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What are the Environmental Costs of Moving Toward Lower Yielding Cropping Systems?

Here are the conclusions from an article just published online in the American Journal of Agricultural Economics

Crop yield development will play a critical role in future land use dynamics. Indeed, it will determine the requirements for additional cropland, and also have a strong impact on grassland expansion. We have illustrated that compared with yield stagnation, maintaining past trends in crop yield growth would save 290 Mha of cropland and avoid additional expansion of about 120 Mha of grassland by 2030. Our results suggest that failing to take into account the effects of livestock sector dynamics and the corresponding grassland requirements when assessing the effect on land sparing of increasing crop yield may lead to significant inaccuracy–a difference of 17% in our example.
With respect to GHG emissions, we show that by 2030 these would be lower by more than 2 GtCO2-eq per year if crop yields grew according to the past trends as compared to yield stagnation. Crop yield growth also seems to be a cost efficient way of abating GHGs, as the estimated R&D cost involved would be about U.S. $25 per tCO2-eq, while the marginal cost of reaching this target with stagnating yields would be U.S. $75 per tCO2-eq. However, to be effective as a mitigation option, crop yield increases need to be accompanied by policies that prevent further expansion of consumption in rich countries in order to avoid the potential rebound effects illustrated by Choi et al. (2011).
Overall, policies and investments targeting crop yield enhancement should be an important priority for the future of agricultural development (Herrero et al. 2010). Such measures could help to fight food insecurity, while at the same time contributing to climate change mitigation at a cost that is competitive with other mitigation strategies.

Assorted Links

  • I find it hard to take some of this writing seriously, but here is an interesting take on obesity “informed by feminist poststructuralist theory” which argues, among other things that:
Obesity science qualifies as ‘state science,’ to use Foucault’s term: it is a tangled web of government lobbies, academia and its research sponsors, service industries from the human genome sciences to multinational pharmaceutical and agribusiness complexes, the legal-juridical complex, and the insurance industry. Obesity science and its hegemonic norms have instituted a hidden political agenda through the very language and technologies deployed in the name of ‘truth.’ Obesity science and its dominant discourse act as a ‘fascist structure’

Efficacy of Fat Taxes and Thin Subsidies

Science News reported the following results from a recent study:

Taxes on soft drinks and foods high in saturated fats and subsidies for fruit and vegetables could lead to beneficial dietary changes and potentially improve health, according to a study by experts from New Zealand published in this week's PLOS Medicine.

and

The authors say: "Based on modelling studies, taxes on carbonated drinks and saturated fat and subsidies on fruits and vegetables are associated with beneficial dietary change, with the potential for improved health. "

My first reaction was "duh."  Clearly if you raise prices of (say sugar or fat) high enough, you will get people to eat less.  In fact, one way researchers often model a ban on a substance is by simulating what happens when the price gets high enough that no one buys the product.  

Thus, the key question isn't whether one can change consumption and nutrient intake with sufficiently high taxes or subsidies.  The better questions are by how much? and at what cost?  An even better question still: where is the market failure that would justify the tax or subsidy?  The answer to that last question is actually much less obvious than most public health professionals presume (see here or here).

On the former question of how much?, let's turn to the original study mentioned at the first of this post.  The study is actually a literature review, pulling together the findings of previously published papers (including one that I co-authored).  Below is a graph showing some of the key results from different studies simulating how much change in consumption (or energy intake) would occur from a change in the price of a good. Pay attention to the scale of the vertical axis.  My take (see the middle chart) is that it would take very large price changes to get energy consumption to change by much (a 20-40% increase in price results in a 0.2-0.4% reduction in calories consumed).  

Stated differently, these sorts of policies are likely very costly in achieving the desired health outcomes.  Moreover, we must ask why - if these health changes are really so inexpensive and beneficial - people are not already voluntarily making them?

fattaxelasticities.JPG

Pesticide Facts

Over at his NYT blog, Mark Bittman weighs in on pesticide use in agriculture. It is really hard to know where to start to address the misnomers that are raised in his piece. Let me begin by saying, however, that no one (including myself) likes the thought of eating pesticides in food. But, we need to put things in perspective. Here are some UC Berkeley scientists:

We estimate that about 99.9% of the chemicals that humans ingest are naturally occurring. The amounts of synthetic pesticide residues in plant foods are low in comparison to the amount of natural pesticides produced by plants themselves.
Bittman begins by saying:
After the publication of “Silent Spring,” 50 years ago, we (scientists, environmental and health advocates, birdwatchers, citizens) managed to curb the use of pesticides[1] and our exposure to them — only to see their application grow and grow to the point where American agriculture uses more of them than ever before. And the threat is more acute than ever.
But if you click on the link he actually provides in the quote, you'll find front and center from the EPA that:
Total pounds of U.S. pesticide use decreased by approximately 8% from 1.2 to 1.1 billion pounds from 2000 to 2007.

Similarly, if you look at the USDA, you'll find that:

In 2007, roughly 877 million pounds of active ingredients were applied to U.S. cropland at a cost of roughly $7.9 billion. In comparison, in 1980, roughly 1.1 billion pounds of active ingredients were applied at a cost of roughly $7.1 billion (in inflation-adjusted dollars). During 1980-2007 the aggregate quantity of pesticides applied in the U.S. declined at an average rate of 0.6 percent per year
So, it appears the entire premise of the piece is off base. Still, I will briefly remark on some of the other claims raised in this piece:
  • Even if pesticide use were increasing (which according to the above it is not), you have to keep in mind that not all pesticides are created equal. The pesticides farmers now use include much more glyphosate (think Round-Up) than they once did, which is less toxic and environmentally damaging than options they use to use (think atrazine).
  • I agree integrated pest management (IPM) is a promising alternative and it is one that many farmers and food processors are already, voluntarily, pursuing because it can be profit enhancing. Pesticide resistance is a problem - always has been, always will be. Calling something a "superweed" makes it sound as if this is a new problem but it isn't. IPM can help mitigate resistance issues.
  • The piece tries to link trends in pesticide use with autism and IQ. Has anyone heard of the Flynn effect? IQ is rising not falling.
  • It is true that organics tend to (on average) use fewer total pesticides. But it is simply not true that organic farmers can't use pesticides. They can use "natural" pesticides like copper and sulfur, which are more toxic than many synthetics. There is really no way to tell when in the supermarket whether the organic has more or less pesticides than the non-organic.
  • If you want to read a really nice account about pesticide risks in food, see Bjorn Lomborg's book. There you'll find lots of data and statistics showing that the relative risks of food pesticides are very small in the grand scheme of things. Moreover, he shows that the bigger cancer risk is not ingesting too many pesticides but rather not ingesting enough fruits and veggies.
  • On an acre-per-acre basis, which commodities are the biggest users of pesticides? You might be surprised to find out that it is not corn, soybeans, or wheat but rather fruits and veggies like lemons, strawberries, etc. It is true that more pesticide is used in corn than strawberries but that's only because we grow a lot more corn than strawberries. If you look at pesticides per acres planted, a much different picture emerges.