Frequently Asked Questions on 1.5°C and Geoengineering

Answers to the most frequently asked questions about the 1,5°C target and the topic of geoengineering.

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FAQs: 1.5°C Target and Geoengineering


Why 1.5°C?

The small island states . With support from international civil society, these countries argued even then that global warming of 2°C would mean climate change impacts that would not be safe for their own survival and livelihoods. 1.5°C is the maximum temperature increase that would still allow many societies and ecosystems to adapt to the impacts of climate change.


Wenn Gletscher schmelzen und der Meeresspiegel ansteigt, verschwinden kleine Inseln zuerst.

1.5°C is also – and primarily – about climate justice: global emissions are increasing and the major emerging economies have now joined the developed countries as the world’s worst polluters. But the climate crisis was caused primarily by a few countries’ emissions: the vast majority of the world’s people made virtually no contribution yet will suffer most from its medium- and long-term effects. The climate crisis is thus the outcome of a major historical injustice.

Mitigating the effects of this crisis to the greatest possible extent is therefore the only way to move closer to global justice and protect people and ecosystems from the catastrophic impacts of climate change.

The adoption of the 1.5°C limit as a binding international climate target alongside the 2°C limit in the 2015 Paris Agreement was therefore a major achievement.

At the same meeting in Paris, the Conference of Parties to the United Nations Framework Convention on Climate Change commissioned the Intergovernmental Panel on Climate Change (IPCC) to provide a special report on this topic. The report is due to be published in early October and will look at the expected impacts of global warming of 1.5°C above pre-industrial levels and global emission reduction pathways towards 1.5°C.

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What’s the difference between 1.5°C and 2°C?

In the global warming context, the difference between 1.5°C and 2°C is the difference between life and death for millions of people and a matter of survival for numerous island states and ecosystems. A 2°C increase would mean longer heat waves, more extreme weather events and the irreversible destruction of all the world’s tropical coral reefs. Crop failures and water shortages – for example, in the Mediterranean region, including North Africa – would also increase significantly with this 0.5°C difference in warming. Sea levels would rise more quickly, putting coastal regions at greater risk of flooding.


Das Korallenbleichen, die Vorstufe zum Absterben ganzer Korallenriffe, wird das neue "Normal" in der Klimakrise werden.

Beyond 2°C, it is highly likely that key tipping points in the climate system would be reached, triggering a series of mutually reinforcing processes that would put the planet on a "Hothouse Earth" trajectory towards global average temperatures of 4-5°C above pre-industrial levels and a 10-60 metre increase in sea levels.

Limiting global warming to 1.5°C, by contrast, would substantially reduce the risks to humans and ecosystems and would allow many societies and ecosystems to adapt to the impacts of climate change. In regions particularly threatened by climate change, many of which are located in the Global South and have limited adaptive capacities and resources, 0.5°C makes a world of difference.

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Can we limit global warming to 1.5°C?

Our message is clear: limiting global warming to 1.5°C is possible and viable. If we commit to and actively shape the socio-ecological transformation that this requires, we can open up the prospect of a decent life for everyone and protect our global ecosystems at the same time.

But let’s be clear: it is impossible to maintain the profits of polluting industries and transnational corporations and to continue stoking the resource-guzzling growth machine without transgressing planetary boundaries and further eroding social justice and human rights.

We need transformative strategies that empower us to leave fossil fuels in the ground while promoting democratic participation, social justice and the conservation and restoration of already destroyed and degraded ecosystems. This means breaking away from existing power structures that hinder this transformation and making the positive shift towards a decent life for everyone. It is not naive or politically unrealistic to stand up and demand this change. On the contrary, given the multiple global crises we face, it is simply a radically realistic and necessary option.

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But don’t the climate scenarios say that 1.5°C is almost out of reach?

A number of very recent climate scenarios show that it is technically and economically possible to reduce emissions quickly enough to reach the 1.5°C target – without relying on high-risk technologies. All the technologies and strategies needed to achieve these emission reductions and to protect and restore natural sinks (forests, soils, oceans and peatlands) are already available. The difference – compared with the 2°C scenarios – is that they have to be implemented much more rapidly and sweepingly.

However, the political and economic assumptions underlying the vast majority of scenarios derived from so-called Integrated Assessment Models (IAMs) – the type of modelling used in climate economics – are not without their problems: they rely primarily on technological solutions and efficiency increases and face serious challenges describing more transformative social and economic change for the real world. Crucially, all the scenarios are based on continuous and unbroken economic growth, which by its very nature is accompanied by rising resource consumption and greenhouse gas emissions. This is why many of them rely on large-scale deployment of hypothetical geoengineering technologies to remove CO2 from the atmosphere.

A recent brief study by Kai Kuhnhenn from Konzeptwerk Neue Ökonomie shows that a radical rethink, both theoretical and practical, is urgently needed here. Less production and consumption in the Global North and among the wealthy elites in the Global South is essential if we are serious about meeting the 1.5°C target and finding socially just solutions to other socioecological crises such as biodiversity loss, resource depletion and ecosystem degradation.

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What are “negative emissions”? Is it true that we can’t manage without them?

The notion of “negative emissions” has mainly entered the climate policy debate and climate economic scenarios since the publication of the IPCC’s Fifth Assessment Report in 2013/2014. “Negative emissions” is meant to denote removing carbon dioxide from the atmosphere by technological means and storing it underground or in the oceans.

The majority of climate economic models proceed on the assumption that in the second half of the century, we will have technologies available that will allow us to suck vast quantities of CO2 from the atmosphere. Figures ranging from 400 to 1,200 gigatonnes are being bandied about – that’s 10 to 30 times greater than the entire world’s annual greenhouse gas emissions.


SaskPower, ein kanadisches Energieversorgungsunternehmen, dass erfolglos versuchte mit CCS (Carbon Capture and Storage) seine Kohleförderung grün zu waschen.

It is usually assumed that these “negative emissions” will be achieved through the deployment at scale of geoengineering techniques, primarily carbon dioxide removal (CDR) technologies. Sometimes called negative emission technologies (NETs), these techniques are highly problematical and most of them only exist on paper at present. The proposals on the table involve a high level of energy and resource consumption and would benefit the very sectors that bear most of the responsibility for the climate crisis, notably the fossil fuel industry and agribusiness.

Most of these proposed techniques are based on carbon capture and storage (CCS), another technology that is already sparking controversy. CCS was developed as a means of extracting even more coal, oil and gas from the ground – and this is precisely where it is in commercial use today.

Alongside proposals to use industrial-scale technology for underground storage of captured CO2, other strategies being mooted to achieve “negative emissions” rely on afforestation across vast areas. A combination of these two techniques is also under discussion: bioenergy and carbon capture and storage - BECCS. But not only do monoculture plantations rely on intensive use of fertilizers and pesticides and destroy biodiversity: with the prospect of more extreme weather events and warmer temperatures, it is uncertain whether the CO2 will in fact remain permanently sequestered. But that is essential if this approach is to produce the desired climate effect.

In sum, then, there is a great risk that potentially successful strategies to achieve “negative emissions” would ultimately provide an excuse to continue using fossil fuels and postpone any reform of our climate-damaging industrial agriculture. No surprise, then, that the major oil and gas corporations and, by extension, the petrochemical industry are some of the most powerful lobbyists for CCS and “negative emissions”.

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What is geoengineering?

Geoengineering – the large-scale manipulation of the Earth’s natural systems and the climate – is being popularized as a last-resort measure to address global warming and to weaken or suppress some of the symptoms of climate change.

The term refers to a group of technologies which still exist largely on paper and are intended to either remove greenhouse gases from the atmosphere or to cool the Earth by interfering with its radiation balance. These interventions would take place in the ocean, on land and in the Earth’s atmosphere (e.g. the stratosphere). While most of the proposed interventions rely on computer-simulated models, some small-scale commercial projects have already been initiated and outdoor testing is planned.

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What’s the problem with geoengineering?

Geoengineering means large-scale interventions in our global ecosystems, with potentially catastrophic consequences for humans and biodiversity. For any geoengineering technique to have an impact on the global climate, it will have to be deployed on a massive scale. Unintended consequences arising from deployment could therefore also be at massive scale and will likely be transboundary.

The proposed geoengineering techniques are unproven and have not been tested, so there are considerable uncertainties surrounding the question of whether they are ever likely to work. Were they to work, then only with massive risks and dangerous side-effects whose geographical distribution would be extremely uneven, reinforcing social injustice within and between states. In many cases, the real impacts of geoengineering would only be apparent once these technologies were in use. The negative impacts and attendant damage would, in many cases, be irreversible.

Geoengineering is also a perfect excuse for industrial and individual climate deniers and for governments seeking to avoid the political costs of carbon reductions. Investing in research and development of these technologies also diverts resources and funding away from urgently needed, effective, precautionary, ecological, just pathways for mitigation and adaptation to climate change.

For more information about the risks of geoengineering, please refer to our civil society briefing Climate change, smoke and mirrors (ETC Group & Heinrich Böll Foundation 2017).

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Who are the main players / key drivers of geoengineering?

For the past decade or so, a small but growing group of governments, corporations and scientists has been pushing for political acceptance of geoengineering. These proponents generally come from the world’s most powerful countries, which bear the main share of responsibility for the climate crisis. Some have their own commercial interests in developing these technologies.

Geoengineering is a fallacy: it encourages us to believe in a “technofix” for climate change. If greenhouse gases can be sucked out of the atmosphere later on, as carbon dioxide removal (CDR) technologies are intended to do, what’s the point of doing anything about our greenhouse gas emissions right here, right now? Geoengineering therefore serves the interests of the polluters, above all, the fossil fuel industry.

What’s more, if it is possible to artificially cool the planet and rein in global warming, then this technology becomes a very potent resource – not least in the hands of powerful states, which would attempt to adjust the global thermostat in whichever direction best served their strategic interests.

Although geoengineering is packaged as a silver bullet to the climate crisis, a closer look at the key players and their vested interests instantly reveals that its primary purpose is to shore up existing power structures and obstruct the socioecological transformation that we so urgently need.

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Why and how is the Heinrich Böll Foundation working on the topic of geoengineering and the 1.5°C limit?

After the Paris Agreement, which set the binding target of keeping the temperature rise to well below 2°C and possibly even 1.5°C compared to pre-industrial levels, the discourse has changed. Now, geoengineering is increasingly being advanced as an “essential” means to reach this goal as emissions continue to rise.

We are increasingly concerned about the tenor of this debate, largely because it adopts a highly selective approach to mitigation options, disregards possible alternatives and plays straight into the hands of those who profit from the status quo in our extractivist, growth-driven model.

We can offer other solutions to the climate crisis. We do not believe that countries, individuals or corporations should be able to seize control of our global thermostat.

At the Heinrich Böll Foundation, our work focuses primarily on the risks posed by geoengineering and on building awareness and capacities within international civil society. Monitoring planned experiments, projects, technologies, key players and their vested interests and conducting research on these topics are important elements of our work.

Together with civil society partners, we run the Geoengineering Monitor website, which publishes news and background information. Users can also subscribe to our regular newsletter.

In parallel, we are working with our civil society partners on genuine, socioecologically just solutions to the climate crisis. We have compiled this comprehensive information dossier with that in mind.

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What alternatives exist to keep global warming below 1.5°C?

There are numerous alternatives to risky “technofix” proposals such as geoengineering. These alternatives have been properly researched and tested and can be deployed immediately.

For a socially just and ecologically sustainable response to climate change, it is essential to challenge the economic thinking that has imprinted itself on mainstream climate policy. It is clear that we can only progress along the pathway to a 1.5˚C world of climate justice by initiating a genuine socioecological transformation, which must include a much more radical overhaul of our production and consumption patterns and our political and economic institutions.


Kleinbäuerliche Landwirtschaft ist ein sicherer Weg in die Zukunft und ernährt jetzt schon Milliarden von Menschen.

Radical emission reductions in combination with the restructuring of our societies towards a world characterized by ecological, social and genuinely sustainable production and consumption are the only way to limit the extent of the climate catastrophe. Specifically, this means restructuring our food production by switching from industrial agriculture towards an agroecological system. Our consumer society and waste management must evolve into a genuinely circular economy in which we consistently conserve and reuse resources. In addition, we must make use of near-natural climate solutions, which means conserving existing ecosystems that are in particular need of protection and function as natural carbon sinks. Among other things, we need a transformation of forest use, with near-natural management of forests and restrictions on monocultures.

Worldwide, the carbon sink potential of protecting and restoring natural ecosystems is estimated at 370 to 480 gigatonnes of CO2. This can make a major contribution to protecting not only the climate but also biodiversity and local communities’ livelihoods.

A recent study by Greenpeace (Forest Vision 2018) shows, with reference to Germany, that near-natural forest management would reduce the harvest volume by just 14% while allowing substantial quantities of CO2 – as much as 56 million tonnes a year – to be sequestered in German forests.

However, all of these measures will not be enough unless we finally tackle the climate problem at its root: we urgently need a swift and consistent phase-out of the production and use of fossil resources. This not only means the rapid demise of coal; there must also be a politically managed phase-out of oil and gas. If we are serious about keeping to the 1.5˚C limit, we must abandon our continual efforts to develop new fossil resources and, instead, devise and implement action plans to close down existing production infrastructures as soon as possible. This requires political majorities and a thick skin against the powerful corporate lobby.

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Are there any international rules on geoengineering?

The United Nations Convention on Biological Diversity (CBD) has acted as the multilateral forum for critical discussion of geoengineering for more than a decade and has taken a number of ground-breaking decisions.

In 2008, the CBD called for a moratorium on ocean fertilization, taking into account a call for “utmost caution” from the London Convention (Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter), whose parties had previously discussed this geoengineering technique and concluded that it was harmful to the marine environment.


In 2010, the CBD broadened its de facto moratorium to include all climate-related geoengineering activities. Here, the CBD relies primarily on the precautionary principle as a fundamental pillar of international environmental law. The CBD has also produced a number of research reports, drawing attention to the major risks and in some cases catastrophic effects of various geoengineering techniques on biodiversity and global ecosystems.

The parties to the London Protocol of the London Convention (mentioned above) consider that marine geoengineering falls within their purview: since 2013, ocean fertilization has been listed as prohibited in an annex to the Protocol, with an option to add other marine geoengineering activities to the list as well.

At the fourth UN Environmental Assembly, UNEA-4, which took place in Nairobi in March 2019, a push for further steps to establish regulation of geoengineering technologies at UN level has failed due to the massive opposition of some high-emitting, oil-producing countries. The urgent need to regulate geoeningineering internationally remains in place. Here is an evaluation of the UNEA-4 negotiations.

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What does international civil society say about geoengineering?

Key international civil society organizations are increasingly adopting a visibly critical position on geoengineering. It is becoming more and more apparent that geoengineering mainly serves the interests of the climate polluters and climate change deniers, particularly the fossil fuel industry. The opposition to geoengineering as a technofix for climate change thus ties in with the numerous civil society campaigns for social justice, human rights and the protection of the climate and the environment, and these links will become even stronger in future.

In international institutions and multilateral processes such as the United Nations Framework Convention on Climate Change (UNFCCC), the Intergovernmental Panel on Climate Change (IPCC) and the Convention on Biological Diversity (CBD), too, international civil society networks are campaigning against the introduction of geoengineering and its “normalization” in these forums.


Particular resistance is mobilizing against the outdoor testing due to take place on the American continent, not least from indigenous communities whose territories are the intended launchpad for these experiments. In the past, efforts to stop planned experiments from taking place have been successful. For an overview of geoengineering experiments and research projects past, present and planned, please refer to our interactive geoengineering world map.

Hands Off Mother Earth, a global campaign based on the HOME Manifesto, came into existence back in 2010. The HOME campaign was initiated at the 2010 World People’s Conference on Climate Change and the Rights of Mother Earth in Cochabamba, Bolivia, by a coalition of international civil society groups, indigenous peoples’ organizations and social movements.

The HOME campaign is now being relaunched. News about the campaign and background information on geoengineering experiments, technologies, the stakeholders involved and their vested interests are available here:

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