Although many papers have been published claiming that genetically engineered (GMO) foods are harmful and that humans aren't changing the climate, not a single one of them stands up to rigorous scientific scrutiny.
With the recent uptick in extreme weather events around the world — exemplified by catastrophic flooding in Nigeria, Houston and India, all in the same week, followed by multiple hurricanes in the Atlantic — climate change is back in the headlines, and with it a resurgence of skeptical claims denying the existence of an international scientific consensus on global warming.
Responding to these denials, and allegations that skeptical research papers have been “suppressed” and thereby prevented from being published in scientific journals, climate scientist Katharine Hayhoe responded with a Facebook post pointing out that numerous studies purporting to falsify the mainstream view of global warming have in fact been published over the last decade.
Hayhoe wrote that "over the last 10 years, at least 38 papers were published in peer-reviewed journals, each claiming various reasons why climate wasn't changing, or if it was, it wasn't humans, or it wasn't bad. They weren't suppressed. They're out there, where anyone can find them."
However, she also pointed out that when analyzed from scratch, "every single one" of the skeptical papers "had an error — in their assumptions, methodology, or analysis — that, when corrected, brought their results into line with the scientific consensus."
In support of her statement Hayhoe pointed to a paper that she co-authored in 2015, entitled "Learning from mistakes in climate research" and published in the journal Theoretical Applied Climatology. The lead author of the paper was Rasmus Benestad, of the Norwegian Meteorological Institute in Oslo, Norway.
Benestad, Hayhoe and colleagues developed an open-source analytical tool to replicate and test the results and methodologies of these 38 selected climate-skeptic papers, thus revealing "a pattern of common mistakes." These included ignoring inconvenient contextual information or “cherry-picking.” For example, one study made recent climate change look like it fitted natural cycles only by throwing out 6,000 years of inconvenient data.
Other errors arose from biased or inappropriate experimental setups, false dichotomies (such as the implication that any identification of natural climate cycles must necessarily invalidate human influence on climate) and the use of inappropriate statistical methods.
Climate change is not the only area of controversy where skeptical studies challenging scientific consensus have received great play in the media and among ideologically-motivated interest groups. GMOs offer another example of where an international scientific consensus that genetically engineered crops are no less safe than their conventional alternatives is constantly challenged by anti-GMO activists.
Echoing the 2015 paper on climate skeptical analyses, a review of GMO skeptical literature published by two biologists last month similarly concludes that studies purporting to show that genetically modified crops have health dangers suffer from numerous methodological flaws and statistical errors which likely invalidate their claims.
Writing in Plant Biotechnology Journal in a paper entitled "Characterization of scientific studies usually cited as evidence of adverse effects of GM food/feed," Miguel Sanchez and Wayne Parrott analyzed in detail 35 papers published in scientific journals, all of which purported to show health risks arising from genetic modification. These papers were selected because they had either been cited in scientific reviews, or had been highlighted on anti-GMO websites such as GM Free USA and GM Watch.
One point of note was that many of the studies were written or co-authored by the same people. Altogether 87 percent of the GMO-skeptical studies came from just two groups based in Italy. Giles-Eric Seralini was another name appearing on more than one paper. Although all 35 papers declared no conflicts of interest, Sanchez and Parrott found on closer examination that "fewer than half" actually had no financial or professional conflicts of interest. Most were supported by anti-GMO activist groups, organic interests and even Greenpeace. This is analogous to the conflicts of interest alleged for some climate-skeptic authors supported by the fossil fuels industry.
In terms of their scientific quality, Sanchez and Parrott found that all the papers they analyzed violated "at least one of the basic standards for assessment of GM food/feed safety." Like the climate-skeptic studies, these primarily involved the inappropriate use of statistics, including changing statistical tests in the midst of an experiment to try to get a more desirable result.
Most animal feeding studies had insufficient controls, and the GMO/non-GMO diets fed to animal groups were mostly not nutritionally analyzed, making any purported comparisons meaningless.
Many papers also misrepresented the literature that they cited, claiming negative effects from genetic modification when the original authors had drawn no such conclusions. In addition, virtually all the GMO-skeptic papers were published in low-impact journals, sometimes in journals that have no listed impact factor because they rank as predatory or “pay-for-play” and do not have any real peer review.
Several studies claiming to find negative effects on animals consuming diets of genetically modified feed have been retracted by the journals that published them (these were not included in the 35, having been retracted). Seralini's 2012 paper claiming that rats fed with GMO corn suffered tumors is a notorious example. One of the prolific Italian groups had two of its papers retracted amidst allegations of fraud when it was found that digital images had likely been repeated and touched up.
It should be emphasized that neither the climate nor the GM-skeptic studies are very numerous in the context of the overall literature. According to Sanchez and Parrott, the 35 GM-skeptic papers they assessed "represent fewer than 5 percent of all published studies assessing GM food/feed safety."
Following the conclusion of a 97 percent consensus on climate change, the 38 papers that Benesdad and co-authors selected can be seen as an attempt to look at the remaining 3 percent. However, as with the GMOs study, the sample was picked selectively based on contrarian papers with high visibility rather than being statistically representative of the scientific literature as a whole.
After assessing the anti-GMO papers Sanchez and Parrott concluded: "Twenty years after commercial cultivation of GM crops began, a bona fide report of an adverse health effect due to a commercialized modification in a crop has yet to be reported."
A similar conclusion might be drawn with regard to climate change. No paper has yet been published that invalidates this conclusion: global warming is real, and humans are causing most of it.