I have an idea for a story set in an alternate world where an Australia-sized continent exists near South America, near Chile.

Question: what would the climate of this world would be, if this continent existed?

Approximation using true size website:

Australia in the South Pacific, off the coast of Chile

A short description of the continent: it forms by a meeting of three separate landmasses. That created a great plateau around the highest peak making up 35 percent of the total land. Around the tips of the island, particularly in the northeast and southwest, there's Appalachian like mountains. The southern land extends way into polar circle.

A very rough drawing of the land:

a circular landmass with rough edges

more context :

  1. they formed from three sunder land plateau.
  2. the highest peak is around 5000 m tall.
  • $\begingroup$ The size of the continent is not the consideration. You also have to define its geography. In particular the extent (area covered) and height of it's mountain ranges. (I'm assuming of course that your continent is not identicle to Australia in that regard.) $\endgroup$
    – Mon
    May 4, 2022 at 10:55
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    $\begingroup$ How does the continental shelf look like? Is ist close to the continent? Or does it connect to the other continents? $\endgroup$ May 4, 2022 at 11:07
  • $\begingroup$ an edit was made $\endgroup$
    – faddllz
    May 4, 2022 at 11:16
  • $\begingroup$ Impact on whose climate? I can tell you without a shadow of a doubt that an island the size of Australia off the coast of Chile would have exactly zero impact on the climate of China, or Europe, or Russia. $\endgroup$
    – AlexP
    May 4, 2022 at 17:01
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    $\begingroup$ I mean, Antarctica is an "Australia-sized continent near South America, near Chile," just sayin'. $\endgroup$
    – stix
    May 6, 2022 at 17:08

3 Answers 3


The biggest contributors to climate in the context of what you are putting forth, would be the disruption of ocean currents in this region of the globe. the 2 most important The Arctic Circumpolar Current and the South Pacific Gyre. Your land mase looks to be situation directly in the middle of the South Pacific Gyre. To make any prediction (even then would be complete guess work without a super computer) of how this land mass would have on climate you will have to state what the geography of the sub sea continental shelf. How shallow is the seafloor in the regions these currents now flow?

Without the South Pacific Gyre cool water would not be picked up from the south and brought north, thereby heating the northern pacific rising evaporation between your content and south america. Or the Mentor curent (part of the gyre that flows up South America's west coastline may instead be diverted up the coastline of your content. heating the SA coast causing greater rainfall in that region.

All if this is guess work and it gets even worse the farther out you get. Disruptions in the much talked about el nino cycle could have drastic effects as far as Australia Asia and North America.

Perhaps the issue with getting straight forward answers is that; Your not creating a new world and handwaving much of what we don't know. You are taking a lot of what we know, but don't fully understand anyway, and plopping a great big steaming question mark into the middle of it all. As I said, if there was an answer, it would have to come from a super computer and it still would not be correct. Because we can't get accurate predictions with all the hard data that exists in the real world.

  • $\begingroup$ What if we just had the supercomputer say what was the most believable(for scientists, regular joes, everybody, its a supercomputer after all), instead of what was most accurate? $\endgroup$
    – LWS SWL
    May 7, 2022 at 21:10

Obligatory not a meteorologist disclaimer, but to the best of my understanding a continent located where you said would mostly have the climate influenced by the southern westerlies as the prevailing wind pattern. This basically means the western part of your continent would be more humid (since the water from the ocean would be pushed east). I’d expect deserts or grassland at least to form on the eastern side of any mountains you have while the west would have jungles or forest. Also chile and Argentina would be a little drier because your continent blocks a lot of the water that would normally be pushed east, though I don’t think the effect would be extreme since the real mountains there already kind of do that.

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    $\begingroup$ "The western part of your continent would be more humid": as illustrated by the great example of the real-world Australia, where, as we all know, the western part is lush and green and the eastern part is a desolate desert. $\endgroup$
    – AlexP
    May 4, 2022 at 16:59
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    $\begingroup$ Yeah I'mma go sit in a corner and rethink my life now. $\endgroup$
    – Doguskang
    May 6, 2022 at 21:52
  • $\begingroup$ @AlexP He's right though, everything to the east of Australia receives humid air going from West to East. The effect is particularly pronounced during El Nino years. Australia's meteorology, like its egg laying mammals, landscapes, history and football version, is strange, and it's the exception, not the rule. There are no mountains in the West, which means the usual dropping out of humid air doesn't occur. The northwest actually does get quite a lot of rain. $\endgroup$
    – user86462
    May 7, 2022 at 7:10

History itself would be very different. What if there was an society that formed there? What if they created an empire? What if their empire technology was enough to go to Soutch America and eliminate those like the Incas? How would those like Francisco Pizzarro react? Not only that, but there could be a gold rush later on, or that continent could be its own country or colonized. Maybe if there were more details on the wildlife and societies there I can help describe more.


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