Greenhouse gases from biofuels and the reporting of science

You may have read that a study by Nobel Prize winner Paul Crutzen and colleagues currently under review reports that biofuels, like corn-base ethanol and rapeseed biodiesel, emit more greenhouse gases than the fossil fuels they replace. It was covered by Reuters, the Times (UK) and the magazine Chemistry World (update: podcasts available on Scitizen). The news then bounced all over the internet, appearing in Grist, Green Car Congress, and a number of blogs like Alternapower, Green Diary, Biofuels Digest, Climateer Investing, Earth2Tech, Big Biofuels Blog, Classically liberal, After Gutenberg, Digital Journal, I could go on.

The paper, submitted to Atmospheric Chemistry and Physics, uses a global budget of the sources and sinks of atmospheric greenhouse gas nitrous oxide (N2O), which originates in part from nitrogen fertilizer use, to estimate a rate at which N2O is emitted in the production of biofuel crops like corn, rapeseed (canola) and sugarcane. N2O is a much less common greenhouse gas than CO2, but has each molecule has a greater “warming” effect. The authors then contrast the global warming potential of N2O in growing the biofuel crop with that of the CO2 saved by replacing gasoline use. Their results suggest that corn ethanol and rapeseed biodiesel would lead to a net “warming” from the N2O emissions alone.

The problem is, as I was quoted as saying in the Chemistry World article, is that their method and their results are probably wrong. The paper is still under review and many of the comments on the paper, including my own, disagree with both their methods and their conclusions about a net “warming” from N2O emissions.

Let me be clear before continuing: this is not to say that the production and use of biofuels like corn ethanol will certainly emit far fewer greenhouse gases than the production and use of regular gasoline. A number of studies (Farrell et al, 2005) have concluded that when you include the entire production cycle, corn-based ethanol is either a small “win” or possibly a small loss. Either way, these other studies are including all sources of emissions during production, including operating the machinery, producing the fertilizer, processing the grain, and the N2O from fertilizer use. The Crutzen et al. paper reports that the N2O emissions from fertilizer alone makes corn-based ethanol and rapeseed net losers in the emissions reduction game.

Here’s the central science problem: The paper’s global budget analysis leads to the conclusion that 3-5% of nitrogen fertilizer is eventually emitted to the atmosphere as N2O, more than twice the rate of 1-2% found in all previous research. There is no actual physical evidence for the 3-5% result. The budget analysis used to determine that figure is interesting and clever, but it is fraught with problems (for more, I refer you to the comments). The take home message is that if you substitute the lower value, as most of us would, the basic conclusions of the study change.

The larger problem with this story has less to do with the science than with the reporting of science. You no doubt noticed one key phrase in the leading paragraph of this post. Nobel Prize Winner. That jumps out, no? The revered status implies this is research we should trust.

There is one other phrase you are unlikely to have noticed above. Under review. You see, the study in question has not been accepted for publication. It is under review with the journal Atmospheric Chemistry and Physics. That is important. It means that the journal and the reviewers, ostensibly assigned as representatives the scientific community, are deciding whether the methods are appropriate, whether the results can be falsified, whether the conclusions are sensible and whether the article as a whole is worthy of presentation in its submitted form.

The review process is key to science. It filters out fatally flawed research and helps authors improve a questionable paper by providing the judgment of outside experts. There’s no shame in reviews. All of us, whether graduate student or Nobel Prize winner, need them. Safe to say every paper I’ve published is better because of the input of anonymous peer reviewers.

In this case, that process is still underway. But that's where things get screwy. Unlike other journals, where submitted articles are sent to individual expert reviewers selected by the editors, APC includes an open review process. That means in addition to the normal peer review, anyone in the community can read the submitted paper online and offer comments. Personally, I like the system, as it gives authors a wider array of reviews and helps eliminate the chances that one irrational reviewer will derail a good piece of research.

The unintended consequence of the open discussion, however, is that an unpublished, and hence, unfinished paper is there for anyone to read. The paper can be reported in the media and the public can get the mistaken that the findings are accepted by the scientific community.

Science reporting is often a game broken telephone – I’ve argued about this before. As stories move from one medium to the next, the context fades away, the caveats are dropped, the uncertainty disappears, and we are left with just a headline.

If you look at the comments on the paper, you’ll see that several scientists have produced well-referenced arguments questioning the methods and the conclusions. The reporter from Chemistry World spent the time to speak with the critics. So the subsequent article presented not only the results of the study, but the controversy over the methods and the specific critiques of the scientific community.

But Chemistry World begat the Reuters and the Times. There, the context was reduced and the criticism of other scientists was gone. Reuters and the Times begat many, many more children, which spread like good little soldiers over the internet. In many cases, now even the context was gone, leaving us with just a headline: Biofuels are worse than gasoline.

This is also an example of what New York Times science reporter Andrew Revkin famously calls the tyranny of the peg (see Matt Nisbet’s discussion in reference to hurricanes and climate change). The peg is the “new study”, in this case a big strong peg, as it is a “new study by Nobel Prize winner”. The tyranny is that instead of a more democratic story about greenhouse gas emissions from biofuel production, including a full reading of the research, we get a linear story just about the latest study.

Think about this. Anyone writing about biofuels and GHG emissions, whether for a science publication, a general interest publication or even a small blog, knows that there have been a number of published studies comparing emissions from biofuel production with emissions from gasoline since those studies also received media attention. So before pounding this particular peg into the ground, there was one obvious question that should have been asked:

How could the N2O from fertilizer offset the GHG reductions from cutting gasoline use, if other studies accounting for GHG from all aspects of biofuel production, including N2O from fertilizer, found that biofuels were, at the worst, a wash with traditional gas? What, then, has this study done to find such a dramatically different result? And how is the scientific community responding?

I’m not advocating for or against biofuels, that's not the point of this post. Nor am I advocating for or against the open review process. I’m asking that we all stop, breathe and think a little bit before reporting new results. Resist the peg.