Ocean acidification.

It is the lesser known side  effect of our global CO2 emissions.

We put CO2 up into the atmosphere, it gets sucked up into the  ocean, causing the ocean to become more acidic, creating a whole host of problems.

But there  are a lot of researchers and startups working on trying to fix this problem, including some  projects that work like a big bottle of Tums for the ocean.

So can this quick fix basic solution  work to solve our ocean acidification woes?

No, obviously not.

But there is some really cool science here and we might actually be on the right path, or course, or heading...

I dunno what you call…track?

What do you call like a path through the ocean?

My sweater's on backwards.

That whole time.

I'm only now realizing this is, this is the front of the sweater.

Just so we're all on the same page  as CO2 levels in the atmosphere rise, the ocean sucks up some of that CO2 and this  is great, honestly.

The ocean sucks up about 30% of our current annual carbon emissions, which is super helpful.

In the sea water, the CO2 combines with H2O to create carbonic acid.

That then dissociates into bicarbonate ions and hydrogen ions.

The hydrogen ions cause the ocean to become more acidic, hence ocean acidification.

If this reaction is balanced, things stay stable.

But if you start dumping more and more CO2 onto the left side of the equation, increasing its concentration, you're gonna shift the equilibrium and the  reaction is gonna try and relieve the stress.

It's gonna do that by making more and more  carbonic acid trying to return to balance.

This response of a chemical system to stress like a  change in pressure or temperature or concentration is known as Le Chatelier's principle.

Basically,  as you get more and more CO2 on the left, it's more likely that it'll bump into these water  molecules, react and then move the equation to the right.

In the end, that's gonna cause more  hydrogen ions and a more acidic ocean.

And this can be problematic for stuff living in the  ocean, particularly shellfish and corals.

They rely on carbonate ions in the water to build  their shells, but the hydrogen ions react with the carbonate to form even more bicarbonate  reducing the amount of available carbonate for organisms to build their shells.

Average  ocean surface pH has declined by about 0.1 units since pre-industrial times, which works out  to about 16% decrease in available carbonate ions.

But the main problem with ocean acidification  isn't the shellfish or even the impact on industries and communities that depend on  shellfish to survive.

We don't care about the shellfish.

I mean I do, I do, but...

The  bigger problem is that the increased acidity also reduces the ocean's ability to take more  carbon dioxide out of the atmosphere.

You have more hydrogen ions over here, so the reaction  wants to relieve this and get back to balance by pushing things out towards this section and  you get more CO2 and H2O out.

And it would be really helpful if the ocean could keep absorbing  more CO2 since there's already way too much up there and we are still cranking out more.

Stopping  our carbon dioxide emissions would be the actual solution.

But honestly, we have raised CO2 levels  so much that even if we did stop, we would still need to pull carbon outta the atmosphere to try  and mitigate the negative impacts that climate change is already having.

This is all kind of  a bandaid, but it is a bandaid that we really need to work.

Reversing this acidification by  alkalizing the ocean could help the shellfish, reinvigorate the carbon dioxide absorption ability  of the ocean and slow down the rising global temperature.

So let's just raise that pH right.

Well, what we're talking about here is sometimes considered geoengineering.

Geoengineering is  the deliberate, large-scale intervention in the Earth's natural systems to counteract climate  change.

One of the most common types that people think of is solar radiation management, basically  taking big shields or aerosolized particles to bounce the sun's energy away from us.

There are  really people thinking about trying that.

Now the idea is that we've messed up the balance of the  planet, so let's engineer it back.

And as you can imagine, this is controversial.

Proponents note  that even if we stopped all CO2 emissions today, we have already changed the environment so much  that effects would persist for years and years.

In fact, we've put about 420 parts per million of  CO2 and other greenhouse gases into the atmosphere already, resulting in a full degree Celsius of  warming, which is already having effects on our planet.

So we really need to do something to help  set the ecosystem back.

But critics point out that we clearly don't have a great track record of  impacting our planet's climate and our efforts to fix it.

That could be things like bouncing the  sun's rays into outer space, could have unintended consequences, things like, ecological disasters,  weather patterns that destroy the climate or economy of different parts of the world, the  movie "Snowpiercer," et cetera.

Actually really love "Snowpiercer."

I don't wanna love it, but  it was cool.

Ocean alkalinization is in some ways geoengineering, its overall goal is to use the  ocean's ability to store carbon, to draw carbon outta the atmosphere.

So it is a form of carbon  removal, but we're also modifying the state of the ocean in the process, engineering that ocean.

So I  call it semantics.

If we wanna geoengineer our way to a less acidic ocean, why not start with Tums?

Tums are mostly calcium carbonate.

So what's gonna happen is that calcium carbonate is gonna react  with the hydrogen ions that is gonna in turn form HCO3, more of that bicarbonate as well as calcium.

It's gonna leave that calcium behind.

Now, we don't really care about this.

What we care  about is the fact that this bicarbonate is now going to increase in concentration and we're gonna  push this reaction back this way.

The reaction's gonna try and relieve stress.

By now, creating  more of that carbonic acid and then more of the CO2 and H2O.

So this calcium carbonate is gonna  reduce that hydrogen ion concentration and also push this reaction back this way.

Can you have  a singular Tum?

Take a Tum.

I think I, I think I think of it as Tums, a Tums.

But the CO2 byproduct  from calcium carbonate isn't ideal here.

So some researchers are trying it with lime instead.

Lime is mostly calcium hydroxide, Ca 2.

It's commonly used in both cement and corn tortilla  production and it is really great at neutralizing acidic solutions.

These hydroxide ions can  react with the hydrogen ions creating water, pushing the pH up because we're reducing the  concentration of these hydrogen ions or allowing us to pull more CO2 out of the atmosphere this  way.

Early tests look like they are in fact reducing the acidity in areas near releases of  lime.

For example, one trial in an estuary saw a decrease in dissolved CO2 of 70 parts per  million, which is a surprisingly significant amount.

Proponents admit that we'd really have  to target areas in the ocean like this where the alkalinity experiments would have the greatest  effects.

They also note that it matters how the air and ocean water interact.

If your alchemized  water circulates away from the surface too fast, it won't have time to re-equilibrate with the air  above it and actually take that CO2 outta the air.

And that exchange time can vary based on location  from days to months.

But there are some big buts here, both with ocean liming in particular and  with ocean alkalinity enhancement in general.

So first, for liming, where are we getting all that  lime?

Lime comes from limestone.

You first have to mine the limestone, which gives off CO2 and then  usually heat it to get lime, which then also gives off CO2.

One estimate suggests that it would take  1.4 to 1.7 tons of limestone to sequester one ton of CO2.

And turning that amount of limestone into  lime could give off about one ton of CO2.

Now, that CO2 would be produced in a controlled  manner and could ideally be directly captured and sequestered, but we would need a whole system  in place for that too.

We would need green energy, carbon capture, and a whole lot of money to make  it work.

The other thing here that became clear as I read all of these papers and that I think  is really important to understand is that all of these estimates and analyses have huge numbers of  variables.

Things like where exactly is the lime coming from?

Do you need to increase mining  operations to get it?

How are you shipping it to the ocean?

Have you thought at all about  the environmental pollution problems near the mines?

What about any ecological effects to the  surrounding aquatic life?

When you dump in a bunch of lime.

What if your solution actually makes the  calcium carbonate spontaneously precipitate out and then you release even more CO2?

There's also  worries about something called termination shock, which is a potential rebound back to acidic  conditions if you stop alkalizing the area.

And have you factored all of this into your net  carbon calculations for your proposal?

Creating a lifetime assessment of your solution.

Here's  the thing, this isn't to say that any of these are deal breakers, it is just a lot to consider  and good researchers are considering all of it.

And that's why a different analysis, which looked  at what it would take to continuously alkalize the ocean for the next 380 years, putting us  at the nice even year of 2400, came up with a cost estimate between one and several trillion  dollars USD each year.

The difference between one and several isn't large, but the difference  between 1 trillion and 2 trillion is gigantic.

So these estimates have huge ranges in terms of cost,  energy needs, and CO2 output.

So there's another method of ocean alkalization that's getting  some press and investment money, electrolysis.

Seawater, a couple of electrified plates.

Honestly, it is not that much more complicated.

Oh, yeah.

Oh, my gosh, it's working.

That's so  cool.

I love when science works.

Thing is, you would need a lot of these plants to really make a  difference.

One of these startups is planning the launch of a commercial plant in the next year  that aims to pull the equivalent of the annual carbon emissions of 25,000 individuals out a year.

And that's great, but it is 0.0003% of the world's population.

And just like the liming, the energy  to actually do the electrolysis would have to come from a green or renewable source to make sure that  it wasn't producing more CO2 than it was removing.

And I know that I am being a huge downer here  because we all want these solutions to just work.

It would be really helpful if these plants just  snapped on and they solved all the issues we're having and certainly, there are lots of people  investing in them through grants and VC money and carbon credits to try and get them there.

Yeah,  did that last one perk your ears up?

Many of the startups in this space are selling carbon credits  based on their technology.

You give them X amount of money and they'll pull Y amount of carbon out  of the air, so that your airplane or whatever can put Y amount of carbon back into the atmosphere.

But you can slap a carbon neutral sticker on it.

And some of these companies are selling carbon  credits out into the future based on what they expect to be able to do down the line.

So your  next five years of carbon emissions are covered.

And what if those startups which are notorious for  folding and whose technology isn't fully proven yet, fold before those five years are up and all  the carbon is actually pulled out?

No one's gonna come and take your sticker away.

At least that's  what a skeptic might say.

But despite all of the giant caveats I have just mentioned, I am actually  optimistic.

It is a fatal flaw of mine.

These are big complicated problems and the best actual  solution to these problems would be to stop emitting so much CO2.

So keep that in mind.

But  there are lots of smart, motivated people working on this and on reducing the amount of CO2 we put  into the air because if we don't reduce that, this really won't help that much.

If I dump 45 ping  pong balls a year into the ocean, but only pull up five, still gonna be a lot of ping pong balls  floating out there.

And like all climate change problems, there's not just gonna be one solution.

We're gonna need a lot of different solutions in different areas to get to carbon neutral  or carbon negative territory.

And even very skeptical technical analysis have some optimism.

OAE shows promise as a potential CDR solution and pilot projects and research activities have  begun to demonstrate its feasibility in relevant environments.

Continued collaboration among  scientists, engineers, and policy makers will be crucial in optimizing these technologies.

But  that involves confronting the issues and drawbacks head-on, funding to do more research, increasing  our testing sites and finding interesting scientific and chemical solutions to the problems,  not hiding from those issues.

That is science.

Happy Earth Month, everybody.

All this month  PBS is gonna be dropping new episodes about our incredible amazing planet, including an episode  of "Space Time" that talks about how viewing.