I wonder why geoengineering proposals, such as seeding the oceans with iron[1], aren't more often discussed as possible mitigations to climate change.
Arguably, we should rule out solar radiation management - in the models you get the weirdest side effects, for example if you ramp up amount of stratospheric sulfur aerosol to the maximum effect (which doesn't even cover all of the warming we have already committed to btw), the jetstream collapses. Do you want to be the one to run that test for real? Also, they only combat a part of the problem, eg sea acidification is untouched. (Still, there is coffee talk about a sulfur test from the US soon.. the person they have in mind doesn't seem too stoked though. Not sure what the state is.)
Carbon sequestration appears feasible. Options include increased biomass (limited effect and needs protection forever), direct removal (how to store safely and longterm?) and enhanced weathering. All of those cost more per ton of carbon in both energy and price compared to not burning fossil fuels. Techniques don't really exist yet to be deployed at scale either, plus the energy needs to come from somewhere.
However, if you have a look at the 1.5°C IPCC report, all the pathways given there assume some kind of carbon capture. The most optimistic one just needs trees, the business-as-usual one needs a massive effort of capturing about half of our yearly emissions starting in 10 years. (!) [0]
[0] https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SPM3...
edit: By the way, we have enough fossil fuels in the ground to reach 5000 ppm of CO2. At 1000 ppm humans already have measurable cognitive decline.
https://www.bp.com/content/dam/bp/business-sites/en/global/c...
We are talking about GIGATONS a year of CO2 that needs to be captured and put somewhere. For every mountain top that is removed, we would have to figure out where to put three more mountains. Not going to happen.
40% of the worlds electricity is generated using coal.
If we changed this 10 years ago, we’d have less problems today.
If we change this today we’ll have less of a problem in 10 years.
We’re coming up with all kinds of clever ideas to deal with the problem in 2050. This is a slow train wreck happening over decades.
Because enough people make a LOT of money from the status quo
And that's without even getting into the question of who'll pay for it. The countries most affected by climate change - tropical, developing - are least able to pay for it.
If we fail to restrict our release of greenhouse gases and CO2 sequestration doesn't get economical and funded in a sensible way, our best option is probably solar shades in low earth orbit (giant sheets of ultra thin foil). It's more expensive than dumping iron in the oceans or sulphur dioxide into the atmosphere, but it's predictable and easy to undo.
A thin reflective foil would not stay in a stable orbit because of solar radiation pressure. Instead, you can put it near the L1 Langrange point but slightly more sunward to compensate for that pressure.
If we solve emissions, then I think everyone agrees we can look at accelerated weathering and other sequestration strategies.
Yes, it had the predicted effects in terms of plankton growth and the rest of the food chain. It did take a lot of CO2 out of the air. However, some of the animal life fell into the deep ocean and slowly decayed--releasing methane. Methane is a far worse greenhouse gas than CO2. Lots of fish but no climate benefit.
I mean, I suppose that's part of it, but the biggest reason (if by "technical solutions" you're talking about geoengineering) is that it's pants on fire crazy to run uncontrolled global scale geoengineering experiments. Unfortunately it's looking more and more likely that we'll be left with little choice.
https://www.sciencemag.org/news/2020/01/us-geoengineering-re...