Global warming: From the Himalayas to the Arctic, the melting of glaciers is accelerating

WEATHER Glaciers around the world lost 267 billion tonnes of ice on average per year between 2000 and 2019, study finds

Now contributing to more than 20% of the rise in sea level, the melting of the planet’s glaciers , caused by global warming , has accelerated further over the past twenty years, according to a study published on Wednesday.

While the Earth has already gained more than 1 ° C since the start of the pre-industrial era, glaciers, from the Himalayas to the Andes via the Alps, have already been on a slimming diet since the middle of the 20th century.

A first complete mapping of glaciers

But only a few hundred of the planet’s 220,000 glaciers – excluding the Greenland and Antarctic ice caps – are monitored in situ. “There are many regions where we did not know how the glaciers evolved,” explains Romain Hugonnet, lead author of the study, published in Nature . Thanks to half a million satellite images, « the first comprehensive mapping of glacier thinning in the world » concludes that « all glaciers are melting », with a few exceptions, continues the researcher from ETH University in Zurich and the University of Toulouse. The planet’s glaciers lost an average of 267 billion tonnes of ice per year between 2000 and 2019, according to the study.

Enough to completely submerge Switzerland under six meters of water each year, comments ETH Zurich in a press release. And the melting has greatly accelerated: from 227 billion tonnes per year on average between 2000 and 2004 to 298 billion tonnes per year between 2015 and 2019. “Excluding the areas on the outskirts of Greenland and Antarctica, therefore by keeping 70% of the planet’s glaciers, we go in twenty years from an average thinning of about a third of a meter per year to two thirds of a meter per year ”, underlines Romain Hugonnet. “In twenty years, we have doubled this speed of thinning. It is very worrying ”.

Those of Alaska, the Alps and Iceland in peril

The glaciers of Alaska, the Alps and Iceland are among those that have shrunk the fastest. The general conclusions of the study are in line with those of the UN climate experts (IPCC), which however included very large margins of uncertainty. « Ours has an uncertainty reduced by a factor of 10 », assures Romain Hugonnet. In particular concerning the impact on the rise in sea level. This melting has contributed to 21% of this rise since the beginning of the century, or 0.74 mm per year, according to the study.

The new data, much finer geographically, could also help with planning in densely populated areas where glaciers play a major role in water supply and agriculture. “In the short term, glaciers which are melting faster and faster will provide more and more water to rivers, serving as a buffer in certain regions such as India or in the Andes in arid periods. But then we will reach a peak, and the quantity of water will rapidly decrease, until there is no more, ”warns the researcher, estimating that“ in a few decades, most of the regions will begin this downward slope ”.

Global warming is changing the axis of rotation of our planet

The axis of rotation of the Earth is not fixed. This is manifested by a shift in the position of the poles. A movement followed for some time now by scientists. Today, they emphasize that anthropogenic global warming and more broadly, human activities, have significantly accelerated this natural movement.

The inclination of the axis of  rotation of the Earth  with respect to the  plane of the ecliptic  is not constant. Scientists are still trying to understand what exactly are the phenomena behind this variation. But the way water is distributed on the surface of our planet seems to be an important factor. And today,  researchers at the Chinese Academy of Sciences tell  us that the  melting  of  glaciers  due to the ongoing anthropogenic global warming has redistributed the water sufficiently to accelerate the displacement of the North Pole, causing it to swing from south to east. in the mid-1990s.

To reach this conclusion, the researchers calculated the total loss of water stored on land in the 1990s. They relied on data from  melting glaciers  and estimates of groundwater pumping. And the loss of water from the polar regions is the main driver of the polar drift. A drift whose   average speed between 1995 and 2020 is approximately 17 times greater than that of the period 1981-1995.

The amazing impact of human activities on Earth

The increasingly rapid melting of the ice with  global warming,  however, cannot explain all of the drift. Although the researchers did not take their analysis that far, they believe that the remaining gap could result from disturbances in non-polar regions. Due, in particular, to the unsustainable pumping of groundwater for agriculture.

Results which show, according to the researchers, to what extent  human activities  can have an impact on our Earth. Going so far as to move its axis of rotation. Despite everything, without any real effect on our daily life. Since the operation could not, at most, change the  length  of our days by only a few milliseconds.

Our planet is not quite spherical. And its axis of rotation – which connects the North Pole to the South Pole through the center of the Earth – tends to oscillate and drift little by little. The 10 centimeters per year drift, that is to say some 10 meters in the single XX th  century. Of  researchers from NASA  (USA) wanted to study the phenomenon. Using observational data and powerful models, they identified three processes that could explain it.

The glacial rebound, already incriminated by previous studies, is the best known of them. Glaciers tend to sink the surface of the Earth (much like when a person settles on a  mattress ). When the  ice melts , it gradually rises. But, according to NASA researchers, this phenomenon could not explain more than a third   of the rotational drifts observed.

Natural causes and an anthropogenic cause

The  convection of the Earth’s mantle is  also involved for a third. Thus, under the effect of the  heat  emitted by the  core of the Earth , rocks undergo a vertical circulation pattern. What to redistribute the masses and disrupt the rotation of our planet.

The last process involved is attributable to Man. It is indeed the melting ice of  Greenland  resulting from  global warming . No less than 7,500 gigatons would in fact have been transferred to the oceans, responsible for a  rise in sea level … and a drift in the axis of rotation of our planet.

Charles Darwin is not the first father of the theory of evolution, but the Iraqi scientist Al-Jahiz

About 1000 years before Charles Darwin wrote a book on how animals change through a process he called « natural selection, » a Muslim philosopher living in Iraq named Al-Jahiz had already preceded him. .

British scientist Charles Darwin’s theory of evolution is one of the cornerstones of modern science.

The idea that species gradually change over time through a mechanism called natural selection has revolutionized our understanding of the living world.

But it seems that the theory of evolution itself also has an ancestor in the Islamic world.

His real name Abu Usman Amr Bahr Bahr Alkanani al-Basri is remembered by history by his nickname, Al-Jahiz, which means someone whose eyes seem to be sticking out of their sockets.

His most famous work, The Book of Animals, is designed as an encyclopedia featuring 350 animals, in which Al-Jahiz presents ideas that bear a striking resemblance to Darwin’s theory of evolution.

« Animals engage in a struggle for existence and for resources, to avoid being eaten and to reproduce, » writes Al-Jahiz, « environmental factors influence organisms to develop new characteristics to ensure their survival. survival, thus transforming them into new species ”.

He adds, “Animals that survive to reproduce can pass their characteristics on to their offspring. « 

It was clear to Al-Jahiz that the living world was in constant struggle for survival and that one species was always stronger than another.

Charles Darwin rightly deserves his reputation as a scientist who has spent years traveling and observing the natural world, and who founded his theory with unprecedented precision and clarity to transform the way we see the world.

With BBC

Earth’s rotation: one more second and the world can change

To synchronize the rotation of the Earth and atomic clocks, a positive or negative leap second can be used.  © Istock / getty Images

Sometimes the Earth spins too fast. Humans then try to keep pace, to adapt their clocks. But adding 1 second in a digitized world is not without consequences.

Like the Terrans, the blue planet was in a hurry to turn the page of the year 2020. It therefore turned faster than usual. Last year, the days lasted an average of 0.05 milliseconds less than usual. Scientists anticipate an identical scenario for the year 2021. However, a day is supposed to last 24 hours, or 86,400 seconds, measured as 9,192,631,770 periods of cesium-133 radiation, according to international atomic time (TAI). But Coordinated Universal Time (UTC), on which our civil time is based, wants the Sun to peak at noon on the spring equinox at Greenwich Observatory.

Some June 30 and December 31, the minute between 11:59 p.m. and midnight in universal time thus lasts… 61 seconds.

When the Earth is too slow, as has been the case in recent years, for various reasons, we add what is called a « leap second » to make astronomical time coincide with atomic time. Since 1972, 37 leap seconds have been added. Some June 30 and December 31, the minute between 11:59 p.m. and midnight in universal time thus lasts… 61 seconds. If the Earth continues to dance vigorously for another five or six years, the reverse could happen, with a 59-second minute. « It is quite possible that a negative leap second becomes necessary if the speed of rotation of the Earth continues to accelerate », explained in early January Peter Whibberley, researcher at the British National Laboratory of Physics. It’s unlikely, but, if it happens,

Network stability

These leap seconds are not without consequences in a computerized or mechanized economy. In the summer of 2012, the addition of a second thus produced malfunctions of many computer servers, including Mozilla. 135 airlines have had their unusable booking system on 1 st  July, causing flight delays and registration of passengers by hand!

“You should know that electrical network protection devices sample current and voltage values ​​to the nearest microsecond. A leap second presents for them a discontinuity 1 million times greater than their sampling precision, ”explains Hubert Kirrmann, Swiss member of the International Electrotechnical Commission, for“ HD ”. This is particularly true of the European electricity grid. “All the electrical stations, from the North Cape to Gibraltar, have a receiver which gives them the time to the nearest microsecond,” explains the former professor at the Polytechnic University of Lausanne.

The only purpose of the leap second is to make atomic time mean on average at noon in Greenwich once a year.

This is necessary for the electric frequency to be the same across the continent and to ensure grid stability. “Three years ago, in Germany, we escaped a power cut. Not all devices had introduced the leap second at the same time, ”explains Hubert Kirrmann, who advocates abandoning it. Unlike the meter, or the liter, time is the only one that does not have a continuous scale. The only purpose of the leap second is to make atomic time mean on average at noon in Greenwich once a year. « It serves to perpetuate Greenwich as a temporal reference for longitude », deplores Hubert Kirrmann.

The question of putting an end to this leap second is regularly debated at the International Telecommunication Union (ITU), the master of clocks. Certain economic activities have already seceded and do not respect UTC universal time: GPS satellites exclusively use atomic time without a leap second, because a jamming of the receivers during this second would cause deviations of half a kilometer on the vehicle position.

Source : Humanité

What is the mission of the Perseverance robot

published by Jules Bercy

NASA’s perseverance rover, which left Cape Canaveral on July 30, 2020, landed safely on the Red Planet, Thursday, February 18, after having traveled 480 million kilometers. A crucial scientific step to try to find out if life existed on Mars

The main objective pursued with this rover is to search for signs of a possible past microbial life on  Mars . If these predecessors – Spirit, Opportunity and Curiosity – have demonstrated that liquid water flowed over the Red Planet and that it once fulfilled the conditions necessary for the development of life, Perseverance will attempt to determine whether it is. actually sheltered.

The rover will collect rock and soil samples, enclose them in tubes, and leave them on the planet’s surface for a return to Earth by 2031. In addition to studying geology, Perseverance’s instruments will allow the testing of various technologies, with a view to a future mission inhabited by humans on Mars. One of the planned experiments is to produce oxygen from carbon dioxide in the atmosphere of the red planet. This oxygen could be used for respiration and fuel.

Perseverance’s landing on Mars in « seven minutes of terror »

Source : NASA

published by Jules Bercy

About seven months after taking off, NASA’s last vehicle, Perseverance, will still have to survive « seven minutes of terror, » as the ultra-perilous maneuver preceding its landing on Mars is dubbed. 

The chosen location, Jezero Crater, is the most dangerous landing site ever attempted. In seven minutes, the rover must go from a speed of 20,000 km / h to zero. 

The landing will take place at 8:55 p.m. GMT Thursday (3:55 p.m. Washington).

-130km: entry into the atmosphere-

Ten minutes before entering the Martian atmosphere, the vessel separated from the cruise stage which supplied it with fuel during the trip. 

It is then only composed of a rear shield, a heat shield at the front, and, caught between the two, the descent stage, connected to the rover itself. 

At about 130km altitude, it enters the atmosphere at a speed of 20,000km / h, causing friction raising the temperature to 1,300 ° C. The heat shield protects the rover from this infernal heat. 

-11km: opening of the parachute-

But the atmosphere is not enough to slow the ship enough, which is still going at 1,500 km / h. 

At about 11km altitude, at an opportune moment calculated according to the distance remaining to the landing place, a huge supersonic parachute 21 meters in diameter, located in the rear shield, is deployed. 

This slows down the ship to about 300 km / h. 

-9km: heat shield released-

20 seconds after opening the parachute, the heat shield is released: the rover it was protecting is exposed for the first time to the Martian atmosphere. 

A whole new technology, called “Terrain Relative Navigation” (TRN), comes into play: the images recorded live by the cameras of the vessel are compared to maps recorded in its system, where the dangerous zones to be avoided are pre-defined. Taking these data into account, the ship decides on the final landing place.

-2km: retro-propelled phase-

At an altitude of around 2km, the rear shield – and its parachute – are dropped. 

The rover is no longer attached to the descent stage, equipped with eight motors pointed downwards, which light up to finish slowing it down. After performing a maneuver to get away from the parachute, the rover ended up descending vertically, right above its landing site.

-20m: separation of the rover-

At about 20m from the ground, it reached a speed of 2.7km / h, slower than that at which a man walks. The rover then descends along the cables thanks to a system of pulleys, during a final fifteen seconds (stage called « skycrane »). 

The vehicle deploys its wheels at this time. When the latter feel the ground, the lines are cut and the descent stage makes a final push to crash as far as possible. 

Because of the transmission delay between Earth and Mars, when the landing will be confirmed by NASA, it will actually have taken place several minutes earlier. 

Source: Orange with NASA

Could Man survive without the other Species?

could humans survive without other species?

As they tame technology, humans gain independence and break free from the grip of nature. However, could humans survive without other species? The water he drinks and the air he breathes are purified by all living species: biodiversity.

 This biodiversity also provides him with all of what he eats. But also many materials which constitute its world, or the active principles of the majority of these drugs.

Man has industrialized agriculture, but without pollinators his agricultural efforts would be in vain. It must be said that a bee can visit the trifle of a quarter of a million flowers in one season. And there are 50 trillion honey bees on earth. Agriculture also benefits from invertebrates and soil microorganisms that ensure its fertility. One gram of soil contains nearly a billion bacteria, divided into 10 to 100,000 different species, the vast majority of which are still unknown to humans. If we put the DNA of all these bacteria end to end, it would take us to the ends of the universe. A biodiversity of infinite richness.

Each species develops in permanent interaction with other species. That a species disappears, and the remaining links will help to compensate for this absence. That thousands of species disappear at the same time, and the web of living things will be greatly weakened, risking collapse.

Due to its biological nature, humanity remains entirely dependent on the living tissue of its planet, for which its presence as well as its disappearance, as a species are insignificant.

The life of a small second on Earth for man

published by Jules bercy

99.9% of species that lived on earth have now disappeared

The earth is the cradle of humanity. Man reigns supreme there, without anything seeming to be able to stop him. Yet planet earth did not wait for man to begin its history.

Since life appeared, the earth has hosted countless species, which have followed one another for more or less long time. But 99.9% of the species that lived on earth have now disappeared. Some have gradually evolved into other species. Others died suddenly. On average, their passage on earth lasts only a few million years.

If the history of the earth were written in a thousand-page book, life would appear there around page 185. This life would only be represented by single cells for more than 700 pages. Until the explosion of the multicellular species, from pages 870 to 880. The outflow of the waters was only found on page 916.

During this constant transformation, the planet has also undergone 5 major crises including one, 250 million years ago, during which life on earth almost disappeared. This mass extinction has led to the disappearance of 70% of terrestrial species and 96% of marine species. The planet took nearly 10 million years to recover and resume dance of evolution, with its disappearances, and its newcomers like this time the dinosaurs on page 960 of the history of the Earth.

 At the end of the book, the entire history of Homo sapiens from its appearance until today, would be the subject of only a handful of lines, at the very bottom of the very last page. Its presence on earth therefore represents only 0.004% of its very long history. Man has not been around for a long time, but it does not mean to evolve any more.

 All species are at the peak of evolution, and all are perfectly adapted to their natural environment, from the barnacle, firmly anchored on its whale … to the tiny Dik-Dik apparently so fragile but which survives the repeated attacks of eagles , pythons and lions since time immemorial.

There is no indication that the human species should be eternal. Nor even that it will take longer than the others to disappear. The most probable is that its passage on earth represents only a blink of an eye on the scale of the history of its planet.

A derisory duration. Almost… insignificant?

A unique life on one planet

The only planet that shelters living beings, the earth is an oasis of life in the middle of the great cosmic desert

Humans inhabit a planet in their image: special, unique, perfect. The only planet that shelters living beings, the earth is an oasis of life in the middle of the great cosmic desert. But is she really that exceptional?

Man has in fact only a very vague vision of the universe in which he evolves. His scale is so vast and empty, that he called for lack of anything better, « Space ». Far from being deserted, this space is full of a multitude of planets, as diverse as they are varied.
Since there is on average one planet per star in the universe, there are probably over 100 billion planets in the Milky Way alone, and as many in each of the hundreds of billions of other galaxies.

With such a profusion of planets, how could life have evolved only once? Even with ridiculously low odds of occurrence, the universe is probably teeming with life. Especially since this universe is continuously changing.

Every day, 275 million stars and therefore planets are born. As many arrive at the end of their life, and all are in constant motion. Man cannot even identify his own position, which is not fixed. Starting with the orbit of the earth, rushing around its sun at a speed of 100,000 km / h, and of which humans are not even aware. Nor does he perceive that his entire solar system is propelling his galaxy even faster. And finally, his galaxy, like all the others, is itself in motion. And rushes towards the nearest galaxy, Andromeda has the speed of 720,000 km / h.

The man, so superior seems indeed lost in a cosmic ocean in perpetual motion. In this disproportionate universe, doesn’t asserting that it has no life amounts to prolonging a drink in the ocean and concluding that it does not shelter fish?

In the end, humans have no idea of ​​their place in the universe. Are they alone or just insignificant?

The Universe, the infinite and the infinite

What we currently see are not stars but thousands of galaxies.

Human beings have always known that they hold a special place in the universe. Center of the world, jewel of evolution, he raised his eyes to the sky. And then he started exploring. Man discovered that he inhabits one planet among many in the solar system, a small blue dot rotating around its star.

The universe is teeming with stars more notable than the sun, an anonymous spark at the foot of stellar hierarchies.

A planet finally of banal size, orbiting around a rather pale star, which humans have even classified as a yellow dwarf. A ridiculous size alongside the many giants and super giants.

Take the grandiose Eta Carinais for example, a star a million times brighter than the sun, or the majestic Uy scuti 5 billion times larger.

To measure the immense distances between these stars, man had to invent a special unit of length, the one traveled for a year by a particle of light, 10,000 billion kilometers. A light year is therefore one kilometer away, what a kilometer is the size of a virus, and the universe is 80 billion light years.

The stars are incredibly numerous. A single galaxy contains between 100 and 400 billion stars. AND the galaxies themselves are countless. What we currently see are not stars but thousands of galaxies. For the entire visible universe, this represents a total of 400 sextillion stars. A number so important that the human being has difficulty in conceiving it. Yet it is not so hard: there are as many observable stars in the universe as there are drops of water in all the oceans of its planet Earth, or grains of sand on all its beaches and deserts. But this immensity itself only represents the observable universe, this zone beyond which human telescopes cannot see, a very small part of the real universe.

Man lives in the distant suburbs of an innocuous galaxy, lost in a universe so vast that he cannot even conceive of it as a whole.

Faced with these astronomical scales, wouldn’t it be… insignificant?