How much carbon are we removing from the atmosphere?
A conversation with Dr. Greg Nemet, one of the authors of the pioneering 'State of Carbon Dioxide Removal' report
In this week’s edition of the New England Climate Dispatch, we’re diving into carbon dioxide removal (CDR), looking at efforts across the globe to remove carbon from the atmosphere.
While novel technologies for carbon removal often make big headlines, these are still essentially nonexistent at scale, and the vast majority of carbon sequestered is contained in the biosphere, often in the form of trees or soil. Although these methods of storing carbon will never replace the need for rapid reductions in fossil fuel consumption, they will still need to play an important role in stabilizing — and hopefully eventually reducing — levels of atmospheric carbon.
To better understand how carbon removal methods and technologies are developing, a group of leading researchers and IPCC authors have released the first ever global assessment of carbon removal, looking at how much carbon is being removed from the atmosphere today, and how much more we will need to remove avoid climate catastrophe.
I recently spoke with one of the authors of this report, Dr. Gregory Nemet of the University of Wisconsin-Madison, about the findings and major implications of this research. Our conversation below has been condensed and lightly edited for clarity. Thanks for reading!
Can you talk about what got this work started, and how you went about conducting the study?
This started really about five or six years ago, some colleagues and I started doing a series of papers on carbon removal, though at the time we called it negative emissions technologies, and we tried to scope out how big a deal these could be, and one of our colleagues worked on this IPCC 1.5° report in 2018. And that was the report that said “If we want to do 1.5°— which we agreed on in Paris — then we actually have to do a lot of removing CO2 from the atmosphere.
As we were looking at carbon removal, it feels like carbon removal now is kind of where renewables were 20 years ago: lots of potential, lots of interest, but tiny, and the big challenge is scaling it up to something that’s going to be climate relevant. And renewables have been able to do that and are still on this growth trajectory.
And was the main objective of the study to really just catalog how this is scaling up, and the extent that it exists today?
Yea, we tried to do a comprehensive take on carbon removal across a lot of different indicators, but one of the main indicators was just how much has been installed, how much carbon are we removing per year, because a bunch of us authors had worked on the IPCC reports for the last three or four years, and even in that big effort there was no global estimate of how much CO2 is actually being removed today. So that was one objective, and we did that, and we came up with a number of two – two billion tons of CO2 are being removed every year, almost all of it by land use, mainly trees.
But then we wanted to say how much would we need if we want to be Paris-compatible and keep temperatures below 2°, and try to keep them below 1.5°. How much carbon removal would that take, and how does that compare to where we are today, and how does it compare to what countries have in their plans? And that is where we kind of stumbled onto this idea that there’s a gap — there’s a gap between what countries say they’re going to do by 2030 and by 2050, and what the scenarios say we need to get to to be Paris compatible. And the gap is large. It’s on the order of five times as large as the amount of CO2 that we’re removing today. We’re removing two gigatons, and across different scenarios we probably need to do five or ten by mid-century, so we have a lot more to do.
With most removal coming from things like forests right now, is it possible to bridge that gap using the existing ways we’re doing it, or does there need to be more of a technological answer?
One distinction we made was between what we’re calling conventional carbon removal, and that’s anything where the carbon is stored in land, in the biosphere. So that’s like planting trees, some agricultural efforts that store carbon … and then novel CDR, which is everything else. So that’s like biochar, bioenergy to carbon capture, direct air capture, and that’s all tiny. It’s like one thousandth of the size of our conventional CDR on land. And to answer your question, it looks like we need to scale up the conventional land-based CDR by on average about 30 percent by 2030 and 100 percent – so doubling – by 2050.
So that’s a pretty big challenge, it probably includes more land or being more efficient with the land we have to store in different types of trees, so that’s one part of it. But the other part of it is that only gets us to maybe four gigatons. If we need to get to like ten, then we need to be scaling up these novel CDR technologies like biochar, direct air capture, and there we’re starting from something that’s pretty close to zero — like a million tons, or maybe two million tons over the whole world for all those different types — that needs to get up to say two billion tons by 2050. So, we’re talking a factor of a thousand scale up over the next 27 years on that. So that’s the challenge.
Do you think that’s possible?
Yea, if you compare it to previous technologies, like one thing we start with is wind and solar, and those have grown at like 30 percent a year over 30 years, and for something like direct air capture to get from where it is to where it needs to be, it needs to grow not 30 percent but more like 40 percent over that time, so it’s not that far off.
So that takes strong policy, it takes derisking the technology, it involves creating market, it involves improving the technology so it’s perceived as effective and safe. There’s a lot to do, but it’s not unprecedented, and that’s kind of the challenge ahead to make that all happen.
It seems like there’s a pretty clear market for renewable energy, clean energy. Do you think the market exists at the same level to spur that growth, or would demand need to be more coming from governments?
We have to somehow create markets for these, and five years ago when we were doing these other papers, I would’ve said the only way to have a market is for the governments to create a market, because there’s no benefit of removing CO2 — I mean there are small markets for purified CO2 for beverages and greenhouses and maybe getting oil out of oil fields, but those aren’t that big and what you ultimately need is the government to put a price on that or create incentives or create mandates.
But so far, we’ve had more private sector activity that I would’ve expected — a lot of voluntary commitments. We measured $200 million of purchases in the last three years of removed carbon from these novel CO2 methods, and almost all of those are not from policy, those are voluntary commitments by big tech companies, airlines, and large companies that want to offset their emissions from their operations. So, in some ways the private sector’s leading, which is helpful, but we are saying that the public sector really needs to catch up and start creating incentives, because if we’re going to have billion-ton markets — just for example if it’s $100 a ton that means we need a $100 billion market — that’s going to take policy.
And what would these incentives look like? What can governments do to really fast track this technology? Are there some governments that are already doing this well?
Yea, there’s some nascent activity. I would put it in three categories of things we need to do – so one is just funding research, so in materials, figuring out how these technologies work at scale, understanding some of the sustainability impacts at scale. There’s research that would be helpful to do and to fund.
Then the other thing that would be really helpful are demonstration projects, where we start to build large bioenergy and carbon capture plants, or direct air capture [DAC] plants. For example, there’s a proposal by the Department of Energy to do these DAC hubs, so that’s about $3.5 billion, it’d be four large facilities, and that’s exactly what we need. We probably need maybe four times as many of those around the world, and then we probably need a second program after that to scale it up even more, but that’s a really big step in the right direction.
So, there’s the research, there’s the demonstrations, and then on the market side, creating policies that will derisk the technology. What worked with solar and wind was giving these guaranteed contracts where we’d say “if you build solar, we’ll buy electricity from you for two times the grid price for the next 20 years,” Germany did that. And you could do something similar for carbon removal.
Are there things that can be done at a local level with state governments or with city or municipal governments to spur this along as well?
Yea, there are a lot of local efforts. And some of these are large-scale technologies like a large bioenergy with carbon capture plant, but some of these are potentially really small, like forestry and sequestering carbon in soils and then putting biochar on the soils. Those are all things that could have a local impact, local benefit, create local opportunities.
There’s also infrastructure that’s local — things like pipelines moving CO2 around. And pipelines in general have not been very popular, or things like transmission systems too, even if they’re moving clean energy around. And so I think that’s going to be a big challenge, how to develop infrastructure – for example pipelines – that could be on the scale of the natural gas pipeline system that we have around the world.
Could we repurpose much of the natural gas or crude oil pipeline systems to do that?
Probably not the pipes themselves, CO2’s really corrosive, so you’d have to do some upgrading of the pipes themselves, but the right-of-ways are there, and there’s a lot of reason to be going to a lot of the same places, so I think that’s something that’s proven tricky in the past, to cite entirely new routes, so on existing natural gas pipeline routes, I think that’s something that seems like there’s really potential there.
A lot of offsets can be very problematic, making sure that they’re actually doing what they say they’re doing, and I’m curious how you all dealt with that in this report, and if there’s anything you learned about verifying, or making sure that there weren’t any negative effects of pursuing carbon capture technologies?
Yea, I think it’s super important. And it can be done well and it can be done badly, and we use as our definition of CDR carbon that’s removed and stored durably — and when we say durably we’re talking about scale of decades to centuries, and so if you’re in Iceland and taking CO2 out of the air there and putting it down as a water-based solution and then having that mineralize and turn into rock, that’s pretty much permanent, and so that’s about the gold standard for how long it would stay. And then if you’re protecting a forest that ends up having a wildfire then that’s about the most useless credits or the most short-term you could think about.
So it's a crucial issue, and there’s cost to it. That’s something that we encountered is that in some of these removal methods, the cost of the removal is not that much, but actually verifying and monitoring it is substantial. And there needs to be trust and credibility, and there’s a lot of evidence as you referred to of some of these offset programs not actually being verifiable, or they’re all based on a counterfactual, like what would’ve happened if you didn’t purchase any offset, which is almost like a philosophical issue, or requires some kind of modeling of what would’ve happened.
Getting the monitoring and verification working well is going to be crucial for the credibility of this whole effort, because it won’t have public acceptance if people think it’s just kind of honor.
Even if we meet this five-to-ten billion tons of carbon dioxide removal a year by 2050, how much decarbonization would need to accompany that to meet 1.5 or even 2 degrees of warming?
None of this replaces rapidly reducing emissions. So if you think just simple math, say you were doing ten gigatons of removal, that’s pretty high in the estimate for mid-century, and we’re at 40 gigatons of CO2 a year here today, and we need to get that down to zero, that ten is doing 25 percent of the work, and the rest of it, 75 percent, which is getting from 40 gigatons down to ten, that’s all about cleaning up our energy system, taking emissions out of the building sector, out of industry, out of agriculture, out of transportation, all of it.
It doesn’t really mean we have to do anything different than we had to do before. It’s just a matter of — if we want to do 1.5°, or want to do 2°, we need to get emissions down to zero by mid-century, and if it turns out that we’re too slow, which it looks like we’re being, we’re going to have to compensate with some removal. And if there are some sectors that are really hard to get to zero like agriculture, or industry, or long-distance air travel, then we’re also going to need to do some removal as well. So all of this is predicated on rapid reductions of emissions that get pretty close to zero over the next 30 years.
Climate News Roundup
Connecticut
Climate change is hurting air quality across Connecticut (and basically everywhere) by increasing concentrations of ground-level ozone and airborne particulate matter. The brunt of these issues is disproportionately felt by non-white and/or low-income communities (Jan Ellen Spiegel — CT Mirror)
As temperatures warm, ticks have become active year-round in Connecticut, bringing increased risks of Lyme disease (Michayla Savitt — Connecticut Public)
Maine
In Maine’s new legislative session, public power, carbon storage, public transportation, offshore wind, housing justice, and a windfall tax for fossil fuel companies will all be on the docket (Evan Popp — Maine Beacon)
A coalition of Maine officials, environmental advocates, and business leaders are calling on the EPA to tighten up its standards for tailpipe emissions (Penelope Overton — Portland Press Herald)
Massachusetts
A large group of Mothers Out Front protesters marched to Gov. Maura Healey’s office to deliver a letter calling for improved air quality, a just transition for workers, an end to investments in fossil fuel infrastructure, and the rejection of industry plans to heat the state with hydrogen and biomethane (Alison Kuznitz — MassLive)
Protests have continued against Eversource’s under-construction East Boston substation, which is being built in a flood-prone area next to a jet fuel storage facility in an environmental justice neighborhood (Annie Sandoli — WHDH)
Boston Mayor Michelle Wu announced that all new city construction will be free of fossil fuels by 2030 (Dharna Noor — Boston Globe)
New Hampshire
The city of Dover will join the Community Power Coalition of New Hampshire, which serve as the city’s new electricity supplier, which could help lower rates and give residents more clean energy options (Rhianwen Watkins — Foster’s Daily Democrat)
Rhode Island
In Rhode Island’s new legislative session, new programs relating to a clean heat standard, new hookups for fossil fuels in buildings, energy efficiency, and revoking incentives for fossil fuel appliances could all be up for debate (Alex Kuffner — The Providence Journal)
The proliferation of plastic pollution can lead to serious health risks, in Rhode Island and just about everywhere else. Special thanks go to the oil and gas industry (Mary Lhowe — EcoRI)
Vermont
A new report from the Vermont Climate Council indicates that the state is not on track to meet its 2025 emissions reduction goal. Meanwhile, Republican lawmakers want to backtrack on the binding emissions requirements, and scrap the Climate Council entirely (Kevin Gaiss — WCAX)
Vermont is also not meeting its goals to recycle and compost half of its waste according to a recent report by the Department of Environmental Conservation (Fred Thys — VT Digger)
Across the region and beyond!
A pair of recent reports on offshore wind highlight the need for increased investments in both transmission planning and developing a domestic supply chain (Robert Zullo — Maine Beacon)
Across New England, climate change is increasing the frequency of power outages thanks to stronger storms (Dharna Noor — Boston Globe)
A new study lead by Harvard researcher Geoffrey Supran shows that Exxon’s scientists were spot on in their climate change predictions from the 1970s to the mid-2000s, directly contradicting their public efforts to persuade the public that fossil fuels are not causing major changes to the climate (Supran et al., Science)