aads

When and where did Earth get its oxygen?

Large, flatish rocks in shallow blue water.

Stromatolite in Shark Bay, Western Australia. These fossilized stromatolites are thought to be some of the most ancient forms of life on Earth and are comprised of organisms that probably contributed to the O2 scientists are inferring existed on ancient Earth (i.e., cyanobacteria). Image via Ariel Anbar, Arizona State University.

Oxygen in the form of the oxygen molecule (O2), produced by plants and vital for animals, is abundant in Earth’s atmosphere and oceans. But that hasn’t always been the case. When, and in what environments, did O2 begin to build up on Earth? A new study that looked at ancient rocks in Western Australia suggests it started happening earlier than we thought.

The O2 on Earth was relatively scarce for much of our planet’s 4.6 billion-year existence. But at some point, Earth underwent what scientists call the Great Oxidation Event or GOE for short, as ocean microbes evolved to produce O2 via photosynthesis. O2 first accumulated in Earth’s atmosphere at this time and has been present ever since. It’s been thought that this happened sometime between 2.5 and 2.3 billion years ago.

Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth’s ancient shallow oceans before the GOE. The new study published February 25, 2019 in the peer-reviewed journal Nature Geoscience, has provided evidence for significant ocean oxygenation before the GOE, on a larger scale and to greater depths than previously recognized.

Underwater scene with round bumpy rocks.

Stromatolite in Shark Bay, Western Australia. Image via Ariel Anbar, ASU.

For this study, the team targeted a set of 2.5 billion-year-old marine rocks called stromatolites from Western Australia known as the Mt. McRae Shale. Stromatolites are sedimentary rocks formed by the growth of layer upon layer of cyanobacteria, a single-celled microbe that gets energy through photosynthesis, releasing oxygen as a by-product. Chadlin Ostrander, of Arizona State University’s School of Earth and Space Exploration is the study lead author. He said in a statement:

These rocks were perfect for our study because they were shown previously to have been deposited during an anomalous oxygenation episode before the Great Oxidation Event.

For this research, the team dissolved samples and separated elements of interest in a the lab, then measured isotopic compositions on a mass spectrometer. Their analysis determined that the rocks could only have their chemical signatures of the rock meant that O2 needed to have been present all the way down to the sea floor 2.5 billion years ago. Read more about how the scientists did the study here.

3-D rectangular diagram with layers of pink, purple, blue, and green.

The 2.5 billion-year-old Mt. McRae Shale from Western Australia was analyzed for thallium and molybdenum isotope compositions, revealing a pattern that indicates manganese oxide minerals were being buried over large regions of the ancient sea floor. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago. Image via Chad Ostrander/Arizona State University

The researchers suggest that accumulation of O2 was probably not restricted to small portions of the planet’s surface ocean prior to the GOE. More likely, they say, is that O2 accumulation extended over large regions of the ocean and far into the ocean’s depths – in some of areas, even all the way down to the sea floor.

Ostrander said:

Our discovery forces us to rethink the initial oxygenation of Earth. Many lines of evidence suggest that O2 started to accumulate in Earth’s atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth’s initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth’s oceans — to significant levels, according to our data — well before doing so in the atmosphere.

Man sitting cross-legged on red-brown dirt

Researcher Chad Ostrander with a 2.7 billion-year-old fossilized stromatolite in Western Australia. Image via Chad Ostrander/Arizona State University

Source: Fully oxygenated water columns over continental shelves before the Great Oxidation Event

Bottom line: A new study that looked at ancient rocks in Western Australia suggests the O2 in Earth’s atmosphere started building up earlier than thought.

Via Arizona State University



from EarthSky https://ift.tt/2EEfyFk
Large, flatish rocks in shallow blue water.

Stromatolite in Shark Bay, Western Australia. These fossilized stromatolites are thought to be some of the most ancient forms of life on Earth and are comprised of organisms that probably contributed to the O2 scientists are inferring existed on ancient Earth (i.e., cyanobacteria). Image via Ariel Anbar, Arizona State University.

Oxygen in the form of the oxygen molecule (O2), produced by plants and vital for animals, is abundant in Earth’s atmosphere and oceans. But that hasn’t always been the case. When, and in what environments, did O2 begin to build up on Earth? A new study that looked at ancient rocks in Western Australia suggests it started happening earlier than we thought.

The O2 on Earth was relatively scarce for much of our planet’s 4.6 billion-year existence. But at some point, Earth underwent what scientists call the Great Oxidation Event or GOE for short, as ocean microbes evolved to produce O2 via photosynthesis. O2 first accumulated in Earth’s atmosphere at this time and has been present ever since. It’s been thought that this happened sometime between 2.5 and 2.3 billion years ago.

Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth’s ancient shallow oceans before the GOE. The new study published February 25, 2019 in the peer-reviewed journal Nature Geoscience, has provided evidence for significant ocean oxygenation before the GOE, on a larger scale and to greater depths than previously recognized.

Underwater scene with round bumpy rocks.

Stromatolite in Shark Bay, Western Australia. Image via Ariel Anbar, ASU.

For this study, the team targeted a set of 2.5 billion-year-old marine rocks called stromatolites from Western Australia known as the Mt. McRae Shale. Stromatolites are sedimentary rocks formed by the growth of layer upon layer of cyanobacteria, a single-celled microbe that gets energy through photosynthesis, releasing oxygen as a by-product. Chadlin Ostrander, of Arizona State University’s School of Earth and Space Exploration is the study lead author. He said in a statement:

These rocks were perfect for our study because they were shown previously to have been deposited during an anomalous oxygenation episode before the Great Oxidation Event.

For this research, the team dissolved samples and separated elements of interest in a the lab, then measured isotopic compositions on a mass spectrometer. Their analysis determined that the rocks could only have their chemical signatures of the rock meant that O2 needed to have been present all the way down to the sea floor 2.5 billion years ago. Read more about how the scientists did the study here.

3-D rectangular diagram with layers of pink, purple, blue, and green.

The 2.5 billion-year-old Mt. McRae Shale from Western Australia was analyzed for thallium and molybdenum isotope compositions, revealing a pattern that indicates manganese oxide minerals were being buried over large regions of the ancient sea floor. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago. Image via Chad Ostrander/Arizona State University

The researchers suggest that accumulation of O2 was probably not restricted to small portions of the planet’s surface ocean prior to the GOE. More likely, they say, is that O2 accumulation extended over large regions of the ocean and far into the ocean’s depths – in some of areas, even all the way down to the sea floor.

Ostrander said:

Our discovery forces us to rethink the initial oxygenation of Earth. Many lines of evidence suggest that O2 started to accumulate in Earth’s atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth’s initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth’s oceans — to significant levels, according to our data — well before doing so in the atmosphere.

Man sitting cross-legged on red-brown dirt

Researcher Chad Ostrander with a 2.7 billion-year-old fossilized stromatolite in Western Australia. Image via Chad Ostrander/Arizona State University

Source: Fully oxygenated water columns over continental shelves before the Great Oxidation Event

Bottom line: A new study that looked at ancient rocks in Western Australia suggests the O2 in Earth’s atmosphere started building up earlier than thought.

Via Arizona State University



from EarthSky https://ift.tt/2EEfyFk

Lunar halo over Mobius Arch

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The Mobius Arch is one of the dozens of natural arches in California’s Alabama Hills, a range of hills and rock formations near the eastern slope of the Sierra Nevada.

Photography of the Eternal Nomad captured this lunar halo during the February 18-19, 2019, full moon.

Map of California with location of Alabama Hills identified.

Image via Wikipedia.

Bottom line: Photo of lunar halo over Mobius Arch.



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Help EarthSky keep going! Please donate what you can to our once-yearly crowd-funding campaign.

The Mobius Arch is one of the dozens of natural arches in California’s Alabama Hills, a range of hills and rock formations near the eastern slope of the Sierra Nevada.

Photography of the Eternal Nomad captured this lunar halo during the February 18-19, 2019, full moon.

Map of California with location of Alabama Hills identified.

Image via Wikipedia.

Bottom line: Photo of lunar halo over Mobius Arch.



from EarthSky https://ift.tt/2XxVNGD

Don’t miss moon and Venus before sunup

Before sunrise on March 2, 2019, look east before sunup to see the beautiful pairing of the moon and dazzling planet Venus. Good news. You don’t have to get up much before the sun to view these brilliant worlds. The moon and Venus are bright, the second-brightest and third-brightest sky objects, respectively, after the sun. In fact, people with exceptional eyesight might be able to pick up Venus near the moon after sunrise.

Help EarthSky keep going! Please donate what you can to our annual crowd-funding campaign.

If you arise before the dawn light becomes too overwhelming, two other planets can also be seen in the morning sky. Jupiter, the 4th-brightest celestial object, after the sun, moon and Venus, has risen much earlier and shines in your southern sky (or northern sky if you’re in the Southern Hemisphere). Saturn, the dimmest of the worlds now up before the sun, shines in between Jupiter and Venus. See the sky chart below.

Sky chart of waning moon and planets

It’ll even be harder to spot the thinner, paler moon lower down in the sky before sunrise March 3, 2019.

Note on the sky chart above, which is for middle latitudes in the Northern Hemisphere, that the lunar crescent is C-shaped. The lit side of the moon points in the direction of sunrise, and the moon and planets line-up pretty much in a sideways direction. That’s because the ecliptic – the pathway of the sun, moon and planets – crosses the sky at a very shallow angle on late winter and early spring mornings.

Contrast the sky chart above to the one below for Valdivia, Chile (40 degrees south latitude). The lunar crescent is closer to U-shaped, and the planets are aligned almost vertically (Jupiter is so high up that it’s actually outside the chart). That’s because the ecliptic hits the horizon almost perpendicularly on late summer and early autumn mornings. It’s now late summer for the Southern Hemisphere.

Sky chart of moon and planets from Valdivia, Chile

As viewed from the Southern Hemisphere, the waning crescent moon and the morning planets are found higher in the sky. Jupiter is way higher up, outside the view of the chart.

About a week from now – around March 7 or 8, 2019 – the young waxing crescent moon will make its first appearance in the evening sky. But, this time around, mid-northern latitudes will see a U-shaped evening crescent whereas the folk at Valdivia, Chile, and temperate latitudes in the Southern Hemisphere, will see a C-shaped evening crescent. That’s because the ecliptic hits the evening horizon at a steep angle in late winter and early spring, yet a shallow angle in late summer and early autumn. The charts below show the same sky from differing vantage points.

Sky chart of Mercury and Mars in March 2019 evening sky

A Northern Hemisphere view of the young evening crescent with the planets Mercury and Mars from March 7-10, 2019. Read more.

Sly chart of young moon and planets from Valdivia, Chile

The view of the young March moon from Valdivia, Chile, South America (40 degrees south latitude). Read more.

A slender waning crescent moon that appears in the east a short while before sunrise is known as an old moon. These next few mornings you might notice the dark side of the moon softly illuminated in earthshine – twice-reflected sunlight bouncing from the Earth to the moon, and then from the moon back to Earth.

This earthshine – an ashen glow on the nighttime side of the waning crescent – is sometimes poetically described as the new moon in the old moon’s arms.

A portion of the moon, illuminated by earthshine, with what looks like crepuscular rays emanating from it.

View at EarthSky Community Photos. | This is earthshine, the faint illumination on the darkened portion of a crescent moon – captured on a waxing moon, on February 7, 2019 – by Radu Anghel in Bacau, Romania. Thank you, Radu.

Bottom line: On the morning of March 2, 2019, watch for the old moon and dazzling planet Venus in the east before sunup.



from EarthSky https://ift.tt/2ILHyLb

Before sunrise on March 2, 2019, look east before sunup to see the beautiful pairing of the moon and dazzling planet Venus. Good news. You don’t have to get up much before the sun to view these brilliant worlds. The moon and Venus are bright, the second-brightest and third-brightest sky objects, respectively, after the sun. In fact, people with exceptional eyesight might be able to pick up Venus near the moon after sunrise.

Help EarthSky keep going! Please donate what you can to our annual crowd-funding campaign.

If you arise before the dawn light becomes too overwhelming, two other planets can also be seen in the morning sky. Jupiter, the 4th-brightest celestial object, after the sun, moon and Venus, has risen much earlier and shines in your southern sky (or northern sky if you’re in the Southern Hemisphere). Saturn, the dimmest of the worlds now up before the sun, shines in between Jupiter and Venus. See the sky chart below.

Sky chart of waning moon and planets

It’ll even be harder to spot the thinner, paler moon lower down in the sky before sunrise March 3, 2019.

Note on the sky chart above, which is for middle latitudes in the Northern Hemisphere, that the lunar crescent is C-shaped. The lit side of the moon points in the direction of sunrise, and the moon and planets line-up pretty much in a sideways direction. That’s because the ecliptic – the pathway of the sun, moon and planets – crosses the sky at a very shallow angle on late winter and early spring mornings.

Contrast the sky chart above to the one below for Valdivia, Chile (40 degrees south latitude). The lunar crescent is closer to U-shaped, and the planets are aligned almost vertically (Jupiter is so high up that it’s actually outside the chart). That’s because the ecliptic hits the horizon almost perpendicularly on late summer and early autumn mornings. It’s now late summer for the Southern Hemisphere.

Sky chart of moon and planets from Valdivia, Chile

As viewed from the Southern Hemisphere, the waning crescent moon and the morning planets are found higher in the sky. Jupiter is way higher up, outside the view of the chart.

About a week from now – around March 7 or 8, 2019 – the young waxing crescent moon will make its first appearance in the evening sky. But, this time around, mid-northern latitudes will see a U-shaped evening crescent whereas the folk at Valdivia, Chile, and temperate latitudes in the Southern Hemisphere, will see a C-shaped evening crescent. That’s because the ecliptic hits the evening horizon at a steep angle in late winter and early spring, yet a shallow angle in late summer and early autumn. The charts below show the same sky from differing vantage points.

Sky chart of Mercury and Mars in March 2019 evening sky

A Northern Hemisphere view of the young evening crescent with the planets Mercury and Mars from March 7-10, 2019. Read more.

Sly chart of young moon and planets from Valdivia, Chile

The view of the young March moon from Valdivia, Chile, South America (40 degrees south latitude). Read more.

A slender waning crescent moon that appears in the east a short while before sunrise is known as an old moon. These next few mornings you might notice the dark side of the moon softly illuminated in earthshine – twice-reflected sunlight bouncing from the Earth to the moon, and then from the moon back to Earth.

This earthshine – an ashen glow on the nighttime side of the waning crescent – is sometimes poetically described as the new moon in the old moon’s arms.

A portion of the moon, illuminated by earthshine, with what looks like crepuscular rays emanating from it.

View at EarthSky Community Photos. | This is earthshine, the faint illumination on the darkened portion of a crescent moon – captured on a waxing moon, on February 7, 2019 – by Radu Anghel in Bacau, Romania. Thank you, Radu.

Bottom line: On the morning of March 2, 2019, watch for the old moon and dazzling planet Venus in the east before sunup.



from EarthSky https://ift.tt/2ILHyLb

What's in the Green New Deal? Four key issues to understand

In the few weeks since it was introduced as a non-binding resolution before the U.S. Senate and House of Representatives, the Green New Deal (GND) Resolution has generated more discussion and coverage of climate change – positive and negative – among, by, and aimed at policymakers than we’ve seen in more than a decade.

The nonbinding initiative introduced by Rep. Alexandria Ocasio-Cortez (D-NY) and Edward Markey (D-MA) proposes embarking on a 10-year mobilization aimed at achieving zero net greenhouse gas emissions from the United States. The mobilization would entail a massive overhaul of American electricity, transportation, and building infrastructure to replace fossil fuels and improve energy efficiency, leading some to call it unrealistic, idealistic, politically impossible, and “socialistic.”

Analysis

Proponents of GND portray it as an early focus for meaningful climate policy discussion if political winds lead to changes in 2020 for the presidency and the Senate majority. They say the GND is the first proposal to grasp the scale and magnitude of the risks posed by the warming climate. And while begrudgingly accepting the insurmountable odds against full enactment before 2021 at the earliest, they see it as a worthwhile and long-overdue discussion piece.

Many commentators and policy analysts argue that the changes it calls for would be too expensive, radical, and disruptive. Others have argued that anyone who doesn’t support this sort of emergency transition away from fossil fuels is in denial about the magnitude of the climate problem. Many are confused about the Resolution’s vague contents, in part because Ocasio-Cortez’s office also released an inaccurate fact sheet that subsequently had to be retracted. That document provided early and low-hanging targets for those disposed to wanting to dampen GND enthusiasm.

A nonbinding ‘sense of the Senate’ resolution

Critically, GND must be recognized as a non-binding “sense of the Senate/House” resolution. It is not intended as proposed legislation, and certainly not as a specific climate policy bill. Think of it as being more of a framework on which to build actual climate legislation. In effect, a “yes” vote in either the Senate or the House would signify acceptance of climate change as a sufficiently urgent threat to merit full consideration of an expansive 10-year mobilization to transition away from polluting fossil fuels. In addition, the resolution isn’t intended to be exclusionary: at least five House co-sponsors are also co-sponsoring a revenue-neutral carbon tax bill (the Energy Innovation and Carbon Dividend Act).

Whether and exactly when the GND resolution will come to a full vote remains unclear, but Senate Majority Leader Mitch McConnell (R-KY) has said he will bring it to a vote in the Senate. It would likely pose an uncomfortable vote for those potentially vulnerable Democrats up for re-election in 2020 in “red” or coal-dependent states.

For Americans and their elected representatives, the decision whether to support this fundamentally transformative and sweeping resolution – provisions of which go well beyond those directly applying to climate change to include economic and social equity issues – hinges on four key factors. For politicians, the political considerations may weigh most heavily, but let’s deal with those last.

Science and physical considerations

The first consideration is the easiest from a scientific perspective: How much more global warming can occur before its net physical impacts become unacceptably negative?

The science community’s answer is that we’ve already passed that point; that it’s time to act now. Regions around the world are already experiencing more and more severe extreme weather events like heat waves, droughts, wildfires, and floods.

A paper recently published in Nature Communications found that Atlantic hurricanes are undergoing more rapid intensification as a result of global warming. Sea-level rise poses a threat to coastal communities and island nations. The one-two punch of warming and acidifying oceans is killing coral reefs, which are home to 25 percent of marine life. The recent IPCC Special Report found that “Coral reefs would decline by 70-90 percent with global warming of 2.7°F (1.5°C), and more than 99 percent would be lost with 3.6° F (2°C).” Species are dying out at a rate similar to past mass extinction events, with a new study finding that 40 percent of insect species are threatened with extinction. (For a breakdown of climate impacts in each region of the country, the Fourth National Climate Assessment is a wonderful resource.)

In short, if physical impacts were the only consideration, we would want to halt (and even reverse) climate change as quickly as possible. Of course, that’s not the case, which brings us to the second category.

Economic considerations

In a capitalist society, economic considerations are of course important to Americans. The projects involved in the GND mobilization would cost trillions of dollars, but curbing climate change could also prevent trillions of dollars in damages globally.

The GND includes a proposed jobs guarantee, envisioning that huge employment opportunities would arise to bring about the needed infrastructure overhauls. The transition away from fossil fuels would also yield further economic benefits, in terms of costs avoided, by reducing other pollutants, leading to cleaner air and water and healthier Americans. A 2017 study headed by David Coady at the International Monetary Fund estimated that fossil fuel air pollution costs the United States $206 billion per year and that when adding all subsidies and costs, the country is spending $700 billion annually on fossil fuels – more than $2,000 per person every year.

GND opponents counter that the economic costs of a vast 10-year mobilization would exceed the resulting economic benefits, but Stanford University researcher Jonathan Koomey suggests that we can’t predict just how fast of a transition to a clean energy economy would be optimal. Given the difficulties predicting technological breakthroughs and given that pathways with very different energy mixes can end up with similar costs, it’s impossible to say if the U.S. would be wealthier – from a strictly financial perspective – in a world that’s 2 or 3 or 4 degrees hotter.

People, and perhaps in particular politicians, tend to focus most on these economic considerations (and often just on costs while ignoring resulting benefits) to the exclusion of the others. But it’s very difficult to quantify and involve numerous components – capital costs, avoided climate damages, increased employment, improved public health, etc.

In addition, some factors simply cannot be quantified in dollars. As Tufts economist Frank Ackerman has noted, “There are numerous problems with CBA [cost-benefit analyses], such as the need to (literally) make up monetary prices for priceless values of human life, health and the natural environment. In practice, CBA often trivializes the value of life and nature.”

Ethical and moral considerations

Consider a family that loses its home in a climate-amplified wildfire or hurricane. Quantifying the costs of replacing the home and belongings is do-able, but how to account for the psychological trauma of the event and for psychological damages, let alone for lives lost?

Moreover, rebuilding the home will create investments and jobs, which would dampen a disaster’s impact on the national economy. But as a society, we would consider these traumatizing losses quite harmful and well worth preventing for ethical reasons. For example, one study found that nearly half of low-income parents impacted by Hurricane Katrina experienced post-traumatic stress disorder.

Researchers have found that those traditionally underserved and having the fewest resources are the least able to adapt to climate change impacts. A team led by James Samson reported in a 2011 paper that internationally, those populations contributing the least to climate change tend to be the most vulnerable to its impacts. The higher temperatures resulting from global warming do the most harm in regions that are already hot, like developing countries in Africa and Central America that also have the fewest resources to adapt. While the United States is the country responsible for the most historical carbon pollution of any country on Earth, it’s geographically and economically insulated from the projected worst impacts of climate change that these poorer, less culpable countries will face.

This reality makes it more difficult for some to justify an expensive green mobilization based solely on accounting for just this country’s direct national economic interests, particularly when focusing on short time horizons. However, ignoring the harm done by our carbon pollution to the most vulnerable people – both within and beyond our borders – raises daunting ethical and moral questions.

Moreover, as Ralph Waldo Emerson put it, “To leave the world a bit better … that is to have succeeded.” That we are leaving behind a less hospitable world for our children and grandchildren might be considered our generation’s worst moral failure of all.

Political considerations

Finally, given that climate policies must be implemented by policymakers, the question of what’s politically feasible is critical, and for some perhaps dispositive.

As of mid-February, the GND Resolution had been co-sponsored by 68 members of the House and 12 in the Senate, but all were Democrats. Those co-sponsors include many of the hopeful and high-profile 2020 Democratic presidential candidates, though there are some exceptions and some party leaders still wavering.

On the other side of the political aisle, such a large government-run mobilization is generally incompatible with traditional Republican Party orthodoxy, let alone with the President’s views as the titular head of the party. Unless the Democratic Party in 2020 retains its current House majority and gains control of the presidency and of a clear majority in the Senate, passing legislation will require bipartisanship. That’s particularly true in the Senate, where most legislation requires 60 votes to overcome a filibuster, and a two-thirds vote to override a presidential veto.

The current Republican-controlled Senate (in session until January 2021) certainly won’t consider actual legislation involving a vast government climate mobilization, although smaller individual infrastructure components might be considered. There may be growing support for a bipartisan carbon tax bill – one potential component of a GND – but that and any other significant climate legislation also will likely depend on the winners of the White House and of House and Senate majorities in 2021.

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from Skeptical Science https://ift.tt/2BX1d50

In the few weeks since it was introduced as a non-binding resolution before the U.S. Senate and House of Representatives, the Green New Deal (GND) Resolution has generated more discussion and coverage of climate change – positive and negative – among, by, and aimed at policymakers than we’ve seen in more than a decade.

The nonbinding initiative introduced by Rep. Alexandria Ocasio-Cortez (D-NY) and Edward Markey (D-MA) proposes embarking on a 10-year mobilization aimed at achieving zero net greenhouse gas emissions from the United States. The mobilization would entail a massive overhaul of American electricity, transportation, and building infrastructure to replace fossil fuels and improve energy efficiency, leading some to call it unrealistic, idealistic, politically impossible, and “socialistic.”

Analysis

Proponents of GND portray it as an early focus for meaningful climate policy discussion if political winds lead to changes in 2020 for the presidency and the Senate majority. They say the GND is the first proposal to grasp the scale and magnitude of the risks posed by the warming climate. And while begrudgingly accepting the insurmountable odds against full enactment before 2021 at the earliest, they see it as a worthwhile and long-overdue discussion piece.

Many commentators and policy analysts argue that the changes it calls for would be too expensive, radical, and disruptive. Others have argued that anyone who doesn’t support this sort of emergency transition away from fossil fuels is in denial about the magnitude of the climate problem. Many are confused about the Resolution’s vague contents, in part because Ocasio-Cortez’s office also released an inaccurate fact sheet that subsequently had to be retracted. That document provided early and low-hanging targets for those disposed to wanting to dampen GND enthusiasm.

A nonbinding ‘sense of the Senate’ resolution

Critically, GND must be recognized as a non-binding “sense of the Senate/House” resolution. It is not intended as proposed legislation, and certainly not as a specific climate policy bill. Think of it as being more of a framework on which to build actual climate legislation. In effect, a “yes” vote in either the Senate or the House would signify acceptance of climate change as a sufficiently urgent threat to merit full consideration of an expansive 10-year mobilization to transition away from polluting fossil fuels. In addition, the resolution isn’t intended to be exclusionary: at least five House co-sponsors are also co-sponsoring a revenue-neutral carbon tax bill (the Energy Innovation and Carbon Dividend Act).

Whether and exactly when the GND resolution will come to a full vote remains unclear, but Senate Majority Leader Mitch McConnell (R-KY) has said he will bring it to a vote in the Senate. It would likely pose an uncomfortable vote for those potentially vulnerable Democrats up for re-election in 2020 in “red” or coal-dependent states.

For Americans and their elected representatives, the decision whether to support this fundamentally transformative and sweeping resolution – provisions of which go well beyond those directly applying to climate change to include economic and social equity issues – hinges on four key factors. For politicians, the political considerations may weigh most heavily, but let’s deal with those last.

Science and physical considerations

The first consideration is the easiest from a scientific perspective: How much more global warming can occur before its net physical impacts become unacceptably negative?

The science community’s answer is that we’ve already passed that point; that it’s time to act now. Regions around the world are already experiencing more and more severe extreme weather events like heat waves, droughts, wildfires, and floods.

A paper recently published in Nature Communications found that Atlantic hurricanes are undergoing more rapid intensification as a result of global warming. Sea-level rise poses a threat to coastal communities and island nations. The one-two punch of warming and acidifying oceans is killing coral reefs, which are home to 25 percent of marine life. The recent IPCC Special Report found that “Coral reefs would decline by 70-90 percent with global warming of 2.7°F (1.5°C), and more than 99 percent would be lost with 3.6° F (2°C).” Species are dying out at a rate similar to past mass extinction events, with a new study finding that 40 percent of insect species are threatened with extinction. (For a breakdown of climate impacts in each region of the country, the Fourth National Climate Assessment is a wonderful resource.)

In short, if physical impacts were the only consideration, we would want to halt (and even reverse) climate change as quickly as possible. Of course, that’s not the case, which brings us to the second category.

Economic considerations

In a capitalist society, economic considerations are of course important to Americans. The projects involved in the GND mobilization would cost trillions of dollars, but curbing climate change could also prevent trillions of dollars in damages globally.

The GND includes a proposed jobs guarantee, envisioning that huge employment opportunities would arise to bring about the needed infrastructure overhauls. The transition away from fossil fuels would also yield further economic benefits, in terms of costs avoided, by reducing other pollutants, leading to cleaner air and water and healthier Americans. A 2017 study headed by David Coady at the International Monetary Fund estimated that fossil fuel air pollution costs the United States $206 billion per year and that when adding all subsidies and costs, the country is spending $700 billion annually on fossil fuels – more than $2,000 per person every year.

GND opponents counter that the economic costs of a vast 10-year mobilization would exceed the resulting economic benefits, but Stanford University researcher Jonathan Koomey suggests that we can’t predict just how fast of a transition to a clean energy economy would be optimal. Given the difficulties predicting technological breakthroughs and given that pathways with very different energy mixes can end up with similar costs, it’s impossible to say if the U.S. would be wealthier – from a strictly financial perspective – in a world that’s 2 or 3 or 4 degrees hotter.

People, and perhaps in particular politicians, tend to focus most on these economic considerations (and often just on costs while ignoring resulting benefits) to the exclusion of the others. But it’s very difficult to quantify and involve numerous components – capital costs, avoided climate damages, increased employment, improved public health, etc.

In addition, some factors simply cannot be quantified in dollars. As Tufts economist Frank Ackerman has noted, “There are numerous problems with CBA [cost-benefit analyses], such as the need to (literally) make up monetary prices for priceless values of human life, health and the natural environment. In practice, CBA often trivializes the value of life and nature.”

Ethical and moral considerations

Consider a family that loses its home in a climate-amplified wildfire or hurricane. Quantifying the costs of replacing the home and belongings is do-able, but how to account for the psychological trauma of the event and for psychological damages, let alone for lives lost?

Moreover, rebuilding the home will create investments and jobs, which would dampen a disaster’s impact on the national economy. But as a society, we would consider these traumatizing losses quite harmful and well worth preventing for ethical reasons. For example, one study found that nearly half of low-income parents impacted by Hurricane Katrina experienced post-traumatic stress disorder.

Researchers have found that those traditionally underserved and having the fewest resources are the least able to adapt to climate change impacts. A team led by James Samson reported in a 2011 paper that internationally, those populations contributing the least to climate change tend to be the most vulnerable to its impacts. The higher temperatures resulting from global warming do the most harm in regions that are already hot, like developing countries in Africa and Central America that also have the fewest resources to adapt. While the United States is the country responsible for the most historical carbon pollution of any country on Earth, it’s geographically and economically insulated from the projected worst impacts of climate change that these poorer, less culpable countries will face.

This reality makes it more difficult for some to justify an expensive green mobilization based solely on accounting for just this country’s direct national economic interests, particularly when focusing on short time horizons. However, ignoring the harm done by our carbon pollution to the most vulnerable people – both within and beyond our borders – raises daunting ethical and moral questions.

Moreover, as Ralph Waldo Emerson put it, “To leave the world a bit better … that is to have succeeded.” That we are leaving behind a less hospitable world for our children and grandchildren might be considered our generation’s worst moral failure of all.

Political considerations

Finally, given that climate policies must be implemented by policymakers, the question of what’s politically feasible is critical, and for some perhaps dispositive.

As of mid-February, the GND Resolution had been co-sponsored by 68 members of the House and 12 in the Senate, but all were Democrats. Those co-sponsors include many of the hopeful and high-profile 2020 Democratic presidential candidates, though there are some exceptions and some party leaders still wavering.

On the other side of the political aisle, such a large government-run mobilization is generally incompatible with traditional Republican Party orthodoxy, let alone with the President’s views as the titular head of the party. Unless the Democratic Party in 2020 retains its current House majority and gains control of the presidency and of a clear majority in the Senate, passing legislation will require bipartisanship. That’s particularly true in the Senate, where most legislation requires 60 votes to overcome a filibuster, and a two-thirds vote to override a presidential veto.

The current Republican-controlled Senate (in session until January 2021) certainly won’t consider actual legislation involving a vast government climate mobilization, although smaller individual infrastructure components might be considered. There may be growing support for a bipartisan carbon tax bill – one potential component of a GND – but that and any other significant climate legislation also will likely depend on the winners of the White House and of House and Senate majorities in 2021.

Click here to read the rest



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Prices are not Enough

This is a re-post from TripleCrisis by Frank Ackerman.  Fourth in a series on climate policy; find Part 1 here, Part 2 here, and Part 3 here.

We need a price on carbon emissions. This opinion, virtually unanimous among economists, is also shared by a growing number of advocates and policymakers. But unanimity disappears in the debate over how to price carbon: there is continuing controversy about the merits of taxes vs. cap-and-trade systems for pricing emissions, and about the role for complementary, non-price policies.

At the risk of spoiling the suspense, this blog post reaches two main conclusions: First, under either a carbon tax or a cap-and-trade system, the price level matters more than the mechanism used to reach that price. Second, under either approach, a reasonably high price is necessary but not sufficient for climate policy; other measures are needed to complement price incentives.

Why taxes and cap-and-trade systems are similar

A carbon tax raises the cost of fossil fuels directly, by taxing their carbon emissions from combustion. This is most easily done upstream, i.e. taxing the oil or gas well, coal mine, or fuel importer, who presumably passes the tax on to end users. There are only hundreds of upstream fuel producers and importers to keep track of, compared to millions of end users.

A cap-and-trade system accomplishes the same thing indirectly, by setting a cap on total allowable emissions, and issuing that many annual allowances. Companies that want to sell or use fossil fuels are required to hold allowances equal to their emissions. If the cap is low enough to make allowances a scarce resource, then the market will establish a price on allowances – in effect, a price on greenhouse gas emissions. Again, it is easier to apply allowance requirements, and thus induce carbon trading, at the upstream level rather than on millions of end users.

If the price of emissions is, for example, $50 per ton of carbon dioxide, then any firm that can reduce emissions for less than $50 a ton will do so – under either a tax or cap-and-trade system. Cutting emissions reduces tax payments, under a carbon tax; it reduces the need to buy allowances under a cap-and-trade system. The price, not the mechanism, is what matters for this incentive effect.

review of the economics literature on carbon taxes vs. cap-and-trade systems found a number of other points of similarity. Either system can be configured to achieve a desired distribution of the burden on households and industries, e.g. via free allocation of some allowances, or partial exemption from taxes. Money raised from either taxes or allowance auctions could be wholly or partially refunded to households.  Either approach can be manipulated to reduce effects on international competitiveness.

And problems raised with offsets – along the lines of credits given too casually for tree-planting – are not unique to cap and trade. A carbon tax could emerge from Congress riddled with obscure loopholes, which could be as damaging to the integrity of carbon pricing as any of the poorly written offset provisions of existing cap-and-trade systems. More positively speaking, either approach to carbon pricing can be carried out either with or without offsets and tax exemptions.

Why taxes and cap-and-trade systems are different

Compared to the numerous similarities between the two approaches, the list of differences is a shorter one. A carbon tax is easier and cheaper to administer. In theory, a carbon tax provides certainty about the price of emissions, while a cap-and-trade system provides certainty about the quantity of emissions (in practice, these certainties can be undone by too-frequent tinkering with tax rates or emissions caps).

Cap-and-trade systems have been more widely used in practice. The European Union’s Emissions Trading System (EU ETS) is the world’s largest carbon market. Others include the linked carbon market of California and several Canadian provinces, and the Regional Greenhouse Gas Initiative (RGGI) among states in the Northeast.

Numerous critics have pointed to potential flaws in cap-and-trade, such as overly generous, poorly monitored offsets. Many recent cap-and-trade systems, introduced in a conservative era, began with caps so high and prices so low that they have little effect (leaving them open to the criticism that the administrative costs are not justified by the skimpy results). The price must be high enough, and the cap must be low enough, to alter the behavior of major emitters.

The same applies, of course, to a carbon tax. Starting with a trivial level of carbon tax, in order to calm opponents of the measure, runs the risk of “proving” that a carbon price has no effect. The correct starting price under either system is the highest price that is politically acceptable; there is no hope of “getting the prices right” due to the uncertain and potentially disastrous scope of climate damages.

Perhaps the most salient difference between taxes and cap-and-trade is political rather than economic: in an era when people like to chant “no new taxes”, the prospects for any initiative seem worse if it involves a new tax. This could explain why there is so much more experience to date with cap-and-trade systems.

Beyond price incentives

Some carbon emitters, for instance in electricity generation, have multiple choices among alternative technologies. In such cases, price incentives alone are powerful, and producers can respond incrementally, retiring and replacing individual plants when appropriate. Other sectors face barriers that an individual firm cannot usually overcome on its own. Electric vehicles are not practical without an extensive recharging and repair infrastructure, which is just beginning to exist in a few parts of the country. In this case, no reasonable level of carbon price can, by itself, bring an adequate nationwide electric vehicle infrastructure into existence. Policies that build and promote electric vehicle infrastructure are valuable complements to a carbon price: they create a combined incentive to move away from gasoline.

Yet another reason for combining non-price climate policies with a carbon price is that purely price-based decision-making can be exhausting. People could calculate for themselves the fuel saved by buying a more fuel-efficient car and subtract that from the sticker price of the vehicle, but it is not an easy calculation. Federal and state fuel economy standards make the process simpler, by setting a floor underneath vehicle fuel efficiency.

When buying a major appliance, it is possible in theory to read the energy efficiency sticker on the carton, calculate your average annual use of the appliance, convert it to dollars saved per year, and see if that savings justifies purchase of a more efficient appliance. But who does all that arithmetic? Even I don’t want to do that calculation, and I have a PhD in economics and enjoy playing with numbers. My guess is that virtually no one does the calculation consistently and correctly. On the other hand, federal and state appliance efficiency standards have often set minimum levels of required efficiency, which increase over time. It’s much more fun to buy something off the shelf that meets those standards, instead of settling in for an extended data-crunching session any time you need a new fridge, air conditioner, washing machine…

In short, the carbon price is what matters, not the mechanism used to adopt that price. And whatever the price, non-price climate policies are needed as well – both to build things that no one company can do on its own, and to make energy-efficient choices accessible to all, without heroic feats of calculation.

Frank Ackerman is principal economist at Synapse Energy Economics in Cambridge, Mass., and one of the founders of Dollars & Sense, which publishes Triple Crisis. 



from Skeptical Science https://ift.tt/2Ucutfd

This is a re-post from TripleCrisis by Frank Ackerman.  Fourth in a series on climate policy; find Part 1 here, Part 2 here, and Part 3 here.

We need a price on carbon emissions. This opinion, virtually unanimous among economists, is also shared by a growing number of advocates and policymakers. But unanimity disappears in the debate over how to price carbon: there is continuing controversy about the merits of taxes vs. cap-and-trade systems for pricing emissions, and about the role for complementary, non-price policies.

At the risk of spoiling the suspense, this blog post reaches two main conclusions: First, under either a carbon tax or a cap-and-trade system, the price level matters more than the mechanism used to reach that price. Second, under either approach, a reasonably high price is necessary but not sufficient for climate policy; other measures are needed to complement price incentives.

Why taxes and cap-and-trade systems are similar

A carbon tax raises the cost of fossil fuels directly, by taxing their carbon emissions from combustion. This is most easily done upstream, i.e. taxing the oil or gas well, coal mine, or fuel importer, who presumably passes the tax on to end users. There are only hundreds of upstream fuel producers and importers to keep track of, compared to millions of end users.

A cap-and-trade system accomplishes the same thing indirectly, by setting a cap on total allowable emissions, and issuing that many annual allowances. Companies that want to sell or use fossil fuels are required to hold allowances equal to their emissions. If the cap is low enough to make allowances a scarce resource, then the market will establish a price on allowances – in effect, a price on greenhouse gas emissions. Again, it is easier to apply allowance requirements, and thus induce carbon trading, at the upstream level rather than on millions of end users.

If the price of emissions is, for example, $50 per ton of carbon dioxide, then any firm that can reduce emissions for less than $50 a ton will do so – under either a tax or cap-and-trade system. Cutting emissions reduces tax payments, under a carbon tax; it reduces the need to buy allowances under a cap-and-trade system. The price, not the mechanism, is what matters for this incentive effect.

review of the economics literature on carbon taxes vs. cap-and-trade systems found a number of other points of similarity. Either system can be configured to achieve a desired distribution of the burden on households and industries, e.g. via free allocation of some allowances, or partial exemption from taxes. Money raised from either taxes or allowance auctions could be wholly or partially refunded to households.  Either approach can be manipulated to reduce effects on international competitiveness.

And problems raised with offsets – along the lines of credits given too casually for tree-planting – are not unique to cap and trade. A carbon tax could emerge from Congress riddled with obscure loopholes, which could be as damaging to the integrity of carbon pricing as any of the poorly written offset provisions of existing cap-and-trade systems. More positively speaking, either approach to carbon pricing can be carried out either with or without offsets and tax exemptions.

Why taxes and cap-and-trade systems are different

Compared to the numerous similarities between the two approaches, the list of differences is a shorter one. A carbon tax is easier and cheaper to administer. In theory, a carbon tax provides certainty about the price of emissions, while a cap-and-trade system provides certainty about the quantity of emissions (in practice, these certainties can be undone by too-frequent tinkering with tax rates or emissions caps).

Cap-and-trade systems have been more widely used in practice. The European Union’s Emissions Trading System (EU ETS) is the world’s largest carbon market. Others include the linked carbon market of California and several Canadian provinces, and the Regional Greenhouse Gas Initiative (RGGI) among states in the Northeast.

Numerous critics have pointed to potential flaws in cap-and-trade, such as overly generous, poorly monitored offsets. Many recent cap-and-trade systems, introduced in a conservative era, began with caps so high and prices so low that they have little effect (leaving them open to the criticism that the administrative costs are not justified by the skimpy results). The price must be high enough, and the cap must be low enough, to alter the behavior of major emitters.

The same applies, of course, to a carbon tax. Starting with a trivial level of carbon tax, in order to calm opponents of the measure, runs the risk of “proving” that a carbon price has no effect. The correct starting price under either system is the highest price that is politically acceptable; there is no hope of “getting the prices right” due to the uncertain and potentially disastrous scope of climate damages.

Perhaps the most salient difference between taxes and cap-and-trade is political rather than economic: in an era when people like to chant “no new taxes”, the prospects for any initiative seem worse if it involves a new tax. This could explain why there is so much more experience to date with cap-and-trade systems.

Beyond price incentives

Some carbon emitters, for instance in electricity generation, have multiple choices among alternative technologies. In such cases, price incentives alone are powerful, and producers can respond incrementally, retiring and replacing individual plants when appropriate. Other sectors face barriers that an individual firm cannot usually overcome on its own. Electric vehicles are not practical without an extensive recharging and repair infrastructure, which is just beginning to exist in a few parts of the country. In this case, no reasonable level of carbon price can, by itself, bring an adequate nationwide electric vehicle infrastructure into existence. Policies that build and promote electric vehicle infrastructure are valuable complements to a carbon price: they create a combined incentive to move away from gasoline.

Yet another reason for combining non-price climate policies with a carbon price is that purely price-based decision-making can be exhausting. People could calculate for themselves the fuel saved by buying a more fuel-efficient car and subtract that from the sticker price of the vehicle, but it is not an easy calculation. Federal and state fuel economy standards make the process simpler, by setting a floor underneath vehicle fuel efficiency.

When buying a major appliance, it is possible in theory to read the energy efficiency sticker on the carton, calculate your average annual use of the appliance, convert it to dollars saved per year, and see if that savings justifies purchase of a more efficient appliance. But who does all that arithmetic? Even I don’t want to do that calculation, and I have a PhD in economics and enjoy playing with numbers. My guess is that virtually no one does the calculation consistently and correctly. On the other hand, federal and state appliance efficiency standards have often set minimum levels of required efficiency, which increase over time. It’s much more fun to buy something off the shelf that meets those standards, instead of settling in for an extended data-crunching session any time you need a new fridge, air conditioner, washing machine…

In short, the carbon price is what matters, not the mechanism used to adopt that price. And whatever the price, non-price climate policies are needed as well – both to build things that no one company can do on its own, and to make energy-efficient choices accessible to all, without heroic feats of calculation.

Frank Ackerman is principal economist at Synapse Energy Economics in Cambridge, Mass., and one of the founders of Dollars & Sense, which publishes Triple Crisis. 



from Skeptical Science https://ift.tt/2Ucutfd

These ice-covered Chilean volcanoes could erupt soon

Aerial view of crater with water in it on an ash-covered mountain top.

Image via GlacierHub.

Help EarthSky keep going! Please donate what you can to our once-yearly crowd-funding campaign.

This article is republished with permission from GlacierHub. This post was written by Arley Titzler.

Stretching over 4,350 miles (7,000 km) across seven countries, the Andes are the world’s longest mountain range. They make up the southeastern portion of the Ring of Fire and are well-known for their abundant volcanoes.

The Chilean Andes are home to 90 active volcanoes, all monitored by the Chilean National Geology and Mining Service (Sernageomin). The agency categorizes volcanic activity using four distinct alert levels: green (normal level of activity), yellow (increased level of activity), orange (probable development of an eruption in the short-term), and red (eruption is ongoing or imminent). Increased volcanic activity is associated with frequent earthquakes; plumes of gas, rocks, or ash; and lava flows.

Two areas monitored by Sernageomin are currently showing signs of increased activity: the Nevados de Chillán and Planchón-Peteroa volcanic complexes. The agency issued orange and yellow alert levels for them, respectively.

Wavy lines of high mountain contours with 2 star-shaped white spots.

A satellite image of the Nevados de Chillán volcano complex, showing the glacier-covered volcano peaks. Image via Sernageomin.

Nevados de Chillán Volcanoes: Orange Alert

The Nevados de Chillán volcano complex is comprised of several glacier-covered volcanic peaks. When these volcanoes erupt, the glacial ice sitting atop them melts and mixes with lava, which can result in dangerous lahars, or mudflows. Several small earthquakes and the formation of new gas vents led Sernageomin to issue a yellow alert on December 31, 2015. (To view a detailed map of the Nevados de Chillán complex, click here.)

On April 5, 2018, Sernageomin upgraded the Nevados de Chillán’s yellow alert to an orange alert, following thousands of tremors and a thick, white column of smoke rising from the area. This signaled the likelihood of an eruption in the near future.

Sernageomin’s most recent volcanic activity report for Nevados de Chillán, issued on February 11, 2019, cited persistent seismic activity, which is directly related to increased frequency of explosions, along with the growth and/or destruction of the lava dome that lies in the crater. The expected eruption is most likely to have moderate to low explosive power, but sporadic observations over the last year have shown higher than average energy levels.

On February 15, 2019, the Volcanic Ash Advisory Center in Buenos Aires documented a volcanic-ash plume reaching 12,139 feet (3,700 meters) high at Nevados de Chillán, an example of the above mentioned “higher than average energy levels.”

Bottom line: Recent increased volcanic activity in the Nevados de Chillán prompted Chilean authorities to issue an orange alert in anticipation of an eruption.



from EarthSky https://ift.tt/2Nz7Ij5
Aerial view of crater with water in it on an ash-covered mountain top.

Image via GlacierHub.

Help EarthSky keep going! Please donate what you can to our once-yearly crowd-funding campaign.

This article is republished with permission from GlacierHub. This post was written by Arley Titzler.

Stretching over 4,350 miles (7,000 km) across seven countries, the Andes are the world’s longest mountain range. They make up the southeastern portion of the Ring of Fire and are well-known for their abundant volcanoes.

The Chilean Andes are home to 90 active volcanoes, all monitored by the Chilean National Geology and Mining Service (Sernageomin). The agency categorizes volcanic activity using four distinct alert levels: green (normal level of activity), yellow (increased level of activity), orange (probable development of an eruption in the short-term), and red (eruption is ongoing or imminent). Increased volcanic activity is associated with frequent earthquakes; plumes of gas, rocks, or ash; and lava flows.

Two areas monitored by Sernageomin are currently showing signs of increased activity: the Nevados de Chillán and Planchón-Peteroa volcanic complexes. The agency issued orange and yellow alert levels for them, respectively.

Wavy lines of high mountain contours with 2 star-shaped white spots.

A satellite image of the Nevados de Chillán volcano complex, showing the glacier-covered volcano peaks. Image via Sernageomin.

Nevados de Chillán Volcanoes: Orange Alert

The Nevados de Chillán volcano complex is comprised of several glacier-covered volcanic peaks. When these volcanoes erupt, the glacial ice sitting atop them melts and mixes with lava, which can result in dangerous lahars, or mudflows. Several small earthquakes and the formation of new gas vents led Sernageomin to issue a yellow alert on December 31, 2015. (To view a detailed map of the Nevados de Chillán complex, click here.)

On April 5, 2018, Sernageomin upgraded the Nevados de Chillán’s yellow alert to an orange alert, following thousands of tremors and a thick, white column of smoke rising from the area. This signaled the likelihood of an eruption in the near future.

Sernageomin’s most recent volcanic activity report for Nevados de Chillán, issued on February 11, 2019, cited persistent seismic activity, which is directly related to increased frequency of explosions, along with the growth and/or destruction of the lava dome that lies in the crater. The expected eruption is most likely to have moderate to low explosive power, but sporadic observations over the last year have shown higher than average energy levels.

On February 15, 2019, the Volcanic Ash Advisory Center in Buenos Aires documented a volcanic-ash plume reaching 12,139 feet (3,700 meters) high at Nevados de Chillán, an example of the above mentioned “higher than average energy levels.”

Bottom line: Recent increased volcanic activity in the Nevados de Chillán prompted Chilean authorities to issue an orange alert in anticipation of an eruption.



from EarthSky https://ift.tt/2Nz7Ij5

Ceres had meltwater reservoirs for millions of years

False-color view of Ceres.

False-color view of Ceres from the Dawn spacecraft showing differences in surface materials. The bright spots are salt deposits left over from when salty water (cryomagma) reached the surface and evaporated. New research shows that subsurface reservoirs of salty meltwater existed on Ceres for millions of years. Image via NASA/JPL-CalTech/UCLA/MPS/DLR/IDA.

What astronomers now characterize as dwarf planets might seem to be little more than large asteroids. But, as planetary scientists have been discovering, dwarf planets can share characteristics with full-sized planets; they are indeed actual worlds. That’s certainly true of distant Pluto, with its blue skies, high mountains, and red snows, not to mention its system of moons. Another example is the dwarf planet Ceres, which resides in the main asteroid belt between Mars and Jupiter. Despite being a lot smaller than the primary rocky planets like Earth or even Mercury, and a lot farther from the sun, we now know Ceres has its own unique and active geological history, too.

One of the most intriguing discoveries about Ceres has been evidence for ancient cryovolcanoes – an icy type of volcano that releases water, ammonia or methane instead of hot molten rock. Now, a new research study – a joint project between The University of Texas at Austin and NASA’s Jet Propulsion Laboratory (JPL) – suggests that shallow meltwater reservoirs of salty meltwater were able to stay liquid for millions of years, thanks to an insulating crust. The findings are related to the numerous bright spots seen on Ceres, in particular the largest ones in Occator Crater, which are sodium carbonate salt deposits thought to be the remnants of cryomagma – salty meltwater – that vaporized after reaching Ceres’ virtually airless surface.

Bright spots in Occator Crater.

High-resolution view of the brightest spots on Ceres, in Occator Crater. Image via NASA/JPL-CalTech/UCLA/MPS/DLR/IDA.

Closer view of bright spot in Occator Crater.

An even closer view of one of the bright spots in Occator Crater, on the southwest part of Cerealia Facula. The spots are now thought to be salt deposits on Ceres’ surface. They reached the surface through cracks. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Jason Major.

The new peer-reviewed research was published online on February 8, 2019 in the journal Geophysical Research Letters. From the summary:

We are testing the hypothesis that the bright spots in the center of Occator crater on Ceres are salts extruded from a large brine reservoir in the crust that melted during the asteroid impact that formed Occator Crater. The age difference between the crater and the salt deposits is approximately 16 million years and it is not clear if the brine can remain molten for such a long time. Our simulations show that an isolated impact-induced cryomagma chamber will cool in less than 12 million years. However, our simulations show that the crustal brine reservoir might communicate with a deeper brine reservoir in Ceres’ mantle. Such recharge could extend the longevity of the impact-induced cryomagma chamber beneath Occator Crater.

Cryovolcanism could help mix chemicals that produce the more complex molecules needed for life, such as on Jupiter’s moon Europa. Scientists are interested in studying how similar processes work on Ceres and whether they could could also create the molecules needed for life to begin. According to lead author Marc Hesse, an associate professor at the University of Texas at Austin Jackson School of Geosciences:

Cryovolcanism looks to be a really important system as we look for life. So we’re trying to understand these ice shells and how they behave.

History of the interior of Ceres.

Illustration of the history of the interior of Ceres. Scientists now think that salty meltwater reservoirs (cryomagma) in the crust lasted for millions of years. Image via Neveu/Desch/Arizona State University.

This doesn’t necessarily mean that life itself ever started on Ceres, but the initial chemical interactions needed certainly could have, at least. A subsurface supply of salty water below the surface would have been an ideal environment for that to occur.

The new study focused on the bright salt deposits in Occator Crater. While the crater is about 20 million years old, the deposits are as young as 4 million years old. The cryomagma is thought to have been produced by the impact that created Occator, and was originally estimated to have only been able to remain liquid for about 400,000 years after the impact. But if the deposits are only about 4 million years old, how did the meltwater reservoirs remain liquid so long? To answer that question, Hesse and Julie Castillo-Rogez, a planetary scientist at JPL, looked closer at Ceres’ crustal chemistry and physics. As Castillo-Rogez explained:

It’s difficult to maintain liquid so close to the surface. But our new model includes materials inside the crust that tend to act as insulators consistent with the results from the Dawn observations.

Cryovolcano Ahuna Mons on Ceres.

The large cryovolcano Ahuna Mons (“Lonely Mountain”) on Ceres, which sits in isolation on the surface with no other volcanoes nearby. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

According to their calculations, the melt reservoir of cryomagma could have lasted for 10 million years. As Hess added:

Now that we’re accounting for all these negative feedbacks on cooling – the fact that you release latent heat, the fact that as you warm up the crust it becomes less conductive – you can begin to argue that if the ages are just off by a few million years you might get it.

The bright spots, including those in Occator, tend to be located in the or near the center of impact craters, which suggests that the impacts created the reservoirs of cryomagma, which then came to the surface through cracks. The salty water evaporated, leaving the salt deposits behind.

The new findings will help scientists better understand how Ceres evolved, according to Jennifer Scully, a planetary geologist at JPL:

They used more up-to-date data to create their model. This will help in the future to see if all of the material involved in the observed deposits can be explained by the impact, or does this require a connection to a deeper source of material. It’s a great step in the right direction of answering that question.

Cryovolcano on Pluto.

An ancient cryovolcano called Wright Mons on Pluto, as seen by the New Horizons spacecraft in 2015. Image via NASA/JHUAPL/SwRI.

Cryovolcanism is rather common in the outer solar system – it is known to exist, and suspected to exist, on many icy worlds including Ceres, Titan, Pluto, Europa, Enceladus, Triton and others. This icy form of volcanism mimics the “hot” volcanism of planets and moons like Earth, Venus and Io, and shows that even small, cold bodies in the solar system can be surprisingly geologically active – Ceres itself is only 592 miles (952 km) in diameter.

Bottom line: The dwarf planet Ceres had subsurface meltwater reservoirs of salty water (cryomagma) for millions of years, the new research suggests. Whether any kind of primitive life could have ever evolved in unknown, but the environment could at least have allowed the chemistry to begin that would lead to the creation of the kinds of organic molecules that are the building blocks of life.

Source: Thermal Evolution of the Impact?Induced Cryomagma Chamber Beneath Occator Crater on Ceres

Via Texas Geosciences



from EarthSky https://ift.tt/2T6A5Li
False-color view of Ceres.

False-color view of Ceres from the Dawn spacecraft showing differences in surface materials. The bright spots are salt deposits left over from when salty water (cryomagma) reached the surface and evaporated. New research shows that subsurface reservoirs of salty meltwater existed on Ceres for millions of years. Image via NASA/JPL-CalTech/UCLA/MPS/DLR/IDA.

What astronomers now characterize as dwarf planets might seem to be little more than large asteroids. But, as planetary scientists have been discovering, dwarf planets can share characteristics with full-sized planets; they are indeed actual worlds. That’s certainly true of distant Pluto, with its blue skies, high mountains, and red snows, not to mention its system of moons. Another example is the dwarf planet Ceres, which resides in the main asteroid belt between Mars and Jupiter. Despite being a lot smaller than the primary rocky planets like Earth or even Mercury, and a lot farther from the sun, we now know Ceres has its own unique and active geological history, too.

One of the most intriguing discoveries about Ceres has been evidence for ancient cryovolcanoes – an icy type of volcano that releases water, ammonia or methane instead of hot molten rock. Now, a new research study – a joint project between The University of Texas at Austin and NASA’s Jet Propulsion Laboratory (JPL) – suggests that shallow meltwater reservoirs of salty meltwater were able to stay liquid for millions of years, thanks to an insulating crust. The findings are related to the numerous bright spots seen on Ceres, in particular the largest ones in Occator Crater, which are sodium carbonate salt deposits thought to be the remnants of cryomagma – salty meltwater – that vaporized after reaching Ceres’ virtually airless surface.

Bright spots in Occator Crater.

High-resolution view of the brightest spots on Ceres, in Occator Crater. Image via NASA/JPL-CalTech/UCLA/MPS/DLR/IDA.

Closer view of bright spot in Occator Crater.

An even closer view of one of the bright spots in Occator Crater, on the southwest part of Cerealia Facula. The spots are now thought to be salt deposits on Ceres’ surface. They reached the surface through cracks. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Jason Major.

The new peer-reviewed research was published online on February 8, 2019 in the journal Geophysical Research Letters. From the summary:

We are testing the hypothesis that the bright spots in the center of Occator crater on Ceres are salts extruded from a large brine reservoir in the crust that melted during the asteroid impact that formed Occator Crater. The age difference between the crater and the salt deposits is approximately 16 million years and it is not clear if the brine can remain molten for such a long time. Our simulations show that an isolated impact-induced cryomagma chamber will cool in less than 12 million years. However, our simulations show that the crustal brine reservoir might communicate with a deeper brine reservoir in Ceres’ mantle. Such recharge could extend the longevity of the impact-induced cryomagma chamber beneath Occator Crater.

Cryovolcanism could help mix chemicals that produce the more complex molecules needed for life, such as on Jupiter’s moon Europa. Scientists are interested in studying how similar processes work on Ceres and whether they could could also create the molecules needed for life to begin. According to lead author Marc Hesse, an associate professor at the University of Texas at Austin Jackson School of Geosciences:

Cryovolcanism looks to be a really important system as we look for life. So we’re trying to understand these ice shells and how they behave.

History of the interior of Ceres.

Illustration of the history of the interior of Ceres. Scientists now think that salty meltwater reservoirs (cryomagma) in the crust lasted for millions of years. Image via Neveu/Desch/Arizona State University.

This doesn’t necessarily mean that life itself ever started on Ceres, but the initial chemical interactions needed certainly could have, at least. A subsurface supply of salty water below the surface would have been an ideal environment for that to occur.

The new study focused on the bright salt deposits in Occator Crater. While the crater is about 20 million years old, the deposits are as young as 4 million years old. The cryomagma is thought to have been produced by the impact that created Occator, and was originally estimated to have only been able to remain liquid for about 400,000 years after the impact. But if the deposits are only about 4 million years old, how did the meltwater reservoirs remain liquid so long? To answer that question, Hesse and Julie Castillo-Rogez, a planetary scientist at JPL, looked closer at Ceres’ crustal chemistry and physics. As Castillo-Rogez explained:

It’s difficult to maintain liquid so close to the surface. But our new model includes materials inside the crust that tend to act as insulators consistent with the results from the Dawn observations.

Cryovolcano Ahuna Mons on Ceres.

The large cryovolcano Ahuna Mons (“Lonely Mountain”) on Ceres, which sits in isolation on the surface with no other volcanoes nearby. Image via NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

According to their calculations, the melt reservoir of cryomagma could have lasted for 10 million years. As Hess added:

Now that we’re accounting for all these negative feedbacks on cooling – the fact that you release latent heat, the fact that as you warm up the crust it becomes less conductive – you can begin to argue that if the ages are just off by a few million years you might get it.

The bright spots, including those in Occator, tend to be located in the or near the center of impact craters, which suggests that the impacts created the reservoirs of cryomagma, which then came to the surface through cracks. The salty water evaporated, leaving the salt deposits behind.

The new findings will help scientists better understand how Ceres evolved, according to Jennifer Scully, a planetary geologist at JPL:

They used more up-to-date data to create their model. This will help in the future to see if all of the material involved in the observed deposits can be explained by the impact, or does this require a connection to a deeper source of material. It’s a great step in the right direction of answering that question.

Cryovolcano on Pluto.

An ancient cryovolcano called Wright Mons on Pluto, as seen by the New Horizons spacecraft in 2015. Image via NASA/JHUAPL/SwRI.

Cryovolcanism is rather common in the outer solar system – it is known to exist, and suspected to exist, on many icy worlds including Ceres, Titan, Pluto, Europa, Enceladus, Triton and others. This icy form of volcanism mimics the “hot” volcanism of planets and moons like Earth, Venus and Io, and shows that even small, cold bodies in the solar system can be surprisingly geologically active – Ceres itself is only 592 miles (952 km) in diameter.

Bottom line: The dwarf planet Ceres had subsurface meltwater reservoirs of salty water (cryomagma) for millions of years, the new research suggests. Whether any kind of primitive life could have ever evolved in unknown, but the environment could at least have allowed the chemistry to begin that would lead to the creation of the kinds of organic molecules that are the building blocks of life.

Source: Thermal Evolution of the Impact?Induced Cryomagma Chamber Beneath Occator Crater on Ceres

Via Texas Geosciences



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