Is the past a prologue to the future? As for the Earth, the answer can be: yes and no. As in the past, the Earth continues to be a constantly changing system. The planet faces a series of warming and cooling. Ice ages will return, as will periods of extreme warming. Global tectonic processes will continue to move continents, close and open oceans. The fall of a giant asteroid or the eruption of a super-powerful volcano can again deal a cruel blow to life.

But other events will also occur, as inevitable as the formation of the first granite crust. Myriads of living beings will die out forever. Tigers, polar bears, humpback whales, pandas, and gorillas are doomed to extinction. There is a high probability that humanity is also doomed. Many details of earth's history are largely unknown, if not completely unknowable. But studying this history, as well as the laws of nature, provides insight into what may happen in the future. Let's start with a panoramic view and then gradually focus on our time.

Endgame: the next 5 billion years

The earth is almost halfway through its inevitable demise. For 4.5 billion years, the Sun shone quite steadily, gradually increasing in brightness as it burned through its colossal reserves of hydrogen. For the next five (or so) billion years, the Sun will continue to generate nuclear energy by converting hydrogen into helium. This is what almost all stars do most of the time.

Sooner or later, hydrogen supplies will run out. Smaller stars, reaching this stage, simply fade out, gradually decreasing in size and emitting less and less energy. If the Sun were such a red dwarf, the Earth would simply freeze through. If any life survived on it, it would only be in the form of especially hardy microorganisms deep under the surface, where there could still be reserves of liquid water. However, the Sun does not face such a miserable death, since it has enough mass to have a supply of nuclear fuel for another scenario. Let us remember that each star keeps two opposing forces in balance. On the one hand, gravity attracts stellar matter to the center, reducing its volume as much as possible. On the other hand, nuclear reactions, like an endless series of explosions of an internal hydrogen bomb, are directed outward and accordingly try to increase the size of the star. The current Sun is in the stage of burning hydrogen, having reached a stable
diameter of about 1,400,000 km - this size lasted 4.5 billion years and will last for about 5 billion more.

The sun is large enough that after the end of the hydrogen burnout phase, a new, powerful helium burnout phase begins. Helium, the product of the fusion of hydrogen atoms, can combine with other helium atoms to form carbon, but this stage of the Sun's evolution will have catastrophic consequences for the inner planets. Due to more active helium-based reactions, the Sun will become larger and larger, like an overheated balloon, turning into a pulsating red giant. It will swell to the orbit of Mercury and simply swallow the tiny planet. It will reach the orbit of our neighbor Venus, swallowing it at the same time. The sun will swell a hundred times its current diameter - right up to the orbit of the Earth.

The prognosis for the earthly endgame is very grim. According to some dark scenarios, the red giant Sun will simply destroy the Earth, which will evaporate in the hot solar atmosphere and cease to exist. According to other models, the Sun will eject more than a third of its current mass in the form of an unimaginable solar wind (which will endlessly torment the dead surface of the Earth). As the Sun loses some of its mass, the Earth's orbit may expand, in which case it may avoid being absorbed. But even if we are not devoured by the huge Sun, all that remains of our beautiful blue planet will turn into a barren firebrand that continues to orbit. In the depths, individual ecosystems of microorganisms may survive for another billion years, but its surface will never again be covered with lush greenery.

Desert: 2 billion years later

Slowly but surely, even in the current quiet period of hydrogen burning, the Sun is warming up more and more. At the very beginning, 4.5 billion years ago, the Sun's luminosity was 70% of what it is today. During the Great Oxygen Event, 2.4 billion years ago, the glow intensity was already 85%. In a billion years, the Sun will shine even brighter.

For some time, perhaps even many hundreds of millions of years, the Earth's feedbacks will be able to soften this impact. The more thermal energy, the more intense the evaporation, hence the increase in cloudiness, which contributes to the reflection of most of the sunlight into outer space. Increased thermal energy means faster weathering of rocks, increased absorption of carbon dioxide and reduced levels of greenhouse gases. Thus, negative feedbacks will maintain conditions for maintaining life on Earth for quite a long time.

But a turning point will inevitably come. The relatively small Mars reached this critical point billions of years ago, losing all liquid water on the surface. In a billion years, the earth's oceans will begin to evaporate at a catastrophic rate and the atmosphere will turn into an endless steam room. There will be no glaciers or snow-capped peaks left, and even the poles will turn into the tropics. For several million years, life can persist in such greenhouse conditions. But as the Sun warms up and water evaporates into the atmosphere, hydrogen will begin to evaporate into space faster and faster, causing the planet to slowly dry out. When the oceans completely evaporate (which will probably happen in 2 billion years), the Earth's surface will turn into a barren desert; life will be on the brink of destruction.

Novopangea, or Amasia: 250 million years later

Amazia

The demise of the Earth is inevitable, but it will not happen very, very soon. A look into the less distant future paints a more attractive picture of a dynamically developing and relatively safe planet for life. To imagine the world in a few hundred million years, we must look to the past for clues to the future. Global tectonic processes will continue to play an important role in changing the face of the planet. Nowadays, the continents are separated from each other. Wide oceans separate America, Eurasia, Africa, Australia and Antarctica. But these huge areas of land are in constant motion, and its speed is approximately 2-5 cm per year - 1500 km in 60 million years. We can establish fairly accurate vectors of this movement for each continent by studying the age of the basalts of the ocean floor. The basalt near mid-ocean ridges is quite young, no older than a few million years. In contrast, the age of basalt near continental margins in subduction zones can reach more than 200 million years. It is easy to take into account all these age data on the composition of the ocean floor, rewind the tape of global tectonics back in time and get an idea of ​​the moving
geography of the earth's continents over the past 200 million years. Based on this information, it is also possible to project the movement of continental plates 100 million years into the future.

Taking into account the current trajectories of this movement across the planet, it turns out that all continents are moving towards the next collision. In a quarter of a billion years, most of the earth's land will again become one giant supercontinent, and some geologists are already predicting its name - Novopangea. However, the exact structure of the future united continent remains a subject of scientific debate. Assembling Novopangea is a tricky game. It is possible to take into account the current movements of the continents and predict their path for the next 10 or 20 million years. The Atlantic Ocean will expand by several hundred kilometers, while the Pacific Ocean will shrink by approximately the same distance. Australia will move north towards South Asia, and Antarctica will move slightly away from the South Pole towards South Asia. Africa doesn't either
stands still, slowly moving north, moving into the Mediterranean Sea.

In a few tens of millions of years, Africa will collide with southern Europe, closing the Mediterranean Sea and erecting a mountain range the size of the Himalayas at the site of the collision, in comparison with which the Alps will seem like dwarfs. Thus, the map of the world in 20 million years will seem familiar, but slightly skewed. When modeling a world map 100 million years into the future, most developers identify common geographic features, for example, agreeing that the Atlantic Ocean will overtake the Pacific Ocean in size and become the largest water basin on Earth.

However, from this point on, models of the future diverge. One theory, extroversion, is that the Atlantic Ocean will continue to open and as a result, the Americas will eventually collide with Asia, Australia and Antarctica. In the later stages of this supercontinent assembly, North America will fold eastward into the Pacific Ocean and collide with Japan, and South America will fold clockwise from the southeast, connecting with equatorial Antarctica. All these parts fit together amazingly. Novopangea will be a single continent, stretching from east to west along the equator.

The main thesis of the extraversion model is that large convection cells of the mantle located under tectonic plates will remain in their modern form. An alternative approach, called introversion, takes the opposite view, citing previous cycles of closing and opening the Atlantic Ocean. Reconstructing the position of the Atlantic over the last billion years (or a similar ocean located between the Americas in the west and Europe along with Africa in the east), experts argue that the Atlantic Ocean closed and opened three times in cycles of several hundred million years - this conclusion suggests that heat exchange processes in the mantle are variable and episodic. Judging by the analysis of rocks, as a result of the movements of Laurentia and other continents about 600 million years ago, a precursor to the Atlantic Ocean was formed, called Iapetus, or Iapetus (named after the ancient Greek titan Iapetus, the father of Atlas).

Iapetus became closed after the assembly of Pangea. When this supercontinent began to break apart 175 million years ago, the Atlantic Ocean was formed. According to proponents of introversion (perhaps we shouldn't call them introverts), the Atlantic Ocean continues to expand and will follow the same path. It will slow down, stop and retreat in about 100 million years. Then, after another 200 million years, the Americas will again join Europe and Africa. At the same time, Australia and Antarctica will merge with Southeast Asia, forming a supercontinent called Amasia. This giant continent, shaped like a horizontal L, includes the same parts as New Pangea, but in this model the Americas form its western edge.

Currently, both supercontinent models (extroversion and introversion) are not without merit and are still popular. Whatever the outcome of this debate, everyone agrees that although the Earth's geography will change significantly in 250 million years, it will still reflect the past. The temporary assembly of continents near the equator would reduce the effects of ice ages and mild sea level changes. Where continents collide, mountain ranges will rise, changes in climate and vegetation will occur, and there will be fluctuations in oxygen and carbon dioxide levels in the atmosphere. These changes will repeat throughout Earth's history.

Impact: the coming 50 million years

A recent survey on how humanity will die reflected a very low rate of asteroid impacts - something around 1 in 100,000. Statistically, this is the same as the likelihood of dying from a lightning strike or a tsunami. But there is an obvious flaw in this forecast. Typically, lightning kills about 60 people a year. In contrast, the asteroid impact may not have killed a single person in several thousand years. But one day, a modest blow could destroy everyone.

There is a good chance that we have nothing to worry about, and neither do hundreds of subsequent generations. But there is no doubt that one day there will be a major catastrophe like the one that killed the dinosaurs. In the next 50 million years, the Earth will have to endure such a blow, perhaps more than once. It's just a matter of time and circumstances. The most likely villains are near-Earth asteroids - objects with a highly elongated orbit that passes close to the Earth's nearly circular orbit. At least three hundred such potential killers are known, and in the next few decades, some of them will pass dangerously close to Earth. On February 22, 1995, an asteroid discovered at the last moment, which received the decent name 1995 CR, whistled quite close - at several Earth-Moon distances. On September 29, 2004, the asteroid Tautatis, an elongated object approximately 5.4 km in diameter, passed even closer. In 2029, the asteroid Apophis, a fragment of approximately 325-340 m in diameter, should approach even closer, entering deeply into the lunar orbit. This unpleasant proximity will inevitably change Apophis’s own orbit and, perhaps, in the future will bring it even closer to Earth.

For every currently known asteroid crossing the Earth's orbit, there are a dozen or more that have yet to be discovered. When such a flying object is eventually discovered, it may be too late to do anything. If we find ourselves targeted, we may only have a few days to avert the danger. Dispassionate statistics give us calculations of the probability of collisions. Almost every year, debris about 10 m in diameter falls to Earth. Due to the braking effect of the atmosphere, most of these shells explode and disintegrate into
small parts before contacting the surface. But objects with a diameter of 30 meters or more, encounters with which occur approximately once every thousand years, lead to significant destruction at the impact sites: in June 1908, such a body collapsed in the taiga near the Podkamennaya Tunguska River in Russia. Very dangerous, about a kilometer in diameter, rocky objects fall to Earth about once every half a million years, and asteroids five kilometers or more can fall to Earth about once every 10 million years.

The consequences of such collisions depend on the size of the asteroid and the location of the impact. A fifteen-kilometer boulder will devastate the planet wherever it lands. (For example, the asteroid that killed off the dinosaurs 65 million years ago was estimated to be about 10 km in diameter.) If a 15-kilometer pebble hits the ocean - a 70% chance, taking into account the ratio of areas of water and land - then almost all the mountains on the globe, except for the highest, will be carried away by destructive waves. Everything below 1000 m above sea level will disappear.

If an asteroid of this size hits land, the destruction will be more localized. Everything within a radius of two to three thousand kilometers will be destroyed, and devastating fires will sweep across the entire continent, which will be the unlucky target. For some time, areas remote from the impact will be able to avoid the consequences of the fall, but such an impact will throw up an immense amount of dust from the destroyed stones and soil into the air, clogging the atmosphere with dust clouds that reflect sunlight for years. Photosynthesis will practically disappear. Vegetation will die and the food chain will be broken. Part of humanity
may survive this catastrophe, but civilization as we know it will be destroyed.

Smaller objects would be less destructive, but any asteroid over a hundred meters in diameter, whether it crashed on land or in the sea, would cause a disaster worse than any we know of. What to do? Can we ignore the threat as something distant, not so significant in a world already full of problems that require immediate solutions? Is there any way to deflect large debris?

The deceased, perhaps the most charismatic and influential representative of the scientific community over the past half century, thought a lot about asteroids. Publicly and privately, and mostly on his famous TV show Cosmos, he advocated for concerted action at the international level. He began by telling the fascinating tale of the monks of Canterbury Cathedral who, in the summer of 1178, witnessed a colossal explosion on the Moon - a very close asteroid impact less than a thousand years ago. If such an object crashed onto Earth, millions of people would die. “Earth is a tiny corner in the vast arena of space,” he said. “It’s unlikely that anyone will come to our aid.”

The simplest step that must be taken first is to pay close attention to celestial bodies dangerously approaching the Earth - you need to know the enemy by sight. We need precise telescopes equipped with digital processors to locate flying objects approaching Earth, calculate their orbits, and make calculations about their future trajectories. It doesn't cost that much, and some things are already being done. Of course, more could be done, but at least some effort is being made.

What if we discover a large object that could crash into us in a few years? Sagan, and with him a number of other scientists and military officers, believe that the most obvious way is to cause a deviation in the asteroid’s trajectory. If started in time, even a small rocket push or a few targeted nuclear explosions could significantly shift the asteroid's orbit - and thereby send the asteroid past the target, avoiding a collision. He argued that the development of such a project required an intensive and long-term space research program. In a prophetic 1993 article, Sagan wrote: “As the threat of asteroids and comets touches every inhabited planet in the galaxy, if any, intelligent beings on them will have to band together to leave their planets and move to neighboring ones. The choice is simple - fly into space or die."

Space flight or death. To survive in the distant future, we must colonize neighboring planets. First, we need to create bases on the Moon, although our luminous satellite will remain an inhospitable world for life and work for a long time. Next is Mars, where there are more substantial resources - not only large reserves of frozen groundwater, but also sunlight, minerals and a thin atmosphere. This will not be an easy or cheap undertaking, and Mars is unlikely to become a thriving colony any time soon. But if we settle there and cultivate the soil, our promising neighbor could very well become an important step in the evolution of humanity.

Two obvious obstacles may delay or even make it impossible for humans to settle on Mars. The first is money. The tens of billions of dollars it would cost to develop and implement a mission to Mars would exceed even NASA's most optimistic budget, and that's under favorable financial conditions. International cooperation would be the only way out, but so far such large international programs have not taken place.

Another problem is the survival of astronauts, since it is almost impossible to ensure a safe flight to Mars and back. Space is harsh, with its countless meteorite grains of sand-projectiles capable of piercing the thin shell of even an armored capsule, and the Sun is unpredictable - with its explosions and deadly, penetrating radiation. The Apollo astronauts, with their week-long missions to the Moon, were incredibly lucky that nothing happened during this time. But the flight to Mars will last several months; In any space flight, the principle is the same: the longer the time, the greater the risk.

Moreover, existing technologies do not allow supplying the spacecraft with a sufficient supply of fuel for the return flight. Some inventors are talking about recycling Martian water to synthesize rocket fuel and fill tanks for the return flight, but for now this is a dream, and in the very distant future. Perhaps the most logical solution so far - the one that hurts NASA's pride, but is actively supported by the press - is a one-way flight. If we had sent an expedition, providing it with provisions for many years instead of rocket fuel, reliable shelter and a greenhouse, seeds, oxygen and water, and tools for extracting vital resources on the Red Planet itself, such an expedition could take place. It would be unimaginably dangerous, but all the great pioneers were in danger - such was Magellan’s circumnavigation of the world in 1519-1521, the expedition to the West of Lewis and Clark in 1804-1806, the polar expeditions of Peary and Amundsen at the beginning of the 20th century. Humanity has not lost its gambling desire to participate in such risky enterprises. If NASA announces a volunteer registration for a one-way mission to Mars, thousands of professionals will sign up without a second thought.

In 50 million years, Earth will still be a living and habitable planet, and its blue oceans and green continents will have shifted but will remain recognizable. Much less obvious is the fate of humanity. Perhaps man will become extinct as a species. In this case, 50 million years is quite enough to erase almost all traces of our brief rule - all cities, roads, monuments will be weathered much earlier than the end date. Some alien paleontologists will have to work hard to find the smallest traces of our existence in near-surface sediments.

However, a person can survive, and even evolve, colonizing first the nearest planets, and then the nearest stars. In this case, if our descendants go out into outer space, then the Earth will be valued even higher - as a reserve, a museum, a shrine and a place of pilgrimage. Perhaps only by leaving our planet will humanity finally truly appreciate the birthplace of our species.

Remapping the Earth: The Next Million Years

In many ways, the Earth won't change that much in a million years. Of course, the continents will shift, but no more than 45-60 km from their current location. The Sun will continue to shine, rising every twenty-four hours, and the Moon will orbit the Earth in about one month. But some things will change quite fundamentally. In many parts of the world, irreversible geological processes transform the landscape. The vulnerable contours of ocean shores will change especially noticeably. Calvert County, Maryland, one of my favorite places, where Miocene rocks with their seemingly endless fossil deposits stretch for miles, will disappear from the face of the Earth as a result of rapid weathering. After all, the size of the entire county is only 8 km and decreases by almost 30 cm every year. At this rate, Calvert County will not last 50 thousand years, let alone a million.

Other states, on the contrary, will acquire valuable land plots. An active underwater volcano off the southeastern coast of the largest of the Hawaiian islands has already risen above 3000 m (although still covered with water) and is growing in size every year. In a million years, a new island will rise from the ocean waves, already named Loihi. At the same time, the extinct volcanic islands to the northwest, including Maui, Oahu and Kauai, will correspondingly shrink under the influence of wind and ocean waves.

As for waves, experts who study rocks for future changes conclude that the most active factor in changing the Earth's geography will be the advance and retreat of the ocean. The change in the rate of rift volcanism will have an effect for a very, very long time, depending on how much more or less lava solidifies on the ocean floor. Sea levels can drop significantly during periods of quiet volcanic activity, when rocks near the bottom cool and calm down: this is what scientists believe caused the sharp drop in sea levels just before the Mesozoic extinction event. The presence or absence of large inland seas like the Mediterranean, as well as the cohesion and separation of continents, are causing significant changes in the size of coastal shelves, which will also play an important role in shaping the geosphere and biosphere over the next million years.

A million years is tens of thousands of generations in the life of mankind, which is hundreds of times longer than the entire previous human history. If man survives as a species, then the Earth may also undergo changes as a result of our progressive technological activity, and in ways that are difficult to even imagine. But if humanity dies out, then the Earth will remain approximately the same as it is now. Life will continue on land and sea; the joint evolution of the geosphere and biosphere will quickly restore the pre-industrial equilibrium.

Megavolcanoes: the next 100 thousand years

A sudden, catastrophic asteroid impact pales in comparison to the sustained eruption of a megavolcano or a continuous flow of basaltic lava. Volcanism on a planetary scale accompanied almost all five mass extinctions, including the one caused by an asteroid impact. The consequences of megavolcanism should not be confused with ordinary destruction and losses during the eruptions of ordinary volcanoes. Regular eruptions are accompanied by flows of lava, familiar to the inhabitants of the Hawaiian Islands living on the slopes of Kilauea, whose homes and everything that gets in its path it destroys, but in general such eruptions are limited, predictable and easy to avoid. Somewhat more dangerous in this category are ordinary pyroclastic volcanic eruptions, when a huge amount of hot ash rushes down the mountainside at a speed of about 200 km/h, incinerating and burying everything in its path. This was the case in 1980 with the eruptions of Mount St. Helens, Washington State, and Mount Pinatubo in the Philippines in 1991; thousands of people would have died in these disasters if not for early warning and mass evacuations.

An even more formidable danger is posed by the third type of volcanic activity: the release of huge masses of fine ash and toxic gases into the upper layers of the atmosphere. The eruptions of the Icelandic volcanoes Eyjafjallajökull (April 2010) and Grímsvötn (May 2011) are relatively weak, since they were accompanied by emissions of less than 4 km^3 of ash. However, they paralyzed air traffic in Europe for several days and harmed the health of many people in nearby areas. In June 1783, the eruption of the Laki volcano - one of the largest in history - was accompanied by the release of more than 12 thousand m3 of basalt, as well as ash and gas, which was quite enough to shroud Europe in a toxic haze for a long time. At the same time, a quarter of the population of Iceland died, some of whom died from direct poisoning from acidic volcanic gases, and the majority from starvation during the winter. The consequences of the disaster reverberated over a thousand kilometers to the southeast, and tens of thousands of Europeans, mostly from the British Isles, died from the lingering effects of the eruption.

But the deadliest was the eruption of Mount Tambora in April 1815, which ejected more than 20 km3 of lava. At the same time, more than 70 thousand people died, most of them from mass starvation resulting from damage to agriculture. The Tambora eruption released huge masses of sulfur dioxide gases into the upper atmosphere, blocking the sun's rays and plunging the Northern Hemisphere into a "year without sunlight" ("volcanic winter") in 1816. These historical events still boggle the mind, and not without reason. Of course, the number of victims does not compare with the hundreds of thousands of people who died from the recent earthquakes in the Indian Ocean and Haiti. But there is an important, frightening difference between volcanic eruptions and earthquakes. The size of the most powerful earthquake possible is limited by the strength of the rock. Hard rock can withstand a certain amount of pressure before it cracks; the strength of the rock can cause a very destructive, but still local earthquake - a magnitude of nine on the Richter scale.

In contrast, volcanic eruptions are not limited in scale. In fact, geological data irrefutably testifies to eruptions hundreds of times more powerful than the volcanic disasters preserved in the historical memory of mankind. Such gigantic volcanoes could darken the sky for years and change the appearance of the earth's surface over many millions (not thousands!) of square kilometers. The giant eruption of Mount Taupo on the North Island, New Zealand, occurred 26,500 years ago; More than 830 km^3 of magmatic lava and ash were erupted.

The Toba volcano in Sumatra exploded 74,000 years ago and erupted more than 2,800 km^3 of lava. The consequences of a similar catastrophe in the modern world are difficult to imagine. Yet these supervolcanoes, which produced the greatest cataclysms in Earth's history, pale in comparison to the giant basalt flows (scientists call them "traps") that caused mass extinctions. Unlike one-time eruptions of supervolcanoes, basalt flows cover a huge time period - thousands of years of continuous volcanic activity. The most powerful of these cataclysms, usually coinciding with periods of mass extinction, spread hundreds of thousands of millions of cubic kilometers of lava. The largest catastrophe occurred in Siberia 251 million years ago during the great mass extinction and was accompanied by the spreading of basalt over an area of ​​more than a million square kilometers. The death of the dinosaurs 65 million years ago, often attributed to a large asteroid impact, coincided with a gigantic basaltic lava spill in India, which gave rise to the largest igneous province, the Deccan Traps, with a total area of ​​about 517,000 km2, and the volume of mountains that grew up to 500,000 km2 ^3.

These huge territories could not have formed as a result of a simple transformation of the crust and upper part of the mantle. Modern models of basalt formations reflect the idea of ​​an ancient era of vertical tectonics, when giant bubbles of magma slowly rose from the boundaries of the hot core of the mantle, splitting the earth's crust and splashing out onto the cold surface. Such phenomena occur extremely rarely in our time. According to one theory, the time interval between basalt flows is approximately 30 million years, so it is unlikely that we will live to see the next one.

Our technological society will certainly receive timely warning of the possibility of such an event. Seismologists are able to track the flow of hot, molten magma rising to the surface. We may have hundreds of years to prepare for such a natural disaster. But if humanity falls into another surge of volcanism, there will be little we can do to counter this most severe of earthly tests.

Ice factor: next 50 thousand years

In the foreseeable future, the most significant factor determining the appearance of the earth's continents is ice. Over several hundred thousand years, ocean depth is highly dependent on the global volume of frozen water, including mountain ice caps, glaciers and continental ice sheets. The equation is simple: the greater the volume of frozen water on land, the lower the water level in the ocean. The past is the key to predicting the future, but how do we know the depth of ancient oceans? Satellite observations of ocean water levels, while incredibly accurate, are limited to the last two decades. Sea level measurements from level gauges, although less accurate and subject to local variations, have been collected over the last century and a half. Coastal geologists can map features of ancient coastlines—for example, elevated coastal terraces that can be traced back to tens of thousands of years of coastal-marine sediments—that may reflect periods of rising water levels. The relative position of fossil corals, which typically grow on sun-warmed, shallow ocean shelves, might extend our record of past events back into the centuries, but that record would be distorted as such geologic formations rise, sink, and tilt episodically.

Many experts began to pay attention to a less obvious indicator of sea level - changes in the ratios of oxygen isotopes in small shells of marine mollusks. Such relationships can tell much more than the distance between any celestial body and the Sun. Due to their ability to respond to changes in temperature, oxygen isotopes provide the key to deciphering the volume of the Earth's ice cover in the past and, accordingly, to changes in water levels in the ancient ocean. However, the relationship between the amount of ice and oxygen isotopes is tricky. The most abundant isotope of oxygen, accounting for 99.8% of the oxygen in the air we breathe, is thought to be light oxygen-16 (with eight protons and eight neutrons). One in 500 oxygen atoms is heavy oxygen-18 (eight protons and ten neutrons). This means that one out of every 500 water molecules in the ocean is heavier than normal. When the ocean is heated by the sun's rays, water containing light isotopes of oxygen-16 evaporates faster than oxygen-18, making water in low-latitude clouds lighter than in the ocean itself. As clouds rise into cooler layers of the atmosphere, the heavy oxygen-18 water condenses into raindrops faster than the lighter oxygen-16 water, and the oxygen in the cloud becomes even lighter.

As clouds inevitably move toward the poles, the oxygen in their constituent water molecules becomes much lighter than in seawater. When precipitation falls over polar glaciers and glaciers, light isotopes freeze in the ice and seawater becomes even heavier. During periods of maximum cooling of the planet, when more than 5% of the Earth's water turns into ice, sea water becomes especially saturated with heavy oxygen-18. During periods of global warming and glacier retreat, the level of oxygen-18 in seawater decreases. Thus, careful measurements of oxygen isotope ratios in coastal sediments can provide insight into changes in surface ice volume in retrospect.

This is exactly what geologist Ken Miller and his colleagues have been doing at Rutgers University for several decades, studying the thick layers of marine sediments covering the New Jersey coast. These deposits, which record the geological history of the last 100 thousand years, are rich in the shells of microscopic fossil organisms called foraminifera. Each tiny foraminifera stores oxygen isotopes in its composition in the proportion that was in the ocean at the time the organism grew. Measuring oxygen isotopes in New Jersey's coastal sediments, layer by layer, provides a simple and accurate means of estimating the volume of ice during a relevant time period.

In the recent geological past, the ice cover has waxed and waned, with corresponding large fluctuations in sea level every few thousand years. At the peak of the ice ages, more than 5% of the water on the planet turned into ice, lowering sea levels by about a hundred meters relative to today. It is believed that about 20 thousand years ago, during one of these periods of low standing water, a land isthmus formed across the Bering Strait between Asia and North America - it was along this “bridge” that people and other mammals migrated to the New World. During the same period, the English Channel did not exist, and there was a dry valley between the British Isles and France. During periods of maximum warming, when glaciers virtually disappeared and snow caps thinned on mountain tops, sea levels rose, becoming about 100 m higher than today, submerging hundreds of thousands of square kilometers of coastal areas across the planet.

Miller and his collaborators have calculated more than a hundred cycles of glacial advance and retreat over the past 9 million years, and at least a dozen of them occurred in the last million - the range of these wild fluctuations in sea level reached 180 m. Each cycle may be slightly different from the next, but the events occur with obvious periodicity and are associated with the so-called Milankovitch cycles, named after the Serbian astronomer Milutin Milankovitch, who discovered them about a century ago. He found that well-known changes in the parameters of the Earth's movement around the Sun, including the tilt of the Earth's axis, the eccentricity of the elliptical orbit and slight fluctuations in its own axis of rotation, cause periodic changes in climate with intervals of 20 thousand years to 100. These shifts affect the flow of solar energy , reaching the Earth, and thus causing significant climate fluctuations.

What awaits our planet in the next 50 thousand years? There is no doubt that sharp fluctuations in sea level will continue, and it will fall and rise more than once. Sometimes, probably over the next 20 thousand years, the snow caps on the peaks will grow, the glaciers will continue to increase, and the sea level will drop sixty meters or more - a level the sea has dropped to at least eight times in the last million years. This will have a powerful impact on the contours of continental coastlines. The East Coast of the United States will expand many kilometers eastward, according to
as the shallow continental slope becomes exposed. All major harbors on the East Coast, from Boston to Miami, will become dry inland plateaus. A new ice-covered isthmus will connect Alaska to Russia, and the British Isles could once again become part of mainland Europe. Rich fisheries along continental shelves will become part of the land.

As for sea level, if it decreases, then it must certainly rise. It is quite possible, even very likely, that within the next thousand years sea levels will rise by 30 m or more. Such a rise in sea levels, quite modest by geological standards, would redraw the map of the United States beyond recognition. Thirty meters of sea level rise will flood much of the coastal plains on the East Coast, pushing coastlines up to one hundred and fifty kilometers westward. The main coastal cities - Boston, New York, Philadelphia, Washington, Baltimore, Wilmington, Charleston, Savannah, Jacksonville, Miami and many others - will be under water. Los Angeles, San Francisco, San Diego and Seattle will disappear into the sea waves. It will flood almost all of Florida, and a shallow sea will stretch out in place of the peninsula. Most of the states of Delaware and Louisiana will be under water. In other parts of the world, the damage caused by rising sea levels will be even more devastating.

Entire countries will cease to exist - Holland, Bangladesh, the Maldives. Geological data irrefutably demonstrates that such changes will continue to occur. If warming turns out to be as rapid as many experts believe, water levels will rise quickly, by about 30 cm per decade. Normal thermal expansion of seawater during periods of global warming can increase sea level rise to an average of three meters. This will undoubtedly be a problem for humanity, but will have very little impact on the Earth. Still, this won't be the end of the world. This will be the end of our world.

Warming: the next hundred years

Most of us do not look several billion years ahead, just as we do not look several million years or even a thousand years. We have more pressing concerns: How will I pay for higher education for my child in ten years? Will I get a promotion in a year? Will the stock market go up next week? What to cook for lunch? In this context, we need not worry. Barring an unforeseen catastrophe, our planet will remain almost unchanged in a year or ten years. Any difference between what is now and what will be a year from now is almost imperceptible, even if the summer turns out to be incredibly hot, or the crops suffer from drought, or an unusually strong storm blows up.

And such changes are being observed across the globe. The shores of Chesapeake Bay report a steady increase in tide levels compared to previous decades. Year after year, the Sahara spreads further north, turning Morocco's once fertile farmland into a dusty desert. The ice of Antarctica is rapidly melting and breaking up. Average air and water temperatures are constantly rising. All this reflects a process of progressive global warming - a process that the Earth has experienced countless times in the past and will experience in the future.

Warming may be accompanied by other, sometimes paradoxical, effects. The Gulf Stream, a powerful ocean current that carries warm water from the equator to the North Atlantic, is driven by the large temperature difference between the equator and high latitudes. If global warming reduces the temperature contrast, as some climate models suggest, the Gulf Stream could weaken or stop altogether. Ironically, the immediate result of this change would be to transform the temperate climates of the British Isles and Northern Europe, which are now
heated by the Gulf Stream, in much cooler times. Similar changes will occur with other ocean currents - for example, with the current coming from the Indian Ocean into the South Atlantic past the Horn of Africa - this could cause a cooling of the mild climate of South Africa or a change in the monsoon climate that provides parts of Asia with fertile rains.

When glaciers melt, sea levels rise. According to the most conservative estimates, it will rise by half a meter to a meter in the next century, although, according to some data, in some decades the increase in sea water levels may fluctuate within a few centimeters. Such changes in sea level will affect many coastal communities around the world and pose a real headache for civil engineers and beach owners from Maine to Florida, but in principle a rise of up to one meter in densely populated coastal areas can be managed. At least the next one or two generations of residents will not have to worry about the sea encroaching on the land. However, certain species of animals and plants may suffer much more seriously.

The melting of polar ice in the north will reduce the habitat of polar bears, which is very unfavorable for preserving the population, the number of which is already declining. The rapid shift of climate zones towards the poles will negatively affect other species, especially birds, which are especially susceptible to changes in seasonal migration and feeding zones. According to some data, an average increase in global temperatures of just a couple of degrees, as most climate models suggest over the coming century, could reduce bird populations by almost 40% in Europe and by more than 70% in the fertile rainforests of north-eastern Australia. A major international report says that of the roughly 6,000 species of frogs, toads and lizards, one in three will be in danger, largely due to the spread of a fungal disease that is deadly to amphibians, fueled by a warm climate. Whatever other effects of warming may be revealed in the coming century, it appears that we are entering a period of accelerated extinction.

Some changes in the next century, whether inevitable or only probable, may be instantaneous, be it a major destructive earthquake, the eruption of a supervolcano, or the impact of an asteroid more than a kilometer in diameter. Knowing the history of the Earth, we understand that such events are common and therefore inevitable on a planetary scale. Nevertheless, we build cities on the slopes of active volcanoes and in the most geologically active zones of the Earth in the hope that we will dodge a “tectonic bullet” or a “space projectile.”

Between the very slow and rapid changes are geological processes that usually take centuries or even millennia - changes in climate, sea level and ecosystems that can remain undetected for generations. The main threat is not the changes themselves, but their degree. Because the state of the climate, the position of the sea level or the very existence of ecosystems may reach a critical level. The acceleration of positive feedback processes can hit our world unexpectedly. What would normally take a millennium to complete can
appear in a decade or two.

It's easy to be complacent if you misread the rock record. For a time, until 2010, concerns about modern events were tempered by studies looking back 56 million years ago, the time of one of the mass extinctions that dramatically affected the evolution and distribution of mammals. This terrible phenomenon, called the Late Paleocene Thermal Maximum, caused the relatively abrupt extinction of thousands of species. The study of the thermal maximum is important for our time because it is the most famous, documented sharp temperature shift in Earth's history. Volcanic activity caused a relatively rapid increase in atmospheric levels of carbon dioxide and methane, two inseparable greenhouse gases, which in turn led to a positive feedback that lasted more than a thousand years and was accompanied by moderate global warming. Some researchers see in the late Paleocene thermal maximum a clear parallel with the modern situation, of course, unfavorable - with a rise in global temperature by an average of almost 10 ° C, a rapid rise in sea level, ocean acidification and a significant shift of ecosystems towards the poles, but not so catastrophic, to threaten the survival of most animals and plants.

The shock of the recent findings by Lee Kemp, a geologist at Pennsylvania State University, and his colleagues has left us with little reason for optimism. In 2008, Kemp's team gained access to material recovered from drilling in Norway that allowed them to trace the events of the late Paleocene Thermal Maximum in detail - sedimentary rocks, layer by layer, captured the finest details of the rate of change in atmospheric carbon dioxide and climate. The bad news is that the thermal maximum, which is over a decade
considered the fastest climate shift in Earth's history, was driven by changes in the composition of the atmosphere that were ten times less intense than what is happening today. Global changes in the composition of the atmosphere and average temperature, formed over a thousand years and ultimately leading to extinction, have occurred in our time during the last hundred years, during which humanity burned enormous quantities of hydrocarbon fuels.

This is an unprecedentedly rapid change, and no one can predict how the Earth will react to it. At the Prague conference in August 2011, where three thousand geochemists gathered, there was a very sad mood among specialists, sobered by new data on the late Paleocene thermal maximum. Of course, for the general public, the forecast of these experts was formulated in rather cautious terms, but the comments that I heard on the sidelines were very pessimistic, even frightening. Greenhouse gas concentrations are increasing too quickly, and the mechanisms for absorbing this excess are unknown. Will this not cause a massive release of methane with all the subsequent positive feedbacks that such a development entails? Will sea levels rise by a hundred meters, as has happened many times in the past? We are entering a zone of terra incognita, conducting a poorly designed experiment on a global scale, the likes of which the Earth has never experienced in the past.

Judging by the rock data, no matter how resistant to shocks life may be, the biosphere is under great stress at turning points of sudden climate shifts. Biological productivity, particularly agricultural productivity, will drop to catastrophic levels for some time. In rapidly changing conditions, large animals, including humans, will pay a heavy price. The interdependence of rocks and the biosphere will continue unabated, but humanity's role in this billion-year saga remains incomprehensible.

Perhaps we have already reached a tipping point? Perhaps not in the current decade, perhaps not at all during the lifetime of our generation. But such is the nature of turning points - we recognize such a moment only when it has already arrived. The financial bubble is bursting. The population of Egypt rebels. The stock exchange is crashing. We realize what is happening only in retrospect, when it is too late to restore the status quo. And there has never been such a restoration in the history of the Earth.

Excerpt from Robert Hazen's book: "

On the scale of the history of the planet and even of humanity, the life of one particular person is catastrophically short. We, born at the turn of the millennium, were lucky to witness unprecedented technological progress and the flourishing of civilization. But what will happen next? In 50, 10, 1000 years? In these documentaries, eminent scientists and researchers will try to imagine what awaits humanity and our planet in the future.

Age of Fools

The film will paint us a picture of the near future (2055), when global warming is already destroying humanity. The main character of the film must compose a message for those people who may survive. The purpose of the message is to draw conclusions about why all this happened.

From a scientific point of view: Earth Apocalypse

Imagine our planet in 250 million years. It will faintly resemble today's Earth; most likely it will be one large continent, mostly occupied by deserts. There will be no oceans in today's view. Coastal areas will be destroyed by devastating storms. Ultimately, planet Earth is doomed to destruction.

Wild world of the future

Without a time machine, you will be transported into the future 5,000,000, 100,000,000 and 200,000,000 years to see a world worthy of the pen of a brilliant science fiction writer. But what appears before your eyes is not fiction at all! Using the most complex calculations, strictly substantiated forecasts and a wealth of knowledge in biology and geology, leading scientists from the USA, Great Britain, Germany and Canada, together with masters of computer animation, created a portrait of our planet and its inhabitants many centuries after the last person leaves it.

The world in 2050

Can you imagine our world in 2050? By mid-century, there will already be about 9 billion people on the planet, consuming more and more resources, surrounded by an increasingly technological environment. What will our cities be like? How will we eat in the future? Is global warming coming or will engineers have the opportunity to prevent the climate crisis? This BBC documentary examines the problem of overpopulation on earth. Of course, demographic problems await us in the future. Rockefeller Institute theoretical biologist Joel Cohen suggests that it is likely that most of the world's people will live in urban areas and their average life expectancy will be significantly higher.

New World - Future life on earth

Programs from the “New World” series tell us about the latest technologies, developments, and radical ideas that are already shaping the world of the future today. What will life on our planet be like in a few decades? Will there really be cities under the ocean, bio-suits and space tourism; will machines be able to develop super-speed, and human life expectancy will reach 150 years? Scientists say our descendants will live in floating cities, fly to work and travel underwater. The time of polluted megacities will end, because people will stop driving cars, and the invention of the teleport will save cities from eternal traffic jams.

Earth 2100

The very idea that within the next century, life as we know it could end will seem very strange to many. Our civilization may collapse, leaving only traces of human existence. To change your future, you must first imagine it. It seems outlandish, extraordinary and even impossible. But according to cutting-edge scientific research, it is a very real possibility. And if we continue to live the way we live now, all this will definitely happen.

Life after people

This film is based on the results of a study of territories suddenly abandoned by people, as well as the possible consequences of stopping the maintenance of buildings and urban infrastructure. The abandoned world hypothesis is illustrated with digital images showing the subsequent fate of such architectural masterpieces as the Empire State Building, Buckingham Palace, Sears Tower, Space Needle, Golden Gate Bridge and the Eiffel Tower.

From a scientific point of view: The Death of the Earth

Planet Earth: 4 billion years of evolution, all this will disappear. Titanic forces are already at work that will destroy the world as we know it. Together with scientific researchers, we will make a grand journey into the future of the Earth in which natural disasters will wipe out all life and destroy the planet itself. We begin the countdown to the end of the world.

More than 68% of fresh water is solid, including glaciers, snow cover and permafrost. The ice sheet contains about 80% of all fresh water on the planet. Scientists are inclined to believe that at current rates it will take more than 5 thousand years to melt all the ice on the planet, but if this happens, the level will rise by more than 60 meters. On these maps you will see the world as it would be if all the glaciers had melted. Thin white lines mark the boundaries of the land that still exist today.

Europe

Thousands of years later, in such a scenario, Denmark and the Netherlands would have become almost entirely part of the sea, including the capitals and largest cities of Europe. In Russia, this fate would have befallen the second largest city, St. Petersburg. In addition, the expanding waters of the Black and Caspian seas would swallow many coastal and inland cities, most of which are in Russia.

North America

In this case, the waters of the Atlantic Ocean will completely bury the state of Florida and many coastal cities in the United States. Significant areas of Mexico, Cuba, Nicaragua, Costa Rica, and Panama will also be under water.

South America

The waters of the Amazon will become a giant gulf, as will the waters of the confluence of the Uruguay and Parana rivers on the southeastern coast of South America. The capitals of Argentina, Uruguay, Venezuela, Guyana, Suriname and Peru, as well as a large number of coastal cities, will be under water.

Africa

If global ice melted, Africa would lose less land than other continents. But rising Earth's temperatures would make parts of Africa uninhabitable. The northwestern part of the continent would suffer the most, as a result of which the Gambia would almost completely go under water, and parts of the land would be significantly damaged in Mauritania, Senegal and Guinea-Bissau.

Asia

As a result of the melting of ice, all Asian states that somehow have access to the sea will suffer. Indonesia, the Philippines, Papua New Guinea, and part of Vietnam will be significantly affected. Singapore and Bangladesh will go completely under water.

Australia

The continent, which will almost completely turn into a desert, will acquire a new inland sea, but will lose all the coastal cities where most of the population currently lives. Today, if you leave the coast and travel about 200 kilometers into Australia, you will find only sparsely populated areas.

Antarctica

The Antarctic ice sheet is the largest on Earth and is approximately 10 times larger in area than the Greenland ice sheet. Antarctica's ice reserves amount to 26.5 million km³. The average ice thickness on this continent is 2.5 km, but in some areas it reaches a maximum of 4.8 km. Research shows that due to the severity of the ice cover, the continent subsided by 0.5 km. This is what Antarctica will look like without the ice sheet.

Miscellaneous

What will the Earth look like in 5000 years?

February 28, 2018

Over the past five thousand years, human civilization has made significant progress in its technological development. The appearance of our planet today is a clear indicator of how capable we are of changing the natural landscape.

People and energy

People have learned to influence not only the landscape, but also the climate and biodiversity of the planet. We have learned to build giant skyscrapers for the living and huge pyramids for the dead. Perhaps the most important technological knowledge and skill that we have acquired in the process of development of science and culture is the ability to use the energy of the world around us: geothermal, solar, wind, and so on.

We can already extract energy from the atmosphere and interior of the Earth, but we need more and more all the time.

This inexhaustible appetite for more and more energy has always determined and continues to determine the development of global human civilization. It will be the engine of development over the next five thousand years and will dictate what life will be like on planet Earth in 7010 AD.

Kardashev scale

In 1964, Russian astrophysicist Nikolai Kardashev put forward a theory about the technological development of civilizations. According to his theory, the technical advancement and development of a particular civilization is directly related to the total amount of energy controlled by its representatives.

Taking into account the stated principles, Kardashev identified three classes of advanced galactic civilizations:

• Type I civilizations have learned to manage the entire total energy of their planet, including its interior, atmosphere and satellites.
• Type II civilizations have mastered the star system and mastered its total energy.
• Type III civilizations manage energy on a galactic scale.

Cosmology often uses this so-called Kardashev scale to predict the technological advancement of future and alien civilizations.

Type I civilization

Modern humans don't even appear on the scale yet. In fact, global human civilization belongs to the zero type, that is, it is not advanced. Scientists are confident that in a relatively short time we will be able to achieve the status of a first type civilization. Kardashev himself predicted that this moment would come. But when?

Theoretical physicist and futurist Michio Kaku predicts that the transition will occur within a century, but his colleague, physicist Freeman Dyson, suggests that it will take humans twice as long to achieve advanced civilization status.

Kardashev, during a discussion of his theory, predicted that humanity would reach the status of a Type II civilization in 3,200 years.

If humanity can achieve only the title of Type I civilization in five thousand years, this will mean that we will be free to control atmospheric and geothermal forces and processes. This means that we will be able to solve environmental problems, but wars and self-destruction could still threaten the survival of humanity as a species even in 7020.

Type II civilization

If planet Earth reaches type II status in 5 thousand years, then the people of the 71st century will have enormous technological power. Dyson suggested that such a civilization could surround the star with satellites in order to harness its energy. In addition, the technological achievements of such a civilization will most definitely include the possibility of interstellar travel, the creation of extraplanetary colonies and the movement of space objects, not to mention advances in computer technology and genetics.

People in such a future will most likely be significantly different from us, not only culturally, but perhaps also genetically. Futurists and philosophers call the future representative of our civilization a posthuman or transhuman.

Despite these predictions, a lot can happen to our planet and to us in five thousand years. We could destroy humanity with nuclear war or unwittingly devastate the planet. At the current level, we will not be able to cope with the threat of a collision with a meteorite or comet. Theoretically, we could encounter a Type II alien civilization long before we ourselves reach the same level.

Source: fb.ru

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Miscellaneous
Miscellaneous

Drift theory. All continents are moving. Their movement is based on the theory of lithospheric plate drift. Initially, the basis of theoretical geology at the beginning of the twentieth century was the contraction hypothesis. The earth cools like a baked apple, and wrinkles appear on it in the form of mountain ranges. The German meteorologist Alfred Wegener opposed this hypothesis with a report on continental drift. But his theory was rejected because could not find the force that moves huge continents. Alfred Lothar Wegener German geologist and meteorologist, creator of the theory of continental drift. He died in 1930 during the third expedition to Greenland, without having proven his theory. Types of plate displacement. Continental collision The collision of continental plates leads to the collapse of the crust and the formation of mountain ranges. This is an unstable structure; it is intensively destroyed by surface and tectonic erosion. Active continental margins. An active continental margin occurs where oceanic crust subducts beneath a continent. Island arcs. Island arcs are chains of volcanic islands above a subduction zone, occurring where an oceanic plate subducts beneath a second oceanic plate. Ocean rifts. On the oceanic crust, rifts are confined to the central parts of mid-ocean ridges. New oceanic crust is formed in them. From an analysis of the movements of the continents, an empirical observation was made that every 400-600 million years the continents gather into a huge continent containing almost the entire continental crust - a supercontinent. Modern continents were formed 200-150 million years ago, as a result of the breakup of the supercontinent Pangea. Rodinia. Rodinia (from Russian Rodina) is a supercontinent that existed in the Proterozoic, a zone of the Precambrian period. It emerged about 1 billion years ago and broke up about 750 million years ago. Rodinia is often considered the oldest known supercontinent, but its position and outline are still a matter of debate. Pangea. Pangea is the name given by Alfred Wegener to the procontinent that arose during the Mesozoic era. Pangea split apart approximately 150-220 million years ago. Laurasia and Gondwana. Pangea split into two continents. The northern continent of Laurasia later split into Eurasia and North America, while the southern continent of Gondwana later gave rise to Africa, South America, India, Australia and Antarctica. Tectonics on other planets. There is currently no evidence of modern plate tectonics on other planets in the solar system. Studies of the magnetic field of Mars conducted in 1999 by the Mars Global Surveyor space station indicate the possibility of plate tectonics on Mars in the past. Earth after 50 million years. It is assumed that in 50 million years the Indian and Atlantic oceans will grow, the Pacific will decrease in size. Africa will move north. Australia will cross the equator and come into contact with Eurasia. Earth in 100 million years. The Mediterranean Sea will be halved. North and South America will change their direction and move east. The Atlantic Ocean will split into two parts, the North Atlantic and the South Atlantic. Antarctic snow will gradually begin to thaw. Earth after 250 million years. In 250 million years, Australia will be completely connected to Indochina, Indonesia will turn into a plateau or high mountain plateau. There will be no more Mediterranean Sea. In its place will rise mountains that can give shape to the current peaks of the Himalayas. The southern tip of Africa will be sandwiched between South America and Southeast Asia and will gradually sink and turn into a large lake...

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