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#126 Re: Science, Technology, and Astronomy » The Science of Climate Change » 2019-02-08 21:45:41
Louis,
In order to merely accept the premise of AGW as portrayed by the IPCC and media, you have to believe in some impossible things.
1. A trace gas (CO2) in an open thermodynamic system (Earth) creates climatic forcing effects significantly greater than that of a radiatively restricted black body cavity that absorbs and traps nearly all incident input solar radiation and also doesn't permit convection to carry the heat away.
2. The thermodynamic behavior of a half-irradiated sphere that doesn't restrict convection, as a prototypical greenhouse does, and isn't a blackbody similar in behavior to a radiatively restricted blackbody cavity, somehow produces a greater warming effect than a radiatively restricted blackbody cavity with little to no convective cooling.
3. The greenhouse theory, that's based upon blackbody equations to begin with, somehow applies to Earth, which is not a blackbody and doesn't behave as a blackbody does in response to input thermal energy.
4. The entire theory about why greenhouses are warmer than the surrounding environment, namely opacity to re-emission of long wave radiation, that was subsequently disproved many decades ago through actual experimentation, is in fact how Earth's thermodynamic system behaves. There's no convective heat transfer in a greenhouse and that's why the heat is trapped and increases warming. Put a hole in the top of the greenhouse and the temperature plummets. The people who believe in the greenhouse theory are theorizing that the CO2 in the Earth's atmosphere somehow precludes convective cooling (hot air rising and cold air from the next layer of atmosphere sinking and cooling) and blocks radiative cooling (merely slowing the rate of cooling, which is all that CO2 is actually capable of doing within a narrow band of Earth's atmosphere, is insufficient) and somehow coming up with more thermal energy from the re-radiation process than existed as input thermal energy to begin with.
5. Some of these people also assert that their computer models are an accurate representation of Earth's future climate even though the models' temperature predictions diverge from measured temperature increases. We can't accurately predict the weather more than a week out, but somehow we have computer models that can accurately predict global average temperatures decades into the future? If past performance is any indicator, that claim is dubious at best.
6. These people also assert that CO2 is a pollutant. That's a very interesting assertion, given that all plant life on Earth would cease to exist without adequate levels of CO2 in the atmosphere. During the last glaciation cycle, the CO2 concentration in the atmosphere dropped to levels very close to the levels at which plant life would be subject to mass extinction. The idea that climate is incredibly sensitive to CO2 concentration is also rather perplexing given the fact that the historical period which saw the greatest increase in biodiversity was also associated with atmospheric CO2 concentrations that are several multiples of what we have today. Nobody I'm aware of has attempted to explain why CO2 increases lag temperature increases in the geologic record, either. I was always taught that cause can never follow effect, else causality is broken. I guess correlation has now been substituted for causation.
Well, there it is. Six impossible things before breakfast. Someone let Alice know when it's time to slay the Jabberwocky.
There's some real doozies in here, coming from someone who ought to know better.
One simple but incorrect way to model a planet is as a sphere of uniform temperature absorbing and re-emitting light as a modified blackbody. I calculated in this post that if this were the case Earth would have a temperature of about 255 K. The actual mean temperature is 288 K even with substantial nonuniformity (which lowers the mean temperature due to the T^4 law of radiation).
The three canonical modes of heat transfer are conduction, convection, and radiation. Looking at things on a climactic level, temperature differences are too small, conductances too low, and distances too large for conduction to have a major effect (the ground's heat capacity would seem to even things out a bit but this doesn't seem to have much of a practical effect). That leaves convection and radiation. If I were going to build a model, I would look at four types of convection and three types of radiation. Those four convections are ocean convection (through ocean currents), atmospheric convection (through jetstreams and other weather events as well as between different layers of the atmosphere), surface-to-atmosphere convection (i.e. heat transfer from ground or ocean to atmosphere), and convection heat transfer through phase change of water (evaporation/condensation, freezing/melting, etc.). The three radiations are energy received from the Sun, energy emitted by the ground/water, and energy absorption/reflection/transmission/reemission by the atmosphere.
It happens to be the case that the Earth is surrounded by the hard vacuum of interplanetary space, and also the case that conduction and convection require a medium through which to act. It is therefore the case that Earth's heat equilibrium is fundamentally governed by radiation:
As you see above, the bare, uniform-temperature sphere approximation (UTSA) is off by about -11% as compared to the actual observed mean temperature of Earth. By way of comparison, it's off by about +14% for the Moon (The Moon's estimated temperature according to the UTSA is higher than Earth's due to its low albedo; on Earth, the warming effect of an atmosphere is partially cancelled out by the cooling effect of nonuniform temperature), off by about -2% for Mars (my calculated UTSA temp is 206 K and Wikipedia lists the planetary mean as 210 K; this means that the reduction in temperature from nonuniformity and the increase from the atmosphere are roughly equal in magnitude), and -59% for Venus (the planet's temperature is nearly uniform and its thick atmosphere retains heat very effectively; UTSA for Venus is 301 K as calculated in the post linked to above).
You will notice that the thicker a planet’s atmosphere, the higher its mean temperature when compared to UTSA. This is not a coincidence (the relationship is causal), although I don’t believe you could create a simple, valid equation relating the two as you’d need to get deep into the specifics of each planet’s relevant properties.
I won’t speak to the heat transfer properties of glass-walled greenhouses nor the convection vs. radiation question in that case, but the real answer will naturally be a combination of “neither”, “both”, and “it depends”. Perhaps the “greenhouse effect” is misnamed, perhaps not. In either case, it is real. Edit: If it is indeed the case that scientists used to think warming in greenhouses resulted from radiative inhibition but have since found that convective inhibition is a more important factor, then updated their views based on new information they present a good example to all of us
In general, your post suggests a lack of familiarity with the basic concepts of thermal radiation and heat transfer by radiation. This powerpoint provides a good overview that you might do well to read. Let me give you (and anyone else who’s interested in heat transfer, a topic I personally love) some highlights.
Idealizations are often helpful and necessary in physics. We use them often on this forum as well. When calculating the delta-V for a hohmann transfer, we typically assume that the two planets occupy circular, coplanar orbits. When doing kinematics at low speeds, we typically disregard both special and general relativity, instead assuming that objects obey newtonian mechanics in euclidean space. The equivalent idealization for thermal radiation is the blackbody, which both absorbs and emits perfectly across the entirety of the electromagnetic spectrum, from an energy of 0 eV to a wavelength of 0 nm. A blackbody emits radiation according to the Stefan-Boltzmann law: P=σT^4, where P is power per unit area, σ is the Stefan-Boltzmann Constant, and T is the absolute temperature.
The closest real-world approximation to a blackbody is a small hole in a large, well-insulated cavity. Real materials can both transmit and reflect radiation, and are also not perfect emitters, nor do they emit omnidirectionally. Having said that, it is in general possible to establish values of transmittance, reflectance, absorbance, and emittance that are fairly stable over reasonably wide spectra. For real materials we modify the Stefan Boltzman Law by introducing a constant for Emittance (ϵ) which can take values between 0 and 1: P=ϵσT^4. Measured values for the emittance of most common natural materials (water, ice, dirt, sand, trees, etc.) near room temperature is in the range of 0.90-0.95 and gases can be modelled as having an asymptotic emissivity of 1. Earth as a whole has a transmittance of 0, a reflectance (also known as an albedo) of 0.3, and an absorbance of 0.7.
Gases tend to have more complicated absorbance, transmittance, and emittance behaviors which need to be taken into account when modelling their behavior (just as an example: Rather than treating gases as discrete surfaces you can treat them as having infinitesimal coefficients for absorbance, transmittance, and emittance per infinitesimal distance and then [in principle] could calculate properties like the temperature profile and heat flux. More importantly is that gases do tend to have relatively narrow bands of stronger absorbance. It happens to be the case that CO2 absorbs strongly across much of the most intense part of Earth's thermal radiation spectrum. This is also the case for water vapor, and though there is some overlap there are also plenty of regions of non-overlap; and due to the relatively low concentration of CO2 in Earth's atmosphere its bands aren't completely filled. This means that a marginal increase in the amount of CO2 results in a marginal increase in the atmosphere's absorbance on the relevant wavelengths. (Here's a more easily comprehensible measurement for the amount of CO2 in the atmosphere: If you concentrated it to 100% at 1 atmosphere and normal Earth temperatures, prior to the industrial revolution atmospheric CO2 would create a layer 1.3m (4'3") over the Earth. Today, that layer would be 2m (6'6") high.
In short: It should come as no surprise to you or to anyone that our planet represents a very complicated thermal system where the interplay of many different physical processes interact to form an equilibrium. It should also come as no surprise that of these effects one is the strongest. That effect is blackbody radiation.
#127 Re: Terraformation » Venus » 2019-02-07 19:23:02
The upper atmospher contains the water, and hydrogen which under a heating plus solar wind would strip the planet of things that we would need. Even thou the atmospheric pressure would drop the temperatures would still continue to rise as the clouds which reflect the in coming energy would now be gone and the surface would now be dark with carbon... What we would end up with in the end is a new planet mercury....
Any viable plan to terraform Venus probably requires the importation of huge amounts of water (about as much as the atmosphere we're talking about blowing off) and compared to that the amount of water there now is quite minimal. Likewise, any plan to terraform Venus probably needs to be a two-stage one.
Although now that you mention that...
Rather than exporting CO2 and importing water, it seems like it might be more efficient to turn all of Venus into one big Bosch Reactor.
Send Hydrogen in from the outer system somewhere (Uranus or Neptune?) or out from the Sun (harder), fill the atmosphere with iron nanoparticle dust (a good catalyst--might not be necessary though), keep the whole thing at 700 C, and let it go.
If you start with Venus's 4.5e20 kg of CO2 and add 4e19 kg of H2, you'll end up with 3.6e20 kg of water, 1.2e19 kg of carbon, and 3.5 bar of atmospheric Nitrogen. The carbon will blanket the planet to a depth of 150-300 m and the water to a depth of 500-600 m. Water, being a liquid, would not pool evenly and would instead form oceans. Eyeballing a map of Venus they would cover 30-70% of the planet (Somewhere between Mars and Earth if the former is terraformed), which seems like a good amount.
In order to allow the reactions to continue you'd want to keep the planet hot for as long as possible using mirrors, meaning the water would remain in the atmosphere as steam. When you want the reactions to stop, take away the mirrors (or even reposition them to block sunlight) and pull your camera out for the most incredible rainstorms of all time.
Here's a number: If the Earth were a sphere of uniform temperature with no atmosphere and perfect emissivity (although retaining its albedo of 0.3), its temperature would be 255 K. This is about 15 K warmer than the Moon (as I estimated in this post), which makes sense because slower rotation lowers the mean temperature due to the T^4 Law.
Using this same calculation, Venus would be 301 K, which is substantially hotter. That should come as no surprise, since it's closer to the Sun. Atmospheres are weird though, and it's possible there are ways to make it livable with an Earth-style atmosphere, maybe even (though it seems unlikely) without sunshades.
#128 Re: Terraformation » Venus » 2019-02-07 18:17:43
Here's a concern with that: All that CO2 is going to go somewhere. Venus's atmosphere contains ~4.5e20 kg of CO2. If you bake it off, it has to go somewhere. My guess will be it would be swept outwards.
The next planet out from Venus is Earth. Earth already has more CO2 in its atmosphere than we'd like, plus a strong gravity well that will tend to draw gases in. Since 1750, the atmosphere has added roughly 150 ppm of CO2, corresponding to roughly 1e15 kg. That is to say, if even 2 grams out of every tonne (0.0002%) of the gas from Venus's atmosphere ends up on Earth, it will have a bigger effect on Earth's climate than the entirety of human emissions in the last 250 years.
Now a project like this one is at least a hundred years out, and if you're doing planetary engineering and blowing away 100 bars of CO2 you can probably also take care of 100 ppm of CO2 in Earth's atmosphere (indeed, it's likely that we as a species will cut our teeth in planetary engineering by drawing down CO2 from the atmosphere) but blowing 5e20 kg of gas into interplanetary space (By my extremely rough estimate, 5,000,000 times more gas than exists in the solar wind between the orbits of Mercury and Neptune at any given time) will probably affect something, sooner or later.
#129 Re: Terraformation » Venus » 2019-02-07 16:05:36
This strikes me as an interesting idea and one worth considering.
Terraformer raised two objections: Breaking up the CO2 and loss of nitrogen.
I don't regard a layer of carbon as being a huge loss. It's fertilizer, after all, which on a previously lifeless world will without a doubt be necessary. Venus has a thick atmosphere though, so if all the atmospheric carbon turns into ground carbon it would be a layer 150-300 m thick depending on density.
Loss of nitrogen is a much more serious concern. Venus has 3.5 bar of nitrogen, and when all is said and done we want most of it to stay on planet (not just as a dilutant gas but also as a supply for the belowground part of the nitrogen cycle).
So this means you want to be selective if you can. But how?
One thing you might do would be to direct your light so that it mostly is absorbed by the upper atmosphere in wavelengths absorbed by CO2 but not by Nitrogen. In the ideal case, you would be adding enough energy to directly accelerate the molecules up to Venus escape velocity, which is 10.3 km/s. This corresponds to 53 MJ/kg or 0.5 eV/amu. With a 44 amu CO2 molecule this corresponds to a photon with a wavelength of 56 nm. This is considered extreme UV: The Sun makes very little of it, it's extremely difficult to reflect, and it's actually preferentially absorbed by Nitrogen over CO2.
This makes me wonder if there's a way to pre-fix the Nitrogen so that it can be protected from escape and accessed later if needed. I don't have any ideas on that score but maybe someone else does.
If you're not trying to be selective, frying the exobase and upper atmosphere with IR reflected from the Sun glancing through the atmosphere seems like a good way to go about baking off as much as you can as quickly as you can. Might not even need to heat the planet all that much.
#130 Re: Life support systems » Nutrient Management in Closed system for Martian Greenhouse » 2019-02-06 14:59:26
In this case it seems like they copy-pasted from Wikipedia or MS Office or something.
You used to be able to make subscripts by using a smaller font size but that doesn't seem to work anymore.
#131 Re: Not So Free Chat » Chat » 2019-02-05 16:04:17
What does a 30 foot snowpack look like on flat countryside?
#132 Re: Not So Free Chat » Donald Trump has never cared about workers, and never will » 2019-01-31 16:59:54
Hey EdwardHeisler,
Do you come to this forum to talk about Donald Trump or about Mars?
I have no love for our President but it seems to me that I rarely see you talking about anything else.
#133 Re: Exploration to Settlement Creation » My Hacienda On Mars » 2019-01-31 16:57:30
Hey all,
Seems to me that this topic is basically similar to what we were talking about in the thread Build Your Own with a Martian spin rather than an asteroidal one. Here's what I wrote in the other thread (the settlement is built at the end of a tether attached to a fast-rotating asteroid):
The habitable volume is circular in shape, and covered in a clear dome. The circle is 2 km across and the surface is mostly freshwater, but shallow, perhaps 10-30 m thick on average. Perhaps 20% of the area is composed of islands, which are rocky and very steep (taller than they are wide). People live in cottages made from rock and brick and canvas perched upon outcroppings of rock, as well as smaller boats which moor to the islands or travel around from one to another, or float on the water. People can travel up and down the islands either by hiking/climbing or by taking little gondola trams. To get between islands you can either take a boat or a zipline, or swim I suppose. The climate is mild, averaging 20 C, with low wind.
Mirrors reflect sunlight into the habitation, with a lengthy sunset and a 30 hour day/night cycle. Access to the vacuum outside is via ports which stick up like little islands from the water.
There's some fish in the water and small mammals living on the islands. No birds, though. I hate birds
Much of what people eat is fish coming from the water. There's also some farm-barges where food is grown, which typically dock around the edge of the habitable volume.
I think on Mars I would stick to a similar template, with the habitation built into a smallish crater, ideally one near the equator with a good view.
As far as economic activities go, Mars has no native populations to enslave and oppress, so economic activities have to be done more virtuously than the Spanish did them. On Mars, this means a lot of mining and manufacturing, most done by robots. Included in manufacturing is agrifacturing (agriculture + manufacturing, ie mechanized agriculture, a term that I think ought to be used instead of "factory farming"). I think ideally my settlement would be in the spacelaunch/rocketbuilding business (Rocketeering seems like a cool name), even though probably on Mars spacelaunch will mostly be done via space elevator.
#134 Re: Terraformation » Terraforming the Moon - Your opinion, please » 2019-01-17 10:05:02
As a point of comparison, a 1 mb atmosphere on the Moon (100 Pa, 0.015 psi, 750 mTorr) would have a mass of around 2e15 kg. That's 2,000,000,000,000,000 kg, for an atmosphere 0.1% as thick as Earth's.
a 750 mTorr atmosphere would be considered a very soft vacuum here on Earth.
#135 Re: Science, Technology, and Astronomy » The Science of Climate Change » 2019-01-06 16:02:03
Wow, what a thread.
For my part, I intend to act as if this thread is a discussion between myself and kbd512, with other posters’ comments (and his replies to them) playing no part in that discussion unless they are stating, or he replying to, a point I otherwise would have made. I do this because multi-person discussions very often go off topic, when I believe that this is a topic on which we might actually reach a resolution. I also do this because I'd like to speak for myself to present hypotheses that are falsifiable in form but supported by evidence, with the hope and expectation that my counterpart will do the same.
Given that, the material to which I will respond in this post comes from posts 11 and 15 by kbd512 unless otherwise noted.
I will also follow Einstein's (possibly apocryphal) dictum: "All things should be as simple as possible, but no simpler".
Weather and Climate
So far as I can tell this part of your post does not contain a single relevant assertion nor evidence on the topic. It does, however, contain several strawmen about "climate changers". In your second paragraph, you point out that this is not an important point of discussion. This is something I agree with: In post #8 I described our disagreement as "small but meaningful" after you accused me (in post #6) of dishonesty in "danc[ing] around" a definition of climate which I did not agree with.
In any case, I will take this to be a statement on your part of one of the following:
The definition of climate as I have described it is reasonable and correct
The differences between the definition I proffered and the one you proffered don't matter to this discussion
In either case it is a settled point.
Measuring, Modelling, and Forecasting Climate
You have broken this section down into an organized critique, which I appreciate.
1. You do not believe that the data collection methodology is done in an adequately rigorous way for the following reasons:
A: You do not believe that we can trust our temperature measurements because of instrument error.
In support of this, you provided three links. The first was to a paper describing the challenges associated with temperature measurement. The second was a supplement to another paper. This second link was not useful to me as a source of information because it has neither a description nor an explanation of the information in its graphs. The third is a video in which a climate scientist involved in satellite temperature measurements says that his measurements provide substantial evidence of warming and are consistent with ground measurements, which he believes also show warming.
None of these is really evidence in support of your point. The third link explicitly and repeatedly rejects your point for reasons explained within the video. The second is not evidence of anything unless you also have a link to the paper it is associated with (Call me lazy if you'd like: I am not going to puzzle over pages of graphs and acronyms unless they come along with explanations of what is being measured and why). The first is a bit more complicated, so I will discuss it further.
The paper investigates a few common types of air-temperature thermometers and finds that the error on the measurements is higher than the manufacturers claim, something which surely is not a surprise to anyone (which incidentally probably includes the scientists using them to measure temperatures). Shouldn't this undermine our faith in the conclusion that the temperature of the planet has been rising?
No.
Why not? Because our global temperature measurements are done using (1) many different instruments (2) performing many different measurements (3) over long periods of time. Under these circumstances, the repeatability of individual measurements doesn't really matter (the error falls rapidly as you include more and more measurements), the bias of the measurements doesn't matter (it goes away when you subtract numbers to get an anomaly) and even the degradation of instruments over time doesn't matter (you would expect different instruments to degrade in different directions, averaging out in the long run; and even if they don't you would expect the average age of the instrument to remain similar over time). The only thing that would truly matter would be if, over time, every instrument were changed to read a higher temperature. This would amount to a meaningful redefinition of the temperature standards in the SI system of units which has not happened.
B: You think that variations in the way measurement apparatuses are setup undermines the possible confidence we can have in those measurements.
Interestingly, the paper you cite repeatedly says that incorrect siting of thermometers has produced a lower rate of temperature increase than correctly sited ones, and also suggests that this incorrect siting is partially corrected for in the data analysis because a particular type of thermometer (and therefore the adjustments associated with that type) is more likely to be mis-sited than another kind. I'm not sure how you think this proves your point, frankly. It seems to prove the opposite of your point, or at least provide evidence for it.
C: I'm not sure what to call your assertion in this section. Perhaps the common theme is an assertion that the analysis of the temperature data is being done incorrectly. Full disclosure: I did not watch the hour-long video you posted because I do not consider that to be a good use of my time. Did you watch it? And if so, what points does it make and how does it support them? What portions do you think I ought to watch?
Anyway, other than the video the NASA page (which is something like a press release rather than a scientific document per se) explicitly and repeatedly disagrees with your point (unless your point is that climate science is hard, which is obvious?), so I'm not sure why you posted it.
Lastly, that paper is a discussion of possible sources of error in land and sea temperature measurements. So far as I can tell, the author is attempting to discredit these measurements and their use for determining historical and present temperatures.
I have not done the research to assess the validity of any of his individual claims, but one thing that stands out to me is that he does not provide an estimate for how much he believes the dataset to be off by.
This is a fairly key point: No competent researcher would take any measurement as being the “true” value for anything. All measurements have a precision and a bias, which combine to create uncertainty in the correct value. Climate scientists are well-aware of this and have methods to try to counter it (Data homogenization), and provide error bars on their measurements. For example, the paper you linked to in section B estimated that temperature over land in the United States is rising by 0.32±0.11 degrees celsius per decade.
There is a substantial hypocrisy in your post: You claim that homogenizing data is “bastardizing” it, and yet this reference (as well as your references pointing out the way different measurement techniques can affect results) basically argue that the data needs to be homogenized more.
Here’s a fact: All datasets are imperfect because all data is biased and imprecise. The standard, effective way to handle that is to measure the bias and then subtract it away.
Another problem with your analysis is a persistent confusion between a guess, an estimate, and a measurement. Perhaps you will call this a semantic point. Maybe it is. But words represent concepts, and you are misusing them in a way that suggests a lack of familiarity (or more likely a blindness to) the concepts they exist to convey.
A measurement involves using a device which has been calibrated and tested against an external standard to acquire data to directly answer a question.
A guess involves using anecdotes, dead reckoning, or other faulty sources of information to answer a question. A guess is necessarily a non-rigorous answer.
An estimate is between the two. While you can have very high (although imperfect) confidence in a measurement and should have very little confidence in a guess, an estimate is based on information that is limited, incomplete, or indirect but which can still be analyzed in a rigorous manner. It is often necessary to estimate things when measurements cannot or have not been done, but with sufficient information and well-thought-out methods an estimate can be pretty reliable. When you say that something is an estimate and therefore it is a guess, you are definitionally and conceptually wrong.
2. You claim that different studies use data from a single source.
This is not really accurate. It is true, based on the paper presented in section (1)(C) of your post #11, that there is a single database that appears to contain most of the temperature data used in most studies. A database is not the same thing as a data source. Temperature has been measured in various ways and various places at various times going back many years. In fact, you referenced three of these methods (satellite measurement, land measurement, and sea measurement) within this very post. Presumably an organization maintains a database containing all of the historical temperature measurements they can find. Unless you believe that this organization is not entering the data into their database in a straightforward and honest way, nothing of the sort is true.
3. Climate modelling is hard and imperfect, and therefore we shouldn't trust its conclusions.
I agree that our confidence in the predictions is less than in the models, and our confidence in the models is less than the measurements. Climate models have basically two uses in my opinion: Testing causality (we have no way of performing a real experiment on the planet itself) and forecasting the future.
There are necessarily wide error bars on both of these, but the results generally meet the common sense test. Add greenhouse gases to the atmosphere and the planet will warm. If the planet warms, some polar ice and glacier will melt and sea levels will rise, there'll be more energy to feed certain kinds of storms, local climate and weather will change, sometimes a little and sometimes a lot, etc. It's worth mentioning that because future changes in the climate depend in part on our choices, future models are rarely presented as “predictions”.
In post #15, you added another criticism to this: That climate is chaotic and nonlinear and all forecasting is probabilistic. Your conclusion was that modelling and therefore forecasting climate is impossible.
This is wrong. The scientific definition of chaos is a system in which small changes in inputs result in large differences in output. Because all measurement has an associated uncertainty, small changes in the actual initial values even within the margin of error result in a wide variety of results. This is how we forecast hurricane tracks by the way, which is something we can do pretty accurately.
On the whole, what comes across to me in your various posts is a real derision for the people you call “Climate Changers” which manifests itself in a lot of different ways, but most prominently in a willingness to throw away the work of thousands of very smart people, rather than engaging with it in a meaningful way.
I propose that the structure of a discussion about global warming ought to proceed as follows:
1. Is the planet warming? Or, to put it another way, what is the rate of warming and what are the error bars on that number?
My answer is yes, the planet is warming, and that it is warming at a rate of roughly 0.3±.1 degrees celsius per decade, in accordance with the consensus estimate. I think your basic point is that you have no or very little confidence in our measurements of temperature, either present or past. I would be curious to hear your estimate and confidence interval on the rate of warming. If you provide one, I will not nitpick over small disagreements but I will look at what it says about your reasoning and assessment of the state of the data.
2. Provided your assessment is that the Earth is in fact warming, why is it warming (and how sure are you)?
We haven’t discussed this much because we have focused more on tier one. This is entirely reasonable because it makes no sense to discuss or argue over causes until you have a consistent view of the phenomena. My answer is that the bulk of the warming is human-caused, as a result of greenhouse gases, by mass mostly CO2 but with a few stronger greenhouse gases creating a warming effect out of proportion to their increase in the atmosphere.
3. What happens next?
Forecasting the future of complex systems is hard, especially when changes in those systems will be affected by human decisions (Which are inherently unpredictable and which are both an input and an output to the model). Most of the effects of a changing climate are neutral, which is to say different but neither good nor bad. If the only effect of climate change was that the temperature was uniformly 2 degrees celsius higher across the globe, I would say it really didn’t matter. In fact I would be quite happy if temperatures where I live were uniformly higher by 5 degrees celsius. There may be a few positive effects but likely will be substantially more negative ones, as well as an increase in the probability of unlikely but potentially catastrophic events (such as a 60 meter sea level rise caused by destabilizing the antarctic ice shield). I detailed some of these in post #4.
4. What should we do about it?
While the first three tiers are questions of science and fact, which can be answered using our powerful but imperfect methodologies, this is a political question of values, power, and ideology. It is possible for a person to agree with me on questions 1, 2, and 3 but to believe that the correct response is to stay the course and do nothing. In this thread I have done my best to make this distinction hard and clear. It has been my belief that we should be able to come to an agreement on questions 1, 2, and 3, being matters of fact and evidence, but that we are not highly likely to come to agreement on this question because our political philosophies are so different.
I have been surprised to find the exact opposite, where we have both endorsed nuclear power as a response to climate change even though we have not been able to agree that the climate is really changing, why the climate is changing, or how it will change in the future.
Anyway, I started off this post saying I would try to be brief. 2500 words later it is clear to me that I have failed, but hopefully I have made at least a few good points and addressed yours in direct and honest way.
#136 Re: Civilization and Culture » Holidays » 2018-12-29 07:32:43
I feel like aphelion and perihelion seen important but won't have that much of an effect of people on planet. We don't celebrate them on Earth after all.
#137 Re: Human missions » Space X Mission at risk? » 2018-12-27 23:17:22
Ah yes, the globalists
But consider this:
You are British, which is to say you are a foreigner
This forum is run by the Mars Society, a global organization with chapters in 13 countries
Elon Musk is an immigrant and a billionaire with citizenship in three countries: The United States, Canada, and South Africa
Mr. Musk's various businesses have customers, employees, suppliers, and investors across the world
Seems like you're not clear on who the globalists are or what that term means!
#138 Re: Science, Technology, and Astronomy » The Science of Climate Change » 2018-12-27 17:06:28
Hey kbd512,
In our first foray into climate change in this thread, I quoted an 8 word sentence and replied with 44 words. You replied with 217 words. I replied back with 1,259 words, and you responded to me with 2,369 words. Such is life. But anyway, to prevent things from getting rapidly out of hand I'm going to try to be at least somewhat brief and respond to what I see as being your primary points without responding to your whole post point-by-point. If I miss anything you think is important I will be glad to come back to it.
Weather and Climate
One important thing we've been discussing is what climate is. Your claim, based on various sources, is that climate is a 30-year average of weather. My claim is that this is a way of measuring climate, even the standard way, but is not the conceptual definition of climate. My understanding is that climate is to weather as organ systems are to individual cells. It's true that climate is made from weather, and it's true that you could, if you liked, described as the sumtotal of weather just as you could describe an organ system as the sumtotal of the activities of its cells.
The key difference in my understanding is that weather is a chaotic and dynamic process of matter dancing around equilibrium in a semirandom way while climate hews closer to that equilibrium and perhaps in the ideal case even describes what it is. Maybe it's not a coincidence that n=30 is the most commonly cited number for when a distribution of the mean will approach a normal distribution.
Just to be completely clear: I am not dancing around the question. I have a disagreement with what you are saying that is small but meaningful in that I believe you are conflating the measurement of the thing with the thing itself. It's as if you said temperature is notches on a thermometer, or the voltage produced by a thermocouple pair.
Measuring, Modelling, and Forecasting Climate
I should probably start this section off by saying: My knowledge of statistical methods is very basic, pretty much limited to what you might find in an intro-level probstat course. It seems quite likely that your knowledge strictly encompasses mine and goes far beyond.
On the topic of measurement: Every measurement has a bias and a variance, as you've mentioned. You pointed out that the bias doesn't matter if you're looking at the same temperature, as long as it's consistent. I would argue that the variance likewise matters much less than you have suggested. The reason for this is that the variance on the mean is much smaller than the variance on an individual measurement. I don't know exactly what the granularity of the measurement is, but let's say satellites measure the temperature of each 100 x 100 km square (10,000 km^2) twice per day across the Earth, over the course of one 365 day year (in reality I believe our areal and temporal granularity is much better). The area of the Earth is 510,070,000 km^2 so there are 51,007 such squares, each of which sees 730 measurements over the course of the year, for a total of 37,235,110 measurements per year. Using the naive formula of σ/√ ̅n, you might expect your measurement of the global mean to be 6000 times less than any individual temperature measurement. If your error on temperature is ±1°C, your error on the mean might then be ±0.0002°C according to this naive formula.
I would never claim that to be the case. For starters it seems impossible that you could be that confident in the stability of your measurement. But you can be pretty confident. The following image, from NASA, suggests that our measurement error on the global mean today is ±0.05°C, that in 1950 it is ±0.08°C, and that in 1890 it is ±0.1°C. Not enough to confidently say that the temperature has risen one year over the next in most years (naturally the average temperature will also change a bit from year to year based on the vagaries of various phenomena like el nino/la nina, the sunspot cycle, etc.), but enough that you can be pretty confident on the trendline.
You also suggested that the observed levels of water vapor seem to cast doubt on the measured temperature increase. I'm not sure exactly which data you are referring to (humidity levels? Precipitation? Something else?) but it is true that warm air can hold more water. But do evaporation rates increase or are they already rate-limited somehow? Is there more water in the air but relative humidity is constant? Are the temperatures increasing more over land than over water, meaning that average relative humidity levels could actually be falling? My point is that precipitation and humidity levels are a complicated thing, affected by lots of factors, which makes it hard to say by deductive reasoning alone what ought to happen. In short, you need to build a model. I don't doubt that there have been numerous attempts to quantify how rising temperatures ought to affect humidity and precipitation patterns.
Modelling, naturally, is harder than measuring. A model can be no better than the assumptions and data you put into it, minus any errors made by the modeller. Climate is a very complicated thing, affected by god-knows how many phenomena. If you have a particular climate model you'd like to pick apart I can give it my best but frankly I think that's somewhat beyond my competency. But it helps to do a sanity check on any model.
Here's how I look at it: The average temperature of the Earth is substantially higher than it would be without an atmosphere. We can see this by comparison to the Moon. This paper has a really cool discussion of lunar temperatures, with lots of cool maps and graphs. They don't go and calculate and average temperature as far as I can tell, but by eyeballing the graphs it seems to be around 240 K vs 288 K for Earth. Obviously the Moon isn't the Earth so the Earth's temperature wouldn't be exactly the same without an atmosphere but it should be close. So the atmosphere warms the planet by roughly 50 K.
Most of this difference is a result of water vapor, which the atmosphere has a lot of and which has a very broad absorption spectrum. However, because these bands are so thoroughly blocked and because water vapor tends not to reach the upper atmosphere (condensing and freezing out instead) and because of its relatively short atmospheric lifetime (for the same reason) water vapor doesn't change things very much. Carbon Dioxide's absorption spectrum does not align perfectly with water vapor, has a longer atmospheric lifetime (meaning it builds up instead of reaching an equilibrium), and can loft higher (even if a particular wavelength is "100% blocked" this can still matter because it will warm the lower layers of the atmosphere and ultimately the surface). The concentration of CO2 has risen from 250 ppm to 400 ppm, and depending on our choices will rise either a bit more or a lot more. It seems entirely reasonable that this could raise the temperature a bit. I'm sure different models disagree, but something in the range of low-single-digits K seems entirely reasonable.
I have always been interested in the idea of building some sort of very rudimentary atmospheric model and see what I get. Haven't done it though.
Throughout your post you used words like guess, estimate, and extrapolation to try to discredit the conclusions of climate science. It's true: 100% confidence does not exist in this field, and probably cannot. This is true, in varying degrees, in all domains of life. While you've raised a number of points in question of the general conclusions (some reasonable, some not) you have not raised any sort of theory of a fundamental flaw or a stronger model which provides different conclusions. I haven't seen such an alternative raised.
Environmentalism as Ideology
One striking thing about the climate change discussions is that the issue is much more salient to people who are left-leaning than those who are right-leaning, especially when it comes to policy or personal changes. As a result of this the conversation is dominated by left-leaning people, and (at least in the United States) the technocratic response (there is a problem and we should take steps to fix it) has become wedded to progressive values (climate change is real, therefore we need a green new deal in which carbon taxes fund a government jobs guarantee where people build out solar power and public transportation).
I try to avoid politics on here as much as possible. I'm sure you've noticed that I am much more left-leaning than the median member of this forum. On the issue of climate I think I'm something of a moderate. Lots of progressives use climate change as a coathanger on which to hang policies which they would be pushing anyway. In other words, I think a lot of people are trying to use climate as a technocratic justificiation for policies they believe in for ideological reasons. There's nothing wrong with ideology, by the way, as long as you're honest about it.
If you ask me, the best response to climate change is to convert our grid generators to nuclear power (plus nuclear regulatory reform, finishing yucca mountain, and finally funding new nuclear technologies) electrify transportation where we can (Musk has built some nice cars, though they're not cheap enough yet) and leveling the playing field for the tax treatment of denser vs. suburban development (there's lots of federal subsidies to suburban development including the mortgage interest development, extra federal money to highways, etc.). Those changes will reduce CO2 emissions by a lot without radically changing the face of our society.
#139 Re: Human missions » Human Missions versus Planetary Protection Limitations » 2018-12-27 11:02:27
Sorry for my absence over the holidays, but I've split off the discussion of climate change and moved it to this thread, "The Science of Climate Change", in the "Science, Technology, and Astronomy" subforum.
#140 Re: Life support systems » Solar chimeys - Feasible? » 2018-12-27 10:55:43
OK - why don't we get specific?
How much energy would be required to tow say one ton of frozen CO2 from the polar region to the temperate zone (I am guessing that's about 3500kms, given Mars's extreme "wobble" factor. I think a robot Mars rover truck could cover 500kms per sol...so that would be 7 sols's worth of travel. At 50 kws constant that would be about 8.5 MwHs of energy used in towing one ton that distance. I don't know whether you could do it for less than 50 Kws constant over the 7 sols.
But anyway that is perhaps a starting point and one might ask how much energy one ton of solid CO2 might release when put into the right pressure chamber with a turbine attached....
I can do my best, but any number I give will necessarily be a very rough estimate.
The physical minimum amount of energy required to transport something 3500 km is 0 J/kg (for an object moving on a perfectly level surface in a frictionless vacuum). No real world transportation system is that good, naturally, so that's not good enough. This means that we're really trying to get a handle on what we could expect technologically which is sort of a difficult question.
I think the closest analogy would be the energy use per mile of 18-wheeler trucks. Some factors suggest that the gas mileage will be higher (basically no drag, lower speeds, and lower gravity) while others suggest it might be higher (I don't think Martian roads will be anywhere near a US interstate in quality for a long while). Based on this website the average 18-wheeler gets 4.5 mpg (52.3 L/100 km) and according to this page they can haul up to 80,000 lb (36 tonnes).
Gasoline contains roughly 40 MJ/kg of energy (excluding Oxygen, naturally) and has a density of roughly 0.9 kg/L. This means that these 18-wheeler trucks use ~500 J/kg-km. Over 3500 km that works out to 1.75 MJ/kg (0.5 kWh/kg).
I have low confidence in this number, but it's a start. A reasonable range would be from, say, 300 kJ/kg to 10 MJ/kg (0.1 kWh/kg to 3 kWh/kg). It's worth noting that it would be much less if you use train transportation but it would be a major project to build a railroad through such wild countryside, comparable to the American Transcontinental Railroad. It's also worth noting that internal combustion engines are not very efficient so that you might expect to use 3 times less energy with a battery electric system, but also that a battery-electric system will have some sort of range limitation (necessitating charging stations every 100 or 200 km, which is not crazy at all along a major shipping route) or else will be basically 100% batteries.
My supposition is that you are going to be in favor of batteries, so I won't get into the various aspects of an internal combustion system. For the purposes of this thread I will use a figure of 100 kJ/kg-3.5 MJ/kg (0.03 kWh/kg to 1 kWh/kg). For reference, I estimated in this post that it would take 150 kJ/kg to freeze CO2 out of the atmosphere. The former number ignores the energy required to mine the dry ice, which will be substantial; the latter ignores the inefficiency of refrigeration (50-80%), which is also substantial, but at a first pass it's unlikely that trucking dry ice from the north pole will save any energy at all.
Now, the question of how much energy you can get out likewise is a difficult one. Unlike many chemical fuels, dry ice contains no inherent energy. The answer for how much energy you can get out really depends on what your heating source is. At various points in the steam powered rover thread, which I have linked to, I estimated: 41 kJ/kg, 80 kJ/kg, 166 kJ/kg, and 320 kJ/kg.
In short, having looked at the numbers, I believe that my initial feeling has been confirmed: Mining dry ice from a polar cap to use in an energy generator is a marginal activity in general, but is extremely unlikely to be worthwhile if you are not physically located near a polar cap.
#141 Re: Life support systems » Solar chimeys - Feasible? » 2018-12-21 19:00:34
Hey Louis,
I briefly discussed the possibility of bringing CO2 from the poles to the temperate equatorial regions as fuel in this post
It's certainly conceivable that mining dry ice at the poles could be economical, but it's hard (for me) to imagine that it would actually make sense unless the end user is actually at the poles.
You used coal as an analogy, and it's a pretty decent one. However, rather than showing the potential value of CO2 mining I believe it shows why it probably won't be worthwhile.
I believe the appropriate comparison is the system we were discussing before: a refrigeration system that uses energy to freeze CO2 out of the atmosphere. Here are the costs and benefits of such a system:
Costs:
Requires industrial equipment
Consumes energy
System has not been designed fully yet
Benefits:
Generates ~1 kg per kWh of inert gas (primarily Nitrogen and Argon)
Works equally well anywhere on Mars
Now, by comparison, here are the costs and benefits of pole-mining:
Costs:
Requires an ongoing supply of human labor (All mining does)
Consumes energy
Requires shipment over thousands of kilometers
Requires industrial equipment
System for mining a substance that sublimes at 195 K has never been built and would require some tweaks to existing techniques
Benefits:
Will produce water as a byproduct
In my view, the question is: Is more labor and thousands of km of shipping worth saving yourself 150 kJ/kg? In my opinion, it is not. It's good to compare this to coal: Coal on Earth has an energy content of 30 MJ/kg, 200 times greater than the energy you save. Because the energy content is so high, it really is worth pulling out out of the ground and shipping it to the point of use (or at least it was in times past). I question whether mining CO2 from the poles would save any energy at all.
#142 Re: Science, Technology, and Astronomy » The Science of Climate Change » 2018-12-21 14:03:29
That was such a wild misstatement of what people believe that I am compelled to respond to it.
To start, here's a basic factual error:
You have claimed that climate is a 30-year average of weather. That is not the definition of climate, but it is a reasonable way to measure it. If you have 60 years of data and you care about a 30-year moving average, that means you have 31 datapoints, not 2.
Any literate person, given a set of 60 datapoints on a graph, would be able to tell if the trend is generally up or generally down. A person familiar with methods of statistical analysis would be able to do quite a lot more than that (rate of increase, confidence interval, p-value, correlation with other variables, etc.), especially if they realized that a 30-year moving average is one way of measuring climate but is also a semi-arbitrary round number (Why not 23? Why not 34?).
I would say that I'm shocked you don't know this but actually I am quite confident that you do. You're a smart guy and politics makes us dumb.
Global mean temperature as measured by orbiting satellites is not the only source of data we have on temperature. We also have weather station measurements and various ways of estimating the temperature in past eras. The measurements are less reliable as you go farther and farther back in time but nevertheless are basically consistent with each other and with historical and geological accounts, where we have them.
People who believe in climate change want to change the weather to be the same as it was 100 years ago.
I assure you, as someone who does believe in climate change and someone who knows many people who do (including both people who are highly scientifically literate and people who are much less so), that this is not the case.
Here is what people believe:
Firstly, that the science on this matter is basically good. This means that the planet is in fact warming and that the most likely cause of this warming is the release of greenhouse gases by humans. If you have real, good-faith objections (i.e. hypotheses which are falsifiable and based on evidence) on either score I would be happy to address them (although further discussion of climate change probably belongs in a different thread).
Secondly, that changes in the climate will have negative effects on people. All of the world's societies are built in certain ways in response to the climates in which they were built. Changes to the climate, especially rapid ones, are often costly or deadly.
This is the key point that you did not recognize, so I will speak further on it. Human-caused climate change is causing the climate to change much faster than it has historically and much more than it otherwise would. The desire to prevent climate change is not motivated by a desire to create or specify any particular climate, but rather to prevent the climate from changing too quickly. You said that the climate always changes, and in that you are correct. But the rate of change matters. Here are some examples of how a changing climate can have negative effects on humanity:
Most big cities exist near major bodies of water such as rivers, lakes, and oceans. If sea level rises, these cities will be at risk of flooding, and the frequency of storms big enough to cause major flooding will increase. It is true that it's possible to build seawalls, but it's also true that a low-lying city behind a seawall, once flooded (all systems fail eventually), is much harder to drain.
Most agriculture is located in regions that have good climates for agriculture. If the climate changes, those farms will die or suffer and their owners will suffer or go bankrupt. There won't be famine--at least not in rich countries (in poor countries it's a very real threat)--but the price of food will go up and there may be supply shortages for some items. In the US, food prices going up is not a catastrophe for most people so much as an annoyance, but in other places it would be a very big deal.
People are prepared, to a certain degree, for the natural disasters they are used to experiencing. Floridians know what to do during hurricanes and their buildings are built to withstand them. Texans know how to respond to tornadoes. Northerners know what to do about snow. Arizonans have air conditioning and know how to deal with extreme heat. If there's snow in Atlanta, hurricanes in Boston, tornadoes in Tennessee, and extreme heat in Seattle people are going to die. That's why Hurricane Sandy (which actually wasn't even a tropical storm when it made landfall in NY/NJ) killed 70 people and cause $75 billion in damage. In a changing climate, all of these are more likely. The key point here is that preparedness matters but it's expensive: Most people and places typically are not prepared for things that haven't happened in the past.
The contagiousness of disease is dependent to some degree on local climate. The big one here is Malaria, the scourge of the developing world. As temperatures rise the Tsetse fly will be able to live farther and farther from the equator and people historically not at risk for the disease may become vulnerable. It's true that there's a vaccine for Malaria. It's also true that many people in the US don't have access to healthcare, that infants and older people sometimes, can't be vaccinated, and that there's a growing group of morons who choose to endanger everyone else by not getting vaccinated even when they could and should.
Here's an example that I like (possibly because of its personal relevance): I live in America's Leading Wheat-Producing County (all the signs on the highway say so!). Almost 100% of the land in my county is devoted to wheat, barley, or lentils. There's a number of reasons for this, starting with soil. Our soil is made from dunes of volcanic ash. This means that it is both fertile and porous. The porosity is important, because it rarely rains here during the main growing season (This year it rained 0 times between June and October). Instead, it rains and snows during the winter. The hills suck up the moisture and release it slowly during the summer, allowing crops to grow without the need for irrigation. This saves substantial amounts of money for the farmers and makes their jobs easier.
If the winter precipitation pattern here becomes more like the summer precipitation pattern, that would be a big problem for the local economy. The US produces a lot of wheat so it would be unlikely to have a big effect on the nation as a whole unless something similar happened across wide swaths of the West. Of course the drought was a pretty big deal while it lasted a few years back. As you said, the climate always changes. It could happen with or without human contributions. But if the planet as a whole is getting warmer it seems more likely to be the case that we'll see more summer-like weather and less winter-like weather.
An interesting foil that's stuck with me over the years is the Dubia thought experiment. The author asks what the world might look like in 1000 years if we go on with status quo (as of 2003) policies on climate. It's really interesting and arguably a better world, but most population centers that exist now are underwater. Sort of an optimistic best-case for what could happen after centuries of suffering.
#143 Re: Science, Technology, and Astronomy » The Science of Climate Change » 2018-12-20 20:15:45
When the climate changes, you adapt or die.
"There is a preventable threat to the continued welfare of the human race, but I'd rather take the risk--if something terrible happens we probably deserved it"
Yup, there's that same faulty reasoning again.
An ounce of prevention is worth a pound of cure.
#144 Re: Human missions » Human Missions versus Planetary Protection Limitations » 2018-12-20 00:11:22
I definitely have quibbles with your method and your figures, but ironically I estimated in my post that the odds are 1/1,000,000 of 0.1%, which is 1e-9 or 1e-7%, surprisingly close to your number. Happy coincidence maybe.
Anyway I think we all agree that the probability of back-contamination is extremely small but unlike many other questions or concerns has at least some grounding in science. European colonialism largely worked out okay for Europeans (at least as far as diseases go), but diseases were pretty much civilization-ending catastrophes for the indigenous people of the New World. If we imagine for a second that the disease vectors went the other way history would have been way different.
I'm not really concerned for the explorers and settlers. This is nowhere near the biggest risk to them (not even in the top 1,000 imo) and they'll know what they're getting into.
My expectation is that once the due diligence has been done we'll find that Mars has nothing alive that can hurt us, but it's an unknown with some small chance of ending us as a species and as such deserves extra care.
Hopefully our descendents on Mars will look back and laugh at us for testing the waters with a sacrificial lamb.
#145 Re: Human missions » Human Missions versus Planetary Protection Limitations » 2018-12-19 21:24:37
"That all things are possible is no excuse to speak foolishly" -John Maynard Keyes (possibly apocryphal)
I don't think you and I have particularly different conclusions on what ought to be done, but I really do take issue with the reasoning you used to get there.
Human extinction, whether by asteroid or mars-plague, is a tail risk, something improbable but very bad. Both are preventable to various degrees. The mode of argumentation "We have to go and nothing can stand in our way" doesn't hold much sway with me because frankly certain things ought to change our behavior if we believe them to be a danger.
Naturally we don't control anything, but our actions do have meaningful, material effects on the world we live in. Procedures to avoid contamination are quite well-developed and, depending on our assessment of the risk, could be worth implementing.
The need for pressurized habs and pressure suits gets us most of the way there anyway.
#146 Re: Human missions » Human Missions versus Planetary Protection Limitations » 2018-12-19 19:09:13
If life on another planet eventually disrupts humanity, then that's also evolution in action. Either way, this has happened in the past and will continue to happen.
This would be a fine thing to say if it were a fact from long ago history or something wholly beyond our control, but that's not what this situation is. What if, for example, we had reason to believe there was a small chance (0.1% maybe?) that microbes on Mars would infect the initial explorers and go dormant until it returned to Earth and wiped out a billion people. This has come up a lot in science fiction (I liked Aurora by Kim Stanley Robinson if you're looking for a recent example) but probably doesn't describe the real world.
Under that situation I think we would look prospectively at things and either not go or take precautions. "If humanity goes extinct, it goes extinct" seems like the wrong tack to take about an improbable but conceivable existential threat to our very existence.
I do think it's pretty unlikely that there are lifeforms on Mars that:
Exist
Are in a location where explorers and settlers could be exposed to them
Are infectious to humans or Earth-based lifeforms
I would be fairly confident based on our observations of the planet that most of the surface doesn't have life, even microbial life, but I can't be sure. Life can be a lot of things--basically any self-replicating physical pattern--and it's possible that there could be something on Mars we're just not looking for with the right sensors.
In the somewhat-unlikely case that there is life, I think it's unlikely that it's infectious. There is a spectrum of possibilities from the life being something so similar we could have found it on Earth (perhaps contamination from a Viking mission?) to something so different we're not even sure it's actually life (Rock-based life? Something else? In this thread we got creative). The more similar it is to us the more likely it can infect us or damage our equipment.
Above, I asked what we should do if the probability were 0.1% of there being a human-killer Mars plague. In reality I think the odds are way lower than that, maybe a million times lower. But possibly worth a quick test: With the early landing send down a fungus or something and expose it to some Martian dirt and air at STP.
The opposite question (danger to Martian life from Earth life) is worth looking at too. Martian life would be an incredibly rich area of study and it would be a crime against science to destroy it by carelessness. I don't think it's possible to destroy it without terraforming but if we find some we should definitely exercise extra care.
#147 Re: Civilization and Culture » Holidays » 2018-12-17 14:11:07
It's easy to imagine that, at first, Martian settlers will settle the holidays of whichever nation they come from. Over time though it's easy to imagine that they'll come to celebrate their own unique holidays, or combine the holidays of various nations into something uniquely Martian. Likewise it's easy to imagine that Martians will use dual calendars: The Gregorian Calendar and a Martian Calendar (structure tbd). Terran holidays will presumably be celebrated according to their Gregorian dates, while Martian holidays are more likely to be celebrated on the Martian calendar. Religious holidays (if religion persists) will presumably be celebrated according to the calendar of the respective religion, for example if there is a group of practicing jews on Mars they will celebrate Yom Kippur on the 10th of Tishrei.
Here's a few that come to mind:
Founder's Day: A day to celebrate the founding of whatever settlement people live in. This would be a good day to do ceremonial openings of new habitats and facilities, groundbreakings, etc.
Winter Solstice: Most places on Earth have some sort of Winter Solstice holiday, which makes a lot of sense because that's when the days finally start to get longer.
Summer Solstice: Most places on Earth also celebrate the abundant sunlight of summer solstice. It's easy to imagine this also being the case on Mars.
Thanksgiving/Harvest Festival: While Mars is unlikely to have the same sorts of defined harvest as Earth, seeing as 100% of the farming will be done indoors, there will be an analogous event which is the arrival of cargo from Earth. This will occur 6-9 months after the launch window, every 26 months. This is a great time to celebrate the arrival of new immigrants and needed cargo.
Landing Day: Celebration of the first footsteps of people on Mars.
Those are the ones that come to mind now, what do you all think?
#148 Re: Human missions » Virgin Galactic success » 2018-12-14 16:02:44
I think it's news because they are going to be taking commercial paying customers to the edge of space in 2919.
Maybe I have too little faith but at this rate they may not make it for 2919 
It cost roughly $30,000,000 to develop the SpaceShipOne. I have no idea how much SpaceShipTwo cost but almost definitely substantially more than that, not to mention roughly $50 million in subsidies going to Spaceport America (which has been sitting unused since it opened in 2011) from the taxpayers in New Mexico. It's not unreasonable to think that the whole thing will start off $150 million in the hole before a single passenger can fly and with substantial ongoing operational expenses to cover.
What I'm saying is that when all is said and done this suborbital tourism route will likely be a money-losing boondoggle brought to us by an eccentric billionaire and and benefiting from the largess of under-informed, overly optimistic taxpayers and civil servants (influenced by just this sort of credulous reporting).
I'm sure it's a cool view from up there and perhaps VG will learn something about building reliable, reusable rocket engines on the cheap. But unless VG can inspire repeat customers (which I find quite difficult to imagine) suborbital tourism won't be long for this world.
#149 Re: Human missions » Virgin Galactic success » 2018-12-14 15:17:30
I don't totally understand why this is in the news at all.
Virgin Galactic appears to have replicated the flights performed (on a practically identical craft) in 2004 by Scaled Composites.
Indeed, with a peak altitude of below 83 km this flight wasn't even properly suborbital.
Color me unimpressed.
#150 Re: Pictures of Mars » Real images of Mars » 2018-12-13 14:03:51
Hey Vincent,
The forum is no long doing image hosting, so here's how you can post images:
Upload them to an image hosting site such as tinypic or imgur
Acquire the url for the image by right-clicking on the image (press and hold on most mobile devices) and selecting "open image in new tab". Copy the url for that tab
In your post, write the following: [ img ]your_url_here.url[ /img ]. You will need to remove the spaces between the [ ] and the text in between (adding spaces is the only way I know how to make the code show up).
If you have any other questions about the markup language used by newmars, it is called BBCode and you can google it.