Phosphorus Cycle Notes: Fill & Download for Free

I was about to borrow Dave Consiglio’s phrase: Everyone Dies.(TM) But as I wrote this answer, I became less sure that this would be quite that lethal. It would make for some interesting possibilities, though.For a plant to grow, it has to add mass, and that mass doesn’t come out of nowhere. A relatively small amount comes from the soil—nitrogen, water, and trace minerals—but the great bulk of a plant’s mass comes out of the air, because plants take in carbon dioxide and “fix” the carbon by making more complex molecules, starting with the sugar glucose and using that as the feedstock for everything else. The water that plants take up is dissociated and ends up as the source of the oxygen that the plants give off, while half the oxygen atoms in the CO2 get incorporated into sugars (initially triose) and half end up in new water molecules. About 45% of a plant’s dry mass is oxygen and 44% is carbon—so about 89% of a plant’s dry mass comes directly from carbon dioxide. (Elemental Abundance/Plant Tissue)Back in 1958, C. David Keeling, of the Scripps Institute of Oceanography, started measuring carbon dioxide concentrations directly, from atop Mauna Kea in Hawaii. (Why there? It’s not downwind from any major pollution source, it’s well mixed, and since there’s no vegetation on top, the readings aren’t affected by the local growth and decay of plants in the immediate neighborhood.) Keeling kept supervising these measurements until he retired in 2005, and they’ve been continued ever since. This is what they look like—the Keeling Curve:Yes, the long-term trend has been rising, from 313 ppm in March 1958 to 406 ppm in November 2018—and the rate is consistent with the global rate of burning fossil fuels. Say what you will about Greta Thunberg, but she didn’t make this shit up; Keeling’s first published paper on the Mauna Kea data came out in 1960, in which he also analyzed data from the South Pole and noted that there “the observed rate of increase is nearly that to be expected from the combustion of fossil fuel”. (http://scrippsco2.ucsd.edu/assets/publications/keeling_tellus_1960.pdf)But I digress. Direct your attention to that seasonal variation cycle in the upper left. Atmospheric carbon dioxide in the Northern Hemisphere reaches its annual peak in May, and then drops by about 5 ppm to its low point in September and October, after which it climbs back. That drop is caused by temperate Northern Hemisphere plants, all “waking up” and sucking down CO2 as they start growing and leafing. By the end of the growing season, they’ve pulled 5 ppm of CO2 out of the atmosphere. But when they stop growing, CO2 rises again when plants die, or lose their leaves, and bacteria and fungi break down this decaying plant matter, releasing CO2 back into the air. (You might think this should be balanced by plant growth in the Southern Hemisphere, but the Southern Hemisphere has less land area—I believe it’s only one-third of the Earth’s total land—and much of that land is desert, e.g. most of Australia. The Southern Hemisphere doesn’t have enough land at the right latitudes to sustain any counterpart to the huge forest tracts of Canada and Siberia.)So anyway. . . Northern Hemisphere vegetation pulls about 5 ppm of CO2 out of the atmosphere every year, but it all goes back into the atmosphere because of decay (plus the occasional fire). While I’m generally in favor of planting trees, this means that planting trees by itself won’t solve the problem of climate change—because those trees will draw CO2 out of the atmosphere, but when their leaves fall, and when they themselves rot or burn or get eaten, the CO2 will re-enter the atmosphere. What we’d need to do is grow lots of trees, and then bury them somewhere, so that their carbon is locked out of the global cycle—recreating the processes that formed the coal and oil and gas that we’ve been burning. There have been proposals to do something similar by fetilizing the oceans—but I digress. . .Now imagine that all plants have suddenly started growing at 10x their normal rate. Now, the Northern Hemisphere vegetation is drawing 50 ppm of CO2 out of the atmosphere every year. (Congratulations: now you have ten times as many dead leaves to rake.)At first, I thought that this would permanently decrease the amount of atmospheric CO2, because the bacteria and fungi wouldn’t be able to return CO2 to the atmosphere fast enough to balance the drawdown—their decay rates wouldn’t keep up with plant growth rates. I’m not so sure now—surely, now that the forests are filled with 10x their usual number of dead leaves, bacterial and fungal populations would simply rise to take advantage of these huge amounts of free food. Still, those 5 ppm cycles now take up half the Y-axis of that graph, as CO2 would cycle between about 350 and 400 ppm. That’s got to do something weird to global weather patterns; you’d have stronger greenhouse effects in winter and spring but weaker ones in summer and fall, so maybe that translates into a more even seasonal cycle, with warmer winters but cooler summers. But you’d also get much more serious wildfires—now that the forests contain 10x the dry leaves and 10x the dead wood, and the prairies contain 10x the dry grass, there’s 10x the amount of fuel for fires. So you’d have much more frequent wildfires, and maybe some weird zigzaggy seasonal weather patterns, but maybe we could cope.But there’s another problem we run into: Liebig’s law of the minimum. Plant growth is limited by the scarcest nutrient available. Some folks have claimed that rising CO2 levels will actually be good for plants. The problem is that that only goes so far; you can give a plant loads of CO2, and it may grow better, but at some point growth slows because the plant’s running out of nitrogen. OK, so you give it loads of CO2 and nitrogen fertilizer—and growth slows when the plant starts running out of phosphorus. Give it CO2, nitrogen, and phosphorus, and growth slows because the plant starts running out of magnesium, or maybe boron, or zinc, or selenium, or iron. . . The visual metaphor for Liebig’s law is a barrel with staves of different lengths; you can’t fill the barrel above the height of the lowest stave, no matter how high the other staves are. There will always be some nutrient that limits plant growth. In this diagram, it’s selenium, but it could be something else, depending on the soil and the plant’s needs.So if plants are growing at 10x normal rate, they’re not only extracting 10x the CO2 from the atmosphere—they’re also extracting 10x the trace minerals from the soil. All of a sudden, plant communities all over the world start dying, when soils that were perfectly fertile before suddenly don’t have nearly enough copper / manganese / boron / nickel / selenium / whatever to sustain plant growth at that speed.Agriculture gets weird. First, commodity prices plummet, now that yields are ten times what they used to be. Global trade takes a hit, now that China suddenly discovers that it can grow enough soybeans at home that it doesn’t need to buy anyone else’s. But suddenly, farmers discover that now they either have to shell out huge sums on mineral fertilizers, or compost absolutely all waste in order to keep those minerals returning to the soil.The effect on the forests is worse. Trees grow incredibly rapidly, but once whatever the limiting nutrient is has been exhausted, growth not only slows, but the trees weaken. The population of boring beetles and other tree-feeding insects explodes, taking advantage of the now-diseased trees and killing many. All that dead wood becomes fuel for even more forest fires. I don’t think the forests would die completely—decay of dead plants, and ash from wildfires, would cycle those mineral nutrients back into the soil. But plant communities would be severely disrupted until some sort of new equilibrium state could emerge.It’s 5:00 AM, and I have hypocaffeinemia, so I’m probably overlooking something. My best guess right now is not that Everyone Dies (TM)—sorry, Dave, although if you can come up with a good way to kill everyone under these circumstances I’m all ears. But I think. . .Everyone Is Severely Inconvenienced. (TM)

This is not an easy question to answer, because it is an ill-defined condition. At one level it can simply be defined at a point where we cannot replenish the resources that we are using. However the concept of replenishing resources is itself a very complex question.Our first problem is that the world economy is only deemed to be healthy if it is growing. Growth is a relative term, usually represented as a percentage. Good growth is maybe 4%, while sluggish growth is down at around 1%. This all sounds rather benign, but that belies the fact that growth is essentially a measure of energy usage. So our entire world is expecting to increase its energy consumption ad infinitum. Currently, if this were not the case, the world would fall into recession or even depression. So economically we don’t want this to happen.If we consider some fundamental laws of physics, as we use more energy, we create more waste simply by virtue of the second law of thermodynamics. This waste may be in the form of physical rubbish, pollution or just heat. All of these wastes are now causing us problems, but they are inextricably linked to growth, be it population or economic. If you just look at population growth figures and projections, you are missing most of the interacting components of a highly complex system. Currently humanity is perturbing the natural systems of the planet. There are carbon cycles, which are being perturbed, resulting in increased atmospheric carbon dioxide. There are nitrogen cycles, which are being disturbed. Phosphorus cycles. Water cycles… The term “peak oil” is relatively well known, but there is also looming peak phosphorus and peaks in other natural resources.Overall, humanity is having measurable impacts on many of the Earth’s natural systems. This should be disturbing. We are no longer an insignificant perturbation on our planet. Thus the concept of being overpopulated is not well defined. Now that we have achieved a civilization that has measurable impact on natural systems that are fundamental to sustaining life, we should be looking very hard and very seriously at how we can go forward.Our footprint on the natural world is being studied in academia and the concept of resilience has been raised. Just how resilient are the natural systems to unnatural perturbations? This topic is being actively studied by the Stockholm Resilience Centre, amongst others.One of the more interesting economic studies was conducted in the 1960’s. The world economic system was coupled to its population and resources and waste in a computer model, known as World 3. The results were published as a book called “The limits to growth”. It considered a few different scenarios, one referred to as the business-as-usual scenario, and made some startling predictions. Just like natural populations of foxes and rabbits, the dynamics exhibited both growth and collapse phases. This was strongly evident in the business-as-usual scenario. Following publication, the model was strongly criticised amongst economists. However a 2014 follow up study revealed that the model had almost precisely tracked the world economy up until that point, and that point was very close to the peak, just before the collapse. It should be noted that before a collapse, when looking at past trends, everything is trending upwards. It is only after a collapse phase commences that a downward trend can be seen. This is the danger of just looking at past trends; they don’t necessarily inform you about the future trends.Thomas Malthus predicted the imminent end to the agricultural capacity to feed the growing population in the late 1700’s. This was just before the agricultural revolution, that soundly refuted Malthus’ thesis. Since then we have undergone a number of revolutions in industry and technology that have kept us away from a Malthusian catastrophe. This factor of human ingenuity is even factored into many economic models. This has given rise to an expectation that humanity can think its way out of any and all existential threats. It also generates a level of complacency. If we are always looking behind us, and take comfort that we’ve navigated all past obstacles, we may not be prepared for what actually lies ahead. The role of science is to try and make predictions that will aid us in our journey into the future. Given the number of present existential threats, the time seems fitting for us to listen to what our scientific experts are saying in order to try and chart the safest way forward.Currently, some of the impediments to making the necessary adjustments to our society and economy are capitalism focussed on short term growth, short political cycles, unbalanced political influence towards conducting business-as-usual and lack of adequate scientific funding commensurate with the complexity of the task, and unchecked negative influence on public opinion.Ultimately, the entire Earth system is an incredibly complex system that operates from the energy supplied by the sun. We, as rational beings with high level cognitive ability, have the chance to build upon what is already established by nature. The energy from the sun is all that we need if we can think of new ways to harness it that doesn’t disrupt the other planetary systems.If we aren’t able to ameliorate the changes that we are making to the natural systems, then be prepared for a future collapse. We may think that our society is robust, but history is filled with the collapse of grand civilizations. Maybe Hollywood is already preparing us for the worst, with popular films offering many different visions of dystopian futures.As to what we will do, well in simple terms, industry will no longer be able to supply the demand, which will include food, goods and services. Our environment will have degraded to such an extent that it will no longer support the world population, and so there will be regions of increasing poverty and decreasing standard of living. This will cause the mortality rate to rise and the population to shrink. However, given the current distribution of wealth around the world, it is possible that the rich countries will see less of this effect in the short term. Although the declining world situation will increase political instability and conflicts will ensue. The richer countries will close their borders and try to maintain a local standard of living. This may not be successful in the face of a global downturn and new social and political structures may result. Those in positions of power may seek to shore up their lifestyles at the expense of the general population, resulting in further stratification of society, where the limited supply is preferentially diverted to those who can afford it. In this scenario, life for some will maintain a reasonable standard of living at the expense of a lower class that has to endure a much lower standard with limited access to basic necessities. Society as we know it will have collapsed and we will enter a dystopian future of some form.Will we be able to think our way out of such a future? Currently it seems unlikely simply because of the complex interrelated nature of the problem. Anthropogenic global warming, unsustainable fishing, soil erosion and declining soil quality, peak phosphorus, peak oil, declining water quality, rapidly reducing biodiversity, vast deforestation and more are all interlinked problems relating to our impact on the planet. The problem requires a holistic approach, which doesn’t seem to be forthcoming.

Did Israel use phosphorous bombs on civilians?No.The usage of phosphorus projectiles in the IDF is based on two atrributes unique to this ammunition:Upon detonation it creates a thick, wide and lasting camouflage cloud which enables stealthy infantry manuveur. This of course only makes sense in open areas.It creates intense heat and is able to ignite, innitiate and destroy IED arenas, and that usage is limited to accurate, small caliber ammo, applied on passage areas with clear ID of charges placed.In the sevice of general knowledge accuracy (kinda the point of Quora), it is important to note a third usage - completely irrelevant to the Israeli Palestinian conflict - that belongs to massive ground warfare, between military forces: marking main targets, such as a group of tanks, a military base, a bridge, etc. This is a combination of the two former attributes: Thick smoke, which allows a commander to mark a target in a wide open area, for forces scattered in the area to notice, and intense heat, which does the same at night, through thermal vision goggles.Again, this is a usage irrelevant to this conflict, and relevant for an armour corps regiement commander, who spots the command group of enemy forces, hiding behind a hill in a wide valley, for example. Last time something like this happened with the IDF, other than training, was 1982, against Syrian ground forces targets.Context is very important, and in good Pallywood style, it is the first casualty of any violent cycle this conflict experiences.Do civilian get hurt unintentionally in urban conflicts? Of course. Especially when the areas are controlled by terrorists who do their best to ensure that happens, and people who believe in 100% accurate Intel that can prevent that from happening, had watched too many “24” episodes.Now, I wish I could say this “targeting civilians with phosphorus” libel against the IDF is the worst one I've encountered, but it doesn't even come close.A personal favorite was about the IDF soldiers rescue mission to an earthquake struck Haiti a few years back, being a, quote: “cover up for an organ theft operation”. This was suggested by the Argentinian delegation to the U.N, no less.In good IDF style, we just walk it off. Not much point in anything else.