The scenario being this:

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The red band extending 15 degrees from the equator is a dead zone, too hot for complex, multicellular life to thrive. How hot are we talking? The equator in this scenario scorches up to 165 degrees Fahrenheit. The last time the tropics got this hot was 270 million years ago. How the catastrophe happened is a mystery. After all, we still don't know how the Paleocene-Eocene Thermal Maximum happened so quickly and so dramatically.

But outside the red band, in regards to temperature and circulation, what would the rest of Earth's oceans look like in this scenario?

  • $\begingroup$ When you say "the last time it happened" are you talking about your world or our real world? $\endgroup$
    – L.Dutch
    Jun 12, 2022 at 3:53
  • $\begingroup$ @L.Dutch Either way. $\endgroup$ Jun 12, 2022 at 4:08
  • 2
    $\begingroup$ More information is needed. Is this sea temperature or the air temperature? Is this radiant heat from the Sun or some other source and if it is from the Sun can we assume that the remainder of the planet has been heated in proportion? Or is this a specific equatorial heating event? If it is how long does it last days, years, thousands of years millions of years? $\endgroup$
    – Slarty
    Jun 12, 2022 at 6:29
  • $\begingroup$ Please give some references for your historical temperature statements. Yes, air temps may have peaked at times at 165F, but those would have been absolute maximums. The Permian is a less-studied period and information is thinner with more guesswork. $\endgroup$
    – DWKraus
    Jun 12, 2022 at 14:25
  • $\begingroup$ I think I am repeating the other request for more details about the assumptions. 165 degrees F on land, or in the ocean? The ocean is such a large heat sink... There could be a hot ocean surface layer and very strong thermocline? Without the polar ice caps reflecting light, it seems like the ocean temperatures might not be different between the arctic and equator. $\endgroup$
    – UVphoton
    Jun 12, 2022 at 15:21

2 Answers 2


The effects of this scenario would be far-reaching and complex, but in general, the oceans would be warmer, more stagnant, and have less oxygen.

In the short term, the loss of phytoplankton in the dead zone would lead to a decrease in atmospheric oxygen levels, as these organisms are responsible for a large portion of global oxygen production. This could have severe consequences for animals that rely on oxygen to breathe, including humans.

Outside of the dead zone, ocean temperatures would increase due to the loss of evaporative cooling from the surface waters. This would lead to changes in circulation patterns and ocean currents, which could disrupt local ecosystems and affect global climate patterns. Additionally, the warmer water would hold less dissolved oxygen, leading to "dead zones" where marine life cannot thrive.


Higher temperatures in the equatorial area means also that more energy gets conveyed at higher latitudes: water and air circulation will be stronger because they are pushed by a stronger engine.

Together with the above, higher temperatures mean also higher evaporation and precipitation, probably turning a good part of what is today temperate climate into a warmer and more humid place.

I doubt there would be ice caps in the polar regions: the warmth coming from the equatorial through atmospheric and ocean circulation would prevent it from forming.

  • $\begingroup$ Could you expand on that? Because it doesn't seem to answer the question. $\endgroup$ Jun 12, 2022 at 13:00

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