased the amount of organic matter decomposing at the bottom of the sea by 15%, and increased the dead zones by 5%. The South China Sea was the most sensitive to fossil fuel burning.

Investigation needed

The good news in their research was that cutting this burning would considerably reduce the size of the dead zones.

Yu Yan Yau said: “I hope our study brings more attention to the potential benefit of reducing fossil fuel burning on human and ecosystem health, but also on local economic activities like fisheries, which are severely affected by hypoxia.”

Her supervisor, Dr Benoit Thibodeau, added: “Low levels of oxygen are observed in many coastal seas around the world and it is important to find better ways to tackle this problem.

“While we understand that sewage and nutrient input from the Pearl River drive most of the hypoxia in the Greater Bay Area, we observe low levels of oxygen in regions that are not directly under the influence of these sources. Thus it is important to investigate the impact of atmospheric deposition more locally.”

These findings will be important to many countries that are trying to rescue their coastal fisheries from dead zones. There are about 400 of these globally, including parts of Europe’s Baltic Sea.

Industrial impact

The largest is in the Arabian Sea, covering about 63,000 square miles, and the second largest a vast area in the Gulf of Mexico next to the Mississippi Delta, where a dead zone devoid of marine life develops every summer.

Every year winter rains wash fertiliser from fields in the US corn belt into the river. Combined with sewage overflows, this creates a huge quantity of nutrients that sweep down the river into the sea.

Depending on the size of the winter floods, scientists try to predict the extent of the resultant dead zone. However, the banks of the lower river are also crowded with heavy industrial sites, many burning large quantities of fossil fuels and creating large amounts of NOx, something that previously has not been taken into account.

If the Hong Kong research is correct, then cutting the pollution from these industries will also reduce the size of the Mississippi’s dead zone. − Climate News Network

Air pollution from burning fossil fuels is adding to fertiliser run-off and sewage to kill marine life in global dead zones.

LONDON, 6 April, 2020 − Cutting out coal-burning and other sources of nitrogen oxides (NOx) from heavy industry, electricity production and traffic will reduce the size of the world’s dead zones along coasts where all fish life is vanishing because of a lack of oxygen.

Researchers in Hong Kong report in the journal Environmental Science & Technology that cutting fossil fuel use in China would benefit not only the climate but also the fisheries along all the country’s coasts.

The finding is significant because many countries concerned about the loss of their coastal and lake fisheries caused by dead zones have been concentrating only on reducing agricultural fertiliser run-off from fields and sewage discharges, which are known to load the rivers with nutrients.

When the nutrients reach lakes or the open sea they feed algae, which rapidly grow into huge green masses. When these so-called algal blooms die they sink to the bottom and decompose, using up nearly all the oxygen in the water.

This process, known as eutrophication, leads to hypoxia, a level of oxygen that is too low for most organisms to survive. Fish usually swim away to healthier waters, but life forms which cannot easily move simply die.

“I hope our study brings more attention to the potential benefit of reducing fossil fuel burning on human and ecosystem health, but also on local economic activities like fisheries”

NOx emissions from fossil fuel burning and fertiliser manufacture lead to the formation of ground-level ozone, smog and acid rain, and contribute to global warming through the greenhouse effect.

What the new research shows is that while fertiliser and sewage are very important in creating dead zones, the aerial input of NOx makes a bad situation far worse.

The report’s lead author, Yu Yan Yau, an MPhil student at the University of Hong Kong’s Swire Institute of Marine Science (SWIMS), and her colleagues studied the South China, East China, Yellow and Bohai Seas.

They found that the atmospheric deposition of nutrients from fossil fuel burning on the mainland increased the amount of organic matter decomposing at the bottom of the sea by 15%, and increased the dead zones by 5%. The South China Sea was the most sensitive to fossil fuel burning.

Investigation needed

The good news in their research was that cutting this burning would considerably reduce the size of the dead zones.

Yu Yan Yau said: “I hope our study brings more attention to the potential benefit of reducing fossil fuel burning on human and ecosystem health, but also on local economic activities like fisheries, which are severely affected by hypoxia.”

Her supervisor, Dr Benoit Thibodeau, added: “Low levels of oxygen are observed in many coastal seas around the world and it is important to find better ways to tackle this problem.

“While we understand that sewage and nutrient input from the Pearl River drive most of the hypoxia in the Greater Bay Area, we observe low levels of oxygen in regions that are not directly under the influence of these sources. Thus it is important to investigate the impact of atmospheric deposition more locally.”

These findings will be important to many countries that are trying to rescue their coastal fisheries from dead zones. There are about 400 of these globally, including parts of Europe’s Baltic Sea.

Industrial impact

The largest is in the Arabian Sea, covering about 63,000 square miles, and the second largest a vast area in the Gulf of Mexico next to the Mississippi Delta, where a dead zone devoid of marine life develops every summer.

Every year winter rains wash fertiliser from fields in the US corn belt into the river. Combined with sewage overflows, this creates a huge quantity of nutrients that sweep down the river into the sea.

Depending on the size of the winter floods, scientists try to predict the extent of the resultant dead zone. However, the banks of the lower river are also crowded with heavy industrial sites, many burning large quantities of fossil fuels and creating large amounts of NOx, something that previously has not been taken into account.

If the Hong Kong research is correct, then cutting the pollution from these industries will also reduce the size of the Mississippi’s dead zone. − Climate News Network