Greenpeace have been strongly criticised in recent weeks over the destruction of a trial crop of genetically engineered wheat. Some critics have labelled the organisation ‘anti-science’ and claim that opposition to GM crops somehow contradicts the support of climate science.

Firstly, it is useful to revisit what ‘science’ actually is, and what it isn’t.

Science is broadly defined as the systematic study of the structure and behaviour of the physical and natural world through observation and experiment. The scientific method involves observing the world, putting forward a hypothesis (theory), and then attempting to disprove that hypothesis. Theories that can’t be disproved become accepted, until they are disproved and replaced by a theory that is more robust.

So, contrary to much popular opinion, science really isn’t about ‘proof’ at all. It is about ‘disproof’.

In relation to global warming, after many years of observing trends in nature (rising CO2 levels in the ocean and atmosphere, slow but steady increases in global average temperatures etc.), scientists put forward the theory of ‘man made global warming’. Scientists have been trying to disprove this theory, but so far they haven’t succeeded – it remains the best theory to describe what is happening to the global climate system.

What climate deniers and so-called ‘climate sceptics’ seem to misunderstand amid their attempts to discredit climate science, is that the mainstream scientific process that they are railing against is actually geared around trying to ‘disprove’ the theory of man-made global warming. The reason that I call them ‘climate deniers’ rather than ‘climate sceptics’ is that all climate scientists are sceptical of the theory of global warming as a result of the scientific method they use, but what we see from the deniers is just that – outright denial.

But the scientific method does not stand alone in our decision making about science and technological development. Science is, and must be, guided by values and principles, one of which is the ‘precautionary principle’. The application of the precautionary principle helps to determine where the burden of proof or the burden of disproof should lie.

In the case of climate change, the burden of proof, or the burden of disproof is clear. There is an obvious trend happening in the world that is widely regarded as potentially dangerous. A theory has been identified to describe what is happening, this theory has withstood enormous scientific scrutiny and is therefore widely accepted by the scientific community with a high level of confidence.  The negative consequences of global warming happening are enormous compared to cost of doing something about it. The burden of proof clearly rests upon climate deniers (or indeed climate scientists) to disprove the theory of human induced global warming. I hope they manage to do it because the implications of global warming are almost too disturbing to contemplate.

In the case of genetically engineered foods however, the issues are less straightforward and reveal the political and values based judgements that are also made as part of the scientific process. But firstly, it is important to be clear that genetically engineered foods are not science. Nuclear power isn’t ‘science either. Neither are pop-up toasters. They are the commercial products that rely on scientific understanding for their development.

The ‘science’ involved in genetic engineering is the theory of the genome and the relationships between DNA, RNA and proteins. One of the technological spin-offs of these scientific theories (which thus far have not been disproven) is a technique of inserting genes from one species into the genome of another in order to achieve a beneficial trait in the recipient organism.  The body of scientific evidence suggests that the relationships between DNA, RNA and proteins are extremely complex and the implications of inserting a foreign gene are likely to be many and unpredictable.

For example, the Human Genome Project revealed that we humans have far fewer genes than previously expected – around 20,500 genes that encode the proteins for all the parts of our bodies. On the other hand, the tiny roundworm (Caenorhabditis elegans) has nearly as many genes as we do—approximately 20,100—but far fewer body parts.  It is estimated that some 650,000 protein interactions occur in humans, approximately three times more than that in the roundworm. Moreover, it seems that a single protein can have dozens, if not hundreds, of different interactions.

We need to remember this complexity in the relationships between DNA, RNA and proteins when it comes to how we regulate genetically engineered organisms.

The problem, and a root cause of the controversy over the regulation of GM foods, is that determining where the burden of proof should lie for safety of new products not a scientific ‘given’. It is actually a value judgement based largely on an assessment of costs and benefits. The proponents of GM (biotech companies, chemical companies and some scientists) argue in favour of the doctrine of ‘substantial equivalence’. In effect, it assumes that genetically engineered foods are substantially equivalent to traditionally bred varieties of the same food because only a small number of extra genes have been inserted. As a result of this assumption, GM foods are assumed to be safe until proven otherwise.

On the other hand, many public health organisations, environmental groups and some scientists argue that ‘substantial equivalence’ does not account for the complexity of possible results arising from the insertion of novel genes into organisms, and that unexpected effects are likely. Accordingly, if a precautionary approach is taken, then the burden of proof should be on the proponents of GM to demonstrate that GM foods are safe in much the same way that new pharmaceuticals need to be demonstrated to be safe.

Ultimately, this debate is not about science, it is about politics. It is about evaluating who benefits from GM crops, and who should bear the risks. Greenpeace’s position is influenced by the simple observation that most of the GM crops that have been developed have been done so for the private benefit of agro-chemical companies that wish to extend their control over the food chain.

From our discussions with public health experts around the world, a common view emerges: If the potential risks of negative health impacts from GM foods became manifest, then the impacts could be significant, would be spread widely within the community and would be difficult to detect (in part due to poor labelling requirements).

The high profile public debate about genetically engineered foods has been mischaracterised as a pro vs. anti science debate, but it is really a debate about the politics of technology, and about the risks and benefits of one particular technology. A similar parallel in the climate change debate would not be about whether or not climate change is happening, it would be about whether nuclear power is an appropriate solution to climate change, or whether a particular geo-engineering application should be deployed to remove CO2 from the atmosphere.

Whenever you have a cost/benefit equation, you need to deal with value judgements and vested interests. In cases where the people taking a risk are the people benefitting, you are likely to see widespread acceptance. A good example of this is the mobile phones which offer clear benefits to people even though there are concerns over a possible increased incidence of brain cancer. With GM foods, the companies benefit, consumers bear the health risks, and the risks of GM crops are ‘externalised’ upon the wider environment.

Greenpeace is not opposed to the science of genetics. We are not opposed to research into new and innovative forms of plant breeding. What Greenpeace are opposed to is the widespread release of genetically engineered organisms into the environment and the food chain without due diligence being done on the risk of long-term negative impacts. Our position is based on the precautionary principle, on respect for science, and on critical analysis of the environmental and social risks of new technologies.

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