Past studies have highlighted howgenetically modified(GM) crops
contributed to the alleviation of the effects ofclimate change. But a
new calculation reveals that GM crops may be contributing more than
previously documented.

The researchers behind the study emphasized that previous studies did
not incorporate the reduction of greenhouse gas (GHG) emissions
associated with yield increases of GM cropsand that their new analysis
included carbon opportunity cost (COC) for land use as a factor, given
that increased crop yield reduces the need to clear out new land for
agricultural production thereby preventing additional CO_2 emissions.
The researchers used a method developed by Searchinger/et al./in 2018 to
make new calculations of the climate benefits of GM crops' yield
increase. To test it, they concentrated on the European Union (EU) since
the EU has not widely adopted GM crops and it is undergoing a
reassessment of its GM policies. Concentrating on the EU helped them
compare a hypothetical scenario with GM crop adoptionto the status quo
and the analysis could help provide a more comprehensive picture of the
likely effects of policy change. They also identified insect
resistanceandherbicide tolerancetraits infive mayor GM cropsfor their
analysis, because these traits are known to help increase effective crop
yields, along with two components of GHG emissions: the COC of land use,
and the production emissions (PEM).

The figures that came up after the analysis revealed that GHG emissions
could be reduced by 33 million metric tons of CO_2 equivalents per year
(MtCO_2 e/yr), if GM crops were grown in the EU. This is the equivalent
of 7.5% of total EU agricultural GHG emissions in 2017. For the 5 major
GM crops identified for the study, COC makes up more than 84% of the
total potential avoided GHG emissions than PEM. This emphasizes the
importance of considering COC when estimating the climate impacts of
agricultural production and policy changes. The researchers then
hypothesized that as crop biotechnology research continues, a wider
variety of traitswill become available, each with different yield
impacts. New gene technologies will also likely expand the diversity of
desirable trait combinations. Thus, larger yield increases in more crops
may lead to increased GHG emission reductions. They concluded that their
estimate of 33 MtCO_2 e/yr may only be a small fraction of the global
potential future benefits of GM crops for climate change mitigation.

The climate benefits of yield increases in genetically engineered crops
| bioRxiv [www.biorxiv.org]