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I wouldn't worry about it getting too much traction. Even stratospheric injection of sulfiric acid (something that volcanoes do) is blackballed from even being

I wouldn't worry about it getting too much traction. Even stratospheric injection of sulfiric acid (something that volcanoes do) is blackballed from even being researched, let alone considered.

DennisP 5y ago
This idea actually seems safer to me, since rather than just blocking the sun, it actually takes our excess CO2 emissions back out of the atmosphere. And also methane. It's the first idea I've seen for doing that.
- tambourine_man 5y ago
  And doesn't produce acid rain, like sulfur does.
  - dr_dshiv 5y ago
    Acid rain resulted from the 30+ million tons of sulfur dioxide released into the lower atmosphere. To cut global warming in half, 25,000 tons of sulfur dioxide would be needed in the upper atmosphere. So, 3 orders of magnitude less SO2. Meaning, mitigating global warming with SO2 would not meaningfully increase acid rain. Source: https://www.technologyreview.com/2013/02/08/84239/a-cheap-and-easy-plan-to-stop-global-warming/ https://www.technologyreview.com/2013/02/08/84239/a-cheap-an...
    - bayesianbot 5y ago
      That 25,000 tons figure sounds really controversial. Even the article mentions > David [Keith] thinks it is going to be easy and cheap, and I don’t agree,” says Robock. He estimates that several million tons of sulfur would have to be injected into the atmosphere annually to offset doubled levels of carbon dioxide, but if the particles clump together, “it could be many times that.” I found a review of sulfate injection geoengineering studies[0] published in 2017 and with a quick read I can't find any mentions under millions of tons annually. [0] https://acp.copernicus.org/articles/17/3879/2017/acp-17-3879-2017.pdf https://acp.copernicus.org/articles/17/3879/2017/acp-17-3879...
      - dr_dshiv 5y ago
        Fair enough. We really should be able to test this at some scale that we could know the order of magnitude required for efficacy. We are dangerously ignorant about the solution space.
- willis936 5y ago
  Sulfuric acid is one of the most well understood stratospheric nanoparticles because we have millions of years of geological data to correlate with the climate history. If you're worried about unintended consequences and models being insufficient for prediction, you want to be as conservative as possible with your nanoparticle choices. Terraforming is not something to treat lightly.
  - DennisP 5y ago
    From the article: > Current man-made and natural ISA emissions total over 100,000 tonnes and have many beneficial climate effects. They're only talking about adding another 200,000. And... > By directly copying the main planetary cooling mechanism from the ice ages, ISA has at least twelve identified cooling effects, presenting a balanced natural process. So this also has geological history to draw on. Despite this, they're currently only proposing a small trial, to make sure of safety for more trials. I don't think they're treating anything lightly.

I wouldn't worry about it getting too much traction. Even stratospheric injection of sulfiric acid (something that volcanoes do) is blackballed from even being researched, let alone considered.

DennisP 5y ago

This idea actually seems safer to me, since rather than just blocking the sun, it actually takes our excess CO2 emissions back out of the atmosphere. And also methane. It's the first idea I've seen for doing that.

tambourine_man 5y ago
And doesn't produce acid rain, like sulfur does.
- dr_dshiv 5y ago
  Acid rain resulted from the 30+ million tons of sulfur dioxide released into the lower atmosphere. To cut global warming in half, 25,000 tons of sulfur dioxide would be needed in the upper atmosphere. So, 3 orders of magnitude less SO2. Meaning, mitigating global warming with SO2 would not meaningfully increase acid rain. Source: https://www.technologyreview.com/2013/02/08/84239/a-cheap-and-easy-plan-to-stop-global-warming/ https://www.technologyreview.com/2013/02/08/84239/a-cheap-an...
  - bayesianbot 5y ago
    That 25,000 tons figure sounds really controversial. Even the article mentions > David [Keith] thinks it is going to be easy and cheap, and I don’t agree,” says Robock. He estimates that several million tons of sulfur would have to be injected into the atmosphere annually to offset doubled levels of carbon dioxide, but if the particles clump together, “it could be many times that.” I found a review of sulfate injection geoengineering studies[0] published in 2017 and with a quick read I can't find any mentions under millions of tons annually. [0] https://acp.copernicus.org/articles/17/3879/2017/acp-17-3879-2017.pdf https://acp.copernicus.org/articles/17/3879/2017/acp-17-3879...
    - dr_dshiv 5y ago
      Fair enough. We really should be able to test this at some scale that we could know the order of magnitude required for efficacy. We are dangerously ignorant about the solution space.
willis936 5y ago
Sulfuric acid is one of the most well understood stratospheric nanoparticles because we have millions of years of geological data to correlate with the climate history. If you're worried about unintended consequences and models being insufficient for prediction, you want to be as conservative as possible with your nanoparticle choices. Terraforming is not something to treat lightly.
- DennisP 5y ago
  From the article: > Current man-made and natural ISA emissions total over 100,000 tonnes and have many beneficial climate effects. They're only talking about adding another 200,000. And... > By directly copying the main planetary cooling mechanism from the ice ages, ISA has at least twelve identified cooling effects, presenting a balanced natural process. So this also has geological history to draw on. Despite this, they're currently only proposing a small trial, to make sure of safety for more trials. I don't think they're treating anything lightly.