Author response to GMO Pundit David Tribe

Points in brief:

  • A recent peer-reviewed long-term analysis of North American and Western European staple crop agriculture provides evidence of sustained higher yields and lower pesticide use in Western Europe.
  • Conclusion was that Western Europe has been able to better focus its innovation strategy on the kinds of biotechnology – both germplasm and crop management – that are needed to transition to a more sustainable high yield agriculture than has North America. A notable difference between strategies is the adoption of GM in North America but not in Western Europe.
  • A non-peer reviewed blog article by David Tribe challenges a subset of the findings on the period 1996-2010. Here Chris Preston and the blog author argue that North American yields in GM maize and canola were comparable or superior to non-GM in Western Europe.
  • The blog analysis is flawed because it is based on too small a number of years to be statistically reliable. This is clear when one includes the newly released data for 2011-2012 in their analysis and sees the significant impact one more year has on small data set used the Preston/Tribe findings. Further, the blog author cannot from the small dataset indicate what component of the normal annual yield gain comes from GM.
  • The blog has not provided a convincing counter argument on yields, has not challenged the data on germplasm contraction in the US or the findings of better pesticide use management in comparable European countries.

In a recent peer-reviewed publication, we looked at yield and pesticide use trends in staple crops from two similar modern agroecosystems, North America (US and Canada) and Western Europe (region defined by FAOSTAT).

We analysed yield data in corn/maize, rape/canola and wheat, crops that are grown in both regions at large scales. Our findings were consistent for all three crops. Over the 50 year period we found that the “biotechnology package” (which includes options in germplasm improvement and management approaches) that comes from the Western European innovation strategies in agriculture result in higher yields than those achieved in North America. The robust trends indicate that this will continue. Yield improvement was not due to higher pesticide use because countries such as France have used comparatively less of both herbicides and insecticides per area under production than countries such as the US.

An obvious difference between the two regions is that the North American innovation strategy was compatible with a switch from conventional to genetically modified (GM) crops adopted in the mid 1990s. Western Europe has and continues to raise yields and reduce the use of pesticides without GM. A recent re-examination of our results reported by “Gmopundit” (aka David Tribe) on his blog challenges our findings that GM has been either ineffective at, or unnecessary for, achieving higher yields. He has not, however, attempted to refute our findings of lower pesticide use compared to modern agriculture practiced without the use of GM.

Tribe’s article shows graphs of maize and canola yields in the US and Western Europe for the years 1996 to 2010. For these short periods the linear regressions are marginally in favour of the US. It is well known that small datasets composed of data from arbitrarily selected years can be misleading because they by chance capture runs of years that contradict long-term trend lines. That is why our analyses used the entire dataset – to avoid bias from picking and choosing years to suit our argument.

To illustrate this, by picking a choosing a small number of years we can also change the outcome of Preston and Tribe’s limited analysis. By incrementally adding newly available data on US yields for 2011-12 and Western Europe for 2011 to their small dataset, the trends change again to Western Europe’s favour (Figure 1). This is why we based our analyses on the 25 and 50 year datasets that are available.

Figure 1 Figure 1. What a difference a year makes!
Small datasets are susceptible to high variability and can therefore mislead. When plotting the linear regression of maize yields by agroecosystem to establish trend lines over the short interval beginning in 1996 (year preceding first GM maize plantings in the US), the apparent slope of the line changes dramatically with the inclusion of just one year of data. Compared to Western Europe’s increase in yields by year (black line), the US looks to be increasing yields faster [slope of orange (1996-2011) and green lines (1996-2010)] and much slower [slope of red line (1996-2012)]. The variability in this short dataset is reflected in the poor R2 values calculated from all of the regressions.

Using only data from 1996 onwards as Tribe and Preston did has other problems, including using many years of very low GM maize production (~8% in 1997 to 47% in 2004). The sum total of US GM maize by 2010 was <50% of the maize produced between 1996 and 2010, even if it reached 86% of annual production in 2010. The 1996-2010 dataset is far too small to extract credible evidence of a GM contribution to maize yield above normal breeding gains which would dominate in their time period. The same point applies to the dataset for GM canola.

Figure 2
Figure 2. Cumulative GM maize production in US.
Until 2005, more than 50% of the maize crop in the US was conventional. Thus, over 50% of all the GM maize ever grown in the US has been produced only in the last 5 years.

Seventy-five percent (75%) of the GM maize in the US has been produced since 2005 (Figure 2). During the eight years 2005-2012, yield actually declined (y=‑1423x+3e6) in the US but was increasing in Western Europe (y=2521x-5e6; latest data to 2011 but 2012 is projected to look even better for Western Europe). Ninety percent (90%) of the GM maize in the US has been produced between 2001 and 2012. When we consider this period, annual US yields are nearly static (y=153x-214675), but in contrast Western Europe increased more than 10 times the US rate (y=1695x-3e6). In other words, following the Preston/Tribe approach of concentrating on periods when the US was growing essentially all the GM corn it ever has, the yields are decreasing or static, while Western Europe’s yields increased dramatically over these periods.

As these short-term trends are likely influenced by the 2012 drought in the US, these examples show how unreliable it is to use short time frames for analysis.

The long term trend lines suggest that if any contribution to yield comes from GM, it is very small, unnecessary (given Western Europe’s equal or superior yields) and purchased with comparatively more pesticide use.
The conclusion we drew was that GM crops are not the problem. Instead they are a symptom of a long-term innovation strategy in North America that is not advancing a biotechnology package that both increases yield and reduces pesticide use - characteristics of a future agriculture that we all want.

One might ask then whether GM crops just need more time to demonstrate their value to a sustainable agriculture. If there hasn’t been enough time to prove the benefit of GM products, then how come there is such a strident advocacy of the benefits? For example Nina Fedoroff said that “The science is quite clear” already on the benefits of GM crops and that “The reason farmers turn to genetically modified crops is simple: yields increase and costs decrease.”

And if there has been sufficient time to demonstrate their contribution to North America, as Tribe’s blog implies, then we should legitimately ask why an innovation strategy compatible with GM is preferable to an innovation strategy that instead promotes more farmer participation, less monopoly control of inputs, higher yields and less chemical pesticide use.

Confronted by increasing challenges to the supremacy of the US biotechnology model, advocacy for GM has started to morph into a soft sort of “GM is one of several important tools that need to be explored” or “If future food needs are to be met, the world will need every tool in the toolbox including organics and GM.” On this we agree. However, it is deceiving to equate genetic engineering as a tool in research and development on the one hand with a GM plant as a tool in farming on the other. The latter is a product that in the complex socio-economic context of agriculture can displace other better products. It can also bias both the public and private research and development pipelines because of a GM product’s better fit with strict intellectual property rights instruments that are attractive to big capital.

We think that we need to stop wasting time on debates over marginal technologies and start talking about innovation strategies that work best for a sustainable agriculture.

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