Light From Plant Growth Shows Carbon Budget

Read more of this story here from Truthdig RSS by Tim Radford / Climate News Network.

For the first time, light from plant growth may let humans see – almost at a glance – how greedily the planet’s vegetation sucks carbon dioxide from the atmosphere.

US-based researchers have confirmed that they can detect the same glow – invisible to the human eye – from trees, grasslands, crops, mangroves, marches and desert plants as the green things put chlorophyll to work and photosynthesise leaves, flowers, fruits and roots from atmospheric carbon.

The pay-off is simple: an easier and potentially more accurate way of calculating the global carbon budget and assessing the climate cost of human exploitation of fossil fuels.

But the same information will help biologists and geoscientists advance what is sometimes called earth system science: how carbon-based lifeforms make their living from sunlight, water and carbon dioxide in a continuous trafficking that has fuelled 3bn years of evolution.

And at the heart of the study is a new realisation that images from an orbiting satellite deliver better information in a reliable fashion.

Researchers have exploited data from orbiting earth observation satellites to measure the diminishing thickness of the polar ice caps and their dwindling extent, as human-induced global warming warms the oceans and raises the sea levels.

They have helped measure the response of different kinds of forest to global warming, and changes to ocean chemistry as ever greater levels of greenhouse gas enter the atmosphere, as humans burn ever more fossil fuels.

But one satellite, launched specifically to answer questions about the traffic between living things and the carbon dioxide in the atmosphere, has delivered information with even greater precision that anyone expected.

Researchers from the University of New Hampshire report in the journal Global Change Biology that years of observation of solar-induced fluorescence – a glow from plants that no human could expect to see, but an instrument can detect – have confirmed that there is a direct relationship between gross primary productivity and the amount of fluorescence registered by the eye in the sky.

No exceptions

It means that what is true for the canopy of tropical forests in the Congo would also be true for a landscape of maize in the American mid-West, or the grasses and wildflowers of the savannah, the dusty maquis of the Mediterranean, or the swamps of the Louisiana bayous.

Up till now, researchers have tried to make accurate and reliable estimates on the ground, playing with air temperature, sunlight, rainfall and other factors to arrive at their conclusions about what they like to call carbon “sinks.” The message from OCO-2, the NASA orbiting carbon observatory, is that the gleam from the foliage below provides an answer more swiftly, and perhaps more surely.

“The importance of these results is that rather than look at several different types of data and computer-based models from information collected on the ground to monitor plant photosynthesis across the globe, using the satellite observations will provide a near real-time option that is simple, reliable and fast,” said Jingfeng Xiao, of the University of New Hampshire, the chief investigator.

“This is a big step towards being able to solely rely on satellite measurements.”

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Dinosaurs’ Deaths May Serve as a Guide to Today

Read more of this story here from Truthdig RSS by Tim Radford / Climate News Network.

US geologists have identified the moment of the dinosaurs’ death in the Earth’s deep past as the time when the climate changed, even faster and more severely than it is changing as a consequence of human action.

That fateful moment occurred on the day around 65 million years ago when a vast comet or asteroid smashed into Earth over what is now Chicxulub in the Yucatan peninsula of Mexico and brought the Cretaceous era to a close.

The scientists used tiny bits of fish scales, teeth and bones to compose a temperature chart for the last 50,000 years of the Cretaceous, and the first 100,000 years of the Palaeogene, when planet Earth changed forever.

The planetary average temperatures rose around 5°C and stayed perilously hotter for at least another 100,000 years, and in the course of this the last dinosaurs disappeared, as if violently wiped out in one short episode.

Theorists predict that an impact with something 10kms or so across arriving at a minimum of 20 kms a second would have delivered a ferocious blast of heat, a huge ejection of rock and dust into the upper atmosphere, a darkening of the skies, an all-year-round winter that might have endured for a decade, and then dramatic warming as the air filled with carbon dioxide from blazing forests around the planet.

The researchers report in the journal Science that they see this fateful celestial traffic accident as “an unusually relevant natural experiment to compare to modern climatic and environmental changes.”

The evidence comes from a series of shallow marine marls deposited 65 million years ago in what is now Tunisia: these strata contain fragments of fish, and the phosphate compounds in the hard fragments contain oxygen isotopes that in turn can answer questions about the atmospheric temperatures at the time the ancient fish swam in ancient oceans.

And in this series of sediments is a thin red layer rich in the kind of evidence to be expected from a colossal impact with an interplanetary fireball.

No abrupt cooling

What the scientists did not find was evidence of a sudden, brief dramatic cooling, but they didn’t expect to. But they did find, they say, evidence that “matches expectations for impact-initiated greenhouse warming.”

The impact probably extinguished three fourths of all life on Earth. As so often happens in research, a second, almost simultaneous study in a different publication of a different series of geological sediments – in North Dakota in the US – yielded more details about the Cretaceous calamity.

Plant fossils, pollen and spores, according to a report in the journal Current Biology, confirm indirectly that not only were the world’s forests incinerated during and after the impact, but perhaps all tree-dwelling birds of the time.

Today’s finches, falcons and guinea fowl all seem on separate evidence to have evolved from the ancestors of the kiwi, the ostrich, the cassowary and other ground-dwellers.

Because Earth is a once-only experiment, the only lessons for how climate change happens without human help are to be found in the deep past. But the past is a mysterious and sometimes enigmatic landscape.

Modern speed-up

Climate change happens because of tectonic plate movements, or shifts in planetary orbit, or dramatic losses of oxygen in the oceans, but these changes often happen imperceptibly, over very long periods.

But the change associated with the human expansion and the profligate combustion of fossil fuels – sometimes called the Great Acceleration – in the last 200 years is far, far faster.

Thanks to evidence from the last days of the Cretaceous, though, climate scientists have found an accelerated change even faster than anything humans have yet managed.

So the latest study provides, the scientists say, “a perspective on the response of Earth systems to extremely rapid global perturbations.” So far, that is all it provides: a perspective. There are many more questions to be settled before the dying convulsions of the dinosaurs become a model for what might happen to humanity in the coming century.

Read more

Dinosaurs’ Deaths May Serve as a Guide to Today

Read more of this story here from Truthdig RSS by Tim Radford / Climate News Network.

US geologists have identified the moment of the dinosaurs’ death in the Earth’s deep past as the time when the climate changed, even faster and more severely than it is changing as a consequence of human action.

That fateful moment occurred on the day around 65 million years ago when a vast comet or asteroid smashed into Earth over what is now Chicxulub in the Yucatan peninsula of Mexico and brought the Cretaceous era to a close.

The scientists used tiny bits of fish scales, teeth and bones to compose a temperature chart for the last 50,000 years of the Cretaceous, and the first 100,000 years of the Palaeogene, when planet Earth changed forever.

The planetary average temperatures rose around 5°C and stayed perilously hotter for at least another 100,000 years, and in the course of this the last dinosaurs disappeared, as if violently wiped out in one short episode.

Theorists predict that an impact with something 10kms or so across arriving at a minimum of 20 kms a second would have delivered a ferocious blast of heat, a huge ejection of rock and dust into the upper atmosphere, a darkening of the skies, an all-year-round winter that might have endured for a decade, and then dramatic warming as the air filled with carbon dioxide from blazing forests around the planet.

The researchers report in the journal Science that they see this fateful celestial traffic accident as “an unusually relevant natural experiment to compare to modern climatic and environmental changes.”

The evidence comes from a series of shallow marine marls deposited 65 million years ago in what is now Tunisia: these strata contain fragments of fish, and the phosphate compounds in the hard fragments contain oxygen isotopes that in turn can answer questions about the atmospheric temperatures at the time the ancient fish swam in ancient oceans.

And in this series of sediments is a thin red layer rich in the kind of evidence to be expected from a colossal impact with an interplanetary fireball.

No abrupt cooling

What the scientists did not find was evidence of a sudden, brief dramatic cooling, but they didn’t expect to. But they did find, they say, evidence that “matches expectations for impact-initiated greenhouse warming.”

The impact probably extinguished three fourths of all life on Earth. As so often happens in research, a second, almost simultaneous study in a different publication of a different series of geological sediments – in North Dakota in the US – yielded more details about the Cretaceous calamity.

Plant fossils, pollen and spores, according to a report in the journal Current Biology, confirm indirectly that not only were the world’s forests incinerated during and after the impact, but perhaps all tree-dwelling birds of the time.

Today’s finches, falcons and guinea fowl all seem on separate evidence to have evolved from the ancestors of the kiwi, the ostrich, the cassowary and other ground-dwellers.

Because Earth is a once-only experiment, the only lessons for how climate change happens without human help are to be found in the deep past. But the past is a mysterious and sometimes enigmatic landscape.

Modern speed-up

Climate change happens because of tectonic plate movements, or shifts in planetary orbit, or dramatic losses of oxygen in the oceans, but these changes often happen imperceptibly, over very long periods.

But the change associated with the human expansion and the profligate combustion of fossil fuels – sometimes called the Great Acceleration – in the last 200 years is far, far faster.

Thanks to evidence from the last days of the Cretaceous, though, climate scientists have found an accelerated change even faster than anything humans have yet managed.

So the latest study provides, the scientists say, “a perspective on the response of Earth systems to extremely rapid global perturbations.” So far, that is all it provides: a perspective. There are many more questions to be settled before the dying convulsions of the dinosaurs become a model for what might happen to humanity in the coming century.

Read more