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the world

The setting is a sci-fi/fantasy future Earth ( ~5 million of years in the future) so mountain chains and general elevation is more or less the same of our own Earth, just out of position due to a slightly different poles location. Major difference is the desiccated Mediterranean basin, now a +3500 mt deep (11500 ft) empty salt waste. To help you visualize the current continents in the context of this tilt here’s a map with unaltered coastlines:

earth coastlines

The plausibility of the landmasses and features as I arranged them is not important: what I need is a general idea of the biomes and environments. Although I would like to have a general understanding of the global climate, if you can I would really appreciate a slightly more in-depth analysis of the continent highlighted in the map below (Western Europe + North-western Africa):

continent

OPTIONAL REQUESTS: I would like to keep things as scientifically believable as possible, but (for story reasons) it would be great to have:

  • Climate on the afore-mentioned continent approximating the corresponding climate of North/South America (the yellow dot in the center of the picture above is about same latitude as NY) e.g. North-western African coastline resembling more Florida in climate than Morocco
  • Specifically, I would like to have a continental dry/continental humid climate (or within “European” range) on the “Italian” land bridge across the deadly salty waste that is the empty Mediterranean basin. My explanation for this according to my own researches is that the lands across the empty basin would essentially behave as a high plateau with their own climate different from that of the geographical oddity that is a 3500 mt deep dry chasm. This chasm, according to this paper about climate during the Messinian age (last time the Mediterranean basin was empty), would against expectations actually increase precipitations on nearby mountain ranges especially on the northeastern edge of the basin (ref. line 599 in the paper); rivers would eventually fall into the hollow abyss and gather as hyper-saline lakes at the bottom then evaporate, restarting this closed cycle.
  • Global climate possibly resembling to some degree the Holocene climatic optimum e.g. “Green Sahara”.

Every reasonable explanation that integrates this requests is more than welcomed (but if plainly impossible I’ll just surrender to evidence). There is a lot of useful stuff in this paper about the Messinian Salinity Crisis (MSC) climate, though I honestly can’t understand most of the technical aspects but feel free to read it if you want to (jump to chapter 4. Discussion if you don’t want to read all the details).

TL;DR Can you help me setting the general climate for my world? bonus: is it possible to have a global climate resembling that of the Holocene climatic Optimum? (Or alternatively a climate on the continent depicted above equivalent to latitude to that of North/South America)

THANK YOU! Your help is immensely appreciated :)

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  • $\begingroup$ For the Mediterranean salt basin part, I would take a look at real world salt flats such as the Salar de Uyuni in Bolivia. I'm no climatologist, but it seems to be a reasonable example of what you're looking for, if on a smaller scale. $\endgroup$ – Kys Apr 6 '16 at 19:34
  • $\begingroup$ Not sure about "global climate"(reminds me of Larry Niven's offhand parody of bad SF: "It was raining on Mongo that morning")...if Earth retains its axial tilt and elliptical orbit you will see seasonal variations. I think the climate in that area will be more variable than Florida...if you're at NYC latitude you'll get swings in sunlight plus there will not be enough consistent energy for hot conditions. Also, you're sort of in the rain shadow of the mountain range to the east, which will also block any hurricane-like storms from the ocean. Unless you assume axial procession over 5M years... $\endgroup$ – lonstar Apr 15 '16 at 10:21
  • $\begingroup$ @lonstar Not sure I understood what you mean with "that area". If you mean the yellow dot area (which is NY latitude) I actually never asked for that spot to be Florida-like. Plus, i maybe did some language mistakes when using the word "global" cause i'm definitely not after a STAR WARS-ish "global climate". $\endgroup$ – JRover Apr 15 '16 at 11:25
  • $\begingroup$ It isn’t essential but I was preferentially asking for a climate in Europe and Africa resembling climate of same-latitude American areas (look at this picture for reference s-media-cache-ak0.pinimg.com/originals/b0/e5/a5/…). Florida latitude would be 1200 km south of the yellow spot, corresponding in the map above to the coast of "Morocco". Maybe it is just a very badly-worded question. $\endgroup$ – JRover Apr 15 '16 at 11:26
  • $\begingroup$ Unfortunately, this feels far too broad to me. You may be interested in the Creating a realistic world Series which has links to some questions that you may find useful to study in order to narrow this down a bit. $\endgroup$ – a CVn Apr 19 '16 at 9:42
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Hmm, I'm not sure I agree that the elevation generally remains the same. Given that vast tracts of land now look submerged on the western side of the world, either the sea-level has increased (all that water from the mediterranean has to go somewhere unless it's locked by ice) or the land-level has subsided. The eastern side looks like the land has risen at places (south-east asia/australasia) and sunk at few (southern china). Tectonic plate shift with or without sea-level changes would mean that the mountain chains/general terrain elevation will have changed.

There are two other things that will determine what the climate of this world is like:

  1. What are the median temperatures like? If it's a warm world, there will be little landlocked ice, increasing the amount of liquid water in the weather cycle, indicating a warm, vegetation-filled world with marked storms, extreme weather events and generous precipitation. If it's close to current temperatures, you could expect polar ice caps in the north and south, wet weather along continental peripheries and narrow land isthmuses and dry and arid interiors similar to what we have today. If it's cooler, the polar caps would be larger, locking up fresh water and limiting the rise of sea-level caused due to med sea. This would mean a drier environment overall with vast belts of grasslands and desert interiors.

  2. Are there any human/other-sentient-being-made developments changing the terrain (5my!) such as large scale land reclamation etc? Just how much of the biodiversity have they/we changed by now and how has that pushed the climate?

Now if you like Holocene optimum temperatures, you'd have to decide whether it is due to orbital tilt changes (increasing the temperatures in one hemisphere but working differently in the other) or general global warming (increasing temperatures world wide). Both would mean higher sea-levels that would submerge low-lying places. Possible marshlands, thick tropical forests along the coasts.

The wild card here is the North Atlantic Ocean; it no longer has the same size and is beginning to get landlocked, possibly disturbing the thermo-haline circulation that currently mixes deep-sea and surface sea water and creates a rich nutrient cycle. A large amount of salt would get trapped in the dry Med basin, reducing the salinity of the oceans overall. The current rain patterns may not hold in the adjacent land masses.

The Messinian basin would probably be a very arid and deep salt flat with brine lakes at places fed by inflowing rivers, all of it surrounded by mountain ranges north and south. While it is difficult to compare this with any existing place, there may be clues from the past as you pointed. Adiabatic heating would mean the salt flat would be very hot (the compression hasn't yet lifted the med basin upwards) Winds roaring across the flats, blowing salt dust around during dry weather. Apart from a few salt-tolerant species, no life would be found on the open flats. But there might be little corridors for migration following river beds on the plain, along the green ridges set above the salt plain. While the eastern half might get precipitation, the western half might go into a rainshadow.

As for the yellow dot place: The size of the salt brine lake may not be big enough to set up a closed cycle - eventually the lake would dry up due to the tectonic compression uplifting depending on when exactly you set your world. On the other hand, the possibly ice-capped mountains of the Alps would make a barrier for moisture winds blowing in from the Atlantic and getting funnelled into the Med valley. This would seem to indicate there would be some precipitation on the northern part of the green ridge. What is not sure is the moisture content of these westerlies. while this definitely can't be compared to the current levels of moisture obtained from the Med sea, it wouldn't be completely dry. The landbridge may not exactly be green and verdant unless the precipitation is at certain levels and then you need to take care that the rain (if any) doesn't leach essential nutrients from the soil and salt winds don't spoil the soil quality.

Well, that's my take on it any way, happy to be corrected.

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