The new Scientific American blog Science Sushi dispels some myths about large-scale organic agriculture. Here's one example:
Some people believe that by not using manufactured chemicals or genetically modified organisms, organic farming produces more nutritious food. However, science simply cannot find any evidence that organic foods are in any way healthier than non-organic ones – and scientists have been comparing the two for over 50 years.
Better for the environment does not necessarily mean better for you (or for the climate). Not that the environmental benefits are clear either:
Yes, organic farming practices use less synthetic pesticides which have been found to be ecologically damaging. But factory organic farms use their own barrage of chemicals that are still ecologically damaging, and refuse to endorse technologies that might reduce or eliminate the use of these all together.
It's worth a read.
Tuesday, July 26, 2011
Organic vs. conventional agriculture
Thursday, July 21, 2011
Climate impact of different foods
Earlier this week, the Environmental Working Group, a research and lobby group in DC, released a report on the “environment” and "health" impact of different foods. It found that lamb is the worst offender, followed by grain-fed beef, pork, cheese and farmed salmon.
The report was brought to my attention by a writer at the Huffington Post, who subsequently published this story which includes thoughts on the report a number of outside experts on the issue. I commented on the climate impacts of feed production and the logic of farming top-of-the-food chain fish like salmon, both issues that have been discussed frequently here at Maribo.
Here's a more complete list of my thoughts upon examining the short report:
1. “Environmental” impact or “health” impact can be very different than “climate” impact. For example, I’d expect lamb to be much lower on a list based purely on greenhouse gas emissions (i.e. per gram of food produced). I can't comment on "health" impacts as it is not my area of expertise.
2. What I call the “land use cascade” is potentially the largest contributor of greenhouse gas emissions from food production, but also the hardest to calculate. That’s why GHG emissions from dairy relative to beef cattle tend to be overestimated (more methane from dairy cattle, more land required to grow feed for beef than dairy products). It’s also why any study like this should have large positively skewed error bars.
3. All meat is not created equal in terms of greenhouse gases. Grain-fed beef is far less efficient than pork, which is again far less efficient than poultry.
4. If your food choices are motivated purely by concern about greenhouse gas emissions, eating less grain-fed beef is more important than eating locally.
5. Historically-speaking, we are just starting to develop industrial-scale farming of fish, as discussed in the recent Time cover story. Farming the ocean is, in a sense, thousands of years behind farming on land. Right now, many of the choices we are making are, as I put bluntly in the Huffington Post story, “stupid”. Cattle are logical choice for farm animals. They eat grass, so they are only one step away from the sun. Salmon are much higher up the food chain. That’s why many of us say farming salmon is like farming wolves or tigers – you need the whole ecosystem to support the one salmon.
Sunday, July 17, 2011
Eliminating the US corn ethanol subsidy is no panacea
One possible casualty of the endless U.S. budget fight may be the federal subsidy for corn ethanol production. There's been a lot of quiet, and some not-so-quiet, cheering from the environmental community, based on the premise that eliminating the subsidy will lessen nutrient pollution from growing so much corn.
In reality, cutting or repealing the 45-cents-per-gallon ethanol tax credit is unlikely to have much of an effect on planting decisions. As a recent article in the NY Times nicely explained last week, the subsidy is, at this point, unnecessary. Between laws requiring blending of ethanol into gasoline, the federal ethanol mandate, the tariff on imports, the size of the ethanol production industry, and the high price of corn, there's already enough incentive to maintain the status quo in corn production and corn ethanol production.
There are certainly good reasons to eliminate the subsidy. No one should pretend that doing so will solve of the problem of nutrient levels in the Mississippi River and the Gulf of Mexico. That is a far greater challenge.
Monday, July 11, 2011
Farming the sea
Especially troubling, many of the most popular farmed species are carnivores, meaning they need to be fed at least partly with other fish. By one count, about 2 lb. of wild fish ground up to make fish meal is needed on average to produce 1 lb. of farmed fish, which leaves the ocean at a net loss.
I've written about this before: A substantial proportion of the wild harvest is used to maintain marine aquaculture of carnivorous species like salmon. It is wildly inefficient, the marine equivalent of farming wolves rather than herbivorous cattle. This is why many experts conclude that the future for pescetarians is probably the blander, lower-on-the-food-chain species like tilapia and catfish.
In coverage of aquaculture, we tend to focus on the sexier and scarier subjects: pollution from farms, genes mixing with the wild population, PCBs in farmed salmon, etc. Certainily, no doubt, these are all serious concerns (except perhaps the PCBs). But the feed-to-fish ratio is the very core of the matter; if you get less fish protein out than you put in, aquaculture doesn't make a heck of a lot of sense.
Walsh gets to this central dilemma in the second half of the article:
When producers began raising fish intensively, they picked species that people like to eat: salmon and sea bass. But those species are high on the food chain, and raising them on a farm is a bit like trying to domesticate tigers. [ed - nice. I always say wolves] The aquaculture industry has gotten better at replacing fish meal with plant-based feed, but not fast enough. You're not feeding the world sustainably if you need to remove the base of the marine food chain to do it.
The solution that many propose is expanding the use of plant-based products in fish food. That brings it's own complications. For one, salmon certainly didn't evolve eating soymeal, cornmeal or wheat, so shifting to a majority plant-based diet will likely involve further genetic engineering, which has supporters and detractors.
And second, feeding plant products to fish would add another player in the struggle for the world's productive croplands.
Forget food vs. feed. Or food vs. fuel. In the future, it will be a battle of the 4 Fs: food vs. feed vs. fuel vs. fish.
Wednesday, March 30, 2011
Food prices and the ongoing biofuel debate
People worldwide are being affected by a rise in the price of food. The causes are complex and interacting: last summer's drought in Russia, the price of oil, speculative trading in commodities, economic instability, political unrest on the Middle East, you name it. As Tamino mentions, some people sceptical of efforts to reduce greenhouse gas emissions blame the increase in food prices on those efforts, namely the cultivation of biofuels like corn ethanol. Though I think Tamino's post misses the point of this debate.
The impact of corn ethanol, or an individual drought, or any other individual factor, on the price of a global commodity is very hard to quantify. The diversion of the U.S. corn crop to ethanol production over the past decade has undoubtedly affected food prices, despite U.S. government claims to the contrary. The various factors have interacting, nonlinear effects on the price of each commodity, and the commodity prices each affect the others, so it is hard to work out, say, a coefficient for each driving variable. But that's not the problem.
The real problem with any "climate change mitigation = more corn ethanol = higher food prices" argument is the first part: the claim that producing corn ethanol is addressing climate change.
In reality, the use of ethanol from corn as a fuel might actually result in greater greenhouse gas emissions than the use of gasoline, because of the land and energy required to grow the corn, harvest the corn, and convert the corn to ethanol. As such, the primary motivation for the expansion of corn ethanol production in the US is not climate change. Ethanol production is about appeasing regional interests, maintaining of the agricultural subsidy system and reducing reliance on imported fuels, probably in that order.
The only reason that corn ethanol gets promoted by politicians in the U.S. as a solution to climate change is that in the current political atmosphere, very few actual climate change mitigation proposals can pass, and because of some effective lobbying and the power of the Presidential primary process, expanding corn ethanol production looks like climate change mitigation to the public.
Throw out the word biofuels and people might think action is being taken to address climate change. Look at the acutal conversion efficiencies and total lifecycle greenhouse gas emissions of the current feedstocks in the U.S. and you find a different story.
There is definitely reason to be concerned about the market effects of diverting so much of the U.S. corn crop to ethanol production. The real key to the story, the one to to look for in the coming months, is the price of meat. The majority of cereals and oils, the commodities for which the price has spiked the most, are used to generate animal feed. If you look back to 2008, you’ll see that the price of meat is likely to spike next.
This dynamic demonstrates the real battle we face in the future. It’s not food vs. fuel, it is feed vs. fuel. If the world wants to keep using the most productive croplands to provide biofuel feedstocks, we had better be prepared to eat less or much more expensive meat.
Sunday, July 05, 2009
Abuse of science and logic by the National Corn Growers Association
The National Corn Growers Association released a report arguing that there is no connection between the use of nitrogen fertilizers on corn in the Midwestern US and the seasonal “Dead Zone” in the Gulf of Mexico.
There is no point mincing words about what this “analytical white paper”. It is the corn equivalent of irrational climate change skepticism. This is one truly shoddy piece of work. I encourage others in the scientific community to respond either independently or to append the critique offered here.
First, let’s review the actual science.
The “dead zone” in question, discussed many times before on this blog, is generated most summers on the continental shelf of the northern Gulf of Mexico. Nutrients originating in the Mississippi River Basin in the spring fuel the production of algae (primary production) in the surface waters along the continental shelf. The algae die and sink to the bottom, or something else eats the algae and the fecal matter from the something else sinks to the bottom. All that organic matter needs to decompose, and the process of decomposition (respiration) consumes oxygen. So the bottom waters on the continental shelf during the summer become very depleted in oxygen, or “hypoxic”.
Scientific research over the last few decades has shown that the increase in nitrogen flow from the Mississippi and neighbouring Atchafalaya Rivers since the 1950s has driven the development of these large seasonal periods of hypoxia. The evidence comes from basic ecological theory on nutrient limitation, lab experiments, tracking of the Mississippi River plume, long-term data analysis, sediment cores, isotopic analysis and mathematical modeling. While other nutrients like phosphorus and silica are important, nitrogen is the primary culprit.
There are many possible explanations for the increased flow of nitrogen out of the Mississippi-Atchafalaya River Basin (MARB) including fertilizer use, manure use, NOx emissions from cars and sewage. A simple nutrient budget shows nitrogen fertilizer use in the MARB has increased 20-fold since the 1950s. And today, most of that nitrogen fertilizer is applied to corn fields. Measurements and mathematical modeling of nitrogen loss from corn fields show that corn production is a primary source of nitrogen to the Mississippi and Atchafalaya Rivers, and hence, a primary driver of the development of what's come to be called the “Dead Zone”.
The author of the NCGA report (from the consulting firm StrathKirn Inc.) attempt to counter the mass of scientific evidence with the following largely baseless and unscientific arguments. Basically, he throws a bunch of stuff at the wall to see if anything sticks. I’ll go one by one through the report's chain of five incorrect and comically inconsistent assertions:
Assertion #1: Oxygen levels on the continental shelf are not low in comparison to other parts of the ocean.
This is misleading and irrelevant. First, the large regions of upwelling in the open ocean have low oxygen concentration due to high primary production. There’s no sense in contrasting the naturally and persistently low oxygen levels in the eastern Pacific to the intermittent, seasonal hypoxia on the continental shelf of the Gulf of Mexico. Second, even if there were some sense in this comparison, the data resolution of these maps is far too poor to capture a hypoxia area, which, while among the largest in the world, is still at its largest on the order of 20,000 km2 [here’s a test – can you clearly delineate New Jersey on that map?]. The global map of marine nitrogen concentrations is even more ridiculous. The data is far too coarse to capture the plume of the Mississippi River.
Assertion #2: Hypoxia doesn’t affect the fishery (not there is any hypoxia).
The report shows no change in fish catch over the years. As Steve Carpenter of the University of Wisconsin mentioned in an e-mail, the problem is the report analyses data on fish landings, not fishing effort. The boats may come back with the same weight in fish – but it takes more time and money to get those fish.
Assertion #3: Nitrogen from the Mississippi and Atchafalaya doesn’t cause the hypoxia (not that the hypoxia affects the fishery, or that there is any hypoxia in the first place).
This argument is advanced through a series of graphs relating annual nitrogen export, annual river flow and the annual extent of the hypoxic zone. There are a number of problems here. The nitrogen and flow data are shown only since 1985, despite data existing back to the 1950s. If the graph went back thirty years, you’d see the 2-3fold increase in nitrogen export occurred between the 1950s and the 1980s. Instead, the author reports no evidence of a trend in nitrogen of hypoxia since 1993. That’s not the issue – the issue is the hypoxic zone began growing large in the 1980s because fertilizer use increased between the 1950s and the 1980s, and further increases in corn planting, say for ethanol production, may further increase the average annual extent of hypoxia.
The other glaring problem with this argument is that the report uses no statistics whatsoever. For example, after a chart of nitrogen export and hypoxia extent since 1985 is this unsupported passage:
Again, there appears to be an association between water flow and the amount of nitrite (NO2) plus nitrate (NO3), but these do not relate well to the size of the hypoxic zone (except that they are all low in the year 2000). Thus, many of the statements about the relationship between water flow, nitrogen, and the size of the hypoxic zone are inaccurate.
Some actual statistical analysis, or frankly, just eyeballing the graph, would suggest that there is a significant relationship between the annual nitrogen export from the MARB and the annual extent of the hypoxic zone. It is not a perfect one-to-one relationship between nitrogen and the extent of hypoxia because of how the weather effects mixing of oxygen in the Gulf, the load of other nutrients and a myriad of other mitigating factors. If the author had done any research, they’d find proper statistical analysis and explanations in dozens of published papers, including this one of from my own work, a 2007 paper in Limnology and Oceanography:
Between 1985 and 2004, there is a significant relationship (r2 > 0.61) between midsummer hypoxia area and the May + June nitrate flux (Fig. 1). The strength of this relationship is limited by a number of other variables, including the advection of sub-pycnoclinal waters on the continental shelf, summer tropical storms that increase vertical mixing, recycling of N sequestered in shelf sediments during previous years, and the input of other nutrients such as phosphorus (Rabalais et al. 2002; Scavia et al. 2003; Wawrik et al. 2004).
Assertion #4: Not very much nitrogen is applied to corn (not that nitrogen causes hypoxia, or that hypoxia affects the fishery, or that there is any hypoxia in the first place).
The report displays a graph illustrating that non-crop uses of nitrogen fertilizer, like fertilizer used on lawns, is equal to or greater than the use of nitrogen fertilizer on corn. The problem, or I should say, the most glaring problem? It is national data. Over 90% of the corn grown in the US, and over 90% of the nitrogen fertilizer applied to corn in the US, is grown in the MARB. A 1999 EPA report estimated that non-agricultural fertilizer use is only 5% of total U.S fertilizer use - and that percentage of total fertilizer use in the major producing states of the Corn Belt.
Assertion #5: No nitrogen runs off of corn fields (not that much nitrogen is applied to corn, or that nitrogen causes hypoxia, or that hypoxia affects the fishery, or that there is any hypoxia in the first place).
The report proudly claims that the same amount of nitrogen is now removed during the corn harvest (i.e. in the grain) than is applied as fertilizer, so there can’t be any extra nitrogen left over to run off into the river. Fertilizer use efficiency has indeed increased over the years thanks to genetic technology and improved management. In other word, farmers are getting higher yields with the same amount of nitrogen fertilizer. That is positive news.
But the calculation in the paper is full of flaws. To name just one: the contention that fertilizer inputs = crop outputs = no nitrogen runoff only makes sense if fertilizer were the one and only source of nitrogen to the crops. For one, there is the mineralization of nitrogen in the soil – plant matter on the ground is naturally broken down by microbes, a process that released nitrogen from the plant matter to replenish the soil. This is a fundamental part of soil chemistry. The whole reason the Midwest is good land for growing corn is the high natural mineralization rates!
Final take-home message of the report: The US has a lot of golfers.
The report concludes that all other analyses are ignoring all the fertilizer applied to lawns and present maps and data to support this conclusion. The calculations are extremely suspect. First, the author assumes that the fraction of land devoted to lawns is greater in the MARB than in the rest of the country. Analysing the lawn data, eyeballing the national map, or simply reflecting about the fact that 4/5ths of the US population live outside the MARB, shows that this is a ridiculous assumption. Second, the report assumes that all the fertilizer not applied to corn, wheat, soybeans or cotton – which amounts to about 25% of annual fertilizer sales - is applied to lawns. This ignores all other crops grown in the United States, as well as all the fertilizer applied to rangelands and forests.
The report goes on to argue:
Since most lawns are cut and mulched there is relatively little removal of N, unlike the grain in corn. Consequently, a major portion of the N applied to lawns may be available for leaching… the net N available for leaching per acre is almost infinitely higher for lawns than from corn.
Not only does this argument incorrectly imply that no plant residue whatsoever is ever left behind after harvest to replenish the soil, it ignores the fact that unlike lawns, many corn fields are artificially drained by pipes or drainage tiles, such that excess nitrogen easily leaches to the nearest stream.
All told, the NCGA report is an embarrassment.
There are some legitimate outstanding questions about the nitrogen-hypoxia problem and definitely some legitimate critiques of the media coverage. In particular, the coverage often gives the mistaken impression that corn is the only source of nitrogen, that the hypoxic zone covers a large fraction of the Gulf of Mexico, that water at all depths is hypoxia, and that hypoxia is a permanent phenomena, rather than a seasonal occurrence. The NCGA could have issued on a report on those real concerns. Instead, it issued this dishonest mess of half-truths and pseudo-science.
Wednesday, February 25, 2009
Fuelling the future
In the latest issue of Momentum, a new magazine out of the University of Minnesota, I argue that "our cars aren't alone in needing a new diet". Here's the opening:
It’s been a tough couple of years for the public relations staff in the biofuels industry.
The production of biofuels from crops like corn has been blamed for everything from driving up global food prices and deforestation in the Amazon to depleting oxygen in the Gulf of Mexico (not to mention raising the price of tequila).
Even the basic purpose of today’s commercial biofuels production has been called into question.
A study by researchers at the University of Minnesota, published last year in the journal Science, found that if previously undeveloped landscapes are cleared for biofuels production, then those biofuels emit more greenhouse gases than gasoline and diesel. Policymakers and the public are now asking if it’s efficient or ethical to use croplands to feed machines rather than people.
There’s one obvious place to look for an answer. In North America, we have been feeding the majority of our crops to machines for decades. These elaborate, protein-producing devices are best known by their common names: cows, pigs and chickens...
Click here for the full article. Or continue after the jump.Eating animals is hardly new. Our nomadic hunter-gatherer ancestors relied on meat for a large proportion of their protein intake. But the advent of agriculture and rise in population after the end of the last ice age led humans to settle in villages and shift to a more energy-efficient, grain-based diet. Over time, meat would be reserved for those who could afford the land and workforce required to raise animals.
Diets in the developed world changed again with the discovery of fossil fuels, especially oil. This cheap source of energy allowed us to produce nitrogen fertilizers, transform crop genetics, fuel agricultural machinery and transport agricultural products around the world. Buoyed by high crop yields and newfound agricultural wealth, we began feeding large quantities of grain and oilseeds to our farm animals.
Today, the average American eats as much as 275 pounds of meat each year, up from 197 pounds in the early 1960s.
Feeding the literally billions of cattle, poultry and pigs now requires a large proportion of the world’s—and mainly America’s—croplands. More than two-thirds of the American corn, soybean, sorghum, barley and oats harvest is used to produce animal feed. That’s more than two-thirds of the fuel used to operate machinery, more than two-thirds of the agricultural chemical use and subsequent water pollution, and more than two-thirds of greenhouse gas emissions from croplands.
In the coming decades, the demand for both animal feed and transportation fuels is expected to rise sharply as Asia and the developing world become wealthier. According to the Food and Agriculture Organization of the United Nations, per capita meat consumption in China has doubled since 1990, and it could double again.
Can our agricultural system meet this increasing demand while also reducing greenhouse gas emissions, tropical deforestation and water pollution? The solution may be switching to more efficient machines.
Like the cars we drive, the animals we eat have wide-ranging efficiencies. Beef cattle are the SUVs of animal agriculture. Renowned energy expert Vaclav Smil calculated that the U.S. agricultural system uses 32 kilograms of feed to produce 1 kilogram of edible beef. Poultry is the fuel-efficient compact of the animal world, with around one-eighth the feed ratio of beef.
The good news is that Americans have been slowly shifting their diets from beef toward more efficient forms of food production. Since the 1970s, per capita beef consumption has decreased 20 percent, while per capita poultry consumption increased by 40 percent. And more and more Americans are forsaking beef or all meat out of health concerns.
A more aggressive move toward poultry, dairy and vegetable-based diets could greatly decrease the land, energy and fertilizer needed to feed the population. In turn, this change would decrease direct greenhouse gas emissions from food cultivation and nutrient pollution to waterways. My own research indicates that reducing beef consumption in American diets would also reduce nitrogen pollution in the Mississippi River and shrink the dead zone in the Gulf of Mexico.
Changing diets would also free up productive croplands for cultivating second-generation biofuels based on unfertilized grains, oil crops or grasses. This newly available land would help eliminate concerns that diverting productive croplands to biofuels cultivation causes the clearing of native vegetation and the release of stored carbon elsewhere in the world.
In a carbon-constrained world, food efficiency may be just as important as fuel efficiency.
Friday, August 15, 2008
Over 400 dead zones around the world (Science)
The latest issue of Science features a new review of the world's marine dead zones. Scientists have now reported over 400 regions of the coastal ocean like the Gulf of Mexico dead zone where nutrient pollution fuels the depletion of oxygen from the bottom waters, threatening ecosystem function and marine species. Most of these "hypoxic" - less than 2 mL of oxygen per litre of water - and anoxic zones arose in the last few decades due to nitrogen fertilizer use and associated intensive agricultural activities, and to industrial pollution.
The map below shows the dead zone along with a measure of the human footprint on land. The dead zones have also been plotted on Google Maps.
Wednesday, July 23, 2008
The conflict between ethanol and animal feed
The NY Times reports that at least one major livestock producing state is objecting to the use of corn for ethanol, because it diverts corn away from, and raise the price of, animal feed:
Gov. Rick Perry of Texas is asking the Environmental Protection Agency to temporarily waive regulations requiring the oil industry to blend ever-increasing amounts of ethanol into gasoline. A decision is expected in the next few weeks. Mr. Perry says the billions of bushels of corn being used to produce all that mandated ethanol would be better suited as livestock feed than as fuel.
This are exactly the type of conflict we wrote about in our study on corn-based ethanol production and the Gulf of Mexico "Dead Zone".
From the conclusion:
The land cover analysis in this study raises questions about the availability of land to radically increase ethanol or other biofuel production. Reaching the proposed biofuel production goals will lead to trade-offs between cropland demands for food, feed, and fuel, even when the use of ethanol coproducts as feed is considered. The mitigation scenario demonstrates that reducing the cultivation of animal feed, the majority domestic use of corn and soybeans (2), is one way of attaining the croplands necessary for biofuel production.
A sharp reduction in feed cultivation and animal production in the U.S. is purely hypothetical; it would require a substantial change in culture and the reduction of an industry that provides income and employment to a large number of Americans. However, given the probable ceilings on cropland area, grain yields and use of ethanol coproducts as animal feed, a gradual decrease in use of corn and soybeans for animal feed may be a necessary consequence of the projected increase in demand for biofuels.
Sunday, May 11, 2008
Shifting diets vs. eating local
I finally had the chance to read this terrific paper by Christopher Weber and Scott Matthews of Carnegie Mellon that compares greenhouse gas emissions from the production different types of food and the delivery of that food to your plate. As was reported by some news agencies and blogs, Weber and Matthews conclude that transportation represents only 11% - on average, it depends on the food – of the total life-cycle GHG emissions of U.S. food (there’s little reason to expect a dramatically different result in Canada).
The take home message is shifting your diet will do far more to reduce greenhouse gas emissions than buying local. From the paper:
The results of this analysis show that for the average American household, “buying local” could achieve, at maximum, around a 4-5% reduction in GHG emissions due to large sources of both CO2 and non-CO2 emissions in the production of food. Shifting less than 1 day per week’s (i.e., 1/7 of total calories) consumption of red meat and/or dairy to other protein sources or a vegetable-based diet could have the same climate impact as buying all household food from local providers.
The authors did some simple calculations to demonstrate this point:
To put these figures into perspective, driving a 25 mi/gal (9.4 L/100 km) automobile 12 000 miles/yr (19 000 km/yr) produces around 4.4 t CO2/ yr. Expressed in this manner, a totally “localized” diet reduces GHG emissions per household equivalent to 1000 miles/yr
(1600 km/yr) driven, while shifting just one day per week’s calories from red meat and dairy to chicken/fish/eggs or a vegetable-based diet reduces GHG emissions equivalent to 760 miles/yr (1230 km/yr) or 1160 miles/yr (1860 km/yr), respectively. Shifting totally away from red meat and dairy toward chicken/fish/eggs or a vegetable-based diet reduces GHG emissions equivalent to 5340 mi/yr (8590 km/yr) or 8100 mi/yr (13 000 km/yr), respectively.
It is important to note that macro-scale GHG “accounting” studies always come with a number of caveats. The calculations or model requires a number of simplifying assumptions and often some more complicated factors are often excluded. The two central limitations to this particular study appear to be the simple treatment of direct GHG emissions from animal and crop production (i.e. N2O from manure, fertilizer and the animals themselves) and the exclusion of land use impacts and the “land use cascade” (i.e. carbon released from directly or indirectly transforming land for crop or animal production). Improving those components of their mode should increase the share of GHG emissions from food production and the relative GHG emissions from red meat production. In other words, that provides even more support for the conclusion that eating less beef is one of the best ways to reduce personal greenhouse gas emissions.
Tuesday, April 15, 2008
Food prices and the use of corn
The rise in food prices is finally garnering serious attention from the media and from world governments. The latest NY Times piece has this precious quote from Senator Charles Grassley of Iowa:
“You make ethanol out of corn,” he said. “I bet if I set a bushel of corn in front of any of those delegates, not one of them would eat it.”
Never mind the fact that a bushel is more than 25 kg of corn, Sen. Grassley (in claiming that the diversion of corn for ethanol is not affecting food prices) rather accidentally describes the exact problem. We don't eat the corn. In the U.S., the majority of the subsidized crops corn and soybeans (~75% in our most recent look at the economic data) are used for animal feed. And it is the rise in demand for meat, together with biofuel demand, high oil prices and droughts overseas, that is driving up food prices.
Monday, March 17, 2008
Hypoxic zones around the world
The World Resources Institute and scientist Bob Diaz of Virginia Marine Institute have compiled a new map of the world's coastal hypoxia zones like the famous Gulf of Mexico "Dead Zone" we discuss in the recent PNAS paper on nitrogen pollution and corn production for ethanol. The new map includes 169 documented hypoxic areas, 233 are areas of concern and 13 areas in recovery.
Bottom-water hypoxia can develop when high input of nutrients like nitrogen promote the excessive algae growth. When algae eventually dies and sinks to the bottom, it decomposes, and that process depletes oxygen from the water.
It is worth noting hypoxia will not arise anywhere simply because nutrients are added. To get things started, you still need to feed the algae, and nutrient pollution does the trick. But certain
coastal areas are more naturally prone to hypoxia.
If, for example, the water column is highly "stratified", by that I mean less dense water lying above more dense water there is little mixing between the surface and the bottom waters (think of making a simple oil and vinegar salad dressing). It is then difficult for oxygen from the air to diffuse to the bottom and replace the oxygen consumed by decomposition.
The outlet of big rivers like the Mississippi can be ideal for hypoxia development because the fresh and therefore lighter water introduced by the river creates a stratified water column. That explains some of the year-to-year dynamics of the hypoxic zones like the Gulf Dead Zone. First, hypoxia development can be much worse in a wet or flood year because of the addition of more nutrients and the increased stratification. Second, if a hurricane blows through the Gulf, it encourages mixing just like you do by shaking that bottle of salad dressing, and can break-up the Dead Zone.
The new map supposedly includes only human-driven cases of hypoxia. Which raise the question, what is the cause of the zone between very sparsely populated Somerset and Cornwallis Islands in Nunavut, in the Canadian Arctic? If you have an answer, let me know.
Friday, February 22, 2008
Farming the land and the oceans
Last week's Science featured a fascinating global map of human impact on the world's oceans (top), produced by Halpern et al. The complicated mapping exercise concludes that 41% of the world's oceans are strongly affected by multiple human stresses.
The map is a fascinating - "stark" in the words of Science - aquatic sibling to the global agricultural land use maps that are generated by Navin Ramankutty and colleagues by blending satellite observations and agricultural data. 
The latest cropland and pasture land datasets (bottom) are described in a recent Global Biogeochemical Cycles paper entitled "Farming the Planet". The data shows that ~34% of the planet's ice-free land surface has been converted for human agriculture.
Unlike the ocean maps, the land use maps only reflect locations that has been directly transformed by human activity, and one form (agriculture) of human activity at that.
It'd be terrific to unite the scientists studying terrestrial and marine systems to create a ocean+land dataset of human disturbance that includes all forms of resource extraction on land (including agriculture).
Tuesday, February 12, 2008
Biofuels and the "land use cascade"
As readers of Maribo no doubt heard, two papers in last week’s Science addressed the greenhouse gas emissions that arise from clearing lands for biofuel crop production. It is an important subject that has been widely discussed within the scientific community, including my own collection of colleagues, for the past year or two. You might say these papers are the first to “do the math”. The papers conclude what many carbon cycle experts suspect: that any greenhouse gas benefits that come from using biofuels instead of oil are negated when you include the emissions associated with land clearing.
The publication of both papers at once is enlightening because they tackle slightly different, but complimentary, issues.
Fargione et al. address the direct emissions from the land cleared to plant the actual biofuel crops. The examples includes Brazilian Amazon to soybean biodiesel, Brazilian Cerrado to soybean biodiesel, Brazilian Cerrado to sugarcane ethanol, Indonesian or Malaysian lowland tropical rainforest to palm biodiesel, Indonesian or Malaysian peatland tropical rainforest to palm biodiesel, and US Central grassland to corn ethanol.
Searchinger et al. use a global economic model to look more at the indirect emissions. In the developed world, including Canada and the US , forests or grasslands are not being cleared to plant biofuel crops. Instead, biofuels are being produced on land previously devoted to other crops or from grain diverted from another use (i.e. corn grain goes to the ethanol plant rather than the boat shipping it overseas). The change has a cascading effect on the world market. There is less grain available, which can cause other countries to clear land to feed the market.
I like to call problems like that addressed in the Searchinger et al. paper “land use cascades”. There are countless examples -- one of the my favourites is the effect that the surge in soybean production in the US and Brazil in the 90s had on the Yasawa Islands in Fiji (I tell the whole story is here).
These cascades are becoming increasingly important, and increasingly global in scale. For example, the same thinking needs to be applied to forestry-based carbon credit programs. If a segment of BC coastal rainforest slated for logging is protected, does that mean some other forest must be logged to provide the missing pulp and paper? If so, what effect does that have on the net emissions? We may discover that net greenhouse gas savings only occur if we also reduce demand for the products that would otherwise come from that land either cleared (biofuels) or saved (forest carbon credits). More on that later.
Saturday, January 26, 2008
Greenhouse gases, meat consumption and the Amazon
The Sunday NY Times has a good story on the global environmental burden of meat production, an issue that's been covered here on and off over the past couple years. Meat production, particularly beef, is responsible for a large proportion of the world's greenhouse gas emissions due to the energy required to grow animal feed, the clearing of land for feed crops, N2O emissions from fertilizer application and both N2O and CH4 emissions from the animals themselves. The graph at right shows the consistent rise in per capita consumption in the Americas and Asia over the past 45 years. Meat production and consumption is expected to continue to rise due to rising demand in China and other parts of Asia.
The demand for animal feed, coupled the demand for biofuels, is being felt most of all in the Amazon, the one large area of "unused" and potentially productive farmland left on the planet. The rate of Amazonian deforestation increased in the last few months, and may increase further in the rainy months to come, when most illegal cutting usually occurs.
Monday, July 30, 2007
Dead Zone in Gulf is third largest since 1985
Though I'm reticent to link to any news article under the cable-TV-news-ish heading "Planet in Peril", CNN reports that this summer's Gulf of Mexico dead zone has been measured at about 20, 460 km2 in size. That makes it the third largest since measurement began in 1985.
The hypoxic zone was expected to be unusually large this year because of the high flux of nitrogen -- the nutrient that fuels the high productivity on the continental shelf that leads to the consumption of oxygen from the bottom waters -- from the Mississippi River this spring. The blame can likely be placed on the weather and possibly even the increase in corn planting (due to high prices / ethanol demand).
Now off to grab my cape. The planet is in peril.
Monday, March 05, 2007
Climate and the Gulf of Mexico "dead zone"
My colleague Don Scavia and I have an article in the latest issue of Limnology and Oceanography about the effect of climate on the development of the seasonal “dead zone” in the Gulf of Mexico.
I’ve written a bit about this issue before on Maribo. The intensification of agriculture in the central US since the 1950s – huge increases in nitrogen fertilizer use, planting of more nitrogen-fixing soybeans, drainage of wetlands, installation of artificial drains under fields – caused a 2-3 fold increase in the amount of nitrogen the Mississippi River delivers to the Gulf of Mexico. The large influx of nitrogen now promotes the growth of a seasonal low oxygen or hypoxic zone each summer on the continental shelf of the northern Gulf of Mexico.
From the 1980s until quite recently, however, agricultural land use and land cover were relatively stable in contrast to the more dramatic changes in the previous three decades (the surge in interest for ethanol may end the relative stability). The one factor that changed the most, year to year, is the weather. Our study examines how this year-to-year variability in rainfall influences the amount of nitrogen flooding down the Mississippi in the spring and the extent of hypoxia in the Gulf.
The study finds that, absent any major changes in land use and land cover, the year-to-year variability in precipitation across the “Corn Belt” (in the previous November and December and in March, April and May) is the primary driver of the year-to-year variability in amount of nitrogen delivered by the Mississippi during the late spring (in May and June). Using this relationship, the study then examines how climate variability affects the potential size of the hypoxic zone and the implications for reducing nitrogen losses and the size of the hypoxic zone. During very wet years, a nitrogen reduction of 50-60% – close to twice the original recommended target – is necessary to reach the goal of minimizing the size of the hypoxic zone (< 5000 km2).
The results are a reminder of the importance of factoring climate variability into water quality or aquatic ecosystem policy, particularly given the changes in climate expected to occur in the coming decades.
Sunday, November 12, 2006
As the corn turns
Last week, I was at an EPA symposium about nutrient pollution in the Mississippi River Basin. Although the seminars had titles like “Nitrogen Processing in Flow-Controlled Backwater Systems of the Upper Mississippi River” and “Nitrogen Removal Capacity of Entire River Networks—Interactions of Geomorphic, Hydraulic and Biological Factors”, the same subject kept cropping up:
Ethanol
In 2004, the production of corn-based ethanol reached 3.4 billion gallons – or 2% of all U.S. gasoline by volume – by far the highest in history. The Energy Policy Act calls for ethanol production to more than double, to 7.5 billion gallons, by the year 2012. Since energy independence is likely to be one of the only areas of agreement between the Bush Administration and the newly Democratic Congress and Senate, it would not be surprising to see an even more aggressive policy emerge in the next couple years.
Every passing mention of the inevitable expansion of corn-based ethanol production brought sighs from many of the participants.
Why? First, most of the people I spoke with agree with the conclusion that the energy derived from corn-based ethanol is, at best, only slightly greater than the energy required in production. It may be net energy loss. Second, the participants of the Symposium have for the most part been working on the difficult challenge of reducing nitrogen pollution in the Mississippi River Basin. Increasing the production of the fertilizer-intensive crop will make it even more difficult to goal of shrinking the nitrogen-fuelled “dead zone” in the Gulf of Mexico.
To meet the 2012 ethanol goal, corn production is bound to increase [the only other option is to meet the goal purely by diverting corn grain away from feed or exports – not impossible, but less likely given the financial incentive to expand production]. That will require either the conversion of existing croplands to corn or the cultivation of existing croplands to corn.
The total area of croplands is unlikely to change significantly – it hasn’t in the past century. The best croplands were identified long ago. The change over the century has been in what crops are grown on those lands. Right now, around 2/3s to 3/4s of US croplands are devoted to just three crops: corn, soybeans and wheat.
So the thought it is that the extra corn production will come either at the expense of some other crop or at the expense of croplands currently left uncultivated. Some at the meeting suggested that farmers will replace soybeans with corn. Others, myself included, dismiss that notion: soybeans have been expanding for fifty years in the US and are too valuable crop to abandon (for ecological and economic reasons). It is more likely that either land devoted to other crops or lands contained within US Conservation Reserve Program – essentially farms are paid to leave some croplands fallow – will be used to expand corn production. Unless there is a major change in the production practices, the addition of more corn cultivation does not bode well for the nitrogen cycle.
The one reasonable argument for expanding corn-based ethanol production is that creating a market for biofuels will spur research on more efficient fuels. Thanks to market forces, corn-based ethanol may pave the way for a sensible form of biofuel production: either the “cellulosic” ethanol from high yielding grasses like switchgrass (that require no fertilizer) or biodiesel from oil-crops like soybeans, rapeseed or canola. If so, let’s hope the transition does not take too long.
