Then thereās whether humanity could leave the business-as-usual pathway by one of several plausible exit points well before the end of the century, but find itself on a pathway with the same (or worse) 2100 endpoint for the oceans because of intrinsic feedbacks, for example, due to carbon dumped from the ocean, sudden thaws of permafrost
I agree, weāre pushing some massive changes into complex important systems we really have trouble understanding, this is usually a recipe for disaster.
Iām not a marine biologist (my undergradās in geophysics), but I have painted myself enough of a picture to get, in broad strokes, that marine life will perish under a business-as-usual carbon production and pollution production scenario.
This is a strong conclusion, but I can agree with it.
Just two questions :
Is your conclusion still valid given the estimates of greenhouse gasses that take into account fossil fuels depletion, like I point out at the end of post 2 (i.e. not IPCC models, closer to 2 to 3 degrees of warming) ?
Is pollution (like plastic or eutrophisation) strong enough to make marine life perish at a global level ? Or is it just very bad locally ?
OK, well, Iām running behind, having not read post 2 and having not yet linked up my last post, but if youāre asking whether we stop producing GHGās at 2-3C, then does that include methane and coal? Either way, it comes back to how fast and how much feedback kicks in between 2-3C GAST. Coal matters because thereās an aerosol effect associated with it that we already take advantage of, somewhere in the range of 0.5C degree GAST decrease, from what I remember.
Thereās global methane hydrate melting with slowing of the AMOC and heating of the water below the surface level, the earliest prediction for that from a tipping point expert is after 2C , I think thatās the link, the discussion comes up in the Q and A, itās worth watching. When AMOC slows is model-dependent, and the models donāt agree. I also came across a news article about a recent expedition that found a new methane vent in the laptev sea.
Then thereās abrupt permafrost thaw, wildfires in permafrost land acting as a positive feedback, and the eventual contribution of gradual thaw.
then thereās loss of terrestrial sinks. Need for biomass in an energy crisis will strip forests, drought will cause wildfires, disease will continue to harm forests, and damaging forest management policies, as in the Amazon, could do the rest.
The plastic problem is global. Fishing gear contributes a lot to the problem. My guess is that it gets dumped wherever fish are being harvested, but it could be the opposite. How much of an impact it has on ocean life depends on how much it scales, but notice there are waste streams from land and a separate waste stream of plastic from fishing gear. The fishing gear plastic pollution might be targeted, and possibly less of a matter of scale and more about where it is dumped. Or not, youād have to have a model of ocean circulation, plastic breakdown, and dumping areas to make sense of that. It would help to know how much of the increase in plastic use is burned, landfilled, or dumped at sea in future.
Thereās some discussion about PFAS pollutants, but the fundamentals are about ecology. Are there some pollutants that, if dumped once, could kill most marine life? I believe so, but Iām avoiding research of that topic on purpose for now, first because its about how to poison the ocean, and second, because the lesser cases with the same outcome rely more on marine ecology knowledge, something Iām still lacking.
Regardless of initial pressures on marine life, pressure on human food systems will lead to overfishing, as fisheries suffer declines, fishing fleets will cheat the system, and deplete populations. Between by-catch and abandoned gear, the fishing industry alone could destroy marine ecosystems as human population goes up and as pressure to cheat quota systems, for lack of food or to meet rising demand, also goes up. Not only will that lead to long-term fishery declines and even species extinction, it will lead to increasing amounts of fish that do not meet health and safety standards ending up on peopleās plates, before the fish are gone entirely. This is a bit of a tangent, but is important enough to explore on its own.
Another tangent is what contribution the ocean actually makes as a carbon sink. Iāve seen estimates from 25% to 40% (and one scientist claiming 50%), and the relevance of those numbers is a bit different. For example, the 25% is a historical account over the last few hundred years, whereas the higher numbers could refer to current sink contributions, but I have to track the higher numbers down to research sources.
Does killing off larger organisms lead to collapse of specific plankton populations? Thatās the bottom line as far as loss of the biological pump. Iām still working on it, I donāt have much time, so give me a chance, Iāll try to finish links on this comment tonight, and maybe get a few into the prior comment.
This is really about ocean tipping points as well, another research topic. Yeah, I need time.
Finally, thereās the possibility that leaving the ocean and coastlines entirely alone while reducing GHG emissions could increase the action of the biological pump enough to draw down our current GHGās and reduce GAST overall. By leaving the ocean alone we could undo climate change. But that would mean doing everything right. Not the usual for us humans.
Oops, I though I had answered this commentāsorry about the delay.
Thanks for the links, this is interesting. I am not sure I will dig into this topic right now but I might at some point when looking into ecological collapse, so this might provide a good start.
I was aware of the huge impact of discarded fishing gear on plastic, but probably neglected other impacts you mentioned.
But that would mean doing everything right. Not the usual for us humans.
Well put, exactly the problem. Every time there is an issue, whether social or ecological, someone says āyeah but we can do that to solve the problemā. But we donāt. Thatās the issue.
I agree, weāre pushing some massive changes into complex important systems we really have trouble understanding, this is usually a recipe for disaster.
This is a strong conclusion, but I can agree with it.
Just two questions :
Is your conclusion still valid given the estimates of greenhouse gasses that take into account fossil fuels depletion, like I point out at the end of post 2 (i.e. not IPCC models, closer to 2 to 3 degrees of warming) ?
Is pollution (like plastic or eutrophisation) strong enough to make marine life perish at a global level ? Or is it just very bad locally ?
OK, well, Iām running behind, having not read post 2 and having not yet linked up my last post, but if youāre asking whether we stop producing GHGās at 2-3C, then does that include methane and coal? Either way, it comes back to how fast and how much feedback kicks in between 2-3C GAST. Coal matters because thereās an aerosol effect associated with it that we already take advantage of, somewhere in the range of 0.5C degree GAST decrease, from what I remember.
Thereās global methane hydrate melting with slowing of the AMOC and heating of the water below the surface level, the earliest prediction for that from a tipping point expert is after 2C , I think thatās the link, the discussion comes up in the Q and A, itās worth watching. When AMOC slows is model-dependent, and the models donāt agree. I also came across a news article about a recent expedition that found a new methane vent in the laptev sea.
Then thereās abrupt permafrost thaw, wildfires in permafrost land acting as a positive feedback, and the eventual contribution of gradual thaw.
then thereās loss of terrestrial sinks. Need for biomass in an energy crisis will strip forests, drought will cause wildfires, disease will continue to harm forests, and damaging forest management policies, as in the Amazon, could do the rest.
The plastic problem is global. Fishing gear contributes a lot to the problem. My guess is that it gets dumped wherever fish are being harvested, but it could be the opposite. How much of an impact it has on ocean life depends on how much it scales, but notice there are waste streams from land and a separate waste stream of plastic from fishing gear. The fishing gear plastic pollution might be targeted, and possibly less of a matter of scale and more about where it is dumped. Or not, youād have to have a model of ocean circulation, plastic breakdown, and dumping areas to make sense of that. It would help to know how much of the increase in plastic use is burned, landfilled, or dumped at sea in future.
Thereās some discussion about PFAS pollutants, but the fundamentals are about ecology. Are there some pollutants that, if dumped once, could kill most marine life? I believe so, but Iām avoiding research of that topic on purpose for now, first because its about how to poison the ocean, and second, because the lesser cases with the same outcome rely more on marine ecology knowledge, something Iām still lacking.
Regardless of initial pressures on marine life, pressure on human food systems will lead to overfishing, as fisheries suffer declines, fishing fleets will cheat the system, and deplete populations. Between by-catch and abandoned gear, the fishing industry alone could destroy marine ecosystems as human population goes up and as pressure to cheat quota systems, for lack of food or to meet rising demand, also goes up. Not only will that lead to long-term fishery declines and even species extinction, it will lead to increasing amounts of fish that do not meet health and safety standards ending up on peopleās plates, before the fish are gone entirely. This is a bit of a tangent, but is important enough to explore on its own.
Another tangent is what contribution the ocean actually makes as a carbon sink. Iāve seen estimates from 25% to 40% (and one scientist claiming 50%), and the relevance of those numbers is a bit different. For example, the 25% is a historical account over the last few hundred years, whereas the higher numbers could refer to current sink contributions, but I have to track the higher numbers down to research sources.
Does killing off larger organisms lead to collapse of specific plankton populations? Thatās the bottom line as far as loss of the biological pump. Iām still working on it, I donāt have much time, so give me a chance, Iāll try to finish links on this comment tonight, and maybe get a few into the prior comment.
This is really about ocean tipping points as well, another research topic. Yeah, I need time.
Finally, thereās the possibility that leaving the ocean and coastlines entirely alone while reducing GHG emissions could increase the action of the biological pump enough to draw down our current GHGās and reduce GAST overall. By leaving the ocean alone we could undo climate change. But that would mean doing everything right. Not the usual for us humans.
Oops, I though I had answered this commentāsorry about the delay.
Thanks for the links, this is interesting. I am not sure I will dig into this topic right now but I might at some point when looking into ecological collapse, so this might provide a good start.
I was aware of the huge impact of discarded fishing gear on plastic, but probably neglected other impacts you mentioned.
Well put, exactly the problem. Every time there is an issue, whether social or ecological, someone says āyeah but we can do that to solve the problemā. But we donāt. Thatās the issue.