Paris agreement on climate change has come into force

The Maldives are probably a better example to use!

New agreements may still be needed since the paris accords lacks enforcement mechanisms.

So if we wanted to implement e.g. multi-national CO2 taxes or make some quid-pro-quo deals to get more renewables into developing countries then new deals will need to be made.

There are others involving mineral erosion, or machines that take CO2 out of the atmosphere. There's a scheme for fertilizing oceans with iron particles, creating algae blooms that absorb CO2 then die and sink; that one may or may not work.

The problem is, generally this stuff either has large environmental side effects, doesn't scale enough to absorb all emissions, is much more expensive than just reducing emissions, and/or uses a lot of energy, which would have to be produced by carbon-free sources that could have just replaced emissions in the first place.

None of it is really available yet, and we're rapidly running out of time. We're starting to see positive feedbacks where, with higher temperatures, the planet emits CO2 and methane by itself, taking the temperature even higher without further help from us.

So our best strategy is to reduce emissions as quickly as possible now. Given how far along things are, we will probably also need to reduce atmospheric CO2 levels after we've finally stopped increasing them.

Of course, to whatever extent the negative-emissions techniques become available, safe, and affordable in the short term, they could definitely help. Biochar might be the closest to implementation, with no real downside except at very large scale.

The ability to fix nitrogen from the air and convert it into liquid or solid form on an industrial scale was one of the most important breakthroughs in human history. We can do the same with CO2 but it's cheaper to dig it out if the ground and there is a lot less of it in the air. N makes up 78% of air by volume. CO2 is only 0.04%. You need to handle a lot more air to get the equivalent amount of carbon as you do nitrogen.

While trees do it, they only restore the CO2 they released when we cut them down. They won't restore what was released from oil brought up from underground. We could in principle plant more trees than we cut down, but people are living and farming in many of those places.

As of now, there is nothing in action and little if anything on the horizon.

In general, since CO2 is released when we get energy, you'd need to put that energy in to get CO2 out, which would take away energy from the economy. So a process that took energy would need us to create all the energy our economies needed plus the energy to remove the CO2 without releasing more CO2.

Your question is basically saying, "why don't we just undo the problem?" Sure, sounds great, why don't we just solve all problems by undoing them? Why don't we just end wars by having the combatants sign peace treaties? Well, creating the agreements to sign is the challenge.

"AirCarbon™ | Made from carbon capture

AirCarbon™ is a material made by sequestering carbon emissions that would otherwise become part of the air."

https://newlight.com/aircarbon/

This, competing and similar technologies, are relatively new, but they are scalable and affordable. They will likely be a critical component to Industry 4.0 and circular economies.

Agreements like Paris are important because they provide a roadmap, urgency and awareness.

There is no natural market for "building and selling technology to counter the CO2 emissions" unless one is created by .. treaties.

Regardless of how much money there is to be made in this market (and you're right, there's a lot), Earth is going to be a very different place to live in 50 years unless we rapidly make dramatic and fundamental changes to the way we produce and use energy.

The bleak predictions of acid rain killing forests and the ozone hole making australia uninhabitable may have helped driving policy to avert those scenarios.

Unfortunately there's no Moore's law for cleantech.

All in all, I don't personally have any issues with lighting up the Eiffel Tower if that means a lot of exposure and information about sick planet reaching more people.

More generally, these "solutions" don't work. Billions of people don't suddenly all agree to reduce their quality of life voluntarily. For every energy efficient lightbulb there's some beef they aren't supposed to eat, or a standby device that uses 2W too much power they have to switch off and on 5 times a day. It's never happened before and it won't happen for this, even if the world goes to crap due to climate change. Maybe stop wasting resources on feeling good about optimising the uncommon case and work on systematic stuff like clean power.

https://www.earthhour.org/