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River deltas are ‘drowning’, threatening hundreds of millions of people

The world’s river deltas take up less than 0.5% of the global land area, but they are home to hundreds of millions of people. Many live in major fast-growing cities such as Kolkata in the Ganges delta, Bangkok in the Chao Phraya delta, or Shanghai, one of dozens of large cities in the Yangtze delta region.

With fertile soils and easy access to the coast, deltas are critical hotspots of food production. Vietnam’s Mekong delta alone supplies almost 20% of the world’s rice. They also host unique ecosystems such as the Sundarbans in Bangladesh and India, the largest mangrove forest in the world.

But many of the world’s deltas are now facing an existential crisis. Sea levels are rising as a result of climate change, while deltas are themselves sinking, and together this means the relative sea level is rising extra fast.

Deltas are built from sediments that are carried downstream by rivers and eventually deposited where the river meets the sea. As these sediments compact under their own weight, deltas naturally sink. Where left undisturbed, the supply of new river sediment can compensate for the subsidence and help to maintain the delta surface above sea level.

But deltas are now subsiding much faster than they would do naturally. That’s thanks to groundwater being pumped (or “mined”) from aquifers underneath them and used to irrigate crops and provide water for rapidly growing cities.

In these circumstances, only the continued deposition of sediment on deltas can keep them from “drowning”. We therefore wanted to find out whether supplies of river sediments would be affected by future environmental changes.

To address this question, we used a computer model to project changes in the flows of sediment to almost 50 major deltas worldwide. We used the model to explore the impact of various environmental changes, including climate change, population growth, increases in wealth and the construction of dams. Our results are published in the journal Environmental Research Letters.

Rice farmers in the Mekong Delta, Vietnam.
Phuong D. Nguyen / shutterstock

We found that most of the world’s major deltas will receive less river sediment by the end of the century, regardless of the environmental change scenario. On average, we projected a 38% decrease. Our results suggest that many deltas – already significantly stressed – will become sediment starved, further compounding the risks of rising relative sea levels.

Some of the most severe reductions will be found in major Asian deltas such as the Ganges (81% less sediment) and the Mekong (77%). This is particularly concerning because these deltas are among the largest and most densely populated in the world.

We found that climate change will generally drive a small increase in the flows of sediments as, among other factors, warmer temperatures lead to increased precipitation and more soil is washed into rivers. But in many deltas this modest uptick will be more than offset by dams (which trap river sediments) and improved soil conservation practices as societies become wealthier. The Aswan Dam on the River Nile in Egypt or the Hoover Dam on the Colorado River in the US are among the dams that have already starved their downstream deltas of sediment.

Bad news for a river delta.
Tupungato / shutterstock

Better management of river sediment is vital to improve the outlook for the world’s deltas. International cooperation will be essential in deltas such as the Mekong and Ganges which are supplied by large rivers that drain many countries. For dams specifically, comprehensive environmental risk assessments that fully cost the consequences for downstream regions are required so that plans can be changed or scrapped. For those dams that are to be built in the coming decades, their design must accommodate transport of sediment downstream.

For authorities within deltas, faced with managing a dwindling supply of river sediment, new approaches are needed to better manage this precious declining resource. Flood embankments prevent sediment reaching delta plains and may need to be breached, as is being explored in the Ganges delta. Additionally, the removal of sand from rivers for construction materials, which is pervasive in many deltas around the world, must be better managed.

Ultimately, difficult decisions need to be made about development priorities between countries upstream of deltas and those including the deltas themselves, and there will be trade-offs to be made between hydropower, agricultural practices and delta sustainability.

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Planet Earth

In a Historic Move, Vote to Federally Legalize Marijuana to Take Place in Congress—This Week

Matt Agorist, The Free Thought Project
Waking Times

Washington, D.C. — As countless individuals across the land of the free are rotting in cages for possessing a plant deemed illegal by the government, a historical bill is making its way through Congress that could change everything. A congressional committee reportedly plans to vote on a bill this week that would end the federal prohibition of marijuana.

The Marijuana Opportunity Reinvestment and Expungement (MORE) Act, sponsored by House Judiciary Committee Chairman Jerrold Nadler (D-NY), would remove cannabis from the Controlled Substances Act (CSA). But that is not all. It would go one step further and seek to undo the horrific damage caused by the state’s war on this plant.

According to the legislation, the act would:

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Planet Earth

More than 5,000 birds die suddenly from a mysterious death

Wildlife experts are trying to understand the cause of the massive deaths of birds on the shores of Sambar Lake – India’s largest salt lake. 

Sambar Lake is located 80 km southwest of Jaipur (Jaipur). It covers an area of ​​190 to 230 square kilometers, depending on the season.Many migratory birds, marsh birds, gather at the lake shores at certain times of the year (Wader), flamingos, storks, ducks and dozens of different species. But, about two weeks ago, locals often began to see carcasses of birds.

To date, more than 2,000 dead birds have been found on the coastal stretch, about 12 km wide, and more than 5,000 on unofficial ones. According to locals, the former lively shores of the lake have now become a bird cemetery, among which there are rare species.

According to one resident, there are so many bird carcasses in some places that they look like a large pile of manure from afar!

The cause of the death of the birds has not yet been clarified. They were not killed with a firearm or other weapon. No wounds or signs of disease were found on their bodies. Large piles of dead birds in one place indicate that they died suddenly, exactly at the same place they were in groups overnight.

Local ornithologist Abhinav Vaishnav tells reporters:

“We have never seen anything like this here. About 5,000 birds have died here from a mysterious death …! “

Environmentalists and animal rights activists have voiced several versions of the mass deaths of birds – from a severe hailstorm to pesticides used in nearby agricultural fields. There is also a version for mass infection.

But for the locals, all of these versions seem like a pitiful attempt to put what’s going wrong. For them, such bird death is a mysterious and abnormal phenomenon.

Ramesh Chandra Road says:

“I have not seen anything like this in my 40 years of service in the forestry department. At first, I also thought it might be due to hail, but here every year there are strong hail storms. I also don’t believe in the pesticide version. No trace of them was found in the water samples. “

Some of the dead bird carcasses were sent for analysis to a laboratory in Bopal.

The locals gather the rest of the carcasses in piles, then bury them in deep holes near the beach.

Expect to be informed if further information is available on what is happening.

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Planet Earth

Former Apollo Astronaut Pushes for International Commitment to Protect Earth from Killer Asteroids

There are few astronauts more respected and remembered than those who served on the Apollo missions – thirty-two military jet and test pilots who made or died training for the three-man Apollo missions that eventually sent humans to the Moon and back. When they have spoken – about space travel, the Moon, future missions, UFOs and other subjects – the world has listened. Rusty Schweickart, the Lunar Module pilot on Apollo 9, spoke recently about the need for an international commitment to protect Earth from killer asteroids. As usual, his comments are worth listening to.

“During the Apollo 9 mission we were dark-adapted for an experiment, looking at the spectacular night-time Earth, watching weather fronts, thunder storms and lightning, a really great sight out of the window. Then, who knows who said it first, but one of us said they saw a little flash down there and someone else says ‘yeah, I saw it too,’ but you wouldn’t have mentioned it if the first person hadn’t said it. And then we realized: that was a meteor, burning up below us. Wow, below us – which meant it came down through our altitude!”

A close encounter of the worst kind – an asteroid impact in space – instead became an experience that forever influenced Russell “Rusty” Schweickart. When he was selected in 1963, Rusty Schweickart was a unique member of NASA Astronaut Group 3 – the fourteen astronauts selected by NASA to succeed the two-man Gemini missions in the three-man Apollo flights that would eventually lead to a walk on the Moon. Those names are well-known to the public today — Collins, Cunningham, Gordon, Aldrin, Cernan, Chaffee to list a few – but back then they were better known in the military as fighter pilots and test pilots. Schweickart was an experienced Air Force pilot, but he was also a research scientist at the Experimental Astronomy Laboratory at the Massachusetts Institute of Technology in the fields of upper atmospheric physics, star tracking and stabilization of stellar images.

Astronaut Group Three announced on October 18, 1963. They are (seated, left to right) Edwin E. Aldrin Jr., William A. Anders, Charles A. Bassett II, Alan L. Bean, Eugene A. Cernan, and Roger B. Chaffee. Standing (left to right) are Michael Collins, R. Walter Cunningham, Donn F. Eisele, Theodore C. Freeman, Richard F. Gordon Jr., Russell L. Schweickart, David R. Scott and Clifton C. Williams Jr. (Credit: NASA)

The 1969 flight of Apollo 9 was the first flight of the lunar module, piloted by Schweickart, and the first spacewalk of the Apollo missions, also by Schweickart. During a recent ESA Open Day at the European Space Agency’s ESTEC technical center in Noordwijk, The Netherlands, the former astronaut heard about the latest plans to stop asteroids like the one the Apollo 9 crew encountered before they destructively impact Earth. In 2022, NASA’s Double Asteroid Redirect Test will hit the smaller member of the Didymos binary asteroids. Then, if approved this month by Europe’s space ministers, the ESA’s Hera mission will perform a close-up survey of the asteroid and crater after impact. Schweickart says he likes the idea of a multi-spacecraft mission rather than a single asteroid-seeking rocket.

“And one of the key unknowns of the kinetic impactor technique is a term we call ‘beta’ – when we hit the asteroid, how much stuff is going to come flying off? If it’s moving at greater than escape velocity, then that adds to the momentum shifting the orbit, boosting the technique’s effectiveness. That factor depends on the asteroid’s composition and structure, and we need a close-up look to find out what that is.”

In 2002, Schweickart helped found the B612 Foundation (named for the planetoid in The Little Prince), whose primary mission is “protecting the Earth from asteroid impacts and informing and forwarding world-wide decision-making on planetary defense issues.” Since asteroids can hit anywhere on Earth, Schweickart has long advocated international cooperation in both deflecting space rocks and in determining which ones to hit. He sees the NASA/ESA tandem as the first example of this cooperation. Unfortunately, we’re barely into asteroid defection business and have no idea what an impact will do – it could actually push the space rock into a higher likelihood of impact.

“In that case the observer spacecraft would have another job to do – to switch to gravity tractor mode, using altimeters and ion engines to stay just away from the asteroid, and nudge its orbit enough to miss the keyhole as well as the planet.”

Astronaut Rusty Schweickart (Credit: NASA)

Rusty Schweickart makes it sound so easy and doable, but the former Apollo and Skylab astronaut knows the dangers of space. He was the backup pilot for Roger B. Chaffee on Apollo 1, which ended in the tragic deaths of the crew members in a ground test accident. He also knows how expensive a worldwide asteroid deflection system would be and how difficult it is to get nations to agree on anything, let alone unseen dangers from outer space. That’s why he stays involved in both the technology and the politics of space.

At 84, Rusty Schweickart is still influenced by that near-impact experience on Apollo 9. For that, we should all be grateful.

Source: Mysterious Universe

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