[alexgmcm]

What concerns me about almost all of the Solar Radiation Management (SRM) proposals is that they don't address the root issue of high Greenhouse Gas (GHG) concentrations.

This means that we would have to continue them indefinitely, forever, without fail. (I'm assuming that we would just use the SRM measures to continue with business as usual, but having seen our progress against GHG emissions so far, that doesn't seem an unfair assumption.)

And should we fail to do so then the protective effect would dissipate leaving us with full solar radiation on a planet with presumably much higher GHG concentrations. This would not only cause temperatures to soar to hitherto unseen heights, but to do so in an incredibly rapid manner.

It's not clear that our ecosystems would be able to withstand such a drastic and sudden change.

[willis936]

>This means that we would have to continue them indefinitely, forever, without fail.

This kind of all or nothing rhetoric is damaging to actual progress. Solutions are not mutually exclusive. We can do both. One treats the symptom and buys us a few decades without having to suffer a 4C air temperature rise (and the billions of needlessly lost lives and indeterminate human suffering). The other fixes it in the long term.

[black_puppydog]

Fairly sure GP wasn't implying it's not possible, but also venting the sentiment (shared by me) that availability of effective mitigation will preclude any actual solution by taking the pressure for change off the societal systems.

[hannob]

I'm not a fan of SRM, but this isn't true.

The idea people in the SRM research community have go more like that you have declining CO2 emissions, at some point you turn around by deploying negative emissions tech and SRM is basically your "let's cut off the worst effects in times of highest CO2 concentrations". This is e.g. often described by David Keith, who's one of the leading advocates for SRM research.

Whether any of that is feasible or realistic is of course debatable, also whether one should even go down that path and whether even the prospect of doing SRM is blocking faster climate action. (And I sympathize with all those concerns, but I think paiting a wrong picture doesn't help.)

[alexgmcm]

The issue is I don't think that scenario is realistic.

We don't have declining global CO2 emissions and there are no signs we will have that any time soon. In fact, annual CO2 emissions continue to increase at an almost exponential rate.

So first of all we'd have to decrease emissions and invent and deploy some CO2 extraction tech to help lower the current atmospheric CO2 concentration.

To me, it seems far more likely that if SRM was deployed many would just see it as a way to continue with business as usual without having to suffer the effects of global warming.

[WhompingWindows]

Are you assuming we'd only use SRM and not continue the MASSIVE efforts already underway to lower yearly GHG emissions? And once we go zero, we're already seeing dozens of plans and ideas to handle what we've already emitted. Really, our current playbook is in its infancy and climate change is WAY out in front of us already due to our political and economic foot-dragging. I don't think we should nay-say anything nascent until we've found the most scale-able, economically viable solutions.

[alexgmcm]

Our "MASSIVE efforts" don't seem to be doing much so far: https://ourworldindata.org/grapher/annual-co2-emissions-per-...

And that's just annual emissions, Atmospheric CO2 concentration is even worse: https://climate.nasa.gov/internal_resources/1914

If we go into the 2030's and we are still doing business as usual with our near-exponentially increasing global CO2 emissions then I suspect a large amount of climate damage will already be 'locked in'.