Tag Archives: emissions

Study finds that low carbon dioxide emissions from volcanoes may have caused the Sturtian ‘Snowball Earth’ ice age.

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of Sturtian “Snowball Earth” Ice Age (717 million to 661 million years ago) is considered the most extreme icehouse period in Earth’s history. In a new study, geologists from the University of Sydney and the University of Adelaide used plate tectonics modeling to identify the most likely cause of the Staats Ice Age.

Artist’s impression of “Snowball Earth”. Image credit: Oleg Kuznetsov, http://3depix.com / CC BY-SA 4.0.

“Imagine if the Earth almost completely froze over, which is exactly what happened about 700 million years ago,” said lead author Dr. Adriana Dutkiewicz, a researcher at the University of Sydney. .

“The Earth was covered in ice from the poles to the equator, and temperatures plummeted. But what caused this to happen is an open question.”

“We think we have now solved the mystery. Historically, volcanic carbon dioxide emissions have been low, driven by the weathering of large volcanic rock mountains in what is now Canada. It’s a process that absorbs carbon dioxide.”

Named after Charles Sturt, a 19th-century European colonial explorer of central Australia, the Sturtsian Ice Age spanned 717 million to 660 million years, long before dinosaurs and complex plants existed on land. It continued until ten thousand years ago.

“There are many possible causes for the trigger and end of this extreme ice age, but the most mysterious one is why it lasted 57 million years. It’s hard for humans to imagine,” Dr. Dutkiewicz said.

Dr. Dutkiewicz and his colleagues used a plate tectonics model that simultaneously shows the evolution of continents and ocean basins after the breakup of the ancient supercontinent Rodina.

They connected it to a computer model that calculates the outgassing of carbon dioxide from submarine volcanoes along mid-ocean ridges, where plates diverge and new oceanic crust is born.

They soon realized that the beginning of the Starch Ice Age correlated precisely with the lowest ever levels of volcanic carbon dioxide emissions.

Additionally, carbon dioxide flux remained relatively low throughout the ice age.

“At that time, there were no multicellular animals or land plants on Earth,” Dr. Dutkiewicz said.

“Greenhouse gas concentrations in the atmosphere were determined almost entirely by carbon dioxide emitted by volcanoes and by the weathering processes of silicate rocks that consume carbon dioxide.”

“At that time, geology ruled the climate,” said co-author Professor Dietmar Müller, a researcher at the University of Sydney.

“We think the Staats Ice Age began with a double whammy: plate tectonics realigned to minimize volcanic degassing, while at the same time Canada’s continental volcanic belt began to erode, removing carbon dioxide from the atmosphere. Consumed.”

“As a result, atmospheric carbon dioxide has fallen to levels that could begin an ice age. This is estimated to be less than 200 parts per million, less than half of today’s levels.”

The team’s current research raises interesting questions about the long-term future of the planet.

Recent theories suggest that over the next 250 million years, Earth will evolve toward Pangea Ultima, a supercontinent hot enough to wipe out mammals.

However, the Earth is currently on a trajectory where volcanic carbon dioxide emissions decrease as continental collisions increase and plate velocities decrease.

So perhaps Pangea Ultima will snowball again.

“Whatever the future holds, it is important to remember that geological climate changes of the type studied here occur very slowly,” Dr. Dutkiewicz said.

“According to NASA, human-induced climate change is occurring 10 times faster than ever before.”

of study appear in the diary geology.

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Adriana Dutkiewicz other. The period of the Sturtian “Snowball Earth” ice age is associated with unusually low gas emissions at mid-ocean ridges. geology, published online on February 7, 2024. doi: 10.1130/G51669.1

Source: www.sci.news

Seabed trawling is a significant contributor to global CO2 emissions

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In bottom trawling, a weighted net is dragged across the ocean floor.

NarisaFotoSS/Shutterstock

Bottom trawling releases about 340 million tons of carbon dioxide into the atmosphere each year, according to the first study to estimate these emissions. This represents almost 1% of the world's CO2 emissions, but is a major contribution that has been overlooked until now.

Trawling involves dragging a weighted net across the ocean floor to capture bottom-dwelling fish, crustaceans, and shellfish. Although this method of fishing is widely used around the world, it is controversial because the fishing gear damages undersea environments such as cold-water reefs. Some corals are thousands of years old.

“Trawling is a highly destructive fishing method as the nets and weights dragged along the bottom destroy marine habitat, which can take years to rebuild and recover.” he says. Micah Peck from the University of Sussex, UK, was not involved in the study.

It also stirs up sediment, releasing the oxygen needed by microorganisms to break down organic matter into carbon dioxide. Otherwise, these deposits could continue to accumulate for thousands of years, with the organic matter within them preserved by low-oxygen conditions. This means that carbon is effectively trapped.

In 2021, trisha atwood Researchers at Utah State University in Logan combined a study that looked at the amount of carbon dioxide released during trawling with data on the global scale of trawling. global fishing watch.The team concluded that released in large quantities into the seawater.

But the big unanswered question was how much of the CO2 released from the sediments would be emitted into the atmosphere.

“A lot of countries and different institutions started contacting us about that research,” Atwood says. “But they basically said, as long as it just stays in the ocean, we don't really care.”

So the team teamed up with researchers who had developed computer models of ocean circulation. According to these models, about 55 percent of the CO2 released into the water by trawling will be released into the atmosphere after nine years.

“I was surprised that more than half of them came out,” Atwood said. “And it shows up very quickly.”

According to the global carbon budget, the total amount of CO is2 emissions from human activities Increased to 40.9 billion tons Therefore, if the team's estimates are correct, trawling accounts for about 0.8 percent of global emissions. Air and maritime transport: 2.8%.

Conservationists say the discovery strengthens the case for reducing trawling. “Many marine habitats are trawled at least once a year, resuspending sediment and releasing carbon into the atmosphere,” Peck said. “Banning destructive fishing practices is key to the future of healthy marine ecosystems and the marine ecosystems that depend on them.”

“Measures to reduce the carbon impact of trawling gear are urgently needed, but they must be done as part of a just transition,” said Gareth Cunningham. marine conservation association, is calling for a ban on trawling in so-called marine reserves around the UK. “There is no one-size-fits-all model and solutions will vary by location.”

However, not all researchers are satisfied with this number. “I'm very skeptical of their estimates,” he says. Jan Gerd Hiddink At Bangor University, UK.

Hiddink believes that much of the carbon that reaches the ocean floor is in forms that are difficult to decompose, such as bones, and that carbon is not released even when sediments are disturbed.Atwood's team is probably overestimate emissions Up to 1000x, he claims.

Atwood said this estimate is based on actual measurements. “We conducted a study to measure the amount of carbon dioxide emitted from the ocean floor in areas where trawling takes place,” she says.

She says that the amount of carbon dioxide emitted could be more or less than these studies suggest, although there is a lot of uncertainty because so few such studies have been done. says.

Mr Atwood says the government needs to start calculating the carbon footprint of trawling. “This allows us to decide whether emissions should be regulated,” she says.

What is clear is that Global Fishing Watch's trawling data is based on boats sending automatic signals to satellites, and many trawlers do not have such systems, so the extent of trawling remains under-studied. That means it's bigger than expected.

“We know that we underestimate the global scale and perhaps the intensity of trawling,” Atwood says.

The trawling industry also has an opportunity to sell carbon credits in exchange for reduced emissions, she says. “If you were to put a price on it in today's independent market, it's a $100 million market.”

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Source: www.newscientist.com

The reduction of US emissions was minimal last year

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The United States showed a promising decline in carbon emissions in 2023, despite economic growth, indicating a move towards a more sustainable future. Greenhouse gas emissions dropped by approximately 1.9% according to Rhodium Group’s preliminary analysis, tracking progress towards U.S. climate goals. The economy saw a growth of about 2.4%.

Ben King, an associate director at Rhodium Group, expressed that while this slow reduction in emissions shows progress, it also highlights the need for greater ambition in government and industry to achieve America’s climate goals.

The Biden administration aims to reduce emissions by 50% to 52% by 2030, an ambitious target considering that emissions are currently 17% lower than in 2005, following fluctuations in recent years.

King emphasized the necessity of tripling the 2% reduction in emissions achieved in the past year annually until 2030 to meet the Paris goals, which set limits on global warming to below 2 degrees Celsius. He mentioned that these goals require significant global leadership and effort from governments worldwide, as the pace of efforts to limit global warming remains insufficient according to a November report from the Stockholm Environmental Institute.

While certain sectors like power and buildings contributed to the emissions decline in 2023, others like transportation and industry saw an increase. Efforts to electrify these areas through policies like the Controlled Inflation Act are beginning to take effect, with record-high electric vehicle sales in 2023.

However, King noted that broader climate action may depend on the outcome of the 2024 presidential election.

“To do something more ambitious than just stay on track, we need an executive branch that is committed to climate action and a Congress that stands out from the crowd. We don’t have high hopes for large-scale, comprehensive climate action for 2024, but we will need to see some progress after 2025,” King concluded.

Source: www.nbcnews.com

Greenhouse Gas Emissions Expected to Decrease Starting in 2024

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Carbon emissions from fossil fuels could finally start declining in 2024

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Emissions of greenhouse gases that cause global warming have been on the rise since the Industrial Revolution, and 2023 looks set to be no different. According to him, this year emissions from fossil fuel combustion increased by more than 1% compared to 2022. global carbon budget Edited by Pierre Friedlingstein and his colleagues from the University of Exeter, UK.

However, in 2024, these emissions could begin to decline for the first time, largely due to unprecedented circumstances.

Source: www.newscientist.com

Spiral Galaxies Emitting “Forbidden” Emissions

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This image from the Hubble Space Telescope shows MCG-01-24-014. It is a spiral galaxy with an active galactic nucleus located 275 million light-years away and is classified as a Type 2 Seyfert galaxy. Seyfert galaxies are often closer to Earth than quasars and are distinguished by their unique spectra, especially the “forbidden” emission of type 2 Seyferts.Credit: ESA/Hubble & NASA, C. Kilpatrick

this swirl hubble space telescope This image shows a bright spiral galaxy known as MCG-01-24-014, located about 275 million light-years from Earth. MCG-01-24-014 is called an active galaxy because, in addition to being a well-defined spiral galaxy, it has a very energetic core known as an active galactic nucleus (AGN) .

More specifically, it is classified as a Type 2 Seyfert galaxy. Seyfert galaxies are home to one of the most common subclasses of AGNs, along with quasars. The exact classification of AGNs is nuanced, but Seyfert galaxies tend to be relatively nearby where the host galaxy can be clearly detected alongside the central AGN, whereas quasars are always very distant AGNs and their Its incredible brightness exceeds that of its host galaxy.

Understanding Seyfert galaxies and their spectra

Both Seyfert galaxies and quasars have further subclasses. For Seyfert galaxies, the main subcategories are type 1 and type 2. They are distinguished from each other by their spectra (the pattern created when light is split into its constituent wavelengths). The spectral lines emitted by Type 2 Seyfert galaxies are particularly associated with certain so-called “forbidden” emissions.

To understand why synchrotron radiation from galaxies is thought to be forbidden, it helps to understand why the spectrum exists in the first place. Spectra look the way they do because certain atoms and molecules absorb and emit light very reliably at very specific wavelengths.

The reason is quantum physics. Electrons (tiny particles orbiting the nucleus of atoms and molecules) can only exist at very specific energies, so electrons can only lose or gain very specific amounts of energy. These very specific amounts of energy correspond to specific wavelengths of light that are absorbed or emitted.

Discharge prohibition phenomenon

Forbidden emission lines are therefore spectral emission lines that should not exist according to certain rules of quantum physics. However, quantum physics is complex, and some of the rules used to predict quantum physics use assumptions that are appropriate for laboratory conditions on Earth.

Under these rules, this release is “prohibited” and ignored because it is unlikely. But in space, in the midst of incredibly energetic galactic nuclei, those assumptions no longer apply, and “forbidden” light has a chance to shine towards us.

Source: scitechdaily.com