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When CO2 dissolves in the ocean, some of it will eventually end up as methane ice in ocean mud [0]. Methane ice releases its methane when warmed slightly. Mor

When CO2 dissolves in the ocean, some of it will eventually end up as methane ice in ocean mud [0]. Methane ice releases its methane when warmed slightly. More methane ice means higher chances of runaway global warming. [0] https://en.wikipedia.org/wiki/Methane_clathrate https://en.wikipedia.org/wiki/Methane_clathrate

ncmncm 5y ago
Hint: CO2 is already dissolving in the ocean. Hint: CO2 does not turn into methane. Methane clathrates on the sea bottom got there by seeping out from bottom mud, and froze there. Sometimes the methane was excreted by microbes in sea-bottom mud; other times it comes from the rocks. Often, methane and other seeped hydrocarbons are oxidized to CO2 by microbes.
- mleonhard 5y ago
  > CO2 is already dissolving in the ocean. Yes, and it's saturating the top levels of the ocean. GP suggested mixing the ocean to saturate more of it. > CO2 does not turn into methane. CO2 gets turned into many things, as part of the ocean carbon cycle [0]. Algae near the surface absorb CO2, incorporating it into their cells. Algae is the bottom of the ocean food chain. Increasing the algae increases the overall amount of life in the ocean, increasing the rate of organic detritus accumulating on the ocean floor [1], forming more mud. Bacteria in the mud consume the organic detritus and emit methane [2]. Methane ice is one of the few ways that carbon can exit the cycle. Therefore increasing the volume of carbon in the cycle will make methane ice accumulate faster. Over centuries, the world's CO2 pollution could get converted into methane ice on continental shelves. Then a minor warming event could trigger the release of all that carbon. But the carbon is methane now, which is 70x more warming than CO2. The warming effect could be catastrophic for our ecosystem. I think this is a risk of utilizing the ocean as a CO2 sink. People in the year 4,000 may curse us for our carbon pollution and the resources they must spend to clean it up and convert methane ice into something more stable. [0] https://en.wikipedia.org/wiki/Carbon_cycle https://en.wikipedia.org/wiki/Carbon_cycle [1] https://en.wikipedia.org/wiki/Plankton#Carbon_cycle https://en.wikipedia.org/wiki/Plankton#Carbon_cycle [2] https://en.wikipedia.org/wiki/Methane#Seafloor_sediments https://en.wikipedia.org/wiki/Methane#Seafloor_sediments
  - ncmncm 5y ago
    Hint: Methane clathrates on the deep sea floor will not be releasing their methane. That is possible only where temperature is changing and pressure is low, neither of which will happen without surface changes catastrophic enough to make methane irrelevent. In any case, accumulation happens over eons. There is exactly zero risk of carbon stirred into the deep ocean becoming methane released into the atmosphere in this eon. Carbon in surface water can be metabolized, and may then be released as methane. Carbon moved to deep water is removed from that process. You are reaching. It is not a good look.
    - mleonhard 5y ago
      > Methane clathrates on the deep sea floor will not be releasing their methane. That is possible only where temperature is changing and pressure is low, neither of which will happen without surface changes catastrophic enough to make methane irrelevent. Methane ice forms under certain temperature and pressure. See the phase diagram at [1]. When methane ice forms on a sloping ocean floor, there is a boundary where the methane ice formation stops. The boundary depends on the temperature and pressure (depth). When water warms, this boundary moves deeper and all methane ice above it will convert to gas and eventually leave the ocean. How much deeper does the boundary move per 1C of temperature rise? I examined the phase diagram in Figure 6 of [1]. I found two points: (20 MPa, 275 K) and (40 MPa, 278 K). A change of 10.06 m increases pressure by 1 atm [2] or 101325 Pa [3], about 10 kPa per m or 1 MPa per 100m. So a 3 K increase in temperature results in the boundary pressure increasing 20 MPa or 2 km of ocean depth, a 1.5 K increase moves the boundary down 1000 m. The world's CO2 pollution is expected to raise surface temps by 1.5K. Given that methane is 70x more warming than CO2, if we were to convert most of the world's CO2 to methane and then release 1/70 or 1.4% of it, we would have the same amount of warming and could expect a similar 1.5 K temp rise. What percentage of methane ice will form near the boundary? To answer that, we would need to analyze ocean floor topography. I searched for a chart of depth to area and found none. Do you think the top-most 1km of methane ice forming areas would hold 1.4% of the ocean's recently-formed methane ice? The deepest part of the ocean is 10km deep. If the top-most 1km holds much more than 1.4% then there is the risk of runaway warming. Another risk is a change in ocean currents. Currents keep large areas of the ocean floor cold. If a current is disrupted, even for a short time, the clathrates in that region could release their methane, triggering runaway warming. > You are reaching. It is not a good look. Personal insults are boring and against the site guidelines [4]. Please don't write them any more on this site. [0] https://en.wikipedia.org/wiki/Methane_clathrate#Natural_deposits https://en.wikipedia.org/wiki/Methane_clathrate#Natural_depo... [1] https://doi.org/10.1021/acs.jpcb.7b10581 https://doi.org/10.1021/acs.jpcb.7b10581 [2] https://oceanservice.noaa.gov/facts/pressure.html https://oceanservice.noaa.gov/facts/pressure.html [3] https://en.wikipedia.org/wiki/Pascal_(unit) https://en.wikipedia.org/wiki/Pascal_(unit) [4] https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

ncmncm 5y ago

Hint: CO2 is already dissolving in the ocean. Hint: CO2 does not turn into methane. Methane clathrates on the sea bottom got there by seeping out from bottom mud, and froze there. Sometimes the methane was excreted by microbes in sea-bottom mud; other times it comes from the rocks. Often, methane and other seeped hydrocarbons are oxidized to CO2 by microbes.

mleonhard 5y ago
> CO2 is already dissolving in the ocean. Yes, and it's saturating the top levels of the ocean. GP suggested mixing the ocean to saturate more of it. > CO2 does not turn into methane. CO2 gets turned into many things, as part of the ocean carbon cycle [0]. Algae near the surface absorb CO2, incorporating it into their cells. Algae is the bottom of the ocean food chain. Increasing the algae increases the overall amount of life in the ocean, increasing the rate of organic detritus accumulating on the ocean floor [1], forming more mud. Bacteria in the mud consume the organic detritus and emit methane [2]. Methane ice is one of the few ways that carbon can exit the cycle. Therefore increasing the volume of carbon in the cycle will make methane ice accumulate faster. Over centuries, the world's CO2 pollution could get converted into methane ice on continental shelves. Then a minor warming event could trigger the release of all that carbon. But the carbon is methane now, which is 70x more warming than CO2. The warming effect could be catastrophic for our ecosystem. I think this is a risk of utilizing the ocean as a CO2 sink. People in the year 4,000 may curse us for our carbon pollution and the resources they must spend to clean it up and convert methane ice into something more stable. [0] https://en.wikipedia.org/wiki/Carbon_cycle https://en.wikipedia.org/wiki/Carbon_cycle [1] https://en.wikipedia.org/wiki/Plankton#Carbon_cycle https://en.wikipedia.org/wiki/Plankton#Carbon_cycle [2] https://en.wikipedia.org/wiki/Methane#Seafloor_sediments https://en.wikipedia.org/wiki/Methane#Seafloor_sediments
- ncmncm 5y ago
  Hint: Methane clathrates on the deep sea floor will not be releasing their methane. That is possible only where temperature is changing and pressure is low, neither of which will happen without surface changes catastrophic enough to make methane irrelevent. In any case, accumulation happens over eons. There is exactly zero risk of carbon stirred into the deep ocean becoming methane released into the atmosphere in this eon. Carbon in surface water can be metabolized, and may then be released as methane. Carbon moved to deep water is removed from that process. You are reaching. It is not a good look.
  - mleonhard 5y ago
    > Methane clathrates on the deep sea floor will not be releasing their methane. That is possible only where temperature is changing and pressure is low, neither of which will happen without surface changes catastrophic enough to make methane irrelevent. Methane ice forms under certain temperature and pressure. See the phase diagram at [1]. When methane ice forms on a sloping ocean floor, there is a boundary where the methane ice formation stops. The boundary depends on the temperature and pressure (depth). When water warms, this boundary moves deeper and all methane ice above it will convert to gas and eventually leave the ocean. How much deeper does the boundary move per 1C of temperature rise? I examined the phase diagram in Figure 6 of [1]. I found two points: (20 MPa, 275 K) and (40 MPa, 278 K). A change of 10.06 m increases pressure by 1 atm [2] or 101325 Pa [3], about 10 kPa per m or 1 MPa per 100m. So a 3 K increase in temperature results in the boundary pressure increasing 20 MPa or 2 km of ocean depth, a 1.5 K increase moves the boundary down 1000 m. The world's CO2 pollution is expected to raise surface temps by 1.5K. Given that methane is 70x more warming than CO2, if we were to convert most of the world's CO2 to methane and then release 1/70 or 1.4% of it, we would have the same amount of warming and could expect a similar 1.5 K temp rise. What percentage of methane ice will form near the boundary? To answer that, we would need to analyze ocean floor topography. I searched for a chart of depth to area and found none. Do you think the top-most 1km of methane ice forming areas would hold 1.4% of the ocean's recently-formed methane ice? The deepest part of the ocean is 10km deep. If the top-most 1km holds much more than 1.4% then there is the risk of runaway warming. Another risk is a change in ocean currents. Currents keep large areas of the ocean floor cold. If a current is disrupted, even for a short time, the clathrates in that region could release their methane, triggering runaway warming. > You are reaching. It is not a good look. Personal insults are boring and against the site guidelines [4]. Please don't write them any more on this site. [0] https://en.wikipedia.org/wiki/Methane_clathrate#Natural_deposits https://en.wikipedia.org/wiki/Methane_clathrate#Natural_depo... [1] https://doi.org/10.1021/acs.jpcb.7b10581 https://doi.org/10.1021/acs.jpcb.7b10581 [2] https://oceanservice.noaa.gov/facts/pressure.html https://oceanservice.noaa.gov/facts/pressure.html [3] https://en.wikipedia.org/wiki/Pascal_(unit) https://en.wikipedia.org/wiki/Pascal_(unit) [4] https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html