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.
- making the surface of the planet more reflective. This can be done by growing crops/vegetation of high-reflectance, reflective covering of human-built structures and areas, and introducing masses of tiny bubbles into ocean waters
- brightening clouds so they are more reflective
- injecting sulphate aerosols into the [stratosphere](http://en.wikipedia.org/wiki/Stratospheric_sulfate_aerosols_(geoengineering)
- placing reflectors into space to divert sunlight from the earth.
Another approach is to modify the biogeochemical cycling of radiatively important gases, specifically carbon dioxide, in order to reduce their levels in the atmosphere.
- 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 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.