Environment

Climate change and tsunamis that will come from Antarctica

Published

1 year ago

30/05/2023

pouyan

Climate change and tsunamis that will come from Antarctica. A new study warns that climate change could trigger giant, deadly tsunamis from Antarctica, as sediment slippage beneath the Antarctic seafloor could trigger these massive tsunamis as oceans warm.

Climate change and tsunamis that will come from Antarctica

Climate change could trigger giant tsunamis in the Southern Ocean by triggering underwater landslides in Antarctica, a new study warns. Antarctica is a continent at the south pole of the earth. This continent is the coldest place on earth and more or less its entire surface is covered with ice.

Antarctica is the fifth largest continent on Earth after Asia, Africa, North America, and South America, but it has the least human population among all continents. It also has the highest average height, the lowest average humidity, and the lowest average temperature among all the continents of the world.

More than 80% of the freshwater reserves of the planet are located in Antarctica. In this continent, nearly 30 countries have nearly 70 research bases, of which 40 are annual or permanent bases and 30 are summer bases.

Now, by drilling in sediment cores hundreds of meters below the seabed in Antarctica, scientists found that during previous periods of global warming (3 million years ago and 15 million years ago), loose sedimentary layers were formed and slid to send huge tsunami waves to the coast of South America, New Zealand.

As climate change warms the oceans, researchers think it’s possible that these tsunamis will occur again.

In a statement, Jenny Giles, a lecturer in hydrography and ocean exploration at the University of Plymouth in the UK, said in a statement: “Undersea landslides are a major hazard with the potential to cause tsunamis that could lead to loss of life.

” He added: “Our findings show how we need to urgently increase our understanding of how global climate change affects the stability of these regions and the potential for future tsunamis.”

For the first time in 2017, researchers found evidence of ancient Antarctic landslides in the eastern Ross Sea. Beneath these landslides are layers of weak sediments filled with fossilized marine organisms called phytoplankton.

Scientists returned to this area in 2018 and drilled deep into the seabed to extract sediment cores. These excavations are done by sinking long and thin cylinders into the earth’s crust, which reveal the geological history of the region layer by layer.

By analyzing these sediment cores, the scientists found that the weak sedimentary layers formed during two periods, one about three million years ago during the warmth of the mid-Pliocene period and the other about 15 million years ago during the favorable climate of the Miocene period.

During these periods, the waters around Antarctica were three degrees Celsius warmer than today, which led to an explosion of algae populations that, after dying, filled the seabed with rich, slippery sediment, making the region prone to landslides.

During the subsequent cold climate and Ice Age, these slip layers were covered by thick layers of sand, said Robert McKay, director of the Antarctic Research Center at Victoria University of Wellington and chief scientist of the International Ocean Exploration Program Expedition 374, which extracted sediment cores in 2018. The bulk was covered by glaciers and icebergs.

The exact trigger of past underwater landslides in the region is not known for certain, but researchers have found the most likely cause to be the melting of glacier ice due to global warming. The end of Earth’s periodic ice ages caused the ice sheets to shrink and retreat, lightening the load on Earth’s tectonic plates and pushing them back up in a process called isostatic rebound.

After the formation of enough weak sedimentary layers, the continental growth of Antarctica triggered earthquakes that caused the coarse sand above the sliding layers to spill out from the edge of the continental shelf, which caused landslides and tsunamis.

The scale and size of ancient ocean waves are unknown, but scientists point to two undersea thrusts that generated massive tsunamis and caused significant loss of life. The first was the Grand Banks tsunami in 1929, which created waves 13 meters high and killed about 28 people on the coast of Newfoundland, Canada, and the second tsunami in Papua New Guinea in 1998, which created waves 15 meters high and killed 2,200 people.

Considering that many layers of sediment are buried under the Antarctic bed and the glaciers above the water are also slowly melting, the researchers warn that if their melting really caused tsunamis in the past, landslides and tsunamis in the future may occur again.

Those same layers still exist on the outer continental shelf, says McKay. So it’s a starting point for more of these thrusts to occur, but the big question is whether the trigger for these events is still ongoing.

He added: “We consider isostatic rebound as a logical potential driver, but it could be a random failure or climate change in ocean currents eroding sediment at key locations on the continental shelf that could cause this to happen.” These are things we can use computer models to evaluate in future studies.

This study was recently published in the journal Nature Communications.

Environment

If the dinosaurs did not become extinct, what would our world be like today?

Published

2 months ago

26/07/2024

pouyan

Have you ever wondered what our world would be like if the dinosaurs had not gone extinct? Join us in this article to answer this question.

If the dinosaurs did not become extinct, what would our world be like today?

Sixty-six million years ago, an asteroid with the power of 10 billion atomic bombs hit Earth and changed the course of evolution forever. The sky became dark and the photosynthesis of plants stopped. First, the plants and then the animals that fed on them were destroyed, the food chain collapsed and more than 90% of the species disappeared. As the dust settled in the Earth’s atmosphere, all dinosaurs became extinct except for a group of birds. But this catastrophic event paved the way for human evolution. The surviving mammals, especially the early primates, multiplied, and then humans evolved.

Strangely, Odysseus lived about 66 million years ago and was one of the last dinosaurs on earth.

Now suppose that the said asteroid had not hit the earth and the dinosaurs would have been saved. Imagine evolved raptors flying their flag on the moon. Dinosaur scientists discover relativity or discussing a hypothetical world dominated by mammals.

This hypothesis may seem like a science fiction story, but it contains deep philosophical questions about evolution. Did humans evolve purely by chance, or was the evolution of intelligent tool-using creatures inevitable?

Brains, tools, language, and large social groups have made humans the dominant species on the planet. Eight billion wise humans (homosapiens) live on the seven continents of the earth. According to the same weight, the number of humans is more than all the wild animals in the world. Humans have changed half of the earth’s land to feed themselves. In the 1980s, paleontologist Dale Russell proposed a thought experiment in which a carnivorous dinosaur evolved into an intelligent, tool-using creature. This dinosauroid has a big brain and walks on two legs.

Dinosauroid model

This hypothesis is not impossible but unlikely. The biology of an animal limits its evolutionary path. Your starting point determines your ending point. If you get kicked out of college, you can’t become a brain surgeon, a lawyer, or a NASA rocket scientist; But you may become an artist, actor, or entrepreneur. The paths we take in life open doors and close others. This also applies to evolution.

For example, consider the dimensions of dinosaurs. Sauropod dinosaurs, such as Brontosaurus and its relatives, weighed 30-50 tons and grew up to 30 meters in length during the Jurassic period. Their weight was ten times the weight of current elephants and their length was as long as a blue whale. This evolution has been seen in several groups such as Diplodocidae, Brachiosaurdiea, Turiasaurdiea, Mamenchisaurdiae, and Titanosauria.

Giant dinosaurs and mammals through time

This evolutionary process was also repeated in different continents at different times and in diverse climates from deserts to rainforests, But the other dinosaurs that lived in these environments did not become gigantic giants. The common point of all the above dinosaurs was that they were all sauropods. Anatomical features of sauropods, such as lungs, hollow bones with a high strength-to-weight ratio, metabolism, or all of these, enhanced their evolutionary potential. In this way, these dinosaurs grew in an unprecedented way.

On the other hand, carnivorous dinosaurs evolved into multi-ton hunters with huge ten-meter bodies. During more than 100 million years, megalosaurids, allosaurids, carcharodontosaurids, neovenatorids, and finally tyrannosaurs evolved into giant apex predators.

Brain size relative to body mass in dinosaurs, mammals, and birds

Dinosaurs had huge bodies, But they did not have a big brains. In fact, dinosaur brains rarely grew over time. Jurassic dinosaurs such as Allosaurus, Stegosaurus, and Brachiosaurus had small brains. 80 million years later, in the late Cretaceous period, tyrannosaurus and duck-billed dinosaurs evolved with larger brains; But the weight of the T-Rex brain, despite its gigantic body, was only 400 grams. The brain of Volareceptor was only 15 grams. Meanwhile, the average weight of the human brain reaches 1.3 kg.

Dinosaurs entered a new era over time. Small herbivores became more common and bird biodiversity increased. Later long-legged species evolved. It also seems that dinosaurs had a complex social life. They began a herd life and evolved with heavy horns for fighting. However, dinosaurs seem to have replicated themselves, usually evolving into giant herbivores and small-brained carnivores.

In the span of 100 million years of the history of dinosaurs, no trace of progress can be seen in them. Giant long-necked herbivores and massive tyrannosaur-like predators recurred during this interval. Maybe dinosaurs’ brains got a little bigger over time, but there is little evidence for their evolution into geniuses. It is even unlikely that mammals would have banished them. Dinosaurs were one of the dominant species in their environment until the asteroid hit.

However, mammals had different limitations. They never evolved into giant herbivores and carnivores. Rather, they repeatedly evolved with larger brains. Examples of large brains (human brain size or larger) are seen in orcas, sperm whales, baleen whales, elephants, leopards, and monkeys.

Golden lion tamarin, South American monkey

Today, few descendants of dinosaurs (birds such as crows and parrots) have complex brains. They can use tools, talk, and count; But mammals such as monkeys, elephants, and dolphins evolved with larger brains and more complex behaviors; So can we say that the elimination of dinosaurs ensured the evolution of mammalian intelligence? maybe not

The starting point can determine the ending point, but it cannot guarantee it. Steve Jobs, Bill Gates, and Mark Zuckerberg were all expelled from the university; But not every expulsion from the university leads to this fate. Even if you start at the right point, you need opportunity and luck to continue. The evolutionary history of primates shows that our evolution was not inevitable. African primates evolved in the form of monkeys with big brains in a span of seven million years and ended up with modern humans, But the evolution of primates took a different path in other places.

When monkeys arrived in the Americas about 35 million years ago, they evolved into other monkey species, and primates arrived in North America at least three separate times, 55 million, 50 million, and 20 million years ago. However, they did not become the species that made weapons and smartphones. Rather, they became extinct for reasons we do not know.

Only in Africa did evolution take a unique path. Perhaps something special about the fauna and flora or the geography of Africa caused apes to take a different evolutionary path and become tool-using primates with large bodies and brains. Even with the extinction of the dinosaurs, human evolution required the right combination of opportunity and luck.

Environment

Launching a satellite to investigate the role of clouds in changing the Earth’s climate

Published

4 months ago

29/05/2024

pouyan

The satellite for investigating the role of clouds in the Earth’s climate, which is a joint mission between the European Space Agency and the Japan Aerospace Exploration Agency, was launched into the earth’s orbit by the Falcon 9 rocket of the SpaceX company.

Launching a satellite to investigate the role of clouds in changing the Earth’s climate

May 28 was a busy day for SpaceX.

According to Space, a SpaceX Falcon 9 rocket launched at 6:20 pm EST with the Cloud-Aerosol and Earth Radiation Probe or EarthCARE satellite from the base. Vandenberg Space Force took off in California.

The Earthcore satellite is a joint mission between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). According to the European Space Agency, the mission will investigate the role of clouds and aerosols in reflecting sunlight into space and trapping infrared radiation emitted from the Earth’s surface.

The European Space Agency added: “Learning about the balance of solar radiation on our planet is very important to address climate problems, and it can only be done from space.”

This mission operates at the same orbital altitude as the International Space Station, but with a different program. Arthkar satellite will travel in a sun-synchronous polar orbit. The satellite will look at particles in clouds and aerosol molecules in the atmosphere to see how they interact with precipitation and how fast they fall to our planet.

The officials of the European Space Agency said: “Earthker” satellite will record the distribution of water droplets and ice crystals and how they move in the clouds. Inherent data will improve the accuracy of models of cloud development and their behavior, composition, and interaction with aerosols. Also, they improve future climate models and support numerical weather forecasting.

This satellite has four types of scientific equipment, which include an atmospheric lidar for detailed investigation of clouds and cloud and aerosol characteristics, a cloud-characterizing radar for learning about the movement dynamics and structure of clouds, a broadband radiometer for investigating solar radiation and infrared radiation, and a Multispectral imager.

Arthkar satellite was designed for the first time in 2004 and was designed and built by Airbus and 75 subsidiary companies.

European Space Agency Director General Josef Aschbacher said: I am relieved that the launch was successful. I am very happy for all the people who have worked on this project for decades. I know how much blood, sweat, and tears have gone into this mission to get to where it is today.

Simonetta Cheli, the current director of the European Space Agency’s Earth observation programs, believes that although this satellite was first designed 20 years ago, it appears more relevant today than imagined.

“Earthcare’s mission showcases the relevance of environmental sustainability and shows that climate, in general, is something that is at the top of our member countries’ agenda, both in terms of support programs and participation in projects, as well as the continuation of existing data,” Chelley said. We found that last year was the hottest year on record. Also, all months of 2024 were the warmest on record.

He added: If we want to evaluate the sun’s radiation towards the earth and examine the effect of clouds in terms of cooling, it is necessary to have accurate and innovative information about clouds, aerosols, and precipitation. All of these issues can be explored in more depth today with the data obtained from the four EarthKer satellite instruments.

After launch, Earthcore is expected to undergo a six-month commissioning period, and its initial mission is expected to last at least three years.

This was the second launch of May 28 for SpaceX. The company launched a group of its Starlink internet satellites into Earth orbit this morning from Cape Canaveral Space Force Base in Florida.

According to the SpaceX mission description, the Falcon 9 first-stage booster that was flown in this mission has reached space seven times so far. Among its previous missions, was the launch of the “Dragon” manned capsule in the “Crew-7” mission to the “International Space Station”, the cargo flight of “CRS-29” to the International Space Station. And there were two Starlink missions.

The first stage of the “Falcon 9” rocket was placed on the landing platform shortly after the launch of the “Arthkar” satellite.

The mission booster successfully landed at Vandenberg Space Force Base on May 28, approximately eight minutes after launch. About 2.5 minutes later, the Falcon 9 upper stage placed the Erthkar satellite into orbit as planned.

Environment

How is the dark extinction quietly wiping out life on Earth?

Published

4 months ago

27/05/2024

pouyan

How is the dark extinction quietly wiping out life on Earth? The species that we don’t even know exist are gradually disappearing from the earth and we need to try to deal with this.

How is the dark extinction quietly wiping out life on Earth?

One of the creatures on earth is gone forever, but we don’t know what it is. Like trees falling to the ground in the silence of an empty forest, entire species disappear without anyone witnessing or even realizing their existence. This phenomenon, known as the “dark extinction,” severely undermines our ability to catalog the world’s biodiversity or understand human impact on the web of life on Earth.

What is dark extinction?

The term dark extinction refers to the extinction of species that we don’t even know exist. In other words, the term is used for life forms that become extinct before we can discover or scientifically describe them. These creatures do not find their place in the classification system of living things on Earth.

Typically, the label dark extinction is applied to those plants and animals that have disappeared as a direct result of human-induced habitat changes. Therefore, undiscovered dinosaurs do not count as the dark extinction. However, unknown extinctions are not limited to the modern age and also go back to prehistoric times, when our ancestors first occupied the world’s continents and hunted some of the large animals to extinction.

The term dark extinction refers to the extinction of species that we don’t even know exist

Many human-caused extinctions of large animals are well represented in the fossil record, however, there are probably a few large animal extinctions in the past ten thousand years that we are not aware of.

A major wave of human-caused extinction began around the 14th century across the planet. It was at this time that advances in European maritime technology allowed Westerners to go to remote oceanic islands and bring rats, cats, and other non-native mammals to new lands and destroy native life. Since this period was before the classification of animals at the beginning of the 19th century, many species that disappeared during this period were not scientifically described or recorded in any catalog, meaning that we do not know how many species were lost.

Even since the beginning of the classification period, an unknown number of species have disappeared before anyone had a chance to record their existence. Many of these life forms disappeared without a trace, and others left behind fossils that were discovered after the extinction or have yet to be discovered.

“Great unknowns are things that went extinct before the science of taxonomy began,” Dr. Alexander Lees of Manchester Metropolitan University told IFL Science.

To fill in all the blanks, we’d have to find the remains of any extinct species, though that’s highly unlikely. For many species we have to resort to fossils. Thus, species that fossilize well may have a better record of historical extinctions. For example, birds do not fossilize as well as mammals, and most invertebrates are rare in the fossil record. In other words, we don’t really know how many dark extinctions have occurred throughout human history, although scientists have speculated and the numbers are staggering.

How many species are extinct?

The official IUCN list of extinct flora and fauna currently includes only 909 species. However, this figure is an understatement because it does not account for unknown extinctions or undiscovered species.

Researchers have attempted to develop statistical models to calculate the number of dark extinctions that accompanied these confirmed extinctions. For example, the results of a study have shown that about 1430 species of birds may have disappeared due to human activities, while another study shows that 60% of the total extinctions in some groups of animals may be undiscovered species. Another paper concluded that we may have lost 260,000 species of invertebrates over the past 500 years.

We do not know that there have been several dark extinctions throughout human history

All of the above estimates are very approximate and mostly guesswork, in the sense that we don’t really have any exact numbers to represent all the creatures that disappeared from the face of the earth.

While there have been theoretical studies of dark extinctions, every now and then scientists find actual physical evidence for the phenomenon, and most of them show how wrong our numerical estimates have been. For example, in 2013 a lineage of extinct land snails was discovered in French Polynesia, increasing the total number of confirmed mollusk extinctions by about two percent.

Given that most estimates of dark extinction are based on extrapolations of known extinctions, such findings can have a significant impact on statistical modeling.

Each newly confirmed historical extinction opens up endless possibilities for the loss of companion species that may have been associated with the extinct species, Lee explains. On the other hand, while it may be easy to identify large ancient animals in the fossil record when it comes to the parasites that lived in the bodies of these species, as well as the creatures that consumed their feces, we realize how much we know about We are unaware of the species that have been lost.

How can we prevent the dark extinction?

Extinction is an integral part of the process of natural selection, and even without the help of humans, the world is thought to lose about one species per million each year, known as the background extinction rate.

Current estimates suggest that the world is losing species thousands of times faster than the background extinction rate, leading to the suggestion that we are in the midst of the planet’s sixth mass extinction. Therefore, it is clear that we have not been successful in protecting Earth’s biodiversity, and if we are to reverse this trend, we need major investments in habitat protection now.

Nowhere on Earth is the condition of species destruction more urgent than in the Brazilian Atlas Forest; Where there is the highest abundance of endangered vertebrates in the Americas. This forest, which once covered 1.2 million square kilometers of land, is now reduced to small patches that cannot help sustain the species’ population. “A pair of species might live in the same patch of forest, but there’s no genetic sharing between the patches, and if one of those mojowats is lost, we’ll lose that species,” Liz explains.

86% of terrestrial organisms and 91% of marine organisms have not yet been officially discovered

The problem is so severe that Lees believes many of the region’s threatened species are unlikely to survive in captivity without breeding programs. However, these efforts will be fruitless if there is no immediate plan to rehabilitate forest patches create connections between them, and increase the size of those patches.

Out-of-habitat breeding and propagation programs are designed to save known species but do not directly contribute to mitigating the dark extinction crisis. However, by restoring habitats, we can indirectly bring many undiscovered species back from the brink of extinction.

If we have a more complete list of the world’s inhabitants, the dark extinction will no longer make sense. We may not be able to prevent the extinction of many of these species, but if we describe them all, at least we know what we are missing.

There are thought to be about 8.7 million animal species on Earth, and in more than two centuries of taxonomy, we have described only about 1.2 million of them. According to some calculations, 86% of all terrestrial organisms and 91% of organisms that live in the ocean have not yet been officially discovered.

It is clear that we need to discover the diversity of life, but the pace of work is slow and the science of taxonomy is no longer very popular. “We want to catalog Earth’s biodiversity before it goes extinct, but it’s really slow because there’s not a lot of funding going into taxonomy,” says Lees. The more organisms we identify, the fewer extinctions will fall into the dark category. “You will never be able to find and describe all the creatures, but we hope to reach the target above ten percent.”