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Both are related, as Venus is thought to have lost its water through runaway greenhouse. Without water, tectonics and vulcanism are likely to cease, and CO2 is
by queuebert 3y ago
Both are related, as Venus is thought to have lost its water through runaway greenhouse. Without water, tectonics and vulcanism are likely to cease, and CO2 is unable to be recycled into the deeper layers of the planet. It builds up on the surface, and you get a 70 bar atmosphere of mostly CO2. This "runaway" feedback loop is one of the main reasons why global warming should be avoided, in my opinion.
- soderfoo 3y agoIt's quite terrifying to think of a runaway feedback loop leading to the emptying of the oceans, on the scale of happening within a lifetime.
- Kevin09210 3y agoWait I thought the extreme runaway greenhouse effect had been set aside (read that on here a few years ago IIRC), and it wasn't possible for Earth's atmosphere to turn into Venus'. Found this from April 2023: >How a Stable Greenhouse Effect on Earth Is Maintained Under Global Warming >Plain Language Summary: Observations and model simulations have shown that Earth maintains a stable longwave radiative feedback process. When the surface warms by 1 K, Earth allows for 1.7 to 2.0 Wm−2 of extra thermal cooling to escape to space in cloud-free conditions. Recent studies have claimed that this enhanced thermal cooling to space can be explained by emissions from the surface passing through the atmosphere's infrared window. However, we find that a large portion of the stability actually results from enhanced atmospheric emission during global warming, which arises from the weakening of spectral lines broadening by radiatively inert gases (N2, O2, Ar) as the Earth warms. It is a well-understood phenomenon in spectral physics but has been largely ignored in the feedback literature. As a result, the feedback responses from the thermal radiative effects of greenhouse gases tend to stabilize the climate, rather than initializing a runaway of thermal radiative energy. This study further proposes a simple theory for accurately predicting the clear-sky longwave feedback from climate base states. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022JD038124 https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022...
- queuebert 3y agoThanks for the link -- I hadn't seen that. My issue is that water lost faster than delivered by comets is bad for tectonics, which is bad for atmospheric CO2. They'd have to show no net loss of water, or else the system is not stable over Gyr timescales.
- lamontcg 3y ago> This "runaway" feedback loop is one of the main reasons why global warming should be avoided, in my opinion. The Earth has had a 4,000-7,000 ppm CO2 concentration in the atmosphere before and it hasn't led to Venusification. We've only gone from ~250 to ~420 ppm so far, so we're a long way off, and hopefully we'll stop before we dump another 20+ "industrial revolution units" of CO2 into the atmosphere. Of course long before then we melt Antarctica and the Earth's climate looks a lot different, but it won't be Venus.
- c22 3y agoIn 1860 atmospheric co2 was at 288 ppm [0]. By 1960 it was around 317 ppm [1]. A difference of 29 ppm which works out to about 226.78 gigatons of co2 [2]. In 2022 we emitted 37.5 gigatons of co2, up 0.9% from 2021 [3]. We are currently emitting an "industrial revolution" of co2 every ~6 years. [0]: https://www.chicagotribune.com/news/ct-xpm-2000-05-23-0005230241-story.html https://www.chicagotribune.com/news/ct-xpm-2000-05-23-000523... [1]: https://www.statista.com/statistics/1091926/atmospheric-concentration-of-co2-historic/ https://www.statista.com/statistics/1091926/atmospheric-conc... [2]: https://www.quora.com/How-many-grams-of-CO2-are-in-the-atmosphere-The-number-of-moles-of-air-are-1-8194-x-10-20-10-to-the-20th-power-PPM-is-315-97 https://www.quora.com/How-many-grams-of-CO2-are-in-the-atmos... [3] https://www.statista.com/statistics/276629/global-co2-emissions/ https://www.statista.com/statistics/276629/global-co2-emissi...