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Is your vegetable oil killing the planet?

Vegetable oil pouring on vegetable oil background
Different vegetable oils have VERY different impacts (Getty)

Is the vegetable oil in your kitchen cupboard contributing to climate change? Sadly, the answer is ‘yes’ - and some oils are worse than others.

Despite palm oil receiving lots of negative press over deforestation, it’s actually not the worst in terms of greenhouse gas emissions, the University of Nottingham researchers found.

The study took into account factors such as using agricultural land and the use of nitrogen on farms.

Soybean oil is the worst - but rapeseed and sunflower oil had fewer emissions, and appear to be more sustainable choices.

Scientists from the University of Nottingham's Future Food Beacon analysed greenhouse gas emissions from almost all possible systems that are currently used to produce palm, soybean, rapeseed and sunflower oil around the world.

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The study was a ‘meta-analysis’ using all relevant studies concerning the environmental impact of oil production published between 2000 and 2020 - and is representative of 71% of global vegetable oil production.

Crop specific median emissions ranged from 2.49 kg CO2e (carbon dioxide equivalent) for rapeseed oil to 4.25 kg CO2e for soybean oil per kg refined oil.

When a forest is cut down to make space for agriculture, the carbon stored in the trees and vegetation is released to the atmosphere as CO2.

The researchers analysed the impact of this type of deforestation on crop sustainability.

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They also considered the carbon costs of agricultural land occupation even in cases where deforestation happened more than 100 years ago (as is the case for most of Europe).

The researchers showed that land use made a significant contribution to GHG emissions, generally making up half of the total overall emissions.

Dr Thomas Alcock, Future Food Beacon research fellow and Postdoctoral Researcher at the Technical University of Munich led the research. He says: "The strength of having lots of different production systems included in this study is that we can identify the most sustainable systems for each crop type, and push for these to be adopted more widely.

“The results, particularly around land use, show that we should target production on low carbon storage potential land, although we also need to consider other sustainability indicators such as biodiversity.

“Most previous studies only considered recent land use change, but in this study we considered the impacts of continuing to grow crops on an area of land as well, instead of setting it aside for regeneration of forests."

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The study highlights the need and scope to improve sustainability within current production systems, including through increasing yields whilst limiting application of inputs with high carbon footprints.

In the case of palm oil, sustainability can be improved through more widespread adoption of methane capture technologies in processing stages.

Dr Alcock explains: "This means reducing application of synthetic nitrogen to crops as much as possible. On-farm, this is generally the biggest source of GHG emissions.

“This is tricky, as crops need a lot of nitrogen to be productive, but there are ways to reduce this, such as through choosing crop cultivars that are more nitrogen-use efficient, and by including leguminous plants in the crop rotations, as these provide nitrogen to the soil more naturally.

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