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Possibility for strong high-latitude cooling under negative emissions (nature.com)
85 points by rgrieselhuber on March 6, 2022 | hide | past | favorite | 68 comments

We seem to be so far from a practically-useful level of CO2 removal that this seems like a shrill level of concern. That said, the logic could apply to much quicker solutions that could be distributed globally, such as atmospheric albedo modification or space based solar barriers (the latter being hugely speculative, of course - but I could imagine a few SpaceX starships put to poorly-considered use being able to muster something in a decade or three).

This is an important study because most (all?) scenarios used by the IPCC depend heavily on these (as of now) wildly optimistic CO2 removal levels, either with BECCS or DACs.

In order to hit the "brief and rapidly closing window" we have for effective action, we need to look into lowering material flows and energy use by targeting overconsumption. We simply don't have time to wait for a tech miracle, and – as this study points out – the miracle can have huge downsides.

I have no idea why this comment got downvoted. It points precisely to the point: Many current climate scenarios have already negative emissions "priced in". We absolutely need to have research to better understand what that means, and we should have a plan b if negative emissions at large scales don't work.

I didn't downvote though I noticed this, 'We simply don't have time to wait ...'.

Whatever the topic, I mentally ignore posts which shill the NEXT WORST THING EVER.

Exactly, we have lots of time to wait. Humanity survives pretty much no matter what we do.

Most of the waiting scenarios involve a drastic decrease in farmland for the US/Europe and larger gains in Canada / Russia.

The planet quite frankly doesn’t care if NY / LA / London lose 6 to 12 Ft of land. Even if no one moved and everyone just stayed there to drown, humanity still goes on.

The whole thing mostly fixes itself anyway once population peaks in a few decades. It’s not global warming that kills humanity, it’s our population eventually reaching zero through sub replacement birth rates tho maybe there is a saving grace where once incomes get high enough it rebounds.

At what cost does humanity survive? I don't want to become a climate refugee. Even the 1.5C model has millions of climate refugees. People still talk about Miami and Dubai as if they'll be around in a century.

I am not so arrogant as to think without humans the planet dies. But maybe unlike most Americans I don't want to sacrifice my grandparents so that people can dine in person at Applebee's, nor do I want to live in a worse, less human-friendly world so that oil executives can make another few decades of profit.

We can decarbonize with the technology we have today. We know it will be more expensive economically to wait until it's too late, but it'll be more expensive for taxpayers instead of maybe the companies doing so well they can spend millions on lobbying every year.

Farming isn't really the issue, we can eke out 10x the calories by cutting pork/chicken/beef. Wet bulb temperatures (where you can't cool off by sweating and die cooked inside out) are a larger issue. Tons of other cycles that we're fucking with besides carbon, like nitrogen and phosphorus. We're also losing arable land to desertification. I don't even have to get started on our available freshwater reserves.

To think humanity will just kinda coast by and that it will all mostly fix itself must be a very nice thought, but it flies in the face of what every single person we pay to study this is saying. And they're not saying humans go extinct.

Unless CO2 removal is profitable without subsidies, it's pointless and the money should go into Renewables. If you can cut emissions, the CO2 takes care of itself quickly from natural sinks.

Per the ipcc model, if we could wave a magic wand and have zero emissions tomorrow, CO2 levels would fall faster than they have been increasing.

We already have free CO2 removal. The challenge is and always has been on the emission side.

CO2 levels are about 420 ppm and go up about 1.5 per year. A 120 year half life yields -3.5 ppm per year.

It is worth investing some money in development for the moonshot possibility of economic viability. Unless it becomes cheaper to capture than build renewables, the the money will always be better spent on green energy.

"Per the ipcc model, if we could wave a magic wand and have zero emissions tomorrow, CO2 levels would fall faster than they have been increasing."

Traditionally, the idea is that the ocean would absorb the 'excess' CO2 put there by fossil fuel combustion over the industrial era. However, this is quite a slow process and it's entirely possible to reach a new steady state of relatively high atmospheric CO2 (and high global temperature, i.e. ice-free poles) and stay there for several million years - it's happened in the past. Furthermore, we have the permafrost melt ongoing across the Arctic, and shallow marine sediments are also releasing methane and CO2. This will continue for decades in the immediate zero-emission scenario, that turning point has come and gone.

Maybe if a full transition off fossil fuels had begun in 1980, when the science was clear, we'd be stabilizing at current conditions (*it takes ~100 years for the climate system to finish responding to current forcing, assuming no additional forcing, mainly due to oceanic warming lag effects). We're in for warming for the next 50 years, no matter what, and the world is clearly not getting off fossil fuels any time soon, all the major fossil fuel actors have plans for status quo production for the next 30 years (rather than say 3% reduction per year, which would mean no fossil fuel production in 30 years).

It's going to happen slowly on human time scales, i.e. the scale is decadal for noticeable differences in the year-to-year average, but it's also inexorable. "It's in the post" is the British saying that applies. Like trying to throw the rudder over on the Titanic after the iceberg is detected, it's all too little too late.

This negates none of what I said.

If you can prevent X tons of co2 for $y dollars , it is better than capturing X tons. for $>y dollars.

It only makes sense to capture co2 if you have already prevented everything you can.

Yes it would have been better to start in the 80s, but that doesn't change the math today or tomorrow.

If the carbon cycle changes, it will still be better to stop emissions than capture.

There are many great and economically profitable ways to capture CO2, the only problem with them is they impoverish the wrong people. (More correctly they don’t make the right people even more rich)

> It only makes sense to capture co2 if you have already prevented everything you can.

Like I said in another thread, it’s this kind of stuff that makes net zero never happen as many people, like yourself, are inherently opposed to CO2 emissions.

I would love to hear your profitable idea, seriously. I am looking for a new business.

Obviously if reducing emissions is cheaper than removal we should do that. But building more renewable production doesn't necessarily cut emissions - it might just increase energy consumption.

The profit / reward is your kids get to live and have kids.

You are missing the point. I am spelling out how to save your kids lives. As long as there are finite dollars to save the planet, we need to use them wisely.

How can CO2 removal ever be profitable without 'subsidies', like carbon taxes and credits?

Anything useful you could make out of CO2 can be made much easier from fossil fuels.

That's the point. If x dollars can be spent on carbon free Power generation, or carbon capture, you will get more impact from the former. Spend money where it has the most impact on what you care about.

I think a more important lesson here is that this is not a simple system. its pretty unlikely that we're going to able to calmly walk it back to the state it was in before

There were many prior states. In fact, it changes. Vikings had pastures on Greenland until it got cold and they were driven off. Greenland is now covered in snow and ice. Will Greenland return to pastures? Probably at some time.

The Viking colonies on Greenland were during a relatively warm period, but the difference was rather minor... it's not like now Greenland is covered in snow and ice and then it wasn't, the glaciers weren't any smaller then, they were actually a bit bigger. But during this warm period that lasted a couple of hundred years the summers were a bit longer and probably more sunny. The Viking settlements were in the far South of Greenland, actually further South than their prior home on Iceland, on land that's quite green in Summer today as well (just visit Greenland's official tourism site to see what it looks like). Tundra vegetation is actually excellent pasture, very mineral and protein rich... enough so to have supported lots of the largest mammalian mega-fauna!

Is this correct? I thought that Greenland was always a marketing lie, and that the viking's refusal to absorb Inuit style living meant they simply could not become self sustaining and eventually lost the result ships (vaguely remembered BBC podcast as source)

The even more wild concept is that the atmosphere’s composition was already changing before human involvement, we just sped up the process by like 1000x.

We don’t normatively need the atmosphere to be “natural,” we just need it to be in a state that doesn’t destroy the thousands of years of infrastructure we’ve built.

Approaches aiming at increasing ocean bio activity, thus carbon capture by providing "ocean desert zones" with nutrients by whirling up ocean floor in those regions seems interesting for that purpose. Still a huge inception into the bio system thus risky.

Ah yes, I'd forgotten about iron-seeding - I was thinking entirely in terms of industrial solutions.

I still think iron fertilization is the best bet, not for co2 removal, but for albedo modification. Keeping equatorial kelp or algae mats alive would prevent lots of energy from entering the system. Those mats have albedo close to snow in the infrared, where water is about as absorptive as it gets.

I wonder if we could somehow use strategic placement of fertilisation to encourage processes that laterally help in cleaning up (/collecting) plastic pollution in oceanic gyres?

A girl can dream.

- ed: I am fascinated by the idea that otherwise horrid floating plastic pollution can act as centres for bio-accumlation leading to local, floating bio-domains. I guess the real problem is plastic bags and fishing nets, not toothbrushes that happen to float.

Ive seen stunning simple / passive water column chimney-effect approaches to do this using lower water levels mixing, no sources though, was german tv (arte station)

That’s largely because we aren’t trying it because most geo-engineering solutions have been made illegal and face significant political opposition from those who are point blank against fossil fuels. (Their opposition agains fossil fuels is second only to opposition to nuclear)

Look at the situation in Germany where CO2 emitting Russian oil and gas was preferable by the Greens to zero CO2 nuclear.

Net zero CO2 is the ultimate bike shedding issue, because it’s so easy a child could solve it, it devolves into endless bickering.

In other news: population crisis on Mars.

Global yearly average temperature keeps increasing because not directly by our emissions, but the excess of CO2 and other GHG (that yes, that was mostly our emissions, mostly adding fossil carbon to the cycle). This way we are going head-first towards dangerous levels of it (that cause extreme weather, trigger positive feedback loops and other not so nice things that you won't want to live through)

Keeping our current emissions will keep increasing that excess of CO2 and GHG, getting to some sort of net-zero (not the proposed one in COP26, but one counting with all kind of mankind carbon emissions AND the one emitted by the current already triggered feedback loops) will keep more or less the same amount of GHG in the atmosphere as CO2 lasts there for centuries.

The only way to have some hope that things don't keep getting worse is to manage to do negative emissions, and bring GHG down to pre-industrial levels, or even lower, if we want to drop in some way the global temperature average that had been steady rising for many decades, as that extra temperature is fueling positive feedback loops.

If there is a shortcut for making that temperature drop, because natural processes like the AMOC or whatever, the better, because we are not fighting for how livable will be a particular region of the world, but the entire world.

Sorry but I’m all panicked out.

Tl;dr: Climate change is likely to shut down the Atlantic currents, covering Europe and the US northeast in a glacier.

(I saw a PBS special on this part in the 90's. Recent satellite data strongly suggest this is already happening. The last time this happened, Europe went from "too hot" to "glacier" in the under fifty years.

If we wait for that to happen, then cool the atmosphere, then it'll make the coming ice age worse in the short term.

In other decades-old news, if we don't start capturing CO2 after that, and the predictions about runaway greenhouse gas mechanisms are true, Earth will become like Venus, obliterating life on earth.

Am I the only one that learned about this from watching PBS in the 90s? Is there something novel in the paper? It's good to raise awareness of just how f-cked we are, I guess.

So you feel confident that Europe will be under a glacier in 50 years?

I'm confident we'll get about 50 years warning when/if the current stops. It's currently weakening, and weather is a chaotic system.

I'm also confident that the root cause of the crunching noise and vibrations from the front end of my car will eventually lead to a breakdown, but I don't have any idea if it'll happen tomorrow or in a year.

I see. Of course the North Atlantic current will change/stop at some point regardless of any actions we take (assuming we don’t have technology to keep it going somehow). But delaying that as long as possible is a noble goal.

There's no reason to think it would shutdown in the absence of human intervention. It's extremely stable. Last time it shut down, it was due to elevated CO2 and temperatures, and the conditions that led to that won't naturally reoccur any time soon.

I think you've misunderstood the claim - they're saying that once the currents shut down, it would take 50 years for glaciers to form. But the currents are obviously still flowing today, and my understanding is that a collapse is projected to take many decades.

I get the impression they don't have any way to model the rate at which the currents will shut down, but that it was apparently quickly in the past.

Either way, we're talking about either abandoning most of Europe in our (or our children's) lifetimes, or just using existing technologies to avoid that, along with many other disasters.

Glaciers increase albedo. I suspect there are numerous understated/undiscovered feedback mechanisms which will actually result in cooling as the climate changes and keep the global temperature livable.

Not a feedback, but a reduction in polar soot due to China moving away from dirty coal emissions to nuclear power could also increase albedo.

All that freed, formerly captured carbon comes from trees and plankton. How could burning it all lead to life-destroying conditions when life must have been able to exist under those conditions?

"all that kenetic energy released when jumping off a building was formerly potential energy stored when walking up the stairs. How can that lead to life destroying conditions when life previously held that energy?"

The rapid change in environments can make many species no longer suitable for their environment leading to extinction. Sometimes they can transfer to a new environment, or sustain at a degraded efficiency, but often they cannot if the environment change is drastic enough. This is happening everywhere all at once.

The GP isn't talking about species extinction.

People aren’t going to destroy all life on earth via climate change because humans are going to be dead in conditions that many life forms would happily survive in. Having said that, evolution operates on geologic timescales 100 years isn’t nearly enough time for most species to adapt to significantly different conditions. Florida alligators might happily expand their range further north in response to climate change, but that’s different.

As to the larger point, the sun was ~30% dimmer 4.5 billion years ago and will get about 67% brighter over the next 4.7 billion years. While we would be dead long before we could free up all the worlds trapped carbon, in such a hypothetical situation the world isn’t simply returning to an earlier state.

Some people argue that co2 levels were higher in the past. Yeah but the sun was a few degrees cooler. You simply needed more co2 to reach similar temperatures.

Energy on Earth isn't conserved, as it's not an isolated system - the Sun is constantly adding energy to the Earth, and we are constantly radiating energy out into space as well. Coal and oil were basically batteries filled with solar energy from millions of years ago. We are now discharging those batteries, adding back all of the solar energy captured over millions of years to the Earth today, in addition to all of the energy the Sun is still adding at more or less the same rate.

It's the same principle as what makes a battery fire so destructive - all of the energy stored in the battery in a plant somewhere else suddenly gets discharged all at once in your car.

You are releasing 1e6 to 1e7 years of energy in the space of 1e2.

Every night temperatures drop much more than the temperature increases from the hydrocarbon consumption. Are you sure that the energy of the hydrocarbons is the problem and not the greenhouse effect?

Things could get very bad, but it also turns out that plankton and plate tectonics have locked carbon/energy far away from our reach. It's a very slight glimmer of hope.

Same reason breaching a big dam does more damage than the same volume of water in an undammed river.

The IPCC reports don't predict anywhere near these disasters, even in their worst scenarios.

I'll trust those over a PBS special from the 1900s.

One things for sure, the children born today will be genetically optimistic.

Not a great idea to expect to learn about the world from sensationalist TV. Especially not such an immature field as climate science in the 90's.

You do realize I mean the 1990's right? The show was broadcast in color, so it came after climate change science had "matured".

Concretely, the magnitude of our current predicament was correctly forecast by computer models well before 1980, and the basic mechanisms and effects those models were based on were well-established by the 1960s.

Claims to the contrary have been extensively documented to be part of a paid misinformation campaign the fossil fuel industry ramped up in the early 1980s.

The show wasn't particularly sensationalist, for what its worth. Climate change was a bipartisan concern back then, and it mostly focused on the fossil records that backed up the claims it made. It also talked about the solar cycle's impact on earth's average temperature and compared the magnitude of the effects over time.

All the technology that was needed to head off disaster was already commercialized, assuming a one-two punch, where phase two involved better batteries.

No one imagined we would choose to take no action for another 30 years.

> our current predicament was correctly forecast by computer models well before 1980

So what? There are false climate predictions from back then too, and nobody knew which ones would turn out to be true or false. It was an immature field and predictions were all over the place, including global cooling.

If I produce a dissenting climate prediction, will you produce evidence that that specific piece of research was both paid for by the fossil fuel industry and known to be false by the general climatologist community?

To get an idea of the optimism, Biff from Back to the Future was based on Trump and ends up waxing an engineer's car.

If I had to bet what actor would be president in 2016, I'd have guessed Patrick Stewart, and that his second move (after installing the captain's chair in the oval office) would be pointing at a clean energy plan to replace our carbon nuclear fission power grid with fusion / solar and saying "make it so".

It is so easy to not pay attention to how bad global cooling, and/or co2 reduction curtailing plant growth, could be for the environment and for humans.

Global warming and CO2 rise are such difficult problems, and we put so much focus there, it makes me really glad to see some people taking a broad view.

But aren't we at the end off the small ice age? And is global warming really something we can prevent, or is it part off the normal warming and cooling cycles off the earth? I sometimes wonder if all the effort we do is in vain.

There's a huge difference between warming over a couple tens of thousands of years (natural rate), and warming over a couple of decades (our current trajectory).

That difference is the eradication of much of life on earth that is unable to evolve to a new environment. For example, insect numbers worldwide are drastically lower than decades ago, and insects are required for almost all pollination of plants and a key source of food for small animals. The "food chain" collapses if there is no first chain.

Even a partial loss of ecodiversity can lead to further problems later.

Our efforts are certainly not in vain.

What if we tap sources of energy, like fusion and to some extent(*) fission, which are novel to the normal solar/earth system and release extra heat energy into the atmosphere? Since this study is obviously only relevant in the far future, why not add in likely future technologies to the mix?

It seems to me that at some point we could just wrap the earth in shutters(since we're talking far future anyway) or intentionally release greenhouse gasses to servo the planet's temp.

* - I believe much of the geothermal heat is actually heat from fission already so I don't know if fission energy changes the balance much.

> I believe much of the geothermal heat is actually heat from fission already

On what basis do you believe this?

The fact that the global average temperature anomaly is running about 1/3 of where climate models said it should be, is proof in itself that the anthrpogenic component of climate change is not remotely understood. It might be zero or net beneficial for all we currently know.

H2O is by far the most significant GHG; compared to it, CO2 is a rounding error.

> (From the OP) ...in stark contrast to the fact that net zero CO2 emissions are required by around 2050 to meet a 50% chance of keeping the average surface temperature increase to below 1.5 °C

These forecasts used to be 4.5C or more. Now the forecasts are 1.5C and yet the IPCC is still pushing hard.

It happens that the average tropospheric temperature increase over the last 40 years of satellite measurements is 0.13C per decade, or 1.3C per century if that rate continues.[0] We have still not peaked during this interglacial epoch, but the tropospheric warming appears normal and less than the IPCC target.

[0] https://www.drroyspencer.com/2022/03/uah-global-temperature-...

Quite interesting that this is being published in Nature. I think there are far worse things that need to be removed. But so little is discussed on the affect of the sun moving into a solar minimum. That will have some serious consequences as well.

>That will have some serious consequences as well.

According to NASA [1], that is false.

[1] https://climate.nasa.gov/ask-nasa-climate/2953/there-is-no-i...

This particular issue has been well understood for at least 30 years. Greenhouse gasses are a first order effect. Solar cycles are second order.

The principal greenhouse gas is water vapor, and the effect of solar variation on that is not at all “well understood”.

The sun is moving into a solar minimum for the past decades and temperatures are still rising. Just imagine how much more temperatures would be rising if that wasn't the case.

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