Here is a map of an alternate Earth that I've been building and rebuilding for years:

enter image description here

To make things easier on all of us, myself included especially, at the bottom left is a legend on this world's elevation. The differences become most apparent when comparing this map to our map:

enter image description here

Not that the Old World in the alternate Earth is further eastward than ours, and Australia is closer to Antarctica. Presented below is how one of the artists I commissioned interpreted how these geographical differences affected the ocean currents (name is in the map):

enter image description here

And now here is how "SealBoi" imagined how the differences would affect the overall climate:

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The legend in the map is as follows:

Red - hot desert, e.g. Sahara

Orange - hot/semi-arid steppe, e.g. Sahel

Light-ish blue (in the tropics) - savannah, e.g. Serengeti

Cyan-ish - tropical monsoon forest, e.g. Western Ghats

Dark blue - tropical rainforest, e.g. Amazon

Yellow-green - humid subtropical, e.g. Florida

Very pale green - humid subtropical, but drier, e.g. Northern India

Darker green (usually near previous) - like previous, but colder, e.g. Hengduan Mountains

Bright, "normal" green - temperate oceanic, e.g. Ireland

Dark green (see Tasmania) - subpolar oceanic, e.g. coastal Iceland

Pink - cold desert, e.g. Gobi

Pale orange - cold steppe, e.g. Great Plains

Bright yellow - Mediterranean, e.g. Greece

Darker yellow - the previous, but colder, e.g. Ethiopian Highlands

Light blue (in the temperate zone) - humid continental, e.g. Poland

Very light blue - that, but warmer - e.g. Iowa

Dark blue-green - subarctic/taiga, e.g. Siberia

Pale-ish purple - continental but drier, high-altitude counterpart to Mediterranean, e.g. Zagros Mountains

Dark purple - subarctic but with dry summers, rare, e.g. Brooks Range

Pale grey - tundra, e.g. Arctic Archipelago

Dark grey - ice cap, e.g. Antarctica

So using the provided information above, I ask you this one question--is the climate map, in any way, accurate?

  • $\begingroup$ This appears to be a well researched (as far as I can tell, not my area), thorough, detailed question about your world. (That you seem to have written it as a geographical/climatic proofreading question, I'm going to ignore - for a couple of days - because of the work you've put into it). $\endgroup$ – Rottweiler on market-day. Feb 5 at 2:36
  • $\begingroup$ You label the Sahara region as hot desert, but there are immense lakes in it. Our own Sahara once had vast lakes, but it also had a moist climate at the time. $\endgroup$ – Mike Serfas Feb 5 at 22:10
  • $\begingroup$ @MikeSerfas You will notice that the desert is still not as big as back home. $\endgroup$ – JohnWDailey Feb 5 at 22:49

I'll repost what I told you on Reddit, as this looks like the same map:

For the most part the climate won't be any different as no major currents are interrupted outside the Arctic, but the change there won't make it any warmer so it'll still be Köppen ET/EF. Where you've added large inland bodies of water expect the Köppen classification to distort the classification around it, adding a thin band of moister classification around it—from B to C or near-C in desert areas. Worth noting:

  • From Egypt south to Somalia expect the same climate as SE China down to the east side of peninsular SE Asia

  • Expect inner India to be hotter and drier particularly on the west side

  • Megabangladesh will also be hot/dry inland, subtropical coast

  • Saharan Africa will be more savannah than arid desert, but pockets of arid/semi-arid terrain will persist particularly to the east and southeast of large bodies of water, likely not sandy desert though; ringed with humid subtropical otherwise

  • Western Australia will remain dry but expect humid subtropical or oceanic climate southwest of the inland sea

  • Western central Asia will be wetter but not much warmer; coast will be Mediterranean (think California) stretching into humid continental

  • $\begingroup$ Concur with first bullet point that there will be more moisture in the area between egypt<>somalia. At the very least along the coastline. Depends which way you have winds blowing across your "tethys sea". $\endgroup$ – EveryBitHelps Feb 8 at 13:19

Looks pretty believable. Couple of things I noticed when looking at particular regions.

  • Note on SE.Australian currents.

As whole landmass is located further south, I think you more likely to have cold currents creeping up the SE between NewZealand and Aus. Same as in your S.America Falklands currents. Rather than keeping the same pattern of warm currents from IRL.

I looked up the bathymetry of Tasmanian sea and agree that the deeper cold currents probably won't flow through that gap with force (but I assume some cold currents will make it over the continental shelf barrier). If you haven't already noted, there will be alot of upwelling in that region. Nice spot for fishing probably.

Don't think bright and dark green climate completely accurate. More likely to be a continuation of pink and yellow options, at least around tasmania and the tip of SE Aus. Thinking Tasmania will have more grey artic, like tip of S.America, than the dark green of "coastal Iceland".

  • Note on S.African currents.

With the slight change in angle of the continent orientation I agree that the warmer currents probably won't sneak into the Atlantic anymore. Besides removing the mediterranean climate from the Cape region (which you have done), it will potentially also impact your tornado alley in N.America; as those warm Natal Eddies are suspected of impacting the initial formation of oceanic pressure systems that go onto wreck havoc.

  • Note on the removal of Greenland.

This will mean that the Labrador current will be completely different. This impacts N.America climate as the L.current is said to make winters more severe in part due to lower salinity (due to somewhat poor mixing?). I don't think this changed current has been fully shown in your new NE.America.

I'm not sure how this removal of Grrenland and change in L.current will effect the Gulf Stream but pretty sure there will be more noticable changes than you have mapped. I think the Gulf Stream may become weaker, meaning the UK and W.Europe actually become colder and don't stay the same as IRL (Negated somewhat by your warmer Mediterranean/Tethys sea hybrid).

  • $\begingroup$ Greenland has not been removed. $\endgroup$ – JohnWDailey Feb 8 at 21:37
  • $\begingroup$ JohnWDailey Fine ;) Greenland has been smeared into the top region of the arctic circle, along with the closing of the bering strait. It's not where it was IRL and I believe there would be more of an impact on the ocean currents in that particular region than you have already shown. $\endgroup$ – EveryBitHelps Feb 9 at 9:17
  • $\begingroup$ "there would be more of an impact on the ocean currents in that particular region than you have already shown." In what way? $\endgroup$ – JohnWDailey Feb 10 at 5:08

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