I read once about a really fascinating way to transfer carbon back into the oceans by seeding it with iron, which promotes algae growth. Might transform some local ecosystems, but it gets the carbon out of the air at a shockingly cheap price. (iron and ships)

https://en.wikipedia.org/wiki/Iron_fertilization

Well, at least IS an idea, yes, but its effects at middle and long term are still untested. Could release again the carbon to the air in the next summer. A 400 years old tree on the other side...

"really fascinating way to transfer carbon back into the oceans by seeding it with iron"

Thats a horrible idea. See ocean acidification on Wikipedia.

Ocean acidification happens when CO2 dissolves in the ocean. If that carbon is fixed first by algae then it won't cause acidification.

You seen the replacement rate of energy with solar panels in the last 2 years or so ? Granted, cost calculations for those were done when oil was $100, but they made sense at that point and solar has been lowering in cost by ~27% per year. In other words, despite oil dropping to 50, it's just going to continue. Even China is moving away from coal (thank God for that). Coal generates disproportionate amounts of CO2 so this helps even more than you'd guess from a simple linear estimation. Most oil usage is going to get replaced soon as well (people are talking about electrical engines for non-nuclear navy ships, container carriers, ...)

What we need to invent is cheap, dense, mobile batteries. No amount of blustering by Elon Musk can mask the fact that we can't store electrical power anywhere near as easily, lightly (meaning we need the ability to pack it up and move it around), and small. Yes you can fix it with $50k cars, but electrical cars could be $10k and even less if we assume magic perfect batteries. That'd be great and will get almost every gasoline car of the road.

Batteries are currently about 10% as dense either per liter or per kilogram. A bit of this can be made up because the infrasstructure to "burn" electricity is much simpler and therefore lighter than the infrastructure needed to burn gasoline. So let's say they're 20-25% as dense for locomotion purposes (this makes them not work for powering lights or factories or ... at night though). So we need batteries 4x smaller and lighter than current batteries. Assuming the current rate of improvement in batteries, that would require about 20-30 years (improvement per year is about 5%).

So that's just not good enough. Please invent something to fix it. If we can store energy efficiently, co2 release per year will stabilize probably on less than 10% of it's current value.

Or carbon neutral fuels. I've been a fan of engineering algae to make ethanol and similar from sun water and CO2 and though nothing's ready for primetime yet you never know.