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Geo-engineering: should we change the face of the planet to combat climate change?

In the past few years, there has been growing interest in geo-engineering our climate. Geo-engineering means making sometimes planetary-scale physical or chemical changes to alter the amount of heat coming…

Messing with climate systems is a dangerous step to take.

In the past few years, there has been growing interest in geo-engineering our climate. Geo-engineering means making sometimes planetary-scale physical or chemical changes to alter the amount of heat coming into, or getting out of our atmosphere.

It’s a serious step. Should we even be looking into it?

There is still so much we don’t know

We have increasing evidence that human activities are changing the climate in ways that may have serious consequences for natural ecosystems and human economies.

Despite that knowledge, there are significant delays in global action to limit future climate change. We are not significantly reducing greenhouse gas emissions, and this is exacerbating the potential for greater climate impacts.

Targets exist for cutting greenhouse gas emissions - Australia is aiming for a 5% cut by 2020. But we don’t know enough to accurately assess the probability of future exposures or their impact if they occur (that is the risk).

For example, will the functioning of natural ecosystems be more sensitive to what we currently perceive as small climate changes, than we thought, or will these “small” changes trigger more rapid responses such as the de-glaciation of Greenland or the release of more greenhouse gases from under the sea or ice?

It is not that we know if these outcomes will occur, but simply that there is a risk they might. If they do, our targets for reducing emissions to avoid exposure may turn out to be too conservative.

We now have some capacity, though limited, to anticipate what will happen if we intervene in the climate system. But geo-engineering interventions – as with climate change wrought through greenhouse gases – are likely to result in unanticipated outcomes. And different regions will respond differently.

How does geo-engineering work?

There are many ways to modify the radiative budget of the planet; generally these methods try to stop sunlight getting in to the atmosphere.

They include:

Another approach is to modify the biogeochemical cycling of radiatively important gases, specifically carbon dioxide, in order to reduce their levels in the atmosphere.

Examples include:

  • changing land-cover management; for example, planting more trees
  • sequestering plant residues in the ocean and soil (for example, using biochar or ocean fertilisation)
  • capturing carbon dioxide directly from the atmosphere by passing air over a chemical absorbent that can then be reactivated, leaving a source of captured carbon dioxide to be disposed of
  • enhancing natural weathering processes, which absorbs carbon dioxide from the air.

Local interest, but global repercussions

Entrepreneurial interests are aware of the potential commercial gains of geo-engineering. Many are encouraged by the introduction of carbon pricing, which promises to create a market for those who can demonstrate they have avoided or reversed the release of carbon dioxide into the atmosphere.

But entrepreneurs are often narrowly focused on a particular technology - they may just be interested in developing space mirrors, for example, without looking at the wider context.

Such endeavours may inadvertently create outcomes that do not lead to long-term benefits for the natural world, or to the interests of the wider community or future generations.

Governments are developing policies to institute geo-engineering solutions, often without properly assessing the limits to these possibilities.

Individual nations – with their distinctive economies and environments – are exposed to unique natural and unnatural climate variability. A nation may want to embrace attempts at climate modification that may not respect wider regional or global interests.

With so many groups interested in pursuing geo-engineering, and so many risks involved, we must continue to develop knowledge through scientific and technical research. This knowledge can underpin future climate modification or, indeed, argue strongly against it.

There are great potential dangers if this research if not sensitively undertaken. We need widely accepted guidelines for both its conduct and, if appropriate, its application.

Such guidelines are largely absent and they are urgently needed. There is a serious danger that nationally or sectorally driven interests will succeed at the expense of the wider global community, or indeed intergenerational interests.

Guidelines need to consider the possible inequity of potential responses - how will other societies and species be affected if Australia decides to put sulphates into the atmosphere, for example? They must look at moral and ethical considerations, not just technical ones.

Everyone is doing it: should we?

The need to look more closely at geo-engineering has been recognised in the work of NASA, the Royal Society, the UK House of Commons Science and Technology Committee and the US Climate Institute.

The American Geophysical Union and the American Meteorological Society have prepared formal position statements on the issue.

The Intergovernmental Panel on Climate Change has also commenced its own assessment of the topic.

So should Australian researchers get involved?

The challenge to improve knowledge is always tempting. But it shouldn’t be confused with any commitment to undertake geo-engineering.

Taking an interest in this issue does not mean avoiding the very important tasks of reducing greenhouse-gas emissions and planning for adaptation strategies.

All geo-engineering approaches are often placed in one basket. In reality, they are so enormously different each needs to be considered on its own merits using a rigorous and systematic assessment against a set of criteria.

When looking at any geo-engineering plan we should ask:

  • is the technology proven?
  • at what scale (geographic and temporal) can it be deployed?
  • is it equitable to everyone it is likely to affect?
  • is it ethical in terms of humans and natural systems?
  • what does it cost?
  • is it widely acceptable?
  • what are the risks?

Geo-engineering is not an engineering problem; far from it. It includes physical science, but above all, issues of equity and ethics, legal considerations, and human responsibilities with respect to each other and to the biosphere in general.

Before Australia gets involved in geo-engineering, we need guidelines nationally and globally.

Graeme Pearman will be discussing the risks of geoengineering at “Geoengineering the climate: a southern hemisphere perspective”, held at the Australian Academy of Science on 26 & 27 September.

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13 Comments sorted by

  1. Marc Hendrickx


    Strange argument Graeme. Based on the evidence to date I don't consider that this issue will require drastic intervention in the not so distant future, however I don't think Australia should be closing the door to geo-engineering research, or indeed taking some action about our regional climate now. Indeed there are many issues with our current climate that could benefit from a little "intervention".

    Take Clive McAlpine's recent work (see that tied land…

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  2. John Harland

    bicycle technician

    We face a general ecological crisis, not global warming alone. The problems are not addressable by tackling only the most immediately-evident symptoms.

    Even if we had any real confidence in getting geoengineering strategies right, we should regard them as purely a temporary palliative to give us a little more time to address the causes.

    However the use of geoengineering for this purpose is fairly certain to slow the rate at which those underlying causes are addressed.

    We need to work on just how to stop old-growth forestry, seafloor-devastating methods of fishing, overfishing generally, release of toxic wastes from mining and manufacturing and other causes. And we need to work out how to do that equitably so that the processes will be respected and not generate conflict.

    Fiddling with insolation is not a solution.

  3. Fran Barlow


    I don't think there are good alternatives to the inclusion of active and passive geoengineering measures in a suite of measures aimed at stabilising the climate and protecting the integrity of ecosystem services to humans. It seems very clear that the world's governments will fail collectively to do what is necessary to stabilise emissions on the timeline needed.

    Of course, we do need to address all of the feasibility questions before taking any step in this direction. We must consider not merely technical feasibility -- basically, would it work? -- but scaleability, unintended consequences and interaction with other parts of ecological systems, moral hazard and so forth. It's not a simple thing.

    The problem remains however that we may already be past the time when cuts to emissions will do the job we need, and looking at serious positive feedbacks -- eg loss of the arctic permafrost, and sea-ice cover albedo. We can't be sanguine in the face of that.

  4. Sean Lamb

    Science Denier

    Frankly I wouldn't trust the current crop of planetary scientists to find their way out of a paper bag. We spend ages trying to remove sulphates from the atmosphere (because we thought they might cool the planet) and now we are supposed to pump them back in?

    Anyway what precisely is so bad about our current climate that we are supposed to panic about?

  5. Ken Fabian


    My main concern is that, like Carbon Capture and Storage, unproven and uncertain geo-engineering 'solutions' will be primarily used to excuse ongoing investment in inappropriate infrastructure that entrenches fossil fuel use by interests that have even less intent or real desire to actually invest in these 'solutions' themselves than they do for investing in renewable energy.

    There appear to be an almost endless succession of 'reasons' for failing to reduce emissions - but I hesitate to call any of them Good reasons; Good (as in marketable) excuses is about the most positive spin I can put on them. Even when the proponents of geo-engineering solutions are sincere the heels-dug-in opponents of the shift away from fossil fuels will insincerely promote them simply to undermine support for actual commitments to emissions reductions.

  6. Mark Harrigan

    PhD Physicist

    It was unintentional geo-engineering that has created the problem of AGW.

    The only uncertainties are how warm it will get and how fast that will happen although the paleontological record is not encouraging (temperatures rose 5 degrees C 56 million years ago in response to massive CO2 injections furing the PETM). Also the concensus of every single national science body, and not a few global insurers, is that the problem is significant.

    Given our level of ignorance, and the poor track record we have when attempting to fiddle with nature (cane toads anyone?), geo-engineering strikes me as a last resort rather than a first response. As the article points out - the law of unintended consequences can be applied.

    How about focusing on abatement through weaning ourselves off fossil fuel use as well as sensible adaptation strategies first?

  7. Alex Cannara

    logged in via Facebook

    The climate-warming, ocean-acidification & sea-rise problems was known decades ago, and a direct solution presented to the US Congress and the JFK in 1962...

    We failed to have 700GWe of non-emitting power operating in the US by 2000. In particular, we discontinued Thorium, Molten-Salt Reactor work in 1974, because it doesn't make good bomb material. So, here we are now, with the Chinese, Brits, Indians, even Aussies revisiting our work from over 40 years ago, and moving…

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  8. John McLean

    logged in via email

    "We have increasing evidence that human activities are changing the climate in ways that may have serious consequences..."

    Yet another claim of "increasing evidence" that, like claims of "multiple lines of evidence", is sadly lacking in any substantiation.

    One only has to look at table 2.11 (page 201) chapter 2 of the IPCC 2077 report, and chapter 8, to appreciate that natural climate forces are very poorly understood.

    Playing computer games doesn't cut it, Graeme, you need to demonstrate that those computer games accurately embody every climate force. I think you've got a snowball's chance in hell of doing so. ... and that undermines the rest of your piece.

    1. Mark Harrigan

      PhD Physicist

      In reply to John McLean

      Popper said "True ignorance is not the absence of knowledge, but the refusal to acquire it." - clearly this applies to your comment.

      The evidence is abundantly clear

      1) The "Greenhouse effect" is a real physical phenomenon well established
      2) CO2 is a greenhouse gas that has been on the increase
      3) isotopic and other evidence shows that man put it there (in excess of the natural re-cycling ability) as a result of fossil fuel emissions
      4) Such an increase in greenhouse gases - based on physics…

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  9. Ian Donald Lowe

    Seeker of Truth

    The arrogance of this piece is stunning, as is the arrogance of any human being who thinks that we can meddle in nature to such an extrent and actually impove on a natural system that is so complex and so inter-connected, that no human mind can comprehend the full reality of our existence.

    My main question is why?

    Why should we risk destroying ecosystems and species (and perhaps all terrestial life) in some ridiculous attempt to air-condition the planet so that we can feel comfortable in our manufactured societies and continue this ridiculous age of inequality and massive over-consumption?

    It is time to change mindsets Ladies and Gentlemen. It is time to get right with the natural world and science can either lead the way or become an impediment. Your choice.

  10. Ian Rainbow

    Analytical Chemist

    Graeme, I like your comments” Geo-engineering is not an engineering problem; far from it. It includes physical science, but above all, issues of equity and ethics, legal considerations, and human responsibilities with respect to each other and to the biosphere in general.
    Before Australia gets involved in geo-engineering, we need guidelines nationally and globally.”
    So regarding cloud brightening, I do want to ask some questions about the process proposed in the light of more recent reports in…

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