Wikipedia:Reference desk/Archives/Science/2016 November 16

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November 16

Sea level rising equally everywhere

I hear some places are getting serious sea level rise. Where I live, (Haikou, which is really flat), it seems to be the same. Is this possible or am I just not noticing and should be out buying billy boots? Anna Frodesiak (talk) 00:11, 16 November 2016 (UTC)

Some land areas recently (in the geologic sense) covered by glaciers are slowly rising from the relief of the weight of the ice, and other areas orogeny are being pushed up due to the collision of techtonic plates, as well as the upwelling of magma. which is detectable in Yellowstone and other volcanic hotspots. μηδείς (talk) 01:25, 16 November 2016 (UTC)

Our article is at post-glacial rebound. Matt Deres (talk) 01:37, 16 November 2016 (UTC)

Thanks, I knew there must have been an article. μηδείς (talk) 04:28, 16 November 2016 (UTC)

See also Sea level rise. The actual sea levels will also depend on interactions between astronomical tides and local tidal systems which are affected by prevailing winds and ocean currents. See Sea_level#Change.--Shantavira|^{feed me} 09:08, 16 November 2016 (UTC)

Sorry, I just read what I wrote and it was ambiguous. Haikou is near sea level and the sea doesn't seem to be any higher than it was more than a decade ago.

About the responses: Let's leave aside magma and other forces on the land. I'm talking about the sea rising to flood low, coastal areas. So, could some such areas like Venice get flooded in the next 100 years while Haikou doesn't? Anna Frodesiak (talk) 10:25, 16 November 2016 (UTC)

The sea isn't flat. It has lumps and bumps (relative to the level everything would settle to if there were no influences other than gravity and spin), caused by wind, weather, tides, temperature differences, etc. If the air pressure in an region is low, the sea level will rise. If climate changes so that the pressure in a region is on average lower than before, then the average sea level there will rise. If wind patterns change so that more water gets pushed into a particular location than before, then sealevel would rise. And so forth. So in general, yes, you can have sealevel rise resulting in floods in one place, and not in another. But I don't know enough about the specifics to say what places would or would not be affected. (Although Venice also is suffering subsidence, so it could get increased flooding even without global/regional sea level rise). Iapetus (talk) 10:45, 16 November 2016 (UTC)

Interesting. So is this all short term? I mean, over years, does everyone get higher sea levels if it is on average higher all over the world, or could some place never have a problem? Anna Frodesiak (talk) 12:00, 16 November 2016 (UTC)

There are several things going on affecting local sea level. And we're mostly interested in the level of the sea relative to the level of the land, so locally, sea level rise is as bad as land subsidence.

• Global warming causes global sea level rise as the water expands and glaciers melt. This is a few centimetres per decade, so it's hard to see with the naked eye due to the large variations on shorter time scales, but if it's your job to keep thousands of square kilometres of land dry, you'll notice.
• Post-glacial rebound may cause the land to rise, leading effectively to a drop in sea level. The land around the Gulf of Bothnia rises 80 cm per century. The people of Luleå will never see sea level rise.
• Gravity from large glaciers attracts sea water, increasing sea level close to the glacier. When the glacier melts, areas close to the glacier (less than 1/6th of the world's circumference away) experience sea level drop. As most of the melting of the past century was on Greenland, gauges measuring sea level rise in the past 100 years, mostly located in Europe and North America, have underestimated sea level rise. When the Antarctic ice melts, most of the world will see a big sea level rise, but the shores of Antarctica will see a drop.
• When lowering the ground water table, ground, in particular peat, may reduce in volume. So a century after turning a low-lying swamp into rich farmland, it may sink below sea level. The island of Schokland sank below sea level after the surrounding sea was drained.
• Extraction of natural resources, in particular oil and gas, may cause the land to sink. Around Lake Maracaibo, the land has dropped over 5 metres.
• Building a heavy city on weak soil may cause the soil to sink as the water present in the soil is forced out. Shanghai, Venice and Amsterdam are affected by this. Venice built storm surge barriers, Amsterdam dikes and discharge sluices only opening at low tide, so now it experiences low tide permanently, lowering the water by about 2 m.
• As mentioned above, changes in wind patterns and ocean currents may affect local sea level. Extra fresh water from rivers may locally increase sea level.
• Volcanic activity can move the land up and down quickly. Some ancient Roman and Greek ruins are now on the sea floor, others have been on the sea floor but are now on land again.

So, on average there is sea level rise and people have to deal with that, but locally large differences may exist. It seems that Haikou is on rather solid ground, rising to tens of metres above sea level within a few kilometres of the coast. As long as the Antarctic ice is stable, Haikou won't suffer much. PiusImpavidus (talk) 13:29, 16 November 2016 (UTC)

Also we should mention beach erosion and beach deposition. Depending on the currents, etc., sediment may be deposited or removed from a beach, especially during storms, and this may change the land level relative to the sea. StuRat (talk) 14:02, 16 November 2016 (UTC)

• The mean sea level rise across the globe due to human-induced warming has not yet been large enough to be noticeable. However as mentioned above some locations have experienced much larger than average rises due to changes in prevailing winds. The strongest effects have occurred in parts of the South Pacific. See Sea level rise#Island nations for more information. Looie496 (talk) 16:06, 16 November 2016 (UTC)

It's also becoming evident in some areas of the U.S. East Coast. --47.138.163.230 (talk) 01:36, 17 November 2016 (UTC)

I explored the sinking-island trope here. It is clear that some islands disappear due to local human-induced changes in currents, and the death of others has been greatly exaggerated. Sea level rise is steady, ongoing, and if you look at the data, only slightly accelerating so far, but is still currently far slower than at earlier times when the glaciers were retreating, leaving much room for humans to make it more serious. Wnt (talk) 10:39, 17 November 2016 (UTC)

The major cause of sea levels rising is melting ice at the poles. It's been predicted that all the Arctic ice will disappear within a few decades, but in fact photographs have shown that the area covered at the annual minimum (in September) has recently been increasing. 92.8.63.27 (talk) 10:55, 17 November 2016 (UTC)

Short-range variation (weather) is much larger than the long-range trend (climate), in the short term. The long-range trend has more effect, in the long term. StuRat (talk) 16:09, 17 November 2016 (UTC)

Also, area is not volume: replacing two square kilometers of two-metre thick ice with three square kilometers of one-metre thick ice means you've lost the equivalent of 1km²x1m of ice (which is not in itself a cause of sea level rise, because that Arctic sea ice is floating, but is an indicator – it's also a problem for Polar bears because much Arctic ice is becoming too thin for them to hunt seals on). In any case, the statement is incorrect: the major current cause of sea levels rising is not melting sea ice but rising sea temperatures (as PiusImpavidus mentioned above), because (above 4°C) water expands with heat, and the worlds' oceans average out to something like 12,000 feet deep, so even a 0.01% increase in volume equates to an average rise of 14 inches.

Of course, if warming continues (as is inevitable and can only be mitigated) to the extent that major land ice sheets and glaciers melt, their contribution to ocean volume will indeed become dominant and the rise will be measured in metres. {The poster formerly known as 87.81.230.195} 90.211.130.104 (talk) 18:14, 17 November 2016 (UTC)

I thank everyone here for the very interesting responses. There sure are a lot of variables.

What puzzles me is this: Haikou is pretty close to sea level and that level here is X because it is influenced by all those winds and pressures, etc. In fifty years with the sea level around the world higher and all those winds and pressures will still be acting, (presumably the same way maybe making things worse or better). So, if the world has a higher sea level, how could Haikou somehow not, on average, be higher? Anna Frodesiak (talk) 08:06, 18 November 2016 (UTC)

See shutdown of thermohaline circulation for one scenario where global warming may change currents, and subsequently weather patterns. These would affect local sea levels. The result of all these factors is that it's quite difficult to predict future local sea levels. The best we can do is to extrapolate on current trends, and that process is prone to error. StuRat (talk) 17:28, 18 November 2016 (UTC)

Whoa, shutdown of thermohaline circulation sounds bad, very bad. But assume all conditions are the same in fifty years as they are today. The only difference is a 2m higher average sea level. I isn't it okay to assume Haikou would be 2m higher also? Anna Frodesiak (talk) 21:12, 18 November 2016 (UTC)

I found this:

• http://tidesandcurrents.noaa.gov/sltrends/sltrends.html

Interesting. :) Anna Frodesiak (talk) 23:41, 18 November 2016 (UTC)

Oh, and if you move the map over to the right you will find more North Americas, Europes, etc., none of which are experiencing sea level rises. Obviously the world is bigger than we thought and we should simply move to one of those other continents. Problem solved. Anna Frodesiak (talk) 23:45, 18 November 2016 (UTC)

Does orchiectomy have similar effects on a man's body in order to the effects of menopause on a woman's body?

Does orchiectomy have similar effects on a man's body in order to the effects of menopause on a woman's body? Futurist110 (talk) 04:03, 16 November 2016 (UTC)

Define "similar". If you mean, does cutting the balls off a male result in a cessation of fertility, yes. Otherwise, i dunno, but I've got a knife, want to volunteer so we can find out? Greglocock (talk) 09:05, 16 November 2016 (UTC)

The answer seems to be yes. See Castration#Medical consequences, which says: "Without hormone replacement therapy (HRT), typical symptoms (similar to those experienced by menopausal women) include hot flashes, gradual bone-density loss resulting in osteopenia or osteoporosis, and potential weight gain or redistribution of body fat to the hips/chest. Replacement of testosterone in the form of gel, patches, or injections can largely reverse these effects..." Alansplodge (talk) 11:35, 16 November 2016 (UTC)

I take it you mean the answer to the OP's question is yes. Unfortunately history makes me think the answer to Greglocock's question is also yes. Nil Einne (talk) 13:07, 17 November 2016 (UTC)

Tailbone

Why animals and humans like small pressure on tailbone?--31.84.219.28 (talk) 06:06, 16 November 2016 (UTC)

Would you happen to have a link to your source on this claim? Justin15w (talk) 19:49, 16 November 2016 (UTC)

Hearing that about humans is new to me. It definitely happens with cats. Not all cats, but lots of them. Females in heat especially love it. No idea why, and the internet isn't giving me anything but speculation. Someguy1221 (talk) 20:58, 16 November 2016 (UTC)

Yes, with cats. With humans? That's a new one. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:20, 16 November 2016 (UTC)

Sounds like you're talking about lordosis behavior. Maybe that's what the original poster is getting at as well. Note that, as the article says, the lordosis reflex appears to not exist in hominids (which includes humans). --47.138.163.230 (talk) 01:30, 17 November 2016 (UTC)

May also happen in rabbits. Try it BB.--31.84.219.28 (talk) 02:00, 17 November 2016 (UTC)

I own a cat. I do not own any rabbits. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:02, 17 November 2016 (UTC)

• See perineum, which encircles the coccyx, and which is an erogenous zone in humans, and cats and dogs from what I can tell. μηδείς (talk) 23:54, 17 November 2016 (UTC)

• Please look here.[1] I am assuming the OP is referring to pressure on the supra-caudal scent gland or the caudal glands and the way that cats push against your fingers if you touch this area. Sorry to tell you this, but this is not a sign of affection by your cat, s/he is simply trying to mark you as their territory. Try touching any of the scent gland areas indicated in the diagram and you will observe a very similar response. DrChrissy ^(talk) 00:30, 18 November 2016 (UTC)

The season of profit

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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season technique has a large value, that is did, in what season the economy has a biggest profit?--79.139.144.122 (talk) 09:34, 16 November 2016 (UTC)

Is in the most cheapest season the economy did a biggest profit?--79.139.144.122 (talk) 09:46, 16 November 2016 (UTC)

Why in Russia in the winter season profit of the economy is negligible, if in Russia in the winter season technique has a great value?--79.139.144.122 (talk) 10:15, 16 November 2016 (UTC)

Military company always has more success when the technique has a larger or smaller value?--79.139.144.122 (talk) 11:09, 16 November 2016 (UTC)

Look, it's nice to have you back, but I believe we've told you that your questions make no sense in English, and that you aren't going to get help here at English Wikipedia. Please try Russian Wikipedia or another Russian Language forum where you can communicate more easily in your native language. --Jayron32 12:53, 16 November 2016 (UTC)

We could reach out to the OP. Sales are highly seasonal - the most sales and the most profit are made in the period prior to Christmas. Thanksgiving ("Black Friday"), "Cyber Monday" and "Singles Day" (11 - 11, observed in China) fall within this period. In the west, the post - Christmas lull lasts until the beginning of the second week in January; in Russia it carries on until after Orthodox Christmas which is 7 January. Generally superiority in numbers leads to a favourable outcome of a military campaign. 92.8.63.27 (talk) 13:16, 16 November 2016 (UTC)

We've reached out time and again. This includes in Russian, which if I understand corectly, the OP doesn't seem to speak very well either. Which appears to be part of the reason they're blocked in the Russian wikipedia. Nil Einne (talk) 13:25, 16 November 2016 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Anatomical plane is rectangle or square or can be any shape or different shape?

93.126.88.30 (talk) 14:24, 16 November 2016 (UTC)

Mathematically, a plane (geometry) is infinite. So, it has no boundary shape. However, it's impossible to draw an infinite plane, so a rectangle or square is typically used to represent it. StuRat (talk) 15:16, 16 November 2016 (UTC)

In an anatomical sense, the only part of a plane which matters is the part which intersects with the body - so the effective shape of the plane will be the body cross-section, the exact shape of which will vary according to where the plane is positioned. Wymspen (talk) 15:40, 16 November 2016 (UTC)

Steyr datacode

What's the rationale behind Steyr's date code format here: Steyr_Mannlicher#Date_codes? Using a letter for the month part makes sense since it's shorter, but what's the purpose behind using letters to encode 0 to 9 for the year part? Why not just use "B07" instead of "BOY"? ECS LIVA Z (talk) 21:00, 16 November 2016 (UTC)

I can't speak for Steyr's system, but in general that kind of code makes it harder to alter or misread a year (since they try to choose letters that don't look much like each other). It might also be that they don't want the general public to know what year a gun was manufactured, for whatever reason. Obfuscating the date code creates an information asymmetry that benefits sellers (who would be more likely to understand Steyr's code). Smurrayinchester 08:53, 17 November 2016 (UTC)

There is a precedent. In hallmarking, precious metals are marked with a letter which denotes year of assay. 92.8.63.27 (talk) 09:22, 17 November 2016 (UTC)

Same thing with vehicle registration numbers. In the last scheme, which started around 2000, there was a "year letter". It should have lasted about twenty - five years in its original format, but car manufacturers pressed the Government for more letters (whenever the year indicator changes it causes sales to spike). 92.8.63.27 (talk) 09:41, 17 November 2016 (UTC)