In 1964, the biochemist and science fiction author Isaac Asimov predicted that by the beginning of the 21st century our nutrition would be based on semi-prepared food, and that we would only set aside a small corner in the kitchen to prepare a dish when company was coming. He could not have been more wrong; instead of the move away from nature that Asimov predicted, the new century has brought the opposite trend, a return to the natural, with the consumption of organic food being one of its main banners. And although there is some controversy over whether these products are actually healthier or more nutritious than conventional ones, one thing no one would deny is that they are more environmentally friendly. But are they?
Even in this case, reality seems to be more complex than appearances. Putting aside the differences due to the rules that each country may establish about what is considered an organically produced food, in general one would assume that the environmental impact of these products should be lower due to the fact that synthetic pesticides (or chemicals in common parlance) are not used.
The keyword is “synthetic”; contrary to what the vast majority of consumers of these products understand, organic agriculture does in fact employ pesticides, but they must also be organic. But as some experts have warned, natural pesticides are not necessarily less toxic or harmful than synthetic pesticides (see box at the end of the article). And because they often have to be used in larger quantities, their environmental impact may be greater than that of conventional pesticides, as revealed in a 2010 study by the University of Guelph (Canada) that compared the use of synthetic and organic insecticides in the cultivation of soybeans.
Environmental impact of organic farms
Soil pollution is not the only area in which organic production may fail to live up to its promise of sustainability. In 2012, researchers at Oxford University (United Kingdom) analysed 71 previous studies to compare the environmental impact of organic farms and conventional farms. Their findings indicated that organic farms generally host 30% more biodiversity and have a smaller environmental footprint per unit of land, but this is not always the case per unit of product: while cattle and olive cultivation are more environmentally friendly in their organic versions, pigs, dairy and cereals actually generate more greenhouse gases (GHG) per unit of product than their conventional equivalents.
According to the director of the study, Hanna Tuomisto, “while some organic farming practices do have less environmental impact than conventional ones, the published evidence suggests that others are actually worse for some aspects of the environment.” The researcher points out that “people need to realise that an organic label is not a straightforward guarantee of the most environmentally-friendly product.”
One of the factors that raise the environmental cost of organic product is that more land must be used to generate the same volume of food, due to the reduced use of fertilizers. This need to devote greater acreage to agricultural production leads to deforestation, which reduces the storage capacity of carbon in soils. The final effect is an increase in GHG emissions responsible for climate change.
This effect is highlighted in a study published in 2018 in the journal Nature. The authors analysed two specific crops in Sweden, concluding that organic peas have a 50% greater climate impact than conventional peas, while this difference increases to almost 70% for wheat.
Soils with less carbon
The main novelty of the study was that the authors developed a standardised methodology to measure the opportunity cost of land in terms of carbon storage. Previous research had compared the direct greenhouse gas emissions of organic and conventional production, but according to the authors, the indirect effect due to alternative uses of land if it is not devoted to agriculture is often underestimated.
The authors point out that, thanks to international trade, this effect is transmitted from one region to another. “Agriculture always uses land,” study director Timothy Searchinger of Princeton University (USA) tells OpenMind. “If there are lower yields on one hectare of land, then to produce the same food, you need to have more land producing food elsewhere, and that means this land is storing less carbon,” says Searchinger. “If you are in a country that is not deforesting land, food production still has to come from somewhere.”
In turn, this environmental cost of organic farming is passed on to livestock. However, the authors clarify that each product is a particular case, and that the most ecologically responsible options are therefore about specific food choices: “For example, eating organic beans or organic chicken is much better for the climate than eating conventionally produced beef,” says study co-author Stefan Wirsenius, from Chalmers University of Technology (Sweden). In general, chicken, pork, fish, eggs or vegetables have a lower climate impact than beef and sheep.
Although the figures often vary depending on the methods of analysis, other studies have echoed the same idea that the greater land-use requirements of organic crops result in higher net GHG emissions. In 2019, a study in Nature Communications looked at what would happen if all agricultural production in England and Wales switched to organic. The authors, from the universities of Cranfield and Reading, estimated that emissions from livestock farming would be reduced by 5% and from agriculture by 20%. But given that reducing production by around 40% would mean importing food from other countries, with half of the land used to compensate for this loss having to be converted, the net result would be a 21% increase in emissions, rising to 70% if the opportunity cost of carbon defined by Searchinger and his colleagues is introduced.
However, many experts, including enthusiastic advocates of organic production, admit that this is a complex issue. Blanket assertions that organic farming is always more sustainable than conventional farming, as well as the opposite opinion, are simplifications that do not correspond to reality. In New Scientist magazine, sustainable food and agriculture specialists Christel Cederberg and Hayo van der Werf warned that studies on this issue are often too narrowly focused and do not adequately assess the environmental benefits of organic production on biodiversity or the health of agricultural soils.
Biofuels, a not-so-green alternative
A particularly striking case is that of biofuels, which are used worldwide as a green alternative to fossil fuels. According to the analysis by Searchinger, Wirsenius and their colleagues, this premise does not hold water. From the point of view of their total impact on climate, after adding direct emissions and the opportunity cost of carbon, “it is better to use fossil fuels than biofuels,” says Searchinger. This is because of the large tracts of land occupied by the crops from which the biofuels are extracted; this does not apply to biofuels made from waste.
However, says Searchinger, this does not mean that fossil fuels are the best option, but rather that, “the same money that is now being put into biofuels in the name of climate change, and which is actually increasing greenhouse gas emissions, should be put into other approaches to reduce emissions.” As to which ones, Searchinger is clear: “As rapid a transition as possible toward electric vehicles.”
However, says Searchinger, this does not mean that fossil fuels are the best option, but rather that, “the same money that is now being put into biofuels in the name of climate change that actually increases greenhouse gas emissions could be put into other approaches to reduce emissions.” And regarding which, Searchinger is clear about what is needed: “As rapid as possible a transition toward electric vehicles.”
ORGANIC PESTICIDES, NOT LESS POISONOUS
A University of California survey revealed that the main reason most consumers choose organic food was the avoidance of pesticides (70%), ahead of freshness (68%) or health and nutrition (67%). It is not surprising then that this alleged absence of pesticides is noted as one of the most widespread myths about organic food, as a majority of consumers seem to be unaware that these products can indeed be grown using pesticides, as long as they are also organic, i.e. of non-synthetic origin.
But are natural pesticides safer than artificial pesticides? Not necessarily. In a direct comparison, organic pesticides such as copper sulphate or pyrethrum have higher acute and chronic toxicity than the synthetic pesticides chlorpyrifos or chlorothalonil. The bioinsecticide Bti (natural toxins from the bacterium Bacillus thuringiensis israelensis), used for mosquito control and applied on wetland crops such as rice, is not toxic to humans, but several studies have shown that it is harmful to amphibians. Recent studies have shown that Spinosad, an organic pesticide extracted from another bacterium, is more damaging to insects in general and at much lower doses than imidacloprid, a synthetic insecticide that in 2018 was banned in the European Union because of its damage to bee colonies.
But above all, it is important to remember that, according to the World Health Organisation, “none of the pesticides that are authorized for use on food in international trade today are genotoxic (damaging to DNA, which can cause mutations or cancer). Adverse effects from these pesticides occur only above a certain safe level of exposure.”