Climate scientists: concept of net zero is a dangerous trap

Climate scientists: concept of net zero is a dangerous trap. James Dyke, Robert Watson, Wolfgang Knorr.  April 22,2021.

Sometimes realisation comes in a blinding flash. Blurred outlines snap into shape and suddenly it all makes sense. Underneath such revelations is typically a much slower-dawning process. Doubts at the back of the mind grow. The sense of confusion that things cannot be made to fit together increases until something clicks. Or perhaps snaps.

Collectively we three authors of this article must have spent more than 80 years thinking about climate change. Why has it taken us so long to speak out about the obvious dangers of the concept of net zero? In our defence, the premise of net zero is deceptively simple – and we admit that it deceived us.

The threats of climate change are the direct result of there being too much carbon dioxide in the atmosphere. So it follows that we must stop emitting more and even remove some of it. This idea is central to the world’s current plan to avoid catastrophe. In fact, there are many suggestions as to how to actually do this, from mass tree planting, to high tech direct air capture devices that suck out carbon dioxide from the air.


Read more: There aren’t enough trees in the world to offset society’s carbon emissions – and there never will be

The current consensus is that if we deploy these and other so-called “carbon dioxide removal” techniques at the same time as reducing our burning of fossil fuels, we can more rapidly halt global warming. Hopefully around the middle of this century we will achieve “net zero”. This is the point at which any residual emissions of greenhouse gases are balanced by technologies removing them from the atmosphere.

This is a great idea, in principle. Unfortunately, in practice it helps perpetuate a belief in technological salvation and diminishes the sense of urgency surrounding the need to curb emissions now.

We have arrived at the painful realisation that the idea of net zero has licensed a recklessly cavalier “burn now, pay later” approach which has seen carbon emissions continue to soar. It has also hastened the destruction of the natural world by increasing deforestation today, and greatly increases the risk of further devastation in the future.

To understand how this has happened, how humanity has gambled its civilisation on no more than promises of future solutions, we must return to the late 1980s, when climate change broke out onto the international stage.

Steps towards net zero

On June 22 1988, James Hansen was the administrator of Nasa’s Goddard Institute for Space Studies, a prestigious appointment but someone largely unknown outside of academia.

By the afternoon of the 23rd he was well on the way to becoming the world’s most famous climate scientist. This was as a direct result of his testimony to the US congress, when he forensically presented the evidence that the Earth’s climate was warming and that humans were the primary cause: “The greenhouse effect has been detected, and it is changing our climate now.”

If we had acted on Hanson’s testimony at the time, we would have been able to decarbonise our societies at a rate of around 2% a year in order to give us about a two-in-three chance of limiting warming to no more than 1.5°C. It would have been a huge challenge, but the main task at that time would have been to simply stop the accelerating use of fossil fuels while fairly sharing out future emissions.

Graph demonstrating how fast mitigation has to happen to keep to 1.5℃. © Robbie Andrew,


Four years later, there were glimmers of hope that this would be possible. During the 1992 Earth Summit in Rio, all nations agreed to stabilise concentrations of greenhouse gases to ensure that they did not produce dangerous interference with the climate. The 1997 Kyoto Summit attempted to start to put that goal into practice. But as the years passed, the initial task of keeping us safe became increasingly harder given the continual increase in fossil fuel use.

It was around that time that the first computer models linking greenhouse gas emissions to impacts on different sectors of the economy were developed. These hybrid climate-economic models are known as Integrated Assessment Models. They allowed modellers to link economic activity to the climate by, for example, exploring how changes in investments and technology could lead to changes in greenhouse gas emissions.

They seemed like a miracle: you could try out policies on a computer screen before implementing them, saving humanity costly experimentation. They rapidly emerged to become key guidance for climate policy. A primacy they maintain to this day.

Unfortunately, they also removed the need for deep critical thinking. Such models represent society as a web of idealised, emotionless buyers and sellers and thus ignore complex social and political realities, or even the impacts of climate change itself. Their implicit promise is that market-based approaches will always work. This meant that discussions about policies were limited to those most convenient to politicians: incremental changes to legislation and taxes.

Around the time they were first developed, efforts were being made to secure US action on the climate by allowing it to count carbon sinks of the country’s forests. The US argued that if it managed its forests well, it would be able to store a large amount of carbon in trees and soil which should be subtracted from its obligations to limit the burning of coal, oil and gas. In the end, the US largely got its way. Ironically, the concessions were all in vain, since the US senate never ratified the agreement. 

Postulating a future with more trees could in effect offset the burning of coal, oil and gas now. As models could easily churn out numbers that saw atmospheric carbon dioxide go as low as one wanted, ever more sophisticated scenarios could be explored which reduced the perceived urgency to reduce fossil fuel use. By including carbon sinks in climate-economic models, a Pandora’s box had been opened.

It’s here we find the genesis of today’s net zero policies.

That said, most attention in the mid-1990s was focused on increasing energy efficiency and energy switching (such as the UK’s move from coal to gas) and the potential of nuclear energy to deliver large amounts of carbon-free electricity. The hope was that such innovations would quickly reverse increases in fossil fuel emissions.

But by around the turn of the new millennium it was clear that such hopes were unfounded. Given their core assumption of incremental change, it was becoming more and more difficult for economic-climate models to find viable pathways to avoid dangerous climate change. In response, the models began to include more and more examples of carbon capture and storage, a technology that could remove the carbon dioxide from coal-fired power stations and then store the captured carbon deep underground indefinitely.

This had been shown to be possible in principle: compressed carbon dioxide had been separated from fossil gas and then injected underground in a number of projects since the 1970s. These Enhanced Oil Recovery schemes were designed to force gases into oil wells in order to push oil towards drilling rigs and so allow more to be recovered – oil that would later be burnt, releasing even more carbon dioxide into the atmosphere.

Carbon capture and storage offered the twist that instead of using the carbon dioxide to extract more oil, the gas would instead be left underground and removed from the atmosphere. This promised breakthrough technology would allow climate friendly coal and so the continued use of this fossil fuel. But long before the world would witness any such schemes, the hypothetical process had been included in climate-economic models. In the end, the mere prospect of carbon capture and storage gave policy makers a way out of making the much needed cuts to greenhouse gas emissions.

The rise of net zero

When the international climate change community convened in Copenhagen in 2009 it was clear that carbon capture and storage was not going to be sufficient for two reasons.

First, it still did not exist. There were no carbon capture and storage facilities in operation on any coal fired power station and no prospect the technology was going to have any impact on rising emissions from increased coal use in the foreseeable future.

The biggest barrier to implementation was essentially cost. The motivation to burn vast amounts of coal is to generate relatively cheap electricity. Retrofitting carbon scrubbers on existing power stations, building the infrastructure to pipe captured carbon, and developing suitable geological storage sites required huge sums of money. Consequently the only application of carbon capture in actual operation then – and now – is to use the trapped gas in enhanced oil recovery schemes. Beyond a single demonstrator, there has never been any capture of carbon dioxide from a coal fired power station chimney with that captured carbon then being stored underground.

Just as important, by 2009 it was becoming increasingly clear that it would not be possible to make even the gradual reductions that policy makers demanded. That was the case even if carbon capture and storage was up and running. The amount of carbon dioxide that was being pumped into the air each year meant humanity was rapidly running out of time.

With hopes for a solution to the climate crisis fading again, another magic bullet was required. A technology was needed not only to slow down the increasing concentrations of carbon dioxide in the atmosphere, but actually reverse it. In response, the climate-economic modelling community – already able to include plant-based carbon sinks and geological carbon storage in their models – increasingly adopted the “solution” of combining the two.

So it was that Bioenergy Carbon Capture and Storage, or BECCS, rapidly emerged as the new saviour technology. By burning “replaceable” biomass such as wood, crops, and agricultural waste instead of coal in power stations, and then capturing the carbon dioxide from the power station chimney and storing it underground, BECCS could produce electricity at the same time as removing carbon dioxide from the atmosphere. That’s because as biomass such as trees grow, they suck in carbon dioxide from the atmosphere. By planting trees and other bioenergy crops and storing carbon dioxide released when they are burnt, more carbon could be removed from the atmosphere.

With this new solution in hand the international community regrouped from repeated failures to mount another attempt at reining in our dangerous interference with the climate. The scene was set for the crucial 2015 climate conference in Paris.

A Parisian false dawn

As its general secretary brought the 21st United Nations conference on climate change to an end, a great roar issued from the crowd. People leaped to their feet, strangers embraced, tears welled up in eyes bloodshot from lack of sleep.

The emotions on display on December 13, 2015 were not just for the cameras. After weeks of gruelling high-level negotiations in Paris a breakthrough had finally been achieved. Against all expectations, after decades of false starts and failures, the international community had finally agreed to do what it took to limit global warming to well below 2°C, preferably to 1.5°C, compared to pre-industrial levels.

The Paris Agreement was a stunning victory for those most at risk from climate change. Rich industrialised nations will be increasingly impacted as global temperatures rise. But it’s the low lying island states such as the Maldives and the Marshall Islands that are at imminent existential risk. As a later UN special report made clear, if the Paris Agreement was unable to limit global warming to 1.5°C, the number of lives lost to more intense storms, fires, heatwaves, famines and floods would significantly increase.

But dig a little deeper and you could find another emotion lurking within delegates on December 13. Doubt. We struggle to name any climate scientist who at that time thought the Paris Agreement was feasible. We have since been told by some scientists that the Paris Agreement was “of course important for climate justice but unworkable” and “a complete shock, no one thought limiting to 1.5°C was possible”. Rather than being able to limit warming to 1.5°C, a senior academic involved in the IPCC concluded we were heading beyond 3°C by the end of this century.

Instead of confront our doubts, we scientists decided to construct ever more elaborate fantasy worlds in which we would be safe. The price to pay for our cowardice: having to keep our mouths shut about the ever growing absurdity of the required planetary-scale carbon dioxide removal.

Taking centre stage was BECCS because at the time this was the only way climate-economic models could find scenarios that would be consistent with the Paris Agreement. Rather than stabilise, global emissions of carbon dioxide had increased some 60% since 1992.

Alas, BECCS, just like all the previous solutions, was too good to be true.

Across the scenarios produced by the Intergovernmental Panel on Climate Change (IPCC) with a 66% or better chance of limiting temperature increase to 1.5°C, BECCS would need to remove 12 billion tonnes of carbon dioxide each year. BECCS at this scale would require massive planting schemes for trees and bioenergy crops.

The Earth certainly needs more trees. Humanity has cut down some three trillion since we first started farming some 13,000 years ago. But rather than allow ecosystems to recover from human impacts and forests to regrow, BECCS generally refers to dedicated industrial-scale plantations regularly harvested for bioenergy rather than carbon stored away in forest trunks, roots and soils.

Currently, the two most efficient biofuels are sugarcane for bioethanol and palm oil for biodiesel – both grown in the tropics. Endless rows of such fast growing monoculture trees or other bioenergy crops harvested at frequent intervals devastate biodiversity.

It has been estimated that BECCS would demand between 0.4 and 1.2 billion hectares of land. That’s 25% to 80% of all the land currently under cultivation. How will that be achieved at the same time as feeding 8-10 billion people around the middle of the century or without destroying native vegetation and biodiversity?


Read more: Carbon capture on power stations burning woodchips is not the green gamechanger many think it is


Growing billions of trees would consume vast amounts of water – in some places where people are already thirsty. Increasing forest cover in higher latitudes can have an overall warming effect because replacing grassland or fields with forests means the land surface becomes darker. This darker land absorbs more energy from the Sun and so temperatures rise. Focusing on developing vast plantations in poorer tropical nations comes with real risks of people being driven off their lands.

And it is often forgotten that trees and the land in general already soak up and store away vast amounts of carbon through what is called the natural terrestrial carbon sink. Interfering with it could both disrupt the sink and lead to double accounting.

As these impacts are becoming better understood, the sense of optimism around BECCS has diminished.

Pipe dreams

Given the dawning realisation of how difficult Paris would be in the light of ever rising emissions and limited potential of BECCS, a new buzzword emerged in policy circles: the “overshoot scenario”. Temperatures would be allowed to go beyond 1.5°C in the near term, but then be brought down with a range of carbon dioxide removal by the end of the century. This means that net zero actually means carbon negative. Within a few decades, we will need to transform our civilisation from one that currently pumps out 40 billion tons of carbon dioxide into the atmosphere each year, to one that produces a net removal of tens of billions.

Mass tree planting, for bioenergy or as an attempt at offsetting, had been the latest attempt to stall cuts in fossil fuel use. But the ever-increasing need for carbon removal was calling for more. This is why the idea of direct air capture, now being touted by some as the most promising technology out there, has taken hold. It is generally more benign to ecosystems because it requires significantly less land to operate than BECCS, including the land needed to power them using wind or solar panels.

Unfortunately, it is widely believed that direct air capture, because of its exorbitant costs and energy demand, if it ever becomes feasible to be deployed at scale, will not be able to compete with BECCS with its voracious appetite for prime agricultural land.

It should now be getting clear where the journey is heading. As the mirage of each magical technical solution disappears, another equally unworkable alternative pops up to take its place. The next is already on the horizon – and it’s even more ghastly. Once we realise net zero will not happen in time or even at all, geoengineering – the deliberate and large scale intervention in the Earth’s climate system – will probably be invoked as the solution to limit temperature increases.

One of the most researched geoengineering ideas is solar radiation management – the injection of millions of tons of sulphuric acid into the stratosphere that will reflect some of the Sun’s energy away from the Earth. It is a wild idea, but some academics and politicians are deadly serious, despite significant risks. The US National Academies of Sciences, for example, has recommended allocating up to US$200 million over the next five years to explore how geoengineering could be deployed and regulated. Funding and research in this area is sure to significantly increase.

Difficult truths

In principle there is nothing wrong or dangerous about carbon dioxide removal proposals. In fact developing ways of reducing concentrations of carbon dioxide can feel tremendously exciting. You are using science and engineering to save humanity from disaster. What you are doing is important. There is also the realisation that carbon removal will be needed to mop up some of the emissions from sectors such as aviation and cement production. So there will be some small role for a number of different carbon dioxide removal approaches.

The problems come when it is assumed that these can be deployed at vast scale. This effectively serves as a blank cheque for the continued burning of fossil fuels and the acceleration of habitat destruction.

Carbon reduction technologies and geoengineering should be seen as a sort of ejector seat that could propel humanity away from rapid and catastrophic environmental change. Just like an ejector seat in a jet aircraft, it should only be used as the very last resort. However, policymakers and businesses appear to be entirely serious about deploying highly speculative technologies as a way to land our civilisation at a sustainable destination. In fact, these are no more than fairy tales.

The only way to keep humanity safe is the immediate and sustained radical cuts to greenhouse gas emissions in a socially just way.

Academics typically see themselves as servants to society. Indeed, many are employed as civil servants. Those working at the climate science and policy interface desperately wrestle with an increasingly difficult problem. Similarly, those that champion net zero as a way of breaking through barriers holding back effective action on the climate also work with the very best of intentions.

The tragedy is that their collective efforts were never able to mount an effective challenge to a climate policy process that would only allow a narrow range of scenarios to be explored.

Most academics feel distinctly uncomfortable stepping over the invisible line that separates their day job from wider social and political concerns. There are genuine fears that being seen as advocates for or against particular issues could threaten their perceived independence. Scientists are one of the most trusted professions. Trust is very hard to build and easy to destroy.

But there is another invisible line, the one that separates maintaining academic integrity and self-censorship. As scientists, we are taught to be sceptical, to subject hypotheses to rigorous tests and interrogation. But when it comes to perhaps the greatest challenge humanity faces, we often show a dangerous lack of critical analysis.

In private, scientists express significant scepticism about the Paris Agreement, BECCS, offsetting, geoengineering and net zero. Apart from some notable exceptions, in public we quietly go about our work, apply for funding, publish papers and teach. The path to disastrous climate change is paved with feasibility studies and impact assessments.

Rather than acknowledge the seriousness of our situation, we instead continue to participate in the fantasy of net zero. What will we do when reality bites? What will we say to our friends and loved ones about our failure to speak out now?

The time has come to voice our fears and be honest with wider society. Current net zero policies will not keep warming to within 1.5°C because they were never intended to. They were and still are driven by a need to protect business as usual, not the climate. If we want to keep people safe then large and sustained cuts to carbon emissions need to happen now. That is the very simple acid test that must be applied to all climate policies. The time for wishful thinking is over.

Topic: BECCS, Carbon Capture and Storage; DAC; CDR

Don’t deploy negative emissions technologies without ethical analysis. Nature. Sep. 19, 2018.

Climate policy advice is being undermined by value-laden choices over risky mitigation strategies, warn Dominic Lenzi and colleagues.

Sucking carbon out of the air won’t solve climate change. David Roberts, vox. Jun. 14, 2018.

Bioenergy with Carbon Capture and Storage Approaches for Carbon Dioxide Removal and Reliable Sequestration. Proceedings of a Workshop—in Brief. National Academy. 2018.

Bioenergy with carbon capture and storage (BECCS) is a technology that integrates biomass conversion to heat, electricity, or liquid or gas fuels with carbon capture and sequestration. BECCS could provide a significant portion of the global energy supply if deployed to its theoretical maximum feasible amount. The future role of BECCS is a subject that divides researchers as estimates of potential future biomass supply vary widely due to differences in approaches used to consider factors such as population development, consumption patterns (e.g., diet), economic and technological development, climate change, and societal priorities concerning conservation versus production objectives. Nevertheless, many integrated assessment models use large-scale deployment of BECCS in scenarios that limit climate change to below 2°C. 

On October 23, 2017, the National Academies of Sciences, Engineering, and Medicine convened a third meeting in Irvine, California, to explore the state of knowledge and research needs related to the potential of BECCS as a CDR approach. Invited speakers gave an overview of biomass production pathways and capacities, implications of various feedstocks, advanced conversion technologies, and capture and storage strategies. Presenters at the workshop also discussed cross-cutting issues that include life cycle impacts of large-scale BECCS deployment, policies and incentives for the implementation of these approaches, and social acceptability barriers. The workshop was preceded by an introductory webinar on October 16, 2017, where invited speakers provided a primer on the prospects of BECCS for negative emissions capacity; the capacity for biomass to meet stationary generation and transportation fuel needs; and the status, challenges, and costs of implemented bioenergy and biofuels. This publication summarizes the presentations and discussions from both the webinar and workshop.

The Need for Carbon Removal. Holly Jean Buck, Jacobin. July 24, 2018.

Massive removal of carbon from the atmosphere — also known as negative emissions, carbon drawdown, or regeneration — could be a cornerstone of either dystopian or radically utopian futures. Some of the dystopian ones are well known: vast conversion of land to plantations for biofuels with carbon capture and storage, displacing people from the land, destroying habitats, and spiking food prices. 

But given what we know about climate change in 2018, it’s not enough to protest against dystopian versions of carbon removal. Too much warming is already locked in. We need a radically utopian way of removing carbon. 

If we buy into thinking of carbon removal technologies as substitutes for reducing carbon output, then industrial interests have already won: they have set the narrative and the framing, where carbon capture exists so that they can continue to emit. But we should demand more from these technologies. 

Industrial carbon capture technologies could instead be used as an extension of decarbonization — mitigation to get us to zero, and carbon removal going a step further to take emissions negative and address some of the climate impacts already being felt. 

It won’t be easy. But climate science suggests it’s a challenge the Left must take up. 

Carbon Removal 

Climate change has already warmed the planet over 1°C relative to pre-industrial levels. Paradoxically, cleaning up the air pollution that’s currently masking some of the global warming in the pipeline would raise temperatures another 0.5 to 1.1 degrees. 

This means that if we waved a magic wand and suddenly (1) stopped using fossil fuels, and (2) cleaned up air pollution, we would already be breaching 1.5°C — the amount of warming that most climate advocates have argued for. 

The carbon budget is not an exact science, but it seems we are hovering at the point where 1.5°C of warming is locked in by what has already been emitted. Put differently, the most recent scientific evidence suggests we have zero to five years before every additional ton of carbon dioxide emitted would need to be compensated by a ton of negative emissions to stay below 1.5°C. 

In fact, the scenarios used in the fifth Intergovernmental Panel on Climate Change (IPCC) report rely on massive amounts of negative emissions to curb warming to 1.5°C, primarily via a method known as bioenergy with carbon capture and storage (BECCS). This led a team of modelers to try and see what it would take to achieve 1.5° without BECCS. 

Even a scenario where renewables, electrification, and energy efficiency were aggressively pursued — and 80 percent of meat and eggs were replaced with cultivated meat, flying was reduced, and tumble dryers were eliminated — could not eliminate the need for carbon removal. This scenario still required about four hundred billion tons (Gt) of carbon dioxide removed via reforestation. Reforestation sounds great and green, but it also has the potential to result in dispossession, conflict over land access, and worsened livelihoods for smallholders. 

What about achieving a slightly less ambitious goal of 2°C? Two and 1.5 degrees might not sound all that different, but they are. The difference is one that threatens entire unique coral ecosystems, the homes of five million people (including entire countries), and high increases in the frequencies of extreme events. 

Rapid mitigation could still curb warming to 2°C without the use of negative emissions technologies. But that window is closing fast. If near-term emissions reductions follow the trajectory laid out in the commitments nations made under the Paris agreement, by 2030, 2°C scenarios will also depend upon negative emissions. 

That is, in the next decade, we would have to vastly exceed the Paris promises to not depend upon negative emissions. 

We aren’t even making much progress towards these Paris targets, which if achieved would still produce 3°C of warming — an amount widely agreed to lead to massive disruptions. This is why negative emissions have become such a useful device for the models. 

By the end of the century, scenarios for 1.5°C or 2°C envision pulling out ten billion tons (10Gt) per year. For comparison, current levels of emissions are around forty billion tons of CO2 per year. So 1.5°C means not just zeroing out those forty billion tons, but then working to extract another ten billion on top of that to be net-negative. This would require scaling up current carbon capture and sequestration efforts a thousand-fold. 

Negative emissions help maintain the narrative that although time is running short, we can still stop catastrophic global warming if we act now. Once we understand that this inventive arithmetic has been employed to “solve” for 1.5, what do we do? 

Assuming there will be a complete about-face that puts us on a course towards 100 percent renewables, massive lifestyle changes, and drastic land use change for afforesting millions of hectares in the tropics within the next ten years strikes me as not only magical thinking, but thinking that puts many at risk of great suffering. 

Alternately, accepting that the earth will warm more than 1.5°C means accepting the loss of the world’s coral reefs and the half billion people relying on them, as well as other harms to communities living on the front lines of climate change. 

So we need to ask: is there a form of massive carbon removal that could be put towards socially just ends, pulling carbon out of the atmosphere as a form of collective social good? Can it work as an outgrowth of energy democracy? For if such a collection of technologies, practices, and institutions can exist, we should try to build it. 

Notably, carbon removal at what I’ll call climate-significant scale should not be thought of as a magic wand to wipe carbon away either. For one thing, it will not compensate exactly for emissions. The ocean, for example, currently takes up close to half of the carbon humans emit, and it’s possible that if carbon was removed at a large scale from the atmosphere, the oceans would then give off carbon, perhaps replacing half of the carbon that had been removed. 

The prospect of carbon removal is fraught with complexity, and even peril — all of which we have to talk about. 

The Necessity of Geological Sequestration 

The best way to remove carbon immediately is through “natural climate solutions,” which employ nature’s processes to store carbon in ecosystems. Sequestering carbon in soil, restoring forests and planting new ones, and protecting wetlands can store carbon. These can forestall some amount of warming, in addition to other benefits for both humans and the environment. 

Yet while it seems intuitive to simply let nature take up the carbon, carbon was put into the atmosphere unnaturally, and the available scientific evidence suggests ecosystem-based solutions simply don’t scale well enough to contend with the sheer amount of carbon that has been dumped into the atmosphere. 

Pursued vigorously, reforestation and soil carbon sequestration could each remove a few gigatons per year — for a while. After a few decades, a forest planted to remove carbon reaches a plateau where it becomes saturated and can’t remove any additional carbon, like a bathtub filling up, at which point the already-absorbed carbon must simply be held indefinitely. 

Similarly, a farm that has transitioned to regenerative practices to store more carbon in the soil can only remove additional carbon for a few decades. Moreover, forests can be ravaged by epidemics or fires, resulting in the sudden release of their stored carbon, which means they are vulnerable to global warming itself. 

So while these projects can do important work in the near future, we also need to supplement these one-off, land-based carbon removal projects with systems that can continuously remove carbon and store it reliably over centuries — that is to say, with industrial carbon capture with geological sequestration. We need to build systems that capture carbon emissions from sources like power plants or factories, or even from ambient air, and transport it to underground reservoirs where it can be stored. 

There are major technical and social obstacles to this. But these industrial systems for geological storage, used together and sequentially with natural carbon removal, could help ease the path to a climate-stable world. 

Carbon capture and storage (CCS) technology is not a new technology....

Can we remove a trillion tons of carbon from the atmosphere?  Nick Breeze, Ecologist. May 3, 2018.

'Remove', 'sequester', 'lock-up'. Call it how you like, but to stabilise our climate and surpass the Paris Agreement, we really need to be thinking about storing hundreds of billions of tonnes of carbon. I don’t think anybody on Earth can visualise what numbers like these really look like. Yet, our future depends on us lowering the quantity of greenhouse gases in the atmosphere to safe levels before, so-called self-amplifying feedbacks take over - if they haven’t already. 

There is a clue emerging as to how we might accomplish such a feat - in the image of the Blue Marble NASA image of Earth. Namely that over 70 percent of the planet is ocean and the fate of life on Earth is intrinsically tied to that of the oceans. 

Currently - and it is no secret - the oceans are in a terminal decline, acidifying, heating, losing their biomass and, the worse bit, flipping from carbon sink to carbon source. Fish stocks are also depleted, as ocean ecosystems fall under the sad blanket of degradation. But what if, by a process of biomimicry, we could reverse these processes and restore the life in the oceans?

Guest post: Why BECCS might not produce ‘negative’ emissions after all. Dr. Anna Harper, Carbon Brief. Aug. 14, 2018.

Model scenarios that limit warming to 1.5C or 2C typically rely on large amounts of “negative emissions” to extract CO2 from the atmosphere and store it on land, underground or in the oceans. 

Bioenergy crops with carbon capture and storage (BECCS) is, perhaps, the most prominent of the various negative emissions techniques. There are many attractive features, since this technology would provide energy – thus reducing our need for fossil fuels – and remove CO2 from the atmosphere at the same time. 

However, the full carbon-cycle impacts of large-scale deployment of BECCS are not well studied. And, before now, no studies have looked at these impacts specifically for a scenario that could meet the 1.5C target. 

In our new study, published in Nature Communications, my colleagues and I find that expansion of bioenergy in order to meet the 1.5C limit could cause net losses in carbon from the land surface. Instead, we find that protecting and expanding forests could be more effective options for meeting the Paris Agreement.

Guest post: Six key policy challenges to achieving ‘negative emissions’ with BECCS. Dr. Clara Gough, Dr. Sarah Mander, Dr. Naomi Vaughan of Tyndall Centre for Climate Change Research, via Carbon Brief. Aug. 28, 2018.

scientific journal article here:

Challenges to the use of BECCS as a keystone technology in pursuit of 1.5⁰C. Dr. Gough et al, Journal of Global Sustainability. 2018.

Non-technical summaryBiomass energy with carbon capture and storage (BECCS) is represented in many integrated assessment models as a keystone technology in delivering the Paris Agreement on climate change. This paper explores six key challenges in relation to large scale BECCS deployment and considers ways to address these challenges. Research needs to consider how BECCS fits in the context of other mitigation approaches, how it can be accommodated within existing policy drivers and goals, identify where it fits within the wider socioeconomic landscape, and ensure that genuine net negative emissions can be delivered on a global scale.

Bioenergy carbon capture: climate snake oil or the 1.5-degree panacea? Paul Behrens, RenewEconomy. Oct. 23, 2018.

Carbon Capture’s Global Investment Would Have Been Better Spent On Wind & Solar. Michael Barnard, CleanTechnica. Apr. 21, 2019.

CCS is a rounding error in global warming mitigation. It’s hard to see how it could possibly be more. And it brings into stark relief the unfortunate reality that the IPCC depends far too much on carbon capture and sequestration approaches in terms of dealing with global warming.

Air Carbon Capture’s Scale Problem: 1.1 Astrodomes For A Ton Of CO2. Michael Barnard, CleanTechnica. Mar. 14, 2019.

Chevron’s Fig Leaf Part 1: Carbon Engineering Burns Natural Gas To Capture Carbon From The Air. Michael Barnard, CleanTechnica. Mar. 14, 2019.

The total CO2 load for the energy required for capture, processing, compression, storage, distribution and sequestration is almost certain to be greater than the CO2 removed from the atmosphere. 

This isn’t a one-article drive-by, but a five-piece assessment. 

• The first piece summarizes the technology and the challenges, and does a bottoms-up assessment to give context for what Carbon Engineering is actually doing. 
• The second piece steps through Carbon Engineering’s actual solution in detail. 
• The third piece returns to the insurmountable problem of scale and deals with the sheer volume of air that must be moved and the scale of machinery they have designed for the purpose. 
• The fourth article looks at the market for air carbon capture CO2 and assesses why three fossil fuel majors might be interested. 
• The final article addresses the key person behind this technology and the expert opinions of third parties such as Dr. Mark Jacobson of Stanford.

No path to climate stability without carbon dioxide removal. Walter Reid, Thomson Reuters. Aug. 24, 2018.

As hard as it is to reduce greenhouse gas emissions, an even bigger challenge lies ahead: We now need to remove much of what we’ve already added to the atmosphere. 

The math of climate change is simple and stark. To keep warming below 1.5 degrees Celsius, we can only emit another 600 Gigatons of carbon dioxide into the atmosphere. [ed: and this assumes that our carbon budget has been accurately calculated, which has been based on risk assessments that assume a 50% probability of not meeting our goals, and have been predicated on climate models that leave out factors that are not well-understood, including many amplifying/positive feedback effects; and, as we know, climate scientists have consistently and persistently been surprised by climate impacts and effects being observed much sooner than they had predicted.]

At current rates, this will take 14 years. [ed: as noted above, our true carbon budget, if it had been calculated accurately, including the impact of amplifying feedbacks, and excluding the assumption of future CDR, and allowing for only a tiny possibility (say 1%) of failure, has already likely been exhausted.] As a result, almost all scientific analyses assume large amounts of carbon dioxide begin to be removed from the atmosphere in the next decade, and by the second half of the century we must remove much more than we emit.

How much carbon dioxide are we talking about? Think of all the greenhouse gas emissions that will be emitted from all the cars, power plants, factories, and deforestation over the next 20 years. By 2100, we will need to take about that same amount out of the atmosphere. 

Here is the rub: We don’t know how to do carbon dioxide removal at that scale.

The one proven low-cost technology that we can turn to is the tree. Reforestation is, hands down, the best and most cost-effective approach to carbon dioxide removal. In addition to benefiting the climate, it also slows soil erosion, and often can increase water supplies, restore biodiversity, and provide economic benefits. But we have many competing uses for land – especially as the world population continues its growth towards eight billion people and incomes rise. Even the most promising reforestation scenarios don’t meet the full need for carbon removal. 

There are other promising but costlier approaches in early stages of development. “Direct Air Capture” relies on large fans blowing air through huge devices to capture carbon dioxide. Other strategies include weatherization of rocks and changing agricultural practices to store carbon in soils, which can also improve agricultural productivity. 

For carbon dioxide removal to grow at the pace needed, serious action must be taken now to create demand and to drive down the cost of new technologies. 

Luckily, some progress is already being made. Efforts to promote reforestation, for example, began in 2011 with the “Bonn Challenge,” which led to commitments from 47 national and subnational governments to restore nearly 400 million acres of land. Earlier this summer Sweden declared that it will be carbon neutral (with any emissions offset by carbon dioxide removal) by 2045 and carbon negative after that. 

But much more is needed. Meeting the goals of the Paris Climate Agreement will require gigaton-scale carbon dioxide removal. 

Just as actions to reduce carbon dioxide emissions were first catalyzed when governments and companies announced commitments to reduce emissions to the atmosphere, it is now time for leaders to announce specific, time-bound commitments to remove carbon dioxide from the atmosphere. These goals could be ratcheted up as technologies develop and costs drop. Investments in reforestation or enhanced soil carbon storage could be used to deliver on the commitments, as could procurement policies that create incentives to use carbon dioxide derived from direct air capture. Governments could also mandate that companies emitting greenhouse gases purchase “credits” that would pay for carbon dioxide removal with a technology like direct air capture. 

Since most of these strategies need further development quickly, there is also a vital role for mission investors and philanthropists to promote appropriate policies and identify ways to bring new technology to scale. 

While challenge is daunting, the opportunities are just as real. Markets already exist for carbon dioxide removal in the case of reforestation, and the market for carbon dioxide removal will grow dramatically in the coming decades. 

Next month, leaders from around the world will gather for the Global Climate Action Summit in San Francisco. The opportunity is ripe for governments and businesses to seize the leadership mantle by being among the first to commit to removing carbon dioxide from the atmosphere. Reducing emissions alone will not secure a stable climate and avoid the worst impacts of climate change. Now is the time to recognize that carbon dioxide removal is a central strategy in the fight against climate change.