I have no doubt at we will try this, plus a lot of even dumber ideas, once the shit really starts to hit the fan. The world is not going to just sit back as Manhattan, Mumbai, Shanghai, Sydney, Rio, etc. disappear under a foot or two of water. Politicians (the same one who spent 50 years failing on this issue) will demand action. It's the best argument I can think of for putting serious research effort into geoengineering, odious as it may be.

Artificial trees are not considered geoengineering since they are just reversing the CO2 released. The really sad aspect is we are not putting in the R&D resources needed to develop them to the required scale. No matter what we do about preventing the release of more CO2, we need to deal with the CO2 that has already been released.

Regular trees work quite well and are cheaper. You just have to harvest them and not burn the wood, or turn it to biochar.

Actually burning the wood works just fine, provided you can sequester (see BECCS, along with recent developments in basalt based CCS).

There are not enough natural trees to do the job because we have taken most of the really productive land to grow food. While there is some potential to use biochar in some locations, it is not going to be enough to get the CO2 levels down at the pace we need.

It's probably a lot cheaper for those cities to build flood control systems.

> build flood control systems.

Water is only one problem. By 2070 some places might be uninhabitable according to this[1] study, due to heat.

> At WBTs [wet bulb temperature] above 35C, the high heat and humidity make it physically impossible for even the fittest human body to cool itself by sweating, with fatal consequences after six hours. For less fit people, the fatal WBT is below 35C. A WBT temperature of 35C – the combination of 46C heat and 50% humidity – was almost reached in Bandar Mahshahr in Iran in July 2015.

At some point it's going to cost big bucks. If the study holds water, the Gulf will either need to be evacuated or artificial habitation will need to be built.

[1]: https://www.theguardian.com/environment/2015/oct/26/extreme-...

Will still be a wakeup call. And I seriously doubt that flood control (and/or relocation) for all major costal cities will be cheaper than climate engineering.

I'm very confident the USA will respond effectively to global warming as soon as the Midwest actually sets on fire and not a moment before.

As soon as Houston stops being the 4th largest city in America or people come up with a plan for how to kill a city's main industry without it turning into a hotbed of suicide and violent crime.

Of all these I believe ocean iron seeding to be the most interesting and viable. It may also improve fish stock and have other direct economic benefits.

The negative knee-jerk reaction of my fellow Greens on this matter is is only topped by our anti-nuclear power rhetoric.

Global adoption of LFTR reactors combined with the massive reduction in coal/oil power plants, ocean iron seeding and the adoption of electric vehicles should get global C02 levels close to pre-industrial levels within 200 years, if we start today.

> Global adoption of LFTR reactors ... if we start today

I'm a huge fan of gen IV reactors in general and LFTR in particular, but we are a long way from being able to deploy any MSRs, even if everyone woke up tomorrow and suddenly took the construction of LFTRs as a terminal moral value. All that have been created to date are small research reactors, mostly 40+ years ago. Almost all of the MSR research projects started recently have fizzled out; AFAIK the only project that has any kind of plan for future civilian nuclear energy is China's. The current regulatory and public opinion environment for civil reactors is absolutely abysmal, and that will likely take even longer to change than the research will.