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Suppose the Earth entered a period of intense global warming, say by 50° Fahrenheit (28° Celsius), and then levelled off at the new, higher, temperature. Obviously, anywhere near the equator would not be inhabitable, and melting icecaps would cover much of the coastal regions.

However, would this necessarily spell the end of humanity on Earth? Could people survive just by moving to higher latitudes, and have societies similar to the ones that exist nowadays?

Or would the heat mean the end of the world as we know it?

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    $\begingroup$ What noone seems to mention is that adding too much (fresh) water from the melted ice to the oceans would drastically disrupt the currents, which would lead back to even more major climate changes. $\endgroup$ – user1853181 Dec 8 '14 at 3:16
  • $\begingroup$ en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum $\endgroup$ – Victor Stafusa Dec 8 '14 at 6:05
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    $\begingroup$ Your question is missing the essential estimate of the time it takes to reach that new level. $\endgroup$ – user3106 Dec 8 '14 at 14:47
  • $\begingroup$ BTW expected change is much less (under 10°C - 20°F) but disruptions are global and disastrous, as I mentioned in my answer including some questions to ponder. We have no international framework to solve such kind of problems. $\endgroup$ – Peter M. - stands for Monica Dec 8 '14 at 20:08
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    $\begingroup$ @imallett: ... or failing to plan (or refusing to plan) and assuming someone else will solve it. $\endgroup$ – keshlam Dec 9 '14 at 4:14

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Other answers have mostly concentrated on the persistence of zones of reasonable temperatures and the means to mitigate rises. I think jamesqf is more on track with his answer about photosynthesis.

The problems of that degree of rise won't be direct. It'll be the total ecosystem collapse that causes the problem and the difficulty of transferring it to other places. Antarctica will reach a habitable temperature, sure, but it'll still have a night that lasts months and a day that last months and I doubt that the soil that is revealed will be suitable for growing crops in any short period of time. It isn't just a matter of temperature it's a matter of putting into place all the other factors that support life. The new land won't be like the old land; it'll be altogether most hostile and barren. Moreover, the loss of vegetation across most of the globe could result in catastrophic declines in oxygen levels making things even more difficult for the survivors.

Meanwhile, it's likely that this kind of change would cause catastrophic ecosystem collapse in the oceans too both from changes in water temperature (with accompanying changes in circulation patterns) and from severe acidification from the higher atmospheric levels of carbon. So it's not like looking to the seas will help much.

Now, humans might be able to survive all this by pouring money and tech into it but it's going to get mighty hairy. My inclination would be to think that some people would cling on for a while but one-by-one the last settlements of humanity would fall to one disaster or another until the last humans die out.

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The average high temperature in summer at the south pole is -15F. Add 50F to that, and you just get above freezing. Again, that's at the height of summer. So you are still going to have a very wide range of climate on Earth. Now it gets a little more complicated when you start looking at record breaking high temperatures. You might start seeing 140F or higher in NYC, for example. That obviously starts getting into the fatal range without air conditioning, especially if its for more than a few days. Its possible you'd start seeing major environmental engineering projects designed to keep cities cool.

The biggest impact I think would be the years following as agriculture tries to adapt. So there may be a few years of famine world wide, with the nations with the least sophisticated food distribution systems being worst hit, unless their land happens to be one of the areas that becomes more farmable.

People will move to higher latitudes, as some areas will be down right fatal for much of the year. But other areas might become quite pleasant. You get 2 whole new continents - Antarctica and Greenland to settle, so its not a complete loss.

So the end of Humanity? No, not remotely. It'll be quite an upheaval for humans, but not 'the end'.

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  • $\begingroup$ Neither Greenland nor Antarctica has much/any arable land. Bare rocks under glaciers do not have fertile soils - it will take millennia to rebuild the soils. $\endgroup$ – Peter M. - stands for Monica Dec 8 '14 at 1:29
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    $\begingroup$ They said the same thing about the American west too, at one point. But even if its not great for farming, people can still live there a lot more easily than they can live there now. $\endgroup$ – GrandmasterB Dec 8 '14 at 4:28
  • $\begingroup$ Is Greenland a continent? Major landmass, yes. $\endgroup$ – Gusdor Dec 8 '14 at 12:05
  • $\begingroup$ @GrandmasterB - Yes you can live there is someone else somewhere else produces food for them. According to my reading, productivity of Earth ecosystems will significantly degrade after global climate change and sea level increase. $\endgroup$ – Peter M. - stands for Monica Dec 8 '14 at 15:15
  • $\begingroup$ @Peter Masiar It may take millennia to rebuild the soils naturally, but humans can create fertile soil in a matter of months. $\endgroup$ – Kevin Krumwiede Dec 8 '14 at 16:02
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Certainly no, yes and yes.

Would all Humans die?

No. Humans can happily survive a daily average temperature of 38°C/100°F (Sahara). This does not mean that everyone can, just Humans in generell. The Equator regions may indeed become ininhabitle, but a bit away human life should be easily possible.
Temperature isn't everything though. Higher temperatures and massive movement of humans will spread diseases previously unknown in colder countries, like Malaria ect. Many Humans will die because of this, even with a slow rise in temperature, simply because we coldies have absolutely no idea what this diseases are and how to handle them. Of course, there are scenarios planned for this, but honestly, no plan survives contact with reality.
The next part are natural disasters. Many regions will face climatic specialities they never encountered before (in this strength). Tornados, Hurricans, nearly everything with wind would totaly wreck havoc, simply because the newly affected regions are not used to these disasters. There are Emergency plans, but I believe they do not account for such a dramatic change.

Can people evade the effects of this change?

Yes with a big no. You can not totally evade. Climate is a global thing, which means also higher latitudes will be affected. This means that even at high altidues you'd have to face some of the problems you have at low altidudes. Wind is strong, and even more around the top of a mountain. Good thing though is you can't be washed away by the sea. Pros and Cons.

Will Humanity as we know it end?

Definitly Yes. As mentioned by ArtOfCode there is simply less space to live on. Luckily (in a morbid sense), there are also less competitors over this land because of the mentioned reasons. Almost every state would most likely fall to the panic of the population or the organisatorical parts of the disaster-managment in one way or the other, which means we would have to find other ways to keep the order.
Emergency Goverments would take over at first, but it depends on the people leading them in which way they will develop. Some will fall to Anarchy, others will stabilise. Tyrannies may rise, and we might find new ways to reign countries. War over the remaining ressources may emerge, costing even more lifes.
In short, There would be massive changes in nearly every way of life.


Please note that the drastic picture I drew here is for a rapid rise in temperature. Nobody can say what will happen with a slow increase in temperature to the mentioned point, as new techologies would show up as needed. If given enough time, scientists could develop better detection-systems for natural disasters, and could possible even find ways to stop some. In a slow change, there would be no panic in the population, because it just happens (the Aral Sea almost vanished over the course of 25 years, and there was no public uprise). This means that I can't give a good prediction for the slow case, other than

Humans will adapt or someone makes something reallly stupid so a lot of people die
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  • $\begingroup$ This looks really realistic. I would just say: Once the population is significantly reduced, you'll be very likely able to get enough food from the sea, that's something the new society would manage once it would have settled down a bit. $\endgroup$ – yo' Dec 8 '14 at 20:27
  • $\begingroup$ I would like to ping you on a related post but I can't so hey: There's an email waiting for you on the account with which you signed up to the mapping site. It contains important details about a needed password reset. $\endgroup$ – ArtOfCode Dec 17 '14 at 20:56
  • $\begingroup$ Humans can survive in dry air at 38˚C. If the wet bulb temperature goes above 35˚ then no one can survive for more than a few hours, because the body has no way to cool itself, so 38˚C with 100% humidity is fatal. And a much warmer Earth will have a much more humid atmosphere, since much more water will evaporate. $\endgroup$ – Mike Scott Nov 10 '15 at 11:59
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Problem is not survival of humans (some will survive) - problem is survival of humanity - our cultures and technology.

I read somewhere that carying capacity of Earth in such conditions would be about 1B people, living mostly in high north latitudes (equator region would be uninhabitable) and sea level will increase some 200 feet (70 meters). Now we have 7B, and we will lose substantial part of good productive agricultural land.

So I assume you are looking for the questions to be asked, what changes we can expect. Here are some:

  • Imagine the war for habitable territories and resources: Russia has most of Eurasian territory close to polar circle, and it's population is decreasing. What would India and China do?
  • How would politics in USA change if south will not be habitable? What about all the population of Mexico? Will USA invade/annect Canada?
  • It just happens that Africa and most of Muslim world is doomed by climate changes. What would happen to Israel? And low-lying island nations?
  • What to do with the population of Africa (which still has 8 children per female): if some country will accept them, will they force one-child policy? For all, or for immigrants only? Will they have vote in new countries? Will they have to abandon their old religion?
  • If problem is obvious now when say Nigeria has 100M population, will we save all 300M of Nigerians 200 years from now? or will we force then first to "downsize" by 1 child policy in their own countries? How will local government enforce such policy?
  • Will we provide emergency food for starving people in Africa where they cannot grow enough food for steeply increasing population, but still have steep population growth?
  • Will United Nations develop into single world government?
  • Many cultures will not survive (like low-lying islands). How much resources we dedicate to preserve disappearing cultures of pacific islands if 70% of some country in Africa are starving to death, but not in danger of disappearing as a culture?
  • Is tolerable to downsize population by war for resources? Will we let countries in Africa to fight it for water and arable land? Will we take sides - and what would be the rules?
  • Will "Earth protection league" develop military/terrorist actions against nations which do not comply by population restriction requirements, unleashing deadly diseases to eliminate population in excess of what "world government" allowed for such countries?
  • Will humans become vegetarians? If people are starving, can you spend 10 pound of corn to raise 1 pound of pork meat? Will people tolerate that some people are willing to pay for pork? How much are we willing to spend on protection of endangered species?
  • Will people ask to clawback/surtax the profits of oil-extracting companies to pay for the cost of adaptation to climate change and sea levels? Who will pay of relocating of Bangladesh population, 100M of some of the poorest people on Earth, to higher grounds - and who will provide such grounds?
  • What will happen in the oceans? With increased acidity, many small ocean creatures will not be able to build the shell, so food pyramid would collapse. No more fish, algae and jellyfish takes over.
  • And there are plenty of smaller local problems. Say 30 years ago Afghanistan has population of 7M and was barely able to be self-sufficient in food. Now it has 20M and after 30 years of neglect, irrigation is in disrepair (and in places landmines prevent maintenance). So growing 4 times the wheat wheat for food on less land is no more economically viable. Only viable product is heroin (poppies need no irrigation, and is easy to transport), and population is still growing. Will we force them to grow wheat and starve? Provide with free food? Buy heroin from them?
  • Will be countries which profited most from industrial revolution and which become rich by extracting carbons from earth and releasing them to atmosphere (Europe and USA) required to pay for climate remedies? How such rules will be enforced? By carbon extracted?

Yes, it will definitely will be interesting, and unlikely of anything we've seen before. yes, it does mean end of world as we know it.

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    $\begingroup$ Not that it has a huge effect on the answer, but I can't find a reference that Africa, on average, has 8 children per family. A best it appears closer to 3 or 4: cia.gov/library/publications/the-world-factbook/fields/… $\endgroup$ – DA. Dec 8 '14 at 7:09
  • $\begingroup$ Depends in which country. Even with 4 it will double every generation. And they already don't have resources to feed current population. $\endgroup$ – Peter M. - stands for Monica Dec 8 '14 at 15:08
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The problem of such a climate change (the same as our current one) is not so much the magnitude (there will still be inhabitable zones), but the speed. While many animals might be able to migrate (and many won't), plants simply can't migrate very fast. This means that if this change happens fast enough, the only plants that will be in conditions favorable to them will be

1) some very rough ones (I have no clue which plants, though, probably grass) 2) human cultured plants and trees

Humans can speed up the process of migration, but essentially you will probably lose 99% of all species. In addition, if the climate change is this big, it may be that the oceans get warmer as well. This will wreak havoc for the sea life near shores, and might cause other disasters as well (more evaporation = more rain, algae growth, ...), that might affect both land life and deep sea life.

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My guess? Probably not, as human life depends on having a lot of ecosystem to support it. Start with the fact that photosynthesis basically stops at high temperatures: C3 (the great majority of plants) shuts down at about 45C, C4 at about 55C. (This is leaf temperature, not air temperature, and leaves in sun are likely to be warmer than the surrounding air, unless they can cool themselves by water transpiration.) So, since all life (barring ocean vent communities &c) ultimately gets its energy from photosynthesis, you've drastically reduced the size of the available life support. MAYBE some humans could survive on that, but you've also reduced the margin of error.

And there will be errors. For instance, the postulated sudden warming will actually kill off a lot of life. (That is, trees in the tropics will not instantly be replaced by trees in the polar regions, as even under favorable conditions they'll take decades to grow to any size.) The decaying organic matter could trigger an anoxic event (http://en.wikipedia.org/wiki/Anoxic_event ), with release of H2S that kills off even more life...

AFAIK, the closest real-life example to such a sudden warming is the Permian-Triassic extinction event, AKA the "Great Dying".

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  • $\begingroup$ You can use H<sub>2</sub>S for H2S in the post (not in comments tho). For photosynthesis, remember that seas are almost unsensitive to daily temp changes, and average seas temperature is now below 45C-28C=17C at many places in the world, so it should stay below 45C after the temp raise. $\endgroup$ – yo' Dec 8 '14 at 20:29
  • $\begingroup$ Average, though, is not necessarily what's relevant here. It's whether the maximum will exceed the photosynthesis cutoff levels over large areas for long enough to kill off sea life in those areas, and then what the knock-on effects of all the decomposing dead things would be. My guess is that they would not be pleasant, though I don't think anyone really knows for sure. And that's my basic point: humans are supported by a lot of mostly unappreciated ecosystem. How much of it can you knock out before it collapses? $\endgroup$ – jamesqf Dec 9 '14 at 18:32
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Could people survive intense global warming?

If I'm understanding the sense of the question, I'm guessing probably not.

Disclaimer #1: @JanDoggen in comments, and answers from @Larethian and @kutschkem, all make a point of questioning how fast the change takes place. This is a key parameter: given a long enough timeframe, survival of the human species at these temperatures is much more plausible. However, because of the way the question was phrased, I'm going to give an answer that assumes an extremely fast warm-up: 50° Fahrenheit (28° Celsius) in no more than 200 years. That seems implausible in planetological terms. But hey. This is Worldbuilding.SE, and we traffic in counterfactuals all the time. :-)

Disclaimer #2: Just to be clear on one thing: My answer doesn't apply to the actual world we live in, because neither does the question in the first place. @abcde is asking an interesting worldbuilding hypothetical, and I'm treating it with the respect it deserves.

(I feel I have to say this because, in my experience, questions like this tend to activate our genuine concerns about our primary world. This can make sound reasoning difficult, and carry the discussion off-track. Arguing our opinions about what's actually going to happen to us and our inheritors would step all over the original question and not be particularly helpful to @abcde.)


Why humans probably wouldn't survive such an intense global warming event: This is a question of planetary ecology.

With a tip of the hat to @JackAidley and @jamesqf, the question of human survival is less a question of how you find a survivable latitude/altitude in the rapidly heating world. It's about what happens in the years after you've arrived.

Many of the answers here assume, rightly, that humans would have to migrate for survival. Migration is hard;

enter image description here

but let's talk about the survivors. Let's talk about the skilled, prepared, and extremely lucky people who actually make it to some reasonable place in northern or southern uplands.

Suppose you're one of those lucky ones. You've found a place. Now what are you going to do for food? Never mind medicine, weapons, shelter, etc, and let's take sufficient drinking water as a given: if you don't have food you won't live.

Humans are, in the short term, a whole lot more agile and adaptable than their food base.

  • Humans can travel; farms and gardens and orchards cannot. The best you could have done would have been to carry a lot of seeds - since you are, by definition, lucky, you didn't have to eat your seeds on the march - and to bring some skilled agriculturalists with you.

    So, you plant your crops. And most of them die.

    They die because

    • they need nutrients that they can't get, or

    • because the winds are too savage, or

    • because the cycle of drought and flood is too extreme, or

    • because rampaging pests that you have no idea how to handle kill them.

    In other words, your food crops are not adapted to the new local environment, and cannot adapt because the environment is still unstable.

    If you look around for native vegetation that has edible parts, you're probably not going to find anything, because the changing climate has probably already killed a lot of the local species. (This local ecological collapse probably has a lot to do with why you can't find those nutrients your crops need.)

    ...So maybe you brought animals with you?

  • Herds and flocks of domesticated animals are a lot more difficult to take with you on your long march. Many of them wouldn't have made it; but remember: you are one of the unreasonably lucky ones, so you have enough of a herd to form a stable food base for your little community of settlers.

    Now. What will those animals eat?

    You need a lot of grazing to support a large herbivore. (You should see what just two of my horses do to the grass in their fairly generously sized paddock.) Even under reasonably stable conditions, grazing animals will eat a lot of pasture down, which is why pasturage needs to be rotated several times during growing season.

    How much pasturage can you count on when there's a drought? Or a flood? Or a blight? All of which will be happening.

    Then: what do they eat in the winter? Did you - despite the probable insufficiency of pasturage - also manage to get enough hay mown in the summer that you can feed your animals the whole winter through (which means, until pasture has grown enough to let the animals graze?)

    And yes, growing seasons will be an issue: Even in a rapidly warming climate, you'll have colder times; and even if your winters remain warmer, plants don't feed on warmth, they feed on sunlight. If you've gone far enough north or far enough south, you've got parts of the year in which insolation is so weak that you won't get much to grow.

You can't run away from ecological collapse. The weather patterns will remain crazy. The pests that attack and kill your crops and animals will remain r-selected and thus prone to wild outbursts of population. And the organisms best suited to survival in an unstable environment are microorganisms: bacteria, viruses, yeast, fungi. Things that will kill you and your attempts at sustaining a food population

Even @GrandmasterB, in the most staunchly optimistic answer, notes correctly that

"The biggest impact I think would be the years following as agriculture tries to adapt." (Emphasis mine.)

In this unusually fast warming scenario, agriculture, along with other means of obtaining food over time such as hunting, fishing, and animal husbandry, will all fail because of the ecological collapse.

Humans in an intense global warming event would die off, probably, because they couldn't sustain themselves and their food supply over the long term.


Coda

Kudos on this one to @jamesqf. He deserves credit for a lot of key insights:

  • Mentioning the Permian/Triassic extinction, in which a worldwide ecological collapse brought life to a very rudimentary state.

  • Mentioning the possibility of another Ocean Anoxic Event, which would disastrously prolong any post-warming ecological collapse.

  • And, probably most powerfully, the comment that says "And that's my basic point: humans are supported by a lot of mostly unappreciated ecosystem. How much of it can you knock out before it collapses?"

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First and foremost, not everyone would be able to survive. Much of it depends how quickly this warmup happens: if it's quick and the ice melts very quickly, people on the coast aren't going to get out in time and you'll get much loss of property and life. If it's slower, you'll get less loss but more people competing for the remaining land.

This is the important point really: all the remaining people are going to be competing for much less land. It has been estimated (I'd link it if I could find it) that we'd lose 10% of the Earth's landmass if the ice all melted. The current estimate is that Earth can support around 9-10 billion people (call it 9.5 for now). With 10% less land, that figure goes down around 10% as well (not exactly because of other factors such as percentage arable land, but near enough), so we'd only be able to support 8.65 billion. Theoretically that's doable, but it's not going to work out that nicely.

The heat wouldn't be too much of a problem. 50F is what, 30C? If we stay inside most of the time and most buildings are air conditioned we could survive. It won't be comfortable though.

Finally, think of the impact of more people trying to squidge into the same space. We'd have to make space for some less desirable groups in our countries, such as IS and Al-Qaeda. Admittedly them killing people faster than ever before is going to make more space for everyone else, but do you really want another Holocaust?


So yes, in theory this global warming is survivable. However, I for one would be very interested to read about how humanity gets through without destroying itself. Does technology save it? Is there some diplomatic miracle? Who knows.

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While it probably wouldn't spell the end of humanity on earth there'd probably be a drastically reduced population.

Far less of the earth would be habitable by humans without the use of technology - air conditioning etc. Therefore we'd need use more energy to survive in a much smaller area. This probably wouldn't be sustainable. The new temperatures would affect what crops we could grow and animals we could farm so food could well be scarce too.

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It wouldn't be that large an issue for survival. Colder areas warm more than the already hot areas. This is because cold areas lose sunlight reflecting snow cover resulting in further warming, while hot areas gain evaporation that increases cloud cover and moderates warming. So very little area, possibly none would become uninhabitable due to heat compared to increases in habitable area in cooler climates.

The real problem with global warming is that it is happening faster than we can adapt. Areas that we rely on will be lost to sea or deserts. Including many major cities. Increases in agricultural land somewhere far away are not much of a consolation to people who have to leave their homes behind. And when this happens to hundreds of millions of people in short time, world will have major problems. Large social, political, and economic upheavals would happen. Possibly including wars.

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I would suggest surviving intense global warming would be technically possible for a few "chosen" people. But the issue is not so much intense global warming but on how intense. IF there was the wide variance of the planets warming as it is now, some places would not sustain life unless specialised, but others could. If oceans are looked at, in times past, the convener belt ocean current type of heat transfer could make some areas more or less inhabitable. For the most part, it's suggested we are not able to influence actual planetary climate, and it comes in cycles, so this is the reason migratory patterns for birds and other species to have become established. I would think this might become the pattern for life in the future, and I think species could adapt, depending on the level of increase of global warming. BUT don't be alarmed. Global warming has left a lot of unfinished questions in the "science" of planetary climate and it may be that we are in for global cooling if patterns repeat. Look up this site, http://www.landscheidt.info/ for more questions...AND KEEP ASKING QUESTIONS.

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A 28˚C increase probably kills all life on Earth in the long run, except perhaps bacteria deep underground or in the upper atmosphere, because it turns the Earth into Venus. We're already very close to the inner edge of the habitable zone around the Sun, and such a big increase would push us over.

The problem is that the upper atmosphere gets full of water vapour, which photodissociates into oxygen and hydrogen, and the hydrogen then escapes into space. Over millions of years, the Earth loses all its water. With no plant life, CO2 emitted by geological action is no longer removed from the atmosphere and we get a runaway greenhouse effect ending up with a dense CO2 atmosphere and a very hot surface temperature.

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  • $\begingroup$ Venus is not just 28C hotter, it is a LOT hotter. Also, Venus has a worse problem than temperature - Venus is toxic. If Venus was 72F, it is still toxic. armaghplanet.com/blog/… $\endgroup$ – MikeP Dec 7 '16 at 19:37

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