167

A dragon with a full wingspan of 20000 km (folded to fit into a 10000 km resting area) and surface area of 44 million sqkm will have a terrible impact on the environment. Phase I In the first days of her awakening, as she shifts, freeing herself from the encumbrance of all the cities and forests and so forth that are littering her back, widespread but ...


90

Everyone on the Earth dies and the planet becomes a steaming molten mess circling the Sun. Eventually everything will calm down and life will restart. But why? Fill a bucket with water. Now remove 1 cup of water. The removal of the water causes a wave across the surface of the cup while the water redistributes to fill in the hole. The same basic thing ...


45

No explanation needed: Kashmir The famous Vale of Kashmir is the perhaps the best example on Earth, certainly in Western imagination, of an exotic and fertile valley surrounded by mountains. Below are some pictures of Srinagar and Dal Lake in summer and winter, with mountains in the background (sourced from Wikipedia). The valley floor is about 1500 ...


35

Viruses are highly species-specific, i.e. a human virus will only kill humans. So a biological weapon will do the job. The best virus to use is beyond my knowledge, and I am a bit concerned a terrorist would read this. If we stick to sci-fi convention, then zombie virus is the most obvious choice. But realistically, even the deadliest viruses leave some ...


21

I give you Kelowna, British Columbia, and the Okanagan Valley. Surrounded by mountains, it's a humid continental climate with no shortage of vegetation and is certainly no desert. For a larger example, the entire interior of British Columbia: between the Coast Range and the Rockies, the Interior consists of topographically lower plateaus and valleys with ...


16

I think you have slightly misunderstood the rain shadow. It is caused by the mountains forcing the air flow upwards which in turn causes adiabatic cooling which causes rain. This in turn combined with the water from the rains running down hill away from the mountains means that mountains make more water come down from the atmosphere than goes back up in ...


14

If your dragon is just a very, very large creature then - as ably described by elemtilas - total destruction of the Earth's environment ensues. But this is religion describing a god-like entity, and you didn't slap a science-based tag on this, so perhaps there is some wiggle room. Of course there's no continent-sized physical entity slumbering away with ...


11

Simplest answer is a very large warm water lake in the centre (Around the size of the great lakes if you can, but even a lake half as big will work, even as little as 25km in diameter is good enough to have some effect). The lake will change the pressure in the area, creating some small amounts of rain. The water table can be close to the surface, allowing ...


11

Targeted robotic micro cluster munitions. Some humans might be resistant to a biological weapon, or be able to be isolated before infection sets in. Few humans will be resistant to a micro shaped charge to the head... Designed as hoppers, such devices could be sized such that they wouldn't leave notable damage to any part of the surrounding environment. ...


9

I live in such a valley, Oregon's Willamette valley. It's roughly 25 miles wide, 100 miles long, and is extensively farmed. The coast range, on the upwind side during the rainy season, is substantially lower (most peaks under 2000 feet) than the Cascades on the downwind side (most passes over 5000 feet). So, much of the water passes over the coast range ...


8

Yes The key is the right plants to meet the needs. You have things like the water chestnut, taro, Watercress and lotus You can also dredge up mud from the ponds to build raised garden beds for more conventional foods as well as using potted plants


7

For the question as stated, it is not necessary to use a bioweapon; Slaughterbots programmed to consider all humans "the bad guys" would do, too. In case you cannot see the video: The concept is a swarm of AI-controlled drones, each equipped with a shaped charge designed to penetrate a human skull. The drones are more maneuverable than a human hand, so once ...


7

The short answer to your question is that your plants could be any colour, but that is a massive over-simplification of the processes that lead to plant colours being what they are. I'll go through some of the basics though to spell it out in more detail. Visible light is only 0.0035% of the EMR spectrum For a start, the plant colours we see today are based ...


7

Seriously? Assuming the dragon's belly is more or less spherical, and 5,000 km thick, it should weight about 1020 tons, give or take one order of magnitude, depending on the actual density of a dragon. That's around 1023 kilograms, or ten thousand times the estimated mass of the atmosphere. So, uh, let's hope that dragon doesn't try to fly. You wouldn't ...


6

Because the mountains aren't high enough to block all the rain clouds that come that way. This can be a function of: A. Them actually being relatively low all around i.e. less than 1000m above sea level so they just don't block the rain, mountains of this size may seem small but if they're extensive and broken enough they'd still be impassable. or B. The ...


6

Iron is irreversibly chelated into non-degradable molecules. Consider PCBs or polychlorinated biphenyls. https://en.wikipedia.org/wiki/Polychlorinated_biphenyl These were useful industrial chemicals, but unfortunately persist indefinitely in the environment. Somehow they also cause health problems, which I would not expect for a biologically ...


6

Yes, depending on wind patterns. It's definitely possible for a mountain range to have significant precipitation, so long as there isn't a strong, dominant wind pattern going across the mountains. Globally, climate patterns look like this: Looking at the US, in much of the West there are large rainshadow regions. These are behind the Cascade and Rocky ...


6

In addition to what @TrevorD pointed out there would also be an unprecedented volcano-esque blast as the weight of the continent came off the underlying rocks. The gases dissolved into the mantle under the continent would be liberated. Think of what happens to a shaken bottle of carbonated beverage that's opened suddenly, now imagine that the bottle lid is ...


6

The mythic story says "the land itself", if this can be interpreted as the entire planet you have the classic "World Echinus" theory as put forth in Sir Arthur Conan Doyle's Prof. Challenger story, "The Day the Earth Screamed". The theory surmises that the entire world is a living creature with the surface crust of the Earth being like the "test" or shell ...


5

Face recognition drones You can already find some pretty crazy simulations of swarms of bird sized drones, air dropped, that will just run to your head and detonate a directional explosive charge. add some bigger drones for door or window breaking, and you get a perfectly plausible mass killing weapon. Crazy expensive, but with minimal structure and nature ...


5

Your planet is a linear motor This is something I proposed in some detail in this answer. Your oceans are driven by a magnetohydrodynamic drive to constantly circulates the narrowly bounded ocean around the planet. This is how it works: Two powerful magnetic fields; one from your planet (an iron core like on Earth) and one external (perhaps an Earth-like ...


5

Iron is rather abundant in solid land, but no so much in significant parts of the ocean. Furthermore, plants have difficulty absorbing iron when soil pH is too high, has too much clay, or is overly wet (source). To make matters worse, high amounts of plant particles or manure (which would likely be a rudimentary attempt at fertilization post-apocalypse) ...


4

This is likely going to be a disease Human-only disease. A highly virulent and highly lethal disease which affects only humans can devastate the entire world before humans can do anything to react to it. Incubation period should be long enough that normal quarantine methods are not going to be very effective. The downside here is that there inevitably be a ...


4

Yes. Example: In western North America, there are forests of arid tree species (Juniper, Lodgepole Pine) in the rain shadow of many mountain ranges. The trees are slower-growing than their wet-side counterparts, the forests thinner and more sparse-looking.


4

The answer is almost certainly yes, unless there is a unique localised climate (like the dry valleys in Antarctica or the Atacama Desert). Although smaller in scale than the large continental regions your map depicts, the climate pattern of Te Waipounamu (South Island of New Zealand) is a good example of a rain shadow effect where forest is the primary ...


4

I was putting the following in a comment on @Thorne's answer. Then I realized it was too much. Already gave Thorne a thumbs up. Also, if you are going to have domestic animals, they need to be OK with a swamp. Probably going to include certain kinds of reptiles. Maybe certain kinds of fish. Possibly certain birds, geese and ducks maybe. Maybe there needs ...


4

Frame challenge: the dragon that was "as big as the world" is actually much smaller than we now understand the world to be. Ten billion people could sit comfortably in an area 100 KM square. If the dragon turned out to be real, the environmental consequences would be far less than if it were actually the size of a continent.


3

Certainly. A very good example is the Scandinavian peninsula. As you can see from the map below, there are lots of forest to the east of the north-south mountain range that forms much of the border between Norway and Sweden. They don't get as much rainfall as on the other side, but enough of the rain that falls on the mountains make it into the eastern ...


3

You may not need to look any further than the Andes and the Amazon basin to find an example on Earth. There is dense rain-forest "to the right" of much of the Andes mountains. If you want forest on both sides then there is the Urals with boreal forest on both sides (Urals are obviously lower than the Andes, but still a significant mountain range). If you ...


3

Your world would probably be very jungled in order to create enough oxygen for them. The waters more mineral rich for exoskeleton development. Their exoskeleton could have evolved to be more like the plates of an armadillo or other plated animal in order to accommodate increased heat stresses and allow for lung breathing. When I think of insectoid aliens ...


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