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Global climate targets can only be achieved through negative emissions?

Simon Goess's picture
Co-founder, cr.hub

Simon Göß studied Environmental and Resource Management (B. Sc.) at the Brandenburg University of Technology Cottbus and Sustainable Energy Technology (M. Sc. Honours) at the Delft University of...

  • Member since 2018
  • 117 items added with 161,920 views
  • Aug 18, 2021

Originally published here and co-authored by Hendrik Schuldt, cr.hub


Emissions reductions alone are not enough to achieve ambitious climate targets. That is why there is more and more talk of negative emissions and carbon removal as possible further climate protection measures. In this guest post, Simon Göß from cr.hub explains what the terms negative emissions and carbon removal mean. Following the analysis of five global scenarios with regard to negative emissions, Simon Göß explains the policy implications and highlights some private sector initiatives.

If we look back on the past year, the coronavirus pandemic in particular will be remembered. In the public perception, the pandemic and its effects seem to have displaced climate change as the greatest challenge.

CO2 emissions are rising again

Global energy-related CO 2 emissions fell by around 6 percent in 2020 compared to 2019. In particular, due to the lockdown restrictions and the economic crisis, energy-related emissions fell by more than 2 gigatons (Gt) to a good 30 Gt in 2020. Nobody expected a decrease in emissions at the beginning of 2020. In fact, some countries, such as Germany, only achieved their climate goals because of the coronavirus crisis. Otherwise emissions would hardly have fallen as much.

However, a look at current figures and statistics reveals that energy-related CO 2 emissions have been back to the previous year's level since December 2020 and could only be 1 percent below the pre-corona emissions of 2019 in 2021 .

Net zero terminology

Even after strong reductions in emissions in the coming decades in all economic sectors through the expansion of renewable energies, the increase in energy efficiency and the reduction in energy consumption, residual emissions may still occur. Greenhouse gases must then be actively removed from the atmosphere in order to further reduce emissions in the balance sheet.

A country or organization achieves net zero emissions or carbon neutrality when the amount of emissions removed equals that of the remaining emissions. This means that on balance sheet no more greenhouse gases get into the atmosphere. The amounts removed from the atmosphere are also known as negative emissions. There are various technologies and solutions for negative emissions, most of which today focus on removing CO 2 - the main greenhouse gas - from the atmosphere. Hence these solutions are also known as carbon removal.

However, a distinction must be made between carbon removal, carbon capture and storage (CCS) and carbon capture and use (carbon capture and use or utilization: CCU). CCS prevents fossil fuel emissions from getting into the atmosphere in the first place. However, CCS does not remove any emissions from the atmosphere. As such, it is not a negative emissions technology or solution. CCU refers to the use of captured CO 2 in the manufacture of fuels or other products. Whether or not a specific CCU process and product actually leads to negative emissions depends on where the captured CO 2 comes fromand how long the life of the product in question is. Figure 1 (source: cr.hub ) explains the difference between carbon removal, CCU and CCS.

Differences between carbon removal, CCU and CCS (source: cr.hub).

Figure 1: Differences between carbon removal, CCU and CCS (source: cr.hub).

The right terminology is therefore extremely important if credible net-zero targets or climate strategies are to be set and actually achieved. Likewise, these terms must be clearly defined when evaluating net zero targets or scenarios.

Assessment of global scenarios

Due to the large number of global climate scenarios, we will only focus on a few here. Figure 2 (source: cr.hub ) shows an exemplary emission path for achieving the 1.5 ° C target. Traditional technologies for reducing emissions, such as renewable energies and energy efficiency, as well as carbon removal are presented separately here. The figure is based on the data of the climate scenarios of the Network for Greening the Financial System (NGFS) for central banks and supervisory authorities.

Necessary order of magnitude for carbon removal for an emission path for 1.5 ° C (source: cr.hub).

Figure 2: Necessary order of magnitude for carbon removal for an emission path for 1.5 ° C (source: cr.hub).

In order to keep the scope of this analysis as broad as possible, and not just look in one direction, we consider scenarios and calculations from five different organizations:

The Net Zero by 2050 Roadmap of the International Energy Agency (IEA), the consultation paper Reaching climate objectives: the role of carbon dioxide removals of the Energy Transitions Commission (ETC), the Special report: Global warming of 1.5 ° C of the Intergovernmental Panel on Climate Change (IPCC) and McKinsey’s Climate math: What a 1.5-degree pathway would take and the NGFS climate scenarios . Some information on the required negative emissions was taken from the report The case for Negative Emissions by the Coalition for Negative Emissionsdistilled. We at cr.hub are aware that this selection only represents part of the available literature.

All the scenarios considered aim to keep the temperature rise below 1.5 ° C compared to the pre-industrial level. Nevertheless, the comparison is difficult, as there are different assumptions about which part of the economy and thus which emissions flow into the scenario or what exactly counts as negative emissions and what is not. In addition, the probabilities of maintaining a certain temperature threshold differ between the scenarios and studies.

This means that the assumptions for the modeling and scenarios for Net Zero should be shown as clearly as possible in order to be able to classify and understand the results as best as possible.

Rapid expansion of carbon removal required

What do the scenarios have in common?

Emission reductions through the widespread use of renewable energies and the electrification of large parts of the industrial and transport sector are included in all scenarios. Nevertheless, all scenarios agree that there is a considerable need for negative emissions in the gigatonnes range (Gt CO 2 e) in order to achieve the 1.5 ° C climate target, as Figure 3 (source: cr.hub ) shows ( Data sources: Coalition for Negative Emissions , IEA , ETC ).

Necessary negative emissions for 1.5 ° C climate targets according to various scenarios in Gt CO2e / y (source: cr.hub).

Figure 3: Necessary negative emissions for 1.5 ° C climate targets according to various scenarios in Gt CO2e / y (source: cr.hub).

In addition, technologies for removing CO 2 from the atmosphere must already be available on a large scale by this decade and reach the Gt level from a very low level today by around 2030. Given today's greenhouse gas emissions of almost 50 Gt per year, the level of negative emissions according to the five scenarios in 2050 will amount to around 5 to 20 percent of current global emissions. This is a clear indication that negative emission technologies are not marginal applications on the way to net zero emissions, but an important prerequisite for dealing with the remaining emissions in the sectors that are difficult to decarbonise.

Where do the numbers disagree and why?

At the upper end are the high numbers of the ETC and the IPCC with up to 10 Gt of negative emissions by the middle of the century, while the IEA's Net Zero Roadmap is at the lower end with an expected demand of 2.4 Gt by 2050. The IEA provides for a total separation of 7.6 Gt including CCS and CCU. However, originally negative emissions only make up about 30 percent of them. The scenario assumptions of the IEA do not include any new investments in coal-fired power plants without CCS and in new oil and gas fields or coal mines from 2021, as well as the phase-out of coal-fired power without CCS worldwide by 2030. The level of ambition for classic emission reductions is very high compared to the other four scenarios high.

If a medium path as in the NGFS or McKinsey scenarios is taken seriously, then negative emission technologies (NETs) will have to be scaled up quickly in the coming decades in order to get into the Gt range. According to the report The case for Negative Emissions , a scaling of at least 50 times compared to today's level is required. Especially since the current pipeline of carbon removal projects including nature-based solutions, bioenergy with CCS and direct air capture is only around 0.15 Gt by 2025 (source: Coalition for Negative Emissions ).

An example of how increased climate ambitions require negative emissions is the case of the new German Climate Protection Act. We will also publish an analysis on this soon.

Implications for Politics

Achieving net zero emissions by 2050 while limiting global temperatures to below 1.5 ° C requires unprecedented efforts and seems unlikely to be achieved without large-scale exploitation of negative emissions. In fact, many 2-degree paths are dependent on negative emissions, albeit at a lower level. This is especially true if international climate protection measures remain at today's level and are not tightened (source: Minx, et al ., Fuss et al. ).

Political decision-makers now have to ask themselves the following questions:

  • What options are there for integrating carbon removal into climate policy?
  • What are the interactions between emission reduction policies and negative emissions policies?
  • How can NETs be scaled and innovations in this sector promoted?
  • Where should investments and resources go?
  • How can Carbon Removal Credits be implemented and integrated into emissions trading systems such as the EU ETS?

At the EU level, the first initiatives to support carbon removal, such as the Negative Emissions Platform, are on the way. The European Commission wants to propose a robust certification system for carbon removal by 2023. In addition, research and innovation on carbon removal and CCS are funded by Horizon 2020 and the successor program Horizon Europe. The Innovation Fund, which receives 10 billion euros from the revenues of the EU emissions trading system, also includes funding for commercial demonstration projects for low-carbon technologies such as CCS and NETs.

Carbon removal solutions need support

All solutions are needed to combat climate change, from emission savings and reductions to the removal of greenhouse gases from the atmosphere. For a process or technology to be considered carbon removal, four conditions must be met:

  1. CO 2 is physically removed from the atmosphere.
  2. The extracted CO 2 is stored as permanently outside the atmosphere as possible.
  3. Emissions generated during the process are taken into account in the overall balance.
  4. Emissions generated during the process are lower than the negative emissions produced.

However, some of the scaling and application of the various nature-based and technological solutions for carbon removal are still in their infancy. Figure 4 (source: cr.hub ) shows selected negative emission technologies .

Selected negative emission technologies (source: cr.hub).

Figure 4: Selected negative emission technologies (source: cr.hub).

How is the industry preparing?

For the private sector, especially for corporations and companies that set themselves climate goals and strive for their own net zero goals, the complexity of the discussion increases. Internationally recognized standards for setting climate targets and the role of mitigation and removal, such as the Net Zero Standard of the Science Based Targets Initiative, will be of great importance (source: SBTi ).

Industry-led voluntary carbon market initiatives such as the Task Force for Scaling Voluntary Carbon Markets (TSVCM) are also needed to drive demand and market growth. Cr.hub is part of the TSVCM consultation group, which recently published its report on the second phase of the implementation of a voluntary global CO 2-Market has published. In order to achieve real benefits for the climate, however, it is important that only high-quality certificates for abatement and carbon removal are taken into account in both private and voluntary, as well as government initiatives. The discussion about what constitutes high-quality carbon removal credits and solutions is leading too far here. However, Cr.hub will shed light on this topic in further articles.

In summary, it is clear that many actors and organizations take carbon removal and negative emissions seriously in their climate and energy scenarios as a potential instrument for achieving net zero targets. Furthermore, NETs have to be scaled heavily in order to achieve the necessary size.

Bob Meinetz's picture
Bob Meinetz on Aug 18, 2021

"For the private sector, especially for corporations and companies that set themselves climate goals and strive for their own net zero goals, the complexity of the discussion increases."

Simon, for private entities achieving their own net zero goals is not a priority. Their #1 priority is remaining profitable, and there is no public goal they will permit to stand in the way of that objective.

The idea public pressure will induce private entities to reduce their emissions, or even sequester them underground, has no historical basis - especially when they can announce goals for decades in the future, and an unquestioning public accepts them as genuine. Not one has ever achieved such a goal, for the simple reason there's no financial incentive to do so.

"In summary, it is clear that many actors and organizations take carbon removal and negative emissions seriously..." 

This may come as a shock, but they're lying. And the longer we continue to blindly accept these promises at face value, the deeper in carbon debt we will continue to sink.

Rick Engebretson's picture
Rick Engebretson on Aug 23, 2021

Bob, when I was a kid over 60 years ago I knew carbon soil sequestration was "profitable." Neighbors raked their yard of all dead grass and leaves and I took batches for our yard. Midsummer heat came and when neighbors had to water, my grass remained green. Today we use wood chips and hay for a small farm. Every farmer knows soil carbon is essential for water, nutrients, and root health.

The problem is farmers were replaced by "agribusiness." I don't know how to fix that problem.

There are a frightening number of people in the world today hoping to live off dry, unproductive soil.

Bob Meinetz's picture
Bob Meinetz on Aug 23, 2021

Rick, I agree with you. I don't believe agribusiness is ultimately profitable for the planet, either. I do believe unnecessary consumption of its limited resources is not leading to some future disaster, but a disaster already unfolding.

In 2021 every farmer also knows fuel is essential to run a tractor, and that he would never consider returning to a horse-drawn plow to farm his land. What were once luxuries have become necessities. That's progress, and we're all better for it - until we collectively bump up against the limits of what the Earth has to offer. Then, we're forced to accept that many of the things we now consider necessities have once again become luxuries.

Whether humans will ever be able to unlink success from consumption, in my view, is the fundamental question of whether our race can survive.

Rick Engebretson's picture
Rick Engebretson on Aug 24, 2021

And I agree with you, "a disaster already unfolding."

I think your emphasis on electric generation is important (if often oversimplified). Remember, horses needed feeding every day, using cropland now used for people. A fuel tractor only uses fuel when rarely used. But I think we are also now seeing electrification of farm tools.

Let's hope we can continue innovation freedom.

Julian Jackson's picture
Julian Jackson on Aug 18, 2021

Thanks for the post. It would have been nice to have an explanation of each of the technologies in fig. 4,and how feasible each is.

Ed Reid's picture
Ed Reid on Aug 20, 2021

...both technically and economically.

Jim Stack's picture
Jim Stack on Aug 20, 2021

I agree with Bob more and more. If these is not a profit in it even a big environmentalist will not do it or support it. Yet I do think as we use more Renewable Energy the environment will clean itself. Trees and other of natures greatest creation have a great way of cleaning itself. Also since Renewable Energy does provide a profit we can make progress just not as fast as I would like  

Bob Meinetz's picture
Bob Meinetz on Aug 20, 2021

Jim, though we disagree on what the new energy landscape should look like, we do indeed have a common enemy.

"If these is not a profit in it even a big environmentalist will not do it or support it."

Many environmentalists are surprised to learn:

  • Sierra Club has accepted over $25 million from natural gas producer Chesapeake Energy
  • The two highest-ranking members of Board of Trustees of Natural Resources Defense Council - its Chair and Vice Chair - and one of NRDC’s single largest donors are major investors in natural gas
  • Oil and gas investor Julian Robertson has donated $60 million to Environmental Defense Fund, and sits on EDF’s governing board

You will never, ever see gas companies investing in nuclear energy. Why? It's the only source of energy capable of putting them out of business.


Simon Goess's picture
Simon Goess on Aug 24, 2021

Dear all,

I see that the article sparked quite some discussions.

@Bob: I share your concern about private entities mainly caring about profit. However, if they are not all blinded by short-term profits and if their shareholdes (esp. large financial investors) notice (and they already do) that there might be no more profits due to accelerating climate change in the coming decades, there will be incentives to go forward in getting to net zero.

Secondly, those Gt numbers that need to be taken out of the atmopshere are based on the latest science of climate change in addition to sharp emissin reductions. Granted it will be very hard to achieve those numbers. As long as there is no stronger intervention from governments on the price of carbon and other GHG emissions it will be unlikely to achieve those numbers. But I see at least in the EU that stronger intervention are on the horizon.

@Julien and Edward: I will come back to the different solutions and their technological and economic parameters.

@Jim: Some of the solutions for carbon removal are actually very cost-effective and certainly cheaper than the cost of carbon emissions in some carbon markets. Especially the nature-based solutions also harbor many additional side benefits, such as increased biodiversity, water buffer zones, agricultural resilience, etc.

And on the other hand: If it is more expensive to emit a ton of CO2 due to rising CO2-prices due to regulation (as we see in the EU right now with 55-60 EUR/ton) or if it too expensive to reduce CO2-emissions because you have to change an entire industrial site (cement, steel, chemical industry) it might be cheaper to take the CO2 out of the atmopshere.

All of the above of course requires long-term thinking and stronger state intervention, which might be a more tricky thing in the US than in the EU.


Simon Goess's picture
Thank Simon for the Post!
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