Ken Fabian

It sounds like Canada needs to put power lines underground because the costs of not doing so are so high. Self reliance for rural homes or communities is good but a different problem than reliable supply for urban centres and industry that are important too. To what extent can Canada's grid make use of US energy sources and interconnectors? And vice versa? The nearer to the Arctic circle the more seasonally limited solar is going to be. The more extreme the weather conditions the more significant the ways they are mounted become and more expensive. The concertina packs of solar above are going to work well in Australia and much of the world but not everywhere. Wind and hydro may always be more necessary for Canada than for nations like Australia. I'm not a big fan of nuclear but nor am I strongly opposed; it will have it's place too but it will be up to people who are it's fans to do the promoting - preferably with greater distancing from pro fossil fuels climate science denier politics, that turns it into an anti-renewables rhetorical position more than an actual emissions reductions option. I am not sure if State mandates and guarantees for nuclear are any more palatable to nuclear's more vocal backers than steep carbon pricing that will probably - inadvertantly - aid renewables more than nuclear.

@swansont They unpack E-W, ie the peaks/valleys are running N-S, which gives good morning and afternoon insolation as well as middle of the day - though solar panels laid flat would get similar sun exposure. Better angled I think to shed rain (and dust?) and structurally stronger; the pic looks like a desert site. Not sure now where that pic came from or it's location. Apparently there are installations all over the Australian mainland and around the world already - one in the Atacama desert in Chile. Not all in deserts. It does look like the kind of innovation needed to grow clean energy fast enough to reach net zero goals in a timely manner. It's actually a portable solar farm system, easily moved from one location to another. The company is 5B, Maverick is the name they give their rapid solar deployment system - “100 kilowatts fully installed before lunch, and 1 megawatt in a week”. They pack more panels into a given site area which delivers higher output than fixed angled style - claimed at 180 - 200%, equivalent to single axis tracker systems but at the cost of more panels, made up for by big savings on installation. I assume they will work best nearer the equator; they will work at other latitudes.

Australia is seeing increased rainfall for the North-West but reduced rainfall for most of the rest, especially South, which looks related to changes to High pressure systems from Hadley Cells, ie they are tracking further from the Equator (ie South) due to global warming. Cattle grazing is likely to benefit in the near term but it is mostly not well placed for intensive agriculture. Not so clear about the longer term; it gets very hot there even without extra warming (Australia's hottest place is there) and extreme heatwaves could undo the benefits.

It becomes a trade-off between installation costs and maximising output. Cost usually wins out in the end. This style gains by reducing up front costs (but works best nearer the equator and will not support co-existence with livestock grazing) -

Enough magma convection and volcanic activity still goes on to keep bringing up some minerals from deeper down; it isn't a placid one way sinking of heavier minerals towards the core. I live on the remnants of an extinct volcano, on the rim of what was once it's crater. Whilst not a major deposit, it coughed up enough gold, copper and silver to attract the attention of gold rush prospectors in the late 1800's and mining companies ever since. Not a lot of actual, profitable mining but they keep looking, with hopes of prices going high enough to be economic. The last eruption was 23 million years ago - very recent in geological terms. Is this about the density of the mineral compounds they form or otherwise bind to?

I am a bit skeptical of the promise of large scale weather modification. I think the reason that central Australia is desert is a persistent lack of on-shore winds capable of carrying moist air into the interior, not lack of evaporation over oceans when we get them. There is a preponderance of high pressure systems due to Hadley cells, that drop dry upper level air down over desert areas, with prevailing low level winds blowing coast-wards and/or blocking on-shore winds as a result. I think that is the case for the Sahara and other desert regions too. Mountain ranges and their rain shadows can be a big factor for some deserts too. Greening desert fringes can have an impact but I suspect it works because human activities - introducing grazing livestock, including gone feral (goats, donkeys, camels and rabbits in Australia) - is why they lost their vegetation; in combination with managing those pest species it is possible to bring back vegetation. Whilst vegetation can increase local precipitation it isn't a huge effect; these regions are still highly dependent on occasional rainfall events. There can be - at least over the medium term - some regional greening from changed weather patterns; North West Australia is getting more rainfall out of those rainfall events when they occur - not necessarily more of them or regularly. How that plays out with much raised temperatures is still a question. Other regions of Australia - agriculturally productive ones - are getting less rainfall. I am seriously concerned about the longer term prospects with global warming; 1 C of global average warming is making about 1.4 C of warming on the ground in Australia, so 3 C (which we are on track for with us reaching zero net emissions from a lot more serious commitment than we are seeing) could mean temperatures rise over 4 C. I think we will reduce our emissions a lot but not enough reach zero within the timeframe needed, so 4 C or 5 globally averaged, with temperatures on the ground raised 5 - 6 C seem not just possible but likely; our greening efforts are going to be in big trouble, along with the health of economies capable of undertaking them. That is still assuming reality is nearer the mid-range for climate sensitivity; if it turns out higher it can be worse again. Arid zone plants and animals are only tough in comparison to those in milder conditions; in many cases their survival prospects have been borderline all along - surviving but only just is the rule.

I have read it, a couple of decades ago. I think some elements have found a place - identifying the highest elevation sites for on-farm earth dams, the contour ploughing to slow rainwater runoff and divert it into the soil, using ploughs that break up hard soils and aerate them but don't turn soil over. Swales - was that Yeomans? - likewise to slow rainwater runoff and soak it into the ground; there are some related ideas about making the ground itself the principle water storage around. This is mostly for grazing land rather than intensive cropping. Yeoman's irrigation ideas, not so much; I think in practice it only gave limited benefits and those only where topography and climate suited. High evaporation across much of Australia mean dams have to be deep to last more than a couple of years of drought, even without using any of the water, and irrigation uses a lot of water. It tends to cost more than most farmers or farm companies can afford or count on getting a return on investment. Where on-farm dams are used for irrigation they tend (as with most irrigators) to use drip lines, microsprays and other water saving rather than the ditches and flood irrigation Yeoman used - and it tends to be to some extent opportunistic, with irrigators accepting that the water won't last. Annual crops rather than long lived perennials.

Why do you think susceptibility to allergies of the distant past has not been bred out? We may well tolerate allergens now that our ancient ancestors were plagued with. I expect novel allergens keep emerging - other lifeforms keep evolving them - as well as expect the migrations and expansions into new territories exposed people to different ones. Some of those migrations were very recent. Is absolute immunity to allergies even possible? I am not sure it is something we can expect to evolve.

I think Mistermack has it right. I think it would make a significant difference to overall reproductive success - not necessarily to the birth rate but the group ability to support itself and provide well for the ones that are born. A prevalence of even low grade allergies will impact the group's success.

I would expect susceptibility to the more dangerous allergic responses have been weeded out by natural selection; we are descended from those that didn't die young from them. As medical intervention has become more capable and widely available it is more likely that genetic vulnerability is being passed along, which will be okay so long as the ability to provide medical care is sustained. Seems like increasing genetic variability is occurring but the natural selection part is being held at bay for a time. Some good points from others - we are more likely to face exposure to substances that we haven't encountered before and immune responses can be strengthened or weakened by exposure or lack of it during childhood, apart from genetic vulnerability. We are better at identifying the culprits as well, modifying our food choices and exposure to allergens to avoid problems.

Seems kind of obvious; those that reject mainstream knowledge will overrate the validity of the alternatives that appear to prove mainstream is wrong, which becomes "proof, Proof!" that there is a conspiracy. Being mainstream becomes a principle reason to doubt something. Dunning and Kruger could add that as a corollary if it isn't already.

Approaching 0.042% - Keep in mind that there is ~10 - 15km of atmosphere before outward travelling IR escapes to space - plenty of opportunity for such concentrations of CO2 to absorb IR (to re-radiate in all directions, ie as much down as up... almost the textbook definition of Greenhouse Effect) and enough to prevent most IR from the ground getting to space in one go, even before concentrations were raised. "Only" 0.04% is a very misleading description; very small relative to what? The earliest calculation of the greenhouse effect from lowered and raised CO2, by Svante Arrhenius was in the 1890's, following on from prior work of others that reconciled known incoming solar energy with global average temperatures much higher than could be explained in an absence of greenhouse effect; it is highly significant, even at lower concentrations than 0.04%. And even if CO2 greenhouse contribution to the total GHE is not the largest - 2nd after water vapor - it is what we are changing by fossil fuel burning. With (as previously mentioned) water vapor concentrations changing in response to the warming from other GHG's and amplifying the effect.

@studiot Those kinds of projects can be huge and the engineering and economics rarely add up. More usually we see water caught and stored within existing water catchments during wet times, uphill of the users, stored over several years, hopefully long enough to get refilled before running out. Existing geography and flows are taken advantage of as much as possible - working with rather than against, and most of the better opportunities have already been taken, for irrigation water mostly; climate change is exacerbating things but the same concerns have been around a long time. We have water diverted from coastwards flowing to inland from Australia's Snowy River Hydro scheme but it works by taking advantage of geography; it was a (relatively) short distance tunneling through mountains to divert the Snowy River, but still a huge engineering project. (Ironically Hydro power output had to be constrained due to too much water - to avoid adding to inland flooding - during our recent and still simmering gas and coal supply shortage/price crisis, despite full dams and wholesale electricity prices going into orbit). Rivers themselves are the preferred means of delivery, with pipes, canals and pumping reserved for short distances and rises. They are expensive. Canals have high loss rates - leakages and evaporation; schemes proposed for Australia (that still get thrown up as a thought bubble) had expected losses too high for the water to reach the intended recipients. The specific example - Kentucky floods, Texas and California droughts? I think (US geography not my strong point) Kentucky floodwater will flow into the Mississippi, so it will get a lot closer to parts of Texas on it's own but still way short. California would need floodwater from somewhere much nearer but geographically that seems harder than for Texas, which doesn't have the mountain ranges.

If water vapor were a big problem then nuclear energy won't help reduce it - I don't see shipping as ripe for conversion except as a hope or perhaps an intention; whilst hydrogen can be burned in an internal combustion engine that won't work with existing diesel engines. Whilst some ships are diesel electric, with propellers driven by electric motors hydrogen ships will need to be fuel cell electric. No major shipping companies will commit to them until supply chains and infrastructure is in place and even then there is a lot of development needed. Making shipping zero emissions is a huge task. Short distance ferries running on battery electric already exist, are reliable and a lot less technically challenging to build and operate. Better batteries will emerge, but how much better is still unknown. I don't know what the best solution to shipping emissions is but I suspect not much will happen until and unless the shipping industry knows in it's bones that they have no choice. Currently they appear to be treating it as optional and making the choice to stick with not doing it. Coal contains some water. A lot more in brown coal. But whilst cars burning Hydrocarbons (the name says there is hydrogen in the fuel) make H2O by chemical reactions coal power plants make lots of it by evaporative cooling (similar to the nuclear plant cooling towers above) at the power plants. Whether atmospheric water is overall warming (greenhouse) or cooling (cloud albedo)? Without it as a GHG - the biggest one - I would expect global temperatures to be much lower, probably below freezing, but that is off the top of my head.

Burning fossil fuels emits water vapor too, in similar amounts for similar energy use. I am not aware of any climate significance for the water vapor from fossil fuels, so not for Hydrogen burning either. I expect that lack of significance is because any immediate atmospheric water vapor content change is very small in proportion to how much is there naturally. And it doesn't accumulate over longer time frames. Any long term change to water vapor content is inextricably tied to and limited by air temperature change, not the "sources", which exist naturally in great abundance. I also don't expect Hydrogen use to be as ubiquitous as the hype suggests; for all the talk the principle uses for hydrogen are still in oil production, not in replacing fossil fuels. That is all supplied by Hydrogen made from fossil fuels, with emissions, not clean energy and electrolysis. Any hydrogen transport economy will require about 3 times the electricity as battery electric, without the ability to piggyback onto existing electricity grids. A bit cynical of me but I think the big energy users like Hydrogen in direct proportion to how long to become a readily available option; commitment to hydrogen over other options is a commitment to delay. Iron smelting and chemical production may be the most important uses but are unlikely to require more hydrogen than oil refining uses now.

Should keep in mind that long term change to atmospheric water vapor content is a feedback induced by change in GHG's - because warmer air holds more water vapor. For each measure of enhanced greenhouse effect from increasing any other GHG's water vapor adds two more measures, so causal attribution of the warming induced is to the other GHG's, not water vapor. This gives estimations of the climate change forcings in play (from IPCC AR6 SPM)-

"More collection, storage and distribution" may be what studiot meant but these encompass a wide variety of engineering options. More efficient use is another "obvious" I suppose. I am interested in what people consider obvious. It sounds like for California there is not a lot of spare water to collect and store and redistribute. I suspect the best sites for dams are already dams or else are valued highly for other reasons/uses - which may present as "politix not permitting", though I doubt it is as simple as mere bureaucratic unreasonableness. The less ideal the site the more it can cost - and in many cases the more uncertain that they will catch enough to fill or avoid storage losses long enough to help much in an extended drought. It can become a rob Peter to pay Paul type of problem. Lake Mead (we get bits of US news mixed with our own) isn't in California but stands as an example; probably it will get times with enough upstream precipitation to fill again and for a time provide a relative abundance of water but it doesn't make a whole of problem, lasting solution. Not even by making it bigger/deeper. A lot of historic water use decisions appear problematic in hindsight; as an Australian I can sympathise - water use permits to farmers (pumping from rivers, which may or may not have flows managed with upstream dams and from artesian basins that were considered effectively infinite) - were handed out freely, in aggregate amounts that often far exceeded what is available. These kinds of historic "right of use" are fiercely defended - a different kind of impediment to "obvious" solutions than just bureaucratic. Of course they cannot pump water that is not there and pumping rights can be limited or suspended but often there is water upstream that never reaches downstream, including by "innovative" practices like flood plain harvesting - diverting and empounding flood water; the assumption was it only takes "excess" water, whilst the reality is downstream flows can be dependent on that flood water (and flood plain ecosystems too). A lot was done before the consequences were understood, without any regulation applying and again, those who did it fiercely defend their "right" to do so (and oppose introduction of regulation) without any responsibility taken for the downsides downstream. It does sound like California agriculture has been overutilising it's limited water sources for a long time and the "right" to do so looks deeply entrenched; the obvious solution of limiting such water use can be hard to apply. Texas, I know less about, but suspect similar issues.

What obvious engineering solution? How is lack of permission the principle impediment?

All the documentation and eyewitness "testimony", from watching the launch to the many amateur radio enthusiasts who - by aiming their receivers at the moon - listened in isn't enough? It didn't make it to the moon but I recall a demo from before the mission of a flag "waver" that was developed to give the flag movement; a bent wire in a sleeve within the top of the flag that turned by a small motor. But I think the actual movement of the actual flag was attributed to static electricity.

In a sense, yes; not pre-existing planetary bodies but ones that coalesced in the early formation of the solar system and underwent differentiation from their own gravity and subsequently got broken up by later collisions. Metallic cores that formed when these proto-planets were hot and molten are where the nickel-iron we find now came from. Surely that was Nickel-Iron, but it has been common to refer to metal meteorites as "Iron". So far as I know meteorite metal is always Ni-Fe and the only pure iron found in meteorites are small crystals and tiny nodules within a nickel-iron matrix (and not independent of it). I have previously done some searches to learn whether pure iron or other relatively pure metals (like nuggets and seams of precious metals) are going to be found in asteroids myself - pure iron being more widely useful than alloys with nickel, although the nickel content is a lot more valuable in metal price terms, probably exceeding any precious metal value. I could not find any references to any metallic meteorite sample that was not nickel-iron, with other metals (eg cobalt, Platinum Group Metals) well mixed (in solution) within them. It appears to be a case of processes that mix them occurring but with an ongoing absence of conceivable processes that can separate them again. (I asked this at https://space.stackexchange.com/questions/27329/can-we-expect-to-find-pure-iron-or-only-nickel-iron-alloys-in-asteroids - and someone answered with a claim to have found a very high, near pure iron content meteorite but he couldn't find any experts who agreed that it was a meteorite and not something with human/terrestrial origins.)

@Markus Hanke Thanks for the reply. I have to admit my level of ignorance has not decreased by much; I will defer to people who know more than me and take it as given that the mass within black holes affecting space-time outside it with gravity isn't a contradiction.

Another question out of ignorance - How does a black hole's gravity influence matter around it if it's mass cannot have a causal effect? Is gravity's effect not causal?

I'd be pleased to be wrong but don't really expect any such loopholes; ignorance allows room for speculation... and makes it more likely I am wrong. A singularity, where the laws of physics break down but that doesn't mean anything could happen; maybe the very opposite - is there anything more inert than what is in a black hole?

Whatever happens on the other side of the event horizon of a black hole there is still mass and gravity interacting with spacetime and matter in the present. I am no physicist but it does seem that out of the things we cannot yet explain within a unified theory of everything gravity is up near or at the top. I would like to think that leaves room for some of those "magic" possibilities - FTL, reactionless drives, anti-gravity - but I remain very doubtful that will be the case.

@mistermack I am still inclined towards boreholes into bedrock as the most widely available inter-seasonal thermal storage for heating buildings. High temperature storage can do other things but probably can't do building heating as cost effectively. It looks even better when large scale, ie district heating rather than one building at a time From what I could find out about the Drake Landing example - and in keeping with my prior understanding - such heat masses need to be "primed" before the heat losses to surrounding rock slow sufficiently to give effective insulation; the first few years a lot more heat went in than came out but once the ground mass had gained enough heat the net flow out got a lot closer to the flow in. They claim Coefficient of Performance of 30 after the system was fully operational, ie 30x more heat than (non-solar) energy requirements, with more recent addition of solar PV to run the electricals. No heat pumps in that example so the storage mass must be hot enough to deliver water at temperatures high enough. Bigger storage mass and lower temperatures would use heat pumps.