March 12, 2025 by Ayms Mason
In recent years, genetically modified organisms (GMOs) have been increasingly framed as a solution to climate change – engineered to withstand droughts, resist pests and increase yields in extreme conditions.
However, not only are these claims unproven since no GM crop has yet been developed that outperforms non-GM crops in these traits, but the impacts of climate change on GM crops is unknown. Far from providing a solution to climate change, could a warmer and more volatile world actually increase the environmental risks of these crops?
Research in this area is very thin on the ground but, at a time when weather patterns are becoming increasingly unpredictable, there is good reason to be asking the question now.
Despite the bold promises of genetically modified crops, the reality is that field studies on their long-term impacts remain scarce. There has been even less research on the possible additional risk of climate change. The combination of GMOs and a rapidly changing climate introduces a level of unpredictability that existing risk assessments fail to account for.
Yet, instead of precaution, policymakers in places like the UK are pushing forward with deregulation, removing even the most basic oversight from newer genetic technologies. The new draft regulations for the Genetic Technology Act, for example, require a lower level of risk assessment and monitoring for environmental releases than they do for food system releases. Without sufficient research into how gene flow, enhanced fitness and herbicide resistance will interact with shifting environmental pressures, we risk deepening, rather than solving, agriculture’s vulnerabilities in a warming world.
In the natural environment, genetic material commonly moves between organisms of the same or different (but sexually compatible) species through a process known as gene flow. This typically happens via pollen transfer aided by insects or wind when organisms are in close proximity. One of the significant environmental risks of GM crops is this gene flow to wild species, which could have unknown and potentially disruptive ecosystem effects.
There is reason to believe that climate change could increase the risk of gene flow from GMOs to wild plants. Climate change has been shown to increase flowering duration, which results in a much greater flowering overlap between different species. This is very likely to increase gene flow between sexually compatible species.
Indeed, there are examples of GM traits spreading to, and propagating in, the environment. For example, GM Bt maize (engineered to be toxic to certain insects) grown in Spain has cross-bred with its weedy wild relative, teosinte. The hybrid offspring grow taller and flower earlier than teosinte and also contain Bt toxins, raising concerns that they could become invasive in the environment and hasten the evolution of Bt toxin-resistant pests. Interactions between pest life-cycles and climate shifts could heighten these risks. Also, GM canola (oilseed rape) has cross-bred with non-GM canola and wild relatives in many countries, spreading its herbicide-tolerant traits in the environment and posing challenges to weed control systems.
It is not just plants that are at risk either. The recent escape of approximately 27,000 farmed salmon into the sea from a farm off the Norwegian coast during a storm is of great concern. In this case, the salmon were not GM, but GM salmon have been developed and produced commercially (albeit the developer company, AquaBounty, stopped production in 2024). Severe storms are increasingly likely with climate change, augmenting the risk that GM salmon of the future may escape into the wild. They may outcompete their wild relatives and/or spread traits that would be detrimental in wild populations, even potentially leading to extinction.
One of the most important factors in ascertaining whether or not unintentional escape of genetically modified genes into the environment will cause harm is fitness. Fitness is a term used in evolutionary biology, referring to an individual’s ability to pass its genes onto subsequent generations. Plants that are better at this are likely to outcompete other plants.
There are a variety of ways fitness can be improved through genetic modification and each of these could have environmental impacts that could be worsened by climate change.
Enhanced fitness is one of the intentions of genetically modifying an organism. We often hear promises of crops that can be altered to better withstand environmental stressors, such as drought, salinity and flooding. It stands to reason that escaped modified genes, which persist in wild hybrids, are likely to also have greater fitness when faced with these extremes. If these crops become more widespread in the future, this could reduce rather than increase biodiversity.
Enhanced fitness can also be a side effect of a different modified trait. For example, plants that have been engineered to be resistant to insect predators could outcompete plants that do not have that trait in the case of an insect attack. Studies have shown that unintentional gene flow into wild relatives from the GMO plants also benefits the offspring – i.e. they would better be able to withstand an insect attack than their wild counterparts.
It is also possible that the process of genetic engineering can unintentionally enhance the fitness of the relevant plants. For example, scientists have shown that the enzyme responsible for herbicide-tolerance in GMO plants also affects metabolic processes. As a result, their offspring can produce more seeds and be more resistant to environmental stressors such as drought and heat. This intended trait, when faced with the kinds of environmental extremes that will become more likely with climate change, could have significant impacts on ecosystems.
Other studies show a range of unexpected effects that impact fitness in rice after GMO plants are crossed with wild or cultivated varieties, including lower insect damage, earlier flowering and increased overwintering abilities.
Current risk assessment processes for old-style GMOs do not sufficiently account for long-term or next generation effects. The UK’s Genetic Technology (Precision Breeding) Act, signed into law in 2023, removes all risk assessment and post-market monitoring from newer forms of genetically modified crops. This means our ability – and maybe even our motivation – to understand – how these enhanced risks from climate change actually play out, is substantially reduced.
GM crops developed with herbicide-resistant traits have led to repeated and excessive use of a set of common herbicides, and this has induced resistance in weed populations. The USA, for example, has so reported 131 varieties of herbicide-resistant weeds This is causing increasing problems for farmers, with costs to the UK economy estimated at nearly £400 million and 800,000 tonnes of lost harvest each year.
There is evidence that control of these so-called ‘superweeds’ could get worse with climate change. For example, palmer amaranth, which can grow 10 feet tall and as thick as a baseball bat, is seen by many as the worst weed in America. Under the ‘business as usual’ greenhouse gas emissions scenario, the amount of land with a suitable climate for palmer amaranth in the US would increase by 21%, and in Canada it would increase more than tenfold.
So far, the response to the problem of superweeds has been to further engineer the crop for even more herbicide-resistance, to enable farmers to pair glyphosate with more herbicides – usually glufosinate, 2,4-D and/or dicamba. These ‘post-emergence’ herbicides are even more toxic than glyphosate, as well as highly prone to drift to neighbouring fields and landscapes.
Proponents of industrial agriculture are ignoring these possibilities and instead doubling down on the creation of multi-herbicide tolerant GM plants. Bayer, for example, has just released soybean tolerant to 5 different herbicides.
Likewise, a significant number of “new” GMOs – what the UK is calling “precision bred” organisms – are being bred for herbicide resistance. Without strict regulation, biotech companies have a free hand to cycle through a series of short-term, potentially more environmentally harmful, genetically engineered plant varieties, with no need to face up to the fact that the only genuinely sustainable agricultural system is one that seeks to work with – not against – nature.
Little is known for certain about the impacts of a warming planet. Scientists agree there will be more extreme weather events, such as heatwaves, heavy rain, tropical cyclones and droughts – but the timing and distribution of these events is difficult to predict.
Compounding the unpredictability of the climate itself, is the uncertainty as to exactly how the organisms on earth will respond to these extremes. Scientists are only beginning to understand that plants can respond to stress by changing their gene activity, which can then alter cell structures. The growing field of epigenetics (the study of molecules and mechanisms that can perpetuate alternative gene activity states caused by environmental factors without changing the DNA sequence) has found that climate changes can impact fitness and adaptability. The exact mechanism and impacts of this are not yet understood.
In an increasingly unpredictable world, the need to acknowledge all the uncertainties and unknowns has never been greater. Our current linear, mechanistic, technocratic risk-based paradigm fails to address the dynamic complexity of today’s turbulent world. In the face of climate change, we need more transparency, a wider democratic deliberation and a broader public debate. Instead, we are getting an even more opaque, deregulatory regime that will allow widespread dispersal of genetically modified organisms with no labelling, traceability, or accountability.
The recent narrative surrounding GM has leaned heavily on the supposed potential of the technology to help the world adapt to climate change by creating crops better adapted to hotter/drier/wetter conditions. However, the reality is much more complicated. The traits required for climate resilience – flood tolerance, drought tolerance, heat tolerance – are complex genetic traits involving multiple genes, making them difficult or impossible to genetically engineer effectively.
Conventional breeding, on the other hand, has been very successful at expressing these traits through selection of multi-gene characteristics, often over a long period of time in the specific environment, leading to optimised adaptations.
Climate change is also causing unpredictability in weather patterns, meaning that even if drought-tolerant GM crops were successfully developed, they might perform well one year but poorly the next when faced with wetter, cooler conditions. This single-trait focus contrasts with traditionally bred varieties that often carry broader adaptive capabilities.
In addition, there is a direct link between GM crops and increased greenhouse gas emissions. The cultivation of GM herbicide-tolerant crops has led to a massive increase in herbicide use. These synthetic pesticides are derived from fossil fuels, which emit greenhouse gases through their manufacturing and use.
In a world increasingly shaped by climate change, the risks associated with GMOs extend beyond their limited adaptive capacity. As environmental stresses intensify, the ecological and societal consequences of relying on genetically modified crops become more severe. Research funding and policy options that prioritise biotech solutions over diverse, resilient farming systems can only further lock farmers into an increasingly vulnerable system.
GMOs do not exist in isolation – they depend on environmental factors such as pollinators and soil health, both already threatened by climate change. If these key ecological processes are disrupted, any supposed benefits of GM crops may not materialise in real-world conditions. Yet, the biotech-driven narrative of “GMOs for climate adaptation” continues to dominate agricultural policy and investment.
Far more research is needed to understand the potential impacts of climate change on GMOs and their interaction with the environment. Without thorough research, transparent public discourse, and investment in diversified agricultural strategies, our food system remains not only unsustainable but increasingly fragile in the face of an unpredictable climate future.
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