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BP206G Smoke in a forest, sun comes slowly through the fume, 2010
Sunshine through trees, 2010. Credit: Jochen Tack / Alamy Stock Photo.
11 October 2017 17:17

Geoengineering: Scientists in Berlin debate radical ways to reverse global warming

Daisy Dunne


Daisy Dunne

11.10.2017 | 5:17pm
GeoengineeringGeoengineering: Scientists in Berlin debate radical ways to reverse global warming

Research scientists, policymakers and ethicists gathered in Berlin this week to discuss the emerging field of “climate engineering” and what it could mean for the planet.

Climate engineering, also known as geoengineering, is a term used to describe an array of technologies – many of which remain hypothetical – for altering the global climate in order to lessen the effects of climate change.

The four-day conference has been organised by the Institute for Advanced Sustainability Studies (IASS) in Potsdam, Germany, and includes speakers and participants from across the world, including Japan, Jamaica, the US and India.


Tuesday’s proceedings kicked off with talks aimed at bringing the audience up to speed with the latest research into the two main categories of geoengineering technologies: carbon dioxide removal (CDR) and solar radiation management (SRM).

First up was Dr Naomi Vaughan, a researcher from the Tyndall Centre for Climate Change Research at the University of East Anglia. Her talk touched on recent research into a variety of CDR technologies, including biomass energy carbon capture and storage (BECCS), soil carbon sequestration and reforestation projects, and how important these techniques could be to meeting the goals of the Paris Agreement. She told the conference:

“The Paris goals of 2C and 1.5C require CO2 removal and at the moment most of our future scenarios of the global energy system and land use assume it’s being delivered by biomass energy carbon capture and storage. But the feasibility of this BECCS is difficult to assess – especially at this scale – because it’s highly interconnected with existing social systems around food, energy, water and biodiversity.”

(Carbon Brief has previously published articles on the emergence and importance of BECCS.)

Following on was Dr Ben Kravitz, a researcher at Pacific Northwest National Laboratory in Washington. His talk focused on the recent progress of SRM, a term describing techniques that aim to reflect incoming sunlight in order to cool the Earth’s surface.

Hypothetical SRM technologies include brightening clouds or releasing solar aerosols into the stratosphere to reflect sunlight.

Kravitz claimed that modelling work simulating the impact of such technologies shows that they could theoretically reduce the amount of warming and may even lower the incidence of some extreme weather events.

However, modelling can only take us so far in our understanding of SRMs, he added, stressing the need for outdoor observational studies of such technologies to begin. “If SRMs are unworkable, we need to know now,” he told the audience.

(Carbon Brief has previously reported on the potential benefits and worries of SRM technologies).

On the sidelines of the conference, Kravitz spoke to Carbon Brief about the potential challenges in making SRM techniques a reality. In the clip below, Kravitz says that the primary challenge of SRM is that it exists solely “in the modelling world”, which makes it difficult to understand its true risks and effects.

These talks were followed by short introductions by speakers from a range of research projects and non-governmental organisations. Among the speakers were Dr Phil Williamson, director of the UK Greenhouse Gas Removal Research Programme, and Janos Pasztor, former senior advisor to the UN Secretary-General on climate change.


Following the morning plenary, delegates were invited to join a range of sessions, which were held under the Chatham House rule. The sessions explored everything from how to govern emerging geoengineering to the role that religious leaders could play in engaging the public on climate engineering.

Sessions were also conducted by those who are strongly opposed to geoengineering, including Linda Schneider from the Heinrich Böll Foundation.

Advertising a session called, “A change of course: Radical emission reduction pathways to stay under 1.5C”, she said:

“Climate change is not an engineering problem. There are many viable alternatives to bring our societies on a pathway towards 1.5C without geoengineering. A technofix mentality and powerful vested interests prevent us from implementing them.”

Midway through the sessions, journalists were invited to attended a press conference.

Leading the proceedings was Mark Lawrence, director of the Institute for Advanced Sustainability Studies (IASS). He told the conference:

“It will be very difficult to achieve the Paris Agreement targets without resorting to some form of climate engineering. So we urgently need an open and critical debate on the different forms and consequences of such interventions in the climate system.”

Also in attendance were Lili Fuhr, from the Heinrich Böll Foundation, Prof David Keith, from Harvard University and Pablo Suarez, from the Red Cross Red Crescent Climate Centre in the Netherlands.

A full write-up of the press conference is available here.

As sessions resumed in the afternoon, Carbon Brief spoke to Dr Rob Bellamy, from the Institute for Science, Innovation and Society at the University of Oxford.

Bellamy had been speaking at a session called “Public Engagement and Climate Engineering: Whither and How?” In the clip below, he describes how past efforts to engage the public in climate engineering may have backfired.

Evening talk

In the evening, a public debate was held with a panel including Keith, Fuhr, Suarez, Pasztor, alongside Oliver Geden, from the German Institute for International and Security Affairs, H Elizabeth Thompson, former assistant secretary-general of the United Nations, and Oliver Morton, journalist and author of The Planet Remade.

During the discussion, the panel fiercely debated the case for research into implementing geoengineering strategies, with Keith arguing for more research into the potential effects of geoengineering. He pointed out that, if greenhouse gas emissions were stopped today, there is still a small chance that the world could experience substantial global warming by the end of the century. Therefore, negative emissions technologies could be vital to tackling climate change, he said.

However, others on the panel argued against the progression of geoengineering research, asking the audience to think about the uncertain risks proposed by such experiments. Fuhr said it was wrong to talk of a “binary choice” between geoengineering and a climate disaster, while Thompson asked how geoengineering would help those suffering from the impacts of climate change in the Caribbean.


Wednesday proceedings began with a morning of diverse sessions on the wider implications of climate engineering.

In a session titled, “Trumped! A new politics of climate engineering?”, speakers from as far as Japan, Brazil and Nigeria were asked to comment on how the rise of populism in many countries could influence future implementation of geoengineering.

Topics of conversation ranged from how accepting populist world leaders could be of geoengineering, to whether they can be trusted with the “access to the global thermostat” which could come with new technologies.

“We need to change the [economic] system, not the planet,” one speaker remarked.

Other sessions discussed how SRM strategies involving the release of aerosols could affect air pollution, and how developing world countries could be included in conversations about future geoengineering research.

Heading outdoors

In the afternoon, the delegates of the conference gathered to learn more about one of the world’s first outdoor SRM experiments.

Keith, along with colleagues Lizzie Burns and Prof Frank Keutsch, also from Harvard University, explained the aims and methods of their research project, which is known as SCoPEx.

The SCoPEx experiment plans to use a high-altitude balloon to lift a package containing aerosols 20km up into the atmosphere. There, the aerosols will be released and their potential effects on the stratosphere will be observed. The team plan to launch their first balloon in the autumn next year.

The aim of the experiment is to gather observational data that could tell us more about the potential risks and effects of releasing aerosols into the stratosphere, Keith said. He told the audience:

“There are things that it’s not. It’s not the first solar geoengineering experiment, there have been at least two.

“Second, it’s not a field test. To me, a test is something you do well down the engineering system, where there is a serious decision to deploy that system and you want to test that in a binary way. That’s not what we’re doing. What we’re doing is something much earlier, it’s really applied atmospheric science.”

The wider goal of research into releasing aerosols into the atmosphere is to reflect sunlight, which could help to reduce the amount of warming caused by human-driven climate change.

However, the research team faced criticism from the audience, including from representatives of the Heinrich Böll Foundation, who suggested that SCoPEx marked the beginning of a “slippery slope” into uncontrolled SRM research.

Wednesday’s proceedings rounded off with a plenary exploring the governance challenges caused by climate engineering.

The conference will conclude on Thursday afternoon with a “town hall” final plenary to “take stock of what we have learned” and provide the “opportunity to look ahead and consider the roles that CDR and SRM might play in future climate policy.”

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