Fixing the Climate? How Geoengineering Threatens to Undermine the SDGs and Climate Justice

Author: Linda Schneider


Over the past two decades, policy-makers and economists have often talked about climate policy in terms of the social cost of carbon. The social cost of carbon is the monetary cost that future generations incur due to decreased economic growth caused by the emission of one tonne of CO2 today. Many economists and policy-makers have suggested using the social cost of carbon as a just means of setting a carbon tax. After all, if my emission of 1 tonne of CO2 incurs a cost of $50 to future generations, it seems fair that I should be taxed at $50 per tonne.

Estimates of the social cost of carbon vary widely, and it has a number of practical and philosophical problems. Practically, estimates of the social cost of carbon range over about 7 orders of magnitude, which makes using it in policy challenging. Philosophically, imagine that climate change leads to a famine that kills a few million people. The famine would be a profound social cost of climate change, but might have little impact on the global economy, and thus would not be counted in estimates of the social cost of carbon. Thus, another metric is needed.

Here, we suggest that the costs of atmospheric removal of CO2 could be a better metric for climate change policy. There are a number of technologies that remove CO2 from the atmosphere (called carbon dioxide removal or negative emissions technologies) but, like most other pollution control systems, they require financial inputs. We propose that the per tonne subsidy needed to capture and store CO2 from the atmosphere would be a more appropriate metric than the social cost of carbon because it would allow for a climate policy that is based on an observable cost and could be directly linked to the physical removal of CO2 from the atmosphere. In the proposed policy, emitters would pay a tax, based on the marginal cost of CO2 removal and the proceeds from that tax would be used to remove an equivalent amount of CO2 from the atmosphere.

While more research on the costs of negative emissions technologies is needed, early estimates suggest that a negative emissions-based system would be higher than the social costs of carbon preferred by policy-makers but roughly similar to the average social cost of carbon derived from academic estimates. 


In the early 21st century, the world faces multiple existential challenges and global crises – among them is the climate crisis, but equally dramatic – and intimately related – are the escalating loss of biodiversity and natural ecosystems, growing social inequality, human rights violations, poverty and hunger, concentration of wealth, power and control, and authoritarian state tendencies. 

The international community adopted the Sustainable Development Goals (SDGs) in 2015, which aim to, among other goals, end poverty, hunger, reduce inequality, protect life on land and achieve gender equality, peace and justice. The framework of climate justice, promoted by grassroots social movements around the world, highlights the crucial role of global environmental and social justice in addressing the climate crisis – rather than treating it as a purely technical problem.

Both the SDGs at the international-institutional level, and the call for climate justice from the grassroots and social movement level, serve as a framework for addressing the interrelated crises of the 21st century in an integrated fashion. 

In the wake of the Paris Agreement, however, and with global emissions still on the rise, one set of alleged responses to the climate crisis is pushing to the front in international climate policy discussions. 

Geoengineering—large-scale technological interventions in the Earth’s natural processes and ecosystems are being promoted to counteract or delay some of the symptoms of climate change.

In the present paper I argue that geoengineering – both large-scale Carbon Dioxide Removal and Solar Radiation Management, the two main categories of climate geoengineering – are fundamentally at odds with the SDGs and with the strive for climate justice. In fact, they threaten to undermine the achievement of SDGs and climate justice for three broad reasons that I develop in the present article.

First, geoengineering is bound to exacerbate many of the other socio-ecological and socio-economic global crises we are facing. I show this for several of the proposed geoengineering technologies on land, in the oceans and in the atmosphere and how they would detrimentally affect the SDGs and the strive for climate justice. 

Furthermore, I elaborate on how geoengineering would deepen societal dependence on large-scale technological systems and on technocratic elites controlling them. One of the effects of such technological dominance in trying to solve global problems is that alternative and more holistic forms of knowledge, expertise, and practices that allow for complexity, diversity and resilience are excluded. By the same token, concerns over ecological and social risks and rights violations are pushed aside. Such one-dimensional large-scale technological fixes for the climate crisis run counter the aim of achieving global ecological and social justice and redressing past unjustness.

Finally, rather than overcoming the economic and political power structures that have caused the climate crisis in the first place, they create new spaces for profit and power for new and old economic elites and thereby serve to uphold the current status quo. As such, it is fundamentally incompatible with the notion of climate justice and will make it impossible to achieve the SDGs.

Southern Ocean Iron Fertilization: An Argument Against Commercialization but for Continued Research Amidst Lingering Uncertainty

Author: Tyler Rohr



United States Department of Energy, Water Power Technologies Office, Washington D.C., USA

Past (but at time of original writing):

Massachusetts Institute of Technology, Department of Earth and Planetary Sciences, Cambridge, Massachusetts, USA 

Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, Massachusetts, USA 


With substantive global action on climate change mitigation sputtering, some have begun to look at geoengineering as a possible alternative. Geoengineering is any deliberate, large-scale, manipulation of natural processes to affect the climate system, ostensibly to curb the effects of global warming. One such strategy is Southern Ocean Iron Fertilization, which seeks to remove carbon dioxide from the atmosphere by fertilizing the growth of marine phytoplankton in the ocean. Phytoplankton are microscopic plants that, like land-based plants, convert carbon dioxide into oxygen through photosynthesis. Together, marine phytoplankton produce half the oxygen we breathe. Further, when they die, they can sink out of the surface ocean and trap carbon in the deep ocean for hundreds of years. The goal of Southern Ocean Iron Fertilization is to increase this oceanic drawdown of carbon dioxide by stimulating marine phytoplankton growth by adding iron, an important nutrient, to large parts of the ocean where there is currently not enough iron to support growth. The notion of simply dumping dissolved iron into the ocean is seductively cheap compared to other forms of climate action, but it is not yet clear that fertilizing the Southern Ocean could actually create a sustainable carbon sink. A comprehensive review of the literature reveals that iron fertilization will almost certainly increase phytoplankton growth in the surface ocean, but it is much less clear how much of that carbon will sink out of the surface ocean and stay there versus how much will quickly end up back in the atmosphere. Given the lingering scientific uncertainty, it would be ill-advised to commercialize iron fertilization under emerging carbon offset markets. Offset markets allow companies or individuals to buy and sell activity that offsets their own emissions, either by sequestering carbon or reducing emissions elsewhere. Compliance offset markets, such as many proposed cap-and-trade frameworks, are carefully regulated to ensure activity is legitimate and appropriately compensated; however, voluntary offset markets, powered predominately by a sense of social responsibility, are not necessarily well regulated. Commercializing Southern Ocean Iron Fertilization on compliance offset markets is unlikely, and unadvisable, due to concerns over the strategy’s fundamental feasibility, the potential for unpredictable side-effects, and the inability to establish reliable baselines or accurately measure the full effects of fertilization, making it impossible to provide fair and consistent compensation. Never-the-less, recent history shows that fertilization activity on unregulated voluntary offset markets motivated by a the promise of an easy fix can, and will continue to, emerge. Continued research is needed to constrain the public perception and clarify the reality of an iron bullet.


Figure Caption: Idealized schematic of carbon cycling and the biological  in a natural High Nutrient Low Chlorophyll Region (HNLC) and an iron fertilized HLNC. White arrows represent carbon transport. The addition of iron may dramatically increase surface biomass but only a small fraction of that is additional sequestered in the deep ocean or the sea floor.


Carbon Removal Corporate Action Tracker

The terms carbon neutral, carbon negative, and net-zero, long familiar to scientists and environmentalists, are beginning to pop up in corporate press releases. Recently, corporations from sectors ranging from aviation to finance to retail have made commitments to an emerging form of climate action called carbon removal. Carbon removal, also known as carbon dioxide removal or negative emissions technologies, has been receiving increased attention from corporations since the landmark IPCC Special Report on Global Warming of 1.5°C identified it as crucial to limiting global warming below 1.5°C and warned that the world can no longer hit this target without it. 

As a response to the growing number of corporate climate pledges, the Institute for Carbon Removal Law and Policy at American University has created an Action Tracker outlining some interesting moves regarding climate action in aviation, energy, heavy industry, and other harder-to-abate sector, as well as large financial actors and retail companies. The Action Tracker includes companies that have made climate pledges that entail some use of large scale carbon removal. Some of these  companies have pledged to become carbon neutral or reach net-zero emissions, while others have plans to become carbon-negative, meaning that they will be removing more carbon dioxide from the atmosphere than they emit. Companies with carbon negative pledges include Ikea, Microsoft, Starbucks, AstraZeneca, and Horizon Organics. 

Also included in the Action Tracker are companies in harder-to-abate sectors such as aviation, steel, and cement that are making carbon neutral commitments without any apparent commitment to carbon removal. Given how challenging it is to decarbonize these sectors, any pledge to carbon neutrality in those sectors invites questions about how a particular company aims to become carbon neutral and what role, if any, carbon removal plays in each company’s plan. 

A few companies in the retail sector, such as Horizon Organics and Starbucks, have independently pledged to be carbon-negative (confusingly called “carbon positive” in a few cases) using carbon removal. Many more retail companies have committed to becoming net-zero as part of the Certified B Corporations Net-Zero by 2030 pledge but lack specific plans for fulfilling their commitment.

Finally, the Action Tracker includes actors in the financial sector, such as Barclays and Harvard’s endowment, that have pledged to make their investments carbon neutral, meaning that the net carbon footprint of the activities they finance will be zero. These plans are likely to take different forms. Harvard, for instance, has indicated that its endowment managers will finance carbon removal to balance investments in greenhouse gas-emitting activities, whereas Barclays has aligned itself with the International Energy Agency’s Sustainable Development Scenario, which explicitly excludes carbon removal. Given the importance of finance to reaching net-zero or net-negative emissions globally, the Institute finds these sorts of pledges worth tracking.

The Action Tracker is an ever-evolving resource and will be updated as new commitments are released, current pledges become more detailed, and mechanisms to achieve outlined commitments are specified.

Please email if you have other interesting examples of carbon negative or carbon-neutral-with-carbon-removal pledges.