anlomedad on Nostr: My other pet theory that methane concentration must have been much, much higher on ...

My other pet theory that methane concentration must have been much, much higher on that allegedly much, much warmer planet in the mid #Miocene , because more water evaporates from much warmer oceans and rains down on tropical wetlands – well, that theory is also shattered or made obsolete.
The excessive heat wasn't uniform. Low-latitude surface water was a normal ~2.5°C warmer than today, normal in that CO2 concentration of 400 to 600ppm.
So precipitation over tropical wetlands wasn't excessively high either. So wetlands weren't excessively larger. So methane…
…
oh. Uhm.
But it must have been excessive at least on the edges of the huge landmasses in the Northern Hemisphere exatropics.
Those edges that weren't submerged by sea water, of course.
Then places like Udo's swampy Swabia must have been strong CH4 producers… potentially much larger areas than today's major emitters, the tropical wetlands.

To achieve that excessive yet confined heat via ocean heat transport / currents renders juggling with a theoretical > 6000ppb CH4 unnecessary.

But it's still an interesting topic. All the more so because there are no proxies for Miocene methane. So we are free to speculate to our hearts' content. 😁