Climate scientists and evolutionary biologists love Bill Nye.

Keith Kloor, at his Discover blog Collide-a-Scape, describes him as a “stalwart defender of evolution and climate science” who “relishes verbal debate” and has “become known for taking on creationists and climate skeptics.”

But Nye hasn’t fared nearly as well with defenders of genetically engineered foods. According to Kloor, a 2005 episode of Nye’s television show that looked at genetically engineered crops split defenders of GMOs, some of whom thought he mischaracterized the science while others thought he was right to address the fears.

Kloor isn’t terribly fond of Nye’s position on GMOs, although he mostly criticizes Nye for sins of omission. He quotes a recent reddit exchange in which Nye wrote, in part, “I stand by my assertions that although you can know what happens to any individual species that you modify, you cannot be certain what will happen to the ecosystem.”

That doesn’t strike me as especially controversial, but Kloor was disappointed:

Hmm. It’s interesting that Nye doesn’t bother to express disapproval at the incessant fear-mongering and misinformation that has polluted the public discourse on GMOs–a main point raised by the questioner. Nye could have acknowledged this unfortunate state of affairs and even perhaps mentioned that all the world’s major science bodies and institutions have looked carefully at the technology and not found it harmful to human health or the environment. That alone would have meant a lot coming from someone with his stature. Instead, he avoids the main thrust of the questioner’s comment, invokes an absolutist version of the precautionary principle (rebutted effectively here in the case of GMOs) and closes with some odd remarks about malnourished fat people and an image of him stroking his chin.

Where Kloor writes that “all the world’s major science bodies and institutions” have concluded that agricultural biotechnology is not harmful, he links to a blog post in which Ramez Naam, who identifies himself as a computer scientist and futurist, talks about the safety of GMOs, and cites some of the science bodies that have evaluated the safety of GMOs.

The problem with Kloor’s post–and with many of the reports, blog posts, and reports reassuring us about the safety of GMOs–is that the science is always a little bit more complicated than the blanket assertions of safety would have us believe.

On Nov. 10, Kloor published an open letter to Nye from a plant scientist—Kevin Folta at the University of Florida, Gainesville. Folta wrote, “Over almost two decades, agricultural biotechnology has shown to safely and effectively aid farmers, and offers future promise to deliver higher quality food, more sustainably.”

There is the blanket assertion again: Twenty years of research, and all is well.

The link under “has shown” goes to a 2010 report by the National Research Council of the National Academy of Science. Naam cites the same report, entitled “The Impact of Genetically Engineered Crops on Farm Sustainability in the United States.” It is cited often, and it is often used as the cornerstone of arguments that genetically modified foods are safe.

But its findings are much more subtle and much more complicated than that. They are far from a blanket defense of GMOs.

Many of the key findings are favorable for GMOs, as summarized at the top of the report: “In general, the committee finds that genetic-engineering technology has produced substantial net environmental and economic benefits to U.S. farmers compared with non-GE crops in conventional agriculture.”

But the summary goes on. “However, the benefits have not been universal; some may decline over time; and the potential benefits and risks associated with the future development of the technology are likely to become more numerous as it is applied to a greater variety of crops.” Furthermore, “the social effects of agricultural biotechnology have largely been unexplored, in part because of an absence of support for research on them.”

That is far from a blanket assertion of the safety of GMO foods. And as the report breaks down the findings in more detail, it raises other concerns: The reliance on crops engineered to be resistant to the herbicide glyphosate is now reducing glyphosate’s effectiveness. The potential risk of engineered alterations moving to weeds may increase as the traits are introduced into more crops. The effect of genetically engineered crops on prices received by farmers “is not completely understood.” How the use of GMOs affects non-GMO producers has “not received adequate research.”

And this:

Research on the dissemination of earlier technological development in agriculture suggests that favorable and unfavorable social impacts exist from the dissemination of genetic-engineering technology. However, these impacts have not been identified or analyzed.

I’m cherry picking the negative findings; most were positive. But the point I’m making is that we should not characterize this report as showing that GMOs are safe or that all of the necessary research on GMOs has been done.

Science writers would do well to be careful when they characterize this and other reports on the safety of GMOs. It’s fine for Kloor and others to question Bill Nye, or me, or anyone. But Nye’s beliefs or statements are not the main issue. What’s important is not what he thinks, but that when we write about GMOs, we get the science–and the qualifiers–right.

-Paul Raeburn