Beaches are disappearing, but beaches are growing: what links global warming and the GRU

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Beaches are disappearing, but beaches are growing: what links global warming and the GRU
Beaches are disappearing, but beaches are growing: what links global warming and the GRU
Anonim

Recent scientific work claims that by the end of the century, half of the sandy beaches "will almost disappear", and refers to what appears to be satellite photos. A slightly earlier study in a scientific journal of the same publication says that beaches are growing quite quickly - and also refers to satellite images. And the same ones. How do scientists do this and what will happen to the beaches in reality? Let's try to figure it out.

Not only the economy of tourism-oriented countries depends on the existence of these sand strips, but the stability of the coastline, as well as the operation of ports. So what is really going on with the beaches? / © Wikimedia Commons

Fortune telling: from a photo and without it

The magazine Nature Climate Change published an article according to which sandy beaches are undergoing severe erosion and, combined with the rapid rise in sea level, this means that by the end of the century half of them will "almost disappear" - namely, retreat by up to 100 meters. The British The Guardian (and not only) slightly "sharpened" the headline so that it was more terrible: you have to live on something. It came out: "The beaches of the world are disappearing due to the climate crisis."

In April 2018, Nature Scientific Reports released another paper that received little to no press coverage. It said that beaches around the world are growing. Maybe the newer work takes into account some of the most recent data? This can be easily verified with Sci-Hub, where its text is available.

Alas, there is no mention of new satellite imagery there. On the contrary, links to real beaches in the observed world go to the same place as in the first job. How did it happen that the sandy shores by 2100 will be largely lost?

It's simple: they used modeling of future processes with them in the case of sea level rise predicted for different scenarios of CO2 emissions. Let's remind: some of these scenarios promise a meter rise in the water level before the end of the century. Many of these beaches are very shallow and should be flooded easily in theory.

But there are some details that are in doubt. The rise in sea level did not begin yesterday, for decades it has been growing by two or three millimeters per year. If we proceed from the logic of the authors of the work, according to which the onset of the sea means the death of the beaches, then it should be in full swing right now.

What the photos show, not the models

The importance of photographs taken from space in the study of the Earth cannot be overemphasized. Before them, in the scientific literature, estimates of the length of the sea coast occupied by sandy beaches varied from 10 to 75% of the total length of the coasts, differing many times. This is natural: the coastline in the world is 622 thousand kilometers, scientists do not have enough money and time to study them even with aerial photography, let alone expeditions.

And yet we would definitely like to appreciate the beaches: 44% of the world's population live no further than 150 kilometers from the sea coast, for them it is a typical vacation spot. But even if you are a workaholic or a resident of northern Russia, you still need a close beach: it protects the coast from destruction by waves. Because of the importance of the issue, they tried to investigate it, and a number of scientific works claimed that 70% of all beaches in the world are destroyed.

The situation with the exploration of the world's beaches was corrected by satellite images for 1984-2016. From them it became clear that sandy beaches cover 31% of the world's sea coast. In Europe, this share is minimal, 22%, and in Africa, it is maximal, 66%. At the same time, 27% of all of them attacked the sea at a speed of 0.5 meters per year or more. 24% retreated inland at the same speed. 47% experienced fluctuations below 0.5 meters per year in any direction.

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The picture was not uniform. Australia recorded an average of 0.2 meters of beach loss per year, while Africa experienced an annual loss of 0.07 meters. On all other continents (excluding Antarctica, where there are practically none), beaches have grown. The average growth in the world was 0.33 meters, in Asia - 1.27 meters per year. In total, in 1984-2016, the area of ​​beaches increased by 3,663 square kilometers, that is, it was roughened by 110 square kilometers per year. This is a lot: the fact is that there are only a few tens of thousands of square kilometers of beach areas in the world. It turns out that they have added significant percentages in just a third of a century.

Why? The first answer that comes to mind is human activity. People often wash up sandy beaches around their cities because it reduces damage from storms. They also often deepen the fairways of navigable rivers and large ports so that larger ships can pass there. Sometimes there is nowhere to put the sand raised from the bottom, and then it is thrown ashore.

But on the map above, you can clearly see that the beaches are growing in the uninhabited north of Canada, and in the almost uninhabited south of Chile, and in New Zealand, and in the south of Madagascar, where no one really shores the coast.

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In addition, a person not only lavishes sand onto the shore, but also takes it from there. The authors of the corresponding work cite the example of the Mekong Delta in Asia, where the beaches have been receding 25-30 meters a year for three decades. Another example of a coastline strike is Mauritania and Portugal, where the construction of breakwaters near the ports prevented the sand flowing with the currents near the coast from replenishing existing beaches. As a result, there was observed a beach retreat of 20-30 meters per year.

Undoubtedly, there are also places where it is a person who activates the onset of sand, but the authors of the 2018 work do not dare to conclude that it is he who is the cause of the changes. It seems that a person narrows the beaches in some places by about the same amount as he expands them in others.

What will happen to them in the future

Well, today the beaches are growing by 110 square kilometers per year - despite the rise in sea level by 2-3 millimeters per year. The reasons are not very clear, whether a person or not. But can you imagine what will happen to them in the future?

We must say bluntly: there are no full-scale works on this topic at the moment. The work of 2020, which promises the death of half of the beaches by 2100, cannot be attributed to them. Mainly because she makes no mention of the fact that in the real world today, beaches are rising despite rising sea levels. Accordingly, the authors of the work do not try to explain on the basis of what they believe why, after a third of a century of the onset of the beaches, they will now suddenly begin to retreat. They may be hoping for a sharp acceleration in the rise of sea level, but this is clearly not said anywhere in their work. Therefore, all of us can only guess why they ignore the actual growth of the beaches and promise their rapid reduction.

However, a number of cautious assumptions can be made now. To do this, it is enough to think: where, in fact, does the sand come from in the sea, from which the beaches are formed? It has two main sources: crushed pieces of rocks, which are carried by rivers to the sea, and crushed fragments of coastal rocks and sedimentary rocks, the consequences of wave erosion. In some places at the regional level, coarse sand appears when waves grind the shells of dead molluscs. What will happen to these sources of sand as global warming and the advancing sea?

It is quite obvious that the removal of crushed rocks by rivers will increase: global warming leads to an increase in precipitation (over the past century, they increased by 2%), namely, precipitation causes erosion of various rocks inside the continents. The water fills the rivers and allows them to carry the ground into the sea.

The offensive of the sea (where, of course, it will occur, because in Bangladesh and other densely populated countries, in reality, land is advancing on the sea, due to the activities of people) should significantly increase the erosion of coastal rocks and sedimentary rocks.

The shells of dead molluscs will also only multiply as it warms. It is not difficult to compare the number of shells on the coast of the northern seas and, for example, the Azov seas, in order to understand: there are clearly more mollusks in the warm seas.This is also indicated by fossil remains from past eras: the Cretaceous period is not called that by chance, but precisely because it gave a very thick and therefore stand out layer of shellfish remains.

Green plague

This does not mean that nothing threatens the usual appearance of the beaches. A recent analysis of changes in vegetation in the coastal zone from 1984-2017 showed that coastal dunes are actively covered with vegetation, due to which they can no longer migrate with the winds.

That is, the wind load of sand on actively moving dunes is becoming weaker: overgrown areas do not allow a large amount of dust to be carried off. The reasons for overgrowing are the same as all over the planet. Most of all, plants stimulate an increase in the concentration of CO2 in the air, then a slight increase in precipitation.

All of this will have very big implications for typical beaches. Overgrowth means a sharp decline in the number of mobile dunes - or even their complete disappearance. This is a fairly tough connection, historically confirmed. In the last ice age, the shores of the seas were covered with bare sand dunes, constantly blown by the wind.

Ice samples from Greenland show that the dustiness of the air was 20-25 times higher than today. It is easy to guess that in the Ice Age, there were no sources of sand and dust in Greenland. Solid particles were carried there with the wind, thousands of kilometers away. People of that era had to live in conditions of extremely frequent sandstorms and the rapid onset of wind dunes.

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A local, reduced analogue of such a situation can be considered the situation in the village of Shoina in the Russian Arctic. Just like in the glacial world, it is rather cold here, and the winds, as befits a seaside region, are strong.

Shoyna is an exception to the rule for the modern Polar region, because the river flow in the north is much less today than in low latitudes, and there is not much river sand near the sea coasts. Instead, Shoinu is swept in with sea sand, which is beaten to the shore by the waves, and then freely carried by the wind. In other areas of the Arctic, there is not so much sea sand, therefore, there are no mobile dunes.

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In 1400-1850, a relatively cold period began in Europe, and at the same time, a strong attack of coastal dunes began on continental lands, including fertile ones. The reasons are simple: in cooler climates, there are fewer plants, and it is they who, with their roots, keep the sand masses from rapid wind transfer. At the same time, as recorded in historical sources, the authorities of various European countries began to specially plant forests near the coast - so as not to lose arable land adjacent to the sea.

It looks like we have finally found a threat to the beaches: in many areas, their farthest from the sea (and the area covered by the tide) will be overgrown with grass and shrubs.

What beaches, sharks, corals and New Zealand mussels boiled alive in common

We have to note with regret that turning reality inside out on the topic of "around and around global warming" is happening not only with beaches. It goes on constantly.

In order not to go far for examples, let's look through the news from recent months. Here: "Sharks may be left without scales due to the increase in the acidity of the oceans" (based on real scientific work). Or “Over 500,000 mussels were boiled alive due to global warming” (there was, however, no scientific work behind this, only an obscene video of one New Zealander on Youtube). And here's another: "Coral reefs predicted extinction by 2100." All this hot news has one unpleasant side: people who read it are misinformed.

Let's take sharks. It is known that they have existed for hundreds of millions of years, and just a hundred million years ago (Mesozoic) the ocean was much more acidic than the current warming promises us (it was too warm during the dinosaurs). Why do shark fossils have scales? The authors of the corresponding work did not give any answer to this seemingly simple question.

We will not give it either, we only advise you to remember the school course in biology. Within its framework, teachers sometimes say that sharks enter large rivers 400 kilometers upstream and live there for years. Moreover: in the freshwater lake of Nicaragua, sharks hatch their offspring and also live there for years (including adults). All this happens despite the fact that the pH of fresh water is not higher than 7.0, and in the Amazon, where sharks rise four thousand kilometers from the mouth - up to 4-5. But the pH of seawater, even in the Mesozoic, did not fall below 7, 5. By the way, by 2100 it is not expected to be lower than 7, 7.

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Output? That's right: modern sharks retain their scales at a pH that ocean water will never, under any acidification, in principle, because salt water will not get a pH even at 7.0 (like fresh water). Of course, they will slightly increase their scale renewal rate. But it is obvious that they do not particularly suffer from this - otherwise they would not go to rivers and freshwater lakes of their own free will and would not multiply there at a frantic pace, as they do in Lake Nicaragua.

The reader has already begun to suspect something about mussels, right? He definitely has a reason. The live-boiled mussels video shows green New Zealand mussels. Global warming does not threaten them with extinction, because they are one of the most heat-stable on the planet, and begin to perish only after +32 degrees. And today in the waters where they live, the temperature is only +18, by the end of the century no more than +22 is expected.

In the famous video, they did not die from global warming, as the Western press described it to us. Everything is much more banal: at the time of the addition of the vectors of solar and lunar ebb tides, the water recedes record-breakingly. As a result, many mussels find themselves without a water cushion over their heads for much longer than usual. When such an event coincides with a not too windy afternoon, mussels heat up to 40 degrees (stronger than air - their shell is dark) and die.

Of course, such an event has nothing to do with global warming. In New Zealand, it was sunny enough at noon and before any warming that mussels, spending many hours on the beach at record low tide, died from overheating.

By the way, not only there: overheating mussel frost is an important part of the ecology of coastal zones. If the mussels did not die periodically, their barnacle competitors could not exist at all, because they differ from mussels in better resistance to heat, but they cannot withstand a direct struggle. Only such deaths free up the ecological niche for barnacles, and without them, the biodiversity of the coastal zone will inevitably decrease.

By the way, all these deaths do not threaten the total number of green New Zealand mussels either. Their population is rapidly and steadily growing - they have even become an important object of New Zealand aquaculture. Don't believe me? Go to a good seafood store. New Zealand green mussels are actively sold in Russia, on the other side of the world. Growing them in cages on the open sea, New Zealanders get such an amount of biomass that it becomes economically profitable to export it even for 20 thousand kilometers, especially since they stewed in white wine will be tastier than European ones, and are comparable.

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Finally, corals. The stories of their extinction by the year 2100 are based on … Yes, you guessed it right, solely on modeling. None of the builders of the corresponding models, however, have answered one simple question. At the end of the last ice age, just a dozen thousand years ago, temperatures rose faster than today. But for some reason, neither corals nor the Great Barrier Reef disappeared anywhere. Yes, they moved in the wake of the advancing waters. But on the fossil remains of ice age reefs, it is not noticeable that the species diversity of corals after the glacier melted was less.

It is easy to guess why the corals did not even think to die out at that time: the greatest flowering of these creatures in the past of the Earth fell on epochs much warmer than the present.Moreover, today there are regions where heat-loving coral species are expanding, despite warming. And their expansion is likely to continue until at least 2100. They also endure acidification of ocean water.

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Why, even before the extinction of sharks, corals and mussels, is everyone in a hurry to blame global warming for this? Well, on the one hand, there are reasonable reasons for this. Neither one nor the other, nor the third, as we noted above, will not die out and lose their scales from global warming. Therefore, warming can be blamed for their collapse only before the prediction is fulfilled: it will not work after that, because it will never come true.

There is another reason why global warming is to blame for all this. In the modern media space, it plays the same role as the GRU in the American press. Who supported the villainous Republican Trump in the election? Of course, the GRU - in the States, few dispute this. And who is supporting the villainous Democrat Bernie Sanders? You get the point: of course, again the Russians (and again in this context the GRU is mentioned). Whoever wins - of those who are disagreeable to the American establishment - will certainly be led to victory by Russian interference in the elections.

Likewise, global warming will be blamed for all the bad things that happen in our environment. And often even in what is not happening in it. Like "disappearing" in reality, growing beaches, "extinction" of corals or "dissolution" of shark scales.

What makes some scientists trust models, not observable reality

So, the future fate of the beaches on the planet is relatively predictable. North of 50 degrees, their area will grow in almost any conceivable scenario - because the river sand production will increase. In Africa, sandy beaches will gradually decrease due to the gradual overgrowth and erosion, in Asia and other places they will rather grow (because there is more activity in the reclamation of beaches).

Even if people, for some reason, abandon reclaiming land from the sea, which they are doing right now (despite the rise of the sea, the coastal land area is growing), the transfer of sand by waves will still prevent the beaches from being greatly reduced. Another thing is that part of them far from the sea will gradually overgrow, especially where there are no strong tides.

But what about the recently released work that promises to "nearly disappear" half of the world's beaches by 2100? To understand what prompted its authors to make such predictions and not say a word that beaches are growing in the real world, let us allow ourselves a quote. The recently deceased physicist Freeman Dyson famously commented many years ago:

“I see a bias in the way we are told [about global warming]. Everything that looks bad is reported to us in the press, and everything that looks good is not reported."

And further: “The question is: how could they believe their models [predicting a warming catastrophe]? Well, I've seen it in all sorts of different fields of science. You sit in front of a computer for ten years in a row and start thinking of your model as a reality. And, in truth, the very well-being of such people depends on how much they frighten other people. It is purely psychologically difficult to go out and say, "Don't worry, this is not a problem." No, when their whole life depends on this [global warming] being a problem."

Note that we do not think that the motivation behind the "disappearing" growing beaches boils down to a desire to scare people more so that it will be easier to receive grants for further research. Almost certainly, most of the scientists doing this do believe that beaches will disappear and warming is destructive. In itself, this is not a problem: scientists are people too and can also believe in strange things, everyone has the right to make mistakes. The problem is that such researchers talk about their models ("the death of beaches"), but do not talk about what is happening in real life, where the beaches are growing.

It really looks like a systematic distortion and highlighting only the bad consequences (even if they exist only within the model), while keeping silent about the good ones (even if they exist on the real Earth). And here Dyson is right: there is a systematic bias.

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