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Agriculture Old and New

October 28, 2009


This is the first in a series of reports on the future of agriculture and food security. As you might guess, agricultural is symbiotically tied to weather patterns. One thing that people on both sides of the climate change debate can agree upon is that climate changes have been going on for millions of years. Although climate change may be occurring at a quickened pace, we are not the first generation to experience changes in weather patterns. A professor from the University of Virginia also believes that the emissions from industrial age activities are not the first human activities that have affected climate change [“Climate-Change Study Cites Role of Ancient Farming,” by David A. Fahrenthold, Washington Post, 28 September 2009].

“A professor emeritus at the University of Virginia has suggested that people began altering the climate thousands of years ago, as primitive farmers burned forests and built methane-bubbling rice paddies. The practices produced enough greenhouse gases, he says, to warm the world by a degree or more. Other scientists, however, have said the idea is deeply flawed and might be used to dampen modern alarms over climate change. Understanding the debate requires a tour through polar ice sheets, the inner workings of the carbon molecule, the farming habits of 5,000-year-old Europeans and trapped air bubbles more ancient than Rome. ‘The greenhouse gases went up, and they should have gone down’ many thousands of years ago, said U-Va.’s William Ruddiman. ‘Why did that happen?’ His answer is based on circumstantial evidence. Ruddiman said two events in world history — an apparent shift in the composition of the atmosphere and the first explosion of human agriculture — took place at nearly the same time.”

When Ruddiman first presented his theory in 2003, it was guffawed because critics said there were simply too few humans on the planet thousands of years ago to have made a difference.

“Ruddiman’s response: yes, there were. And in those days, one farmer was as destructive as multiple farmers are today. He and Erle Ellis, a professor at the University of Maryland Baltimore County, wrote in the journal Quaternary Science Reviews that early farmers did not have modern fertilizer or factory-made tools, but they did have a lot of land. They would clear an area by cutting or burning it, farm the ground until it was nearly barren and move on. ‘Those tens of millions [of people] had the impact of hundreds of millions, because per person, they had 10 times the impact,’ Ruddiman said. ‘And that’s enough to start the curve turning around.’ The assertion is the heart of Ruddiman’s arguments — and his critics’ complaints. Where he sees human impact on the curving plot of global temperatures, they see a misunderstanding of what nature was doing at the time.”

The big concern of Ruddiman’s critics is that his arguments will be used by those eager to deny that greenhouse gas emissions are harming the planet.

“‘I think it’s a bunch of bosh,’ said Wallace Broecker, a professor at Columbia University. Broecker said he worried that the idea of pre-modern people as carbon emitters would turn into an argument that the modern world need not worry so much about its own pollution. ‘I get really upset with him, because people who oppose global warming [legislation] can use this as some dodge.'”

Fahrenthold writes about the Earth’s “natural freeze-and-thaw cycles, driven heavily by changes in its orbit.” He says the planet is currently “in a warm ‘interglacial’ period, which began 10,000 years ago with the end of the last Ice Age.” According to Ruddiman, the climate should have started to slowly cool down starting around 8,000 years, but the cooling was slower than expected. He believes his theory explains why.

“He has examined the bubbles and found that about 5,000 years ago, they began showing unexpected increases in carbon dioxide and methane. His theory is that the gases were pollutants, produced by civilizations on several continents that were picking up the settled life of farmers. The carbon dioxide, Ruddiman said, could have come from smoke, from forests burned to create farmland on several continents. It could have seeped out of felled trees as they rotted. The methane, a byproduct of decay in swampy water, could have come from areas of Asia newly flooded to grow rice. It also might have been expelled by livestock. In the atmosphere, Ruddiman says, the gases trap solar heat that might otherwise have bounced back out to space. They were greenhouse gases, the same as now. … The early farmers ‘did not . . . change the actual climate,’ said [Erle Ellis, a professor at the University of Maryland Baltimore County], Ruddiman’s collaborator on the recent paper. ‘They kept the climate from changing.’ But Ruddiman’s critics say he is wrong to see human impact here: nature was in control all along.”

While Ruddiman believes science proves him correct, his critics say the science confirms he’s wrong.

“Critics of Ruddiman say, there is strong scientific evidence to prove him wrong. They say that recent studies of very deep ice samples show that ice ages did not always come and go on the same schedule. That could throw off Ruddiman’s calculations for when the next round of cooling was supposed to start. And there is evidence, they say, inside the carbon atoms themselves. Carbon atoms that come from plants can be tracked, by looking at the number of neutrons in their nucleus. If Ruddiman was right, and ancient farmers burned enough plants to change the climate, then the amount of carbon from plants in those bubbles would rise significantly. But, they say, it did not.”

Ruddiman is dismayed that his arguments could be used to prevent legislation reducing greenhouse gas emissions from passing. He insists “there is still a need to cap and reduce greenhouse gases, since modern smokestacks and tailpipes are pumping them out at a level that dwarfs anything from earlier eras.” In the modern era, many people have pointed fingers at the cattle and dairy industries as major producers of methane. For more on that subject, see my post Cooking and Climate. I’ll write more on this subject in a later post in this series.


Speaking of dairy farmers, anyone following the news has heard about the protests in Europe that have farmers there spilling milk all over the place. Profits for dairy farmers have been hard to find both in Europe and the United States [“From Science, Plenty of Cows but Little Profit,” by William Neuman, New York Times, 28 September 2009]. Neuman talks about a breakthrough in science that permits dairy farmers to selectively breed more female calves than male ones.

“Now the first cows bred with that technology, tens of thousands of them, are entering milking herds across the country — and the timing could hardly be worse. The dairy industry is in crisis, with prices so low that farmers are selling their milk below production cost. The industry is struggling to cut output. And yet the wave of excess cows is about to start dumping milk into a market that does not need it. … Desperate to drive up prices by stemming the gusher of unwanted milk, a dairy industry group, the National Milk Producers Federation, has been paying farmers to send herds to slaughter. Since January the program has culled about 230,000 cows nationwide. But the sorting technique, known as sexed semen, is expected to put 63,000 extra heifers into milk production this year, compared with the number that would be available if only conventional semen had been used, researchers estimate. That number will jump to 161,000 next year, and farmers fear it could double again in 2011. While that is a fraction of the 9.2 million milk cows nationwide, the extra cows this year and next could roughly equal those removed from production by the industry’s culling program.”

Farmers face all sorts of never ending challenges — everything from bad weather and economic woes to crop diseases that affect their bottom line. Tomato growers in the northeast United States faced their own disaster earlier this year [“You Say Tomato, I Say Agricultural Disaster,” by Dan Barber, New York Times, 8 August 2009]. Barber writes:

“If the hardship of growing vegetables and fruits in the Northeast has made anything clear, it’s that the list of what can go wrong in the field is a very long one. We wait all year for warmer weather and longer days. Once we get them, it seems new problems for farmers rise to the surface every week: overnight temperatures plunging close to freezing, early disease, aphid attacks. Another day, another problem. The latest trouble is the explosion of late blight, a plant disease that attacks potatoes and tomatoes. Late blight appears innocent enough at first — a few brown spots here, some lesions there — but it spreads fast. Although the fungus isn’t harmful to humans, it has devastating effects on tomatoes and potatoes grown outdoors. Plants that appear relatively healthy one day, with abundant fruit and vibrant stems, can turn toxic within a few days.”

Barber reports that the usual treatments to prevent blight weren’t as effective as normal this year. As a result, late blight struck hard and fast — devastating entire tomato crops in just a few days. As you might expect, in some places tomato prices shot up 20% over last year. Barber explains why late blight got so out of hand.

“Plant physiologists use the term ‘disease triangle’ to describe the conditions necessary for a disease outbreak. You need the pathogen to be present (that’s the late blight), you need a host (in this case tomatoes and potatoes) and you need a favorable environment for the disease — for late blight that’s lots of rain, moderate temperatures and high humidity. … It has been the weather report for the Northeast this summer, especially in June. … But weather alone doesn’t explain the early severity of the disease this year. … Instead we have to look at two other factors: the origin of the tomato plants many of us cultivate, and the renewed interest in gardening. According to plant pathologists, this killer round of blight began with a widespread infiltration of the disease in tomato starter plants. Large retailers like Home Depot, Kmart, Lowe’s and Wal-Mart bought starter plants from industrial breeding operations in the South and distributed them throughout the Northeast. … Once those infected starter plants arrived at the stores, they were purchased and planted, transferring their pathogens like tiny Trojan horses into backyard and community gardens. … Credit the recession or Michelle Obama or both, but there’s been an increased awareness of the benefits of growing your own food. According to the National Gardening Association, 43 million households planned a backyard garden or put a stake in a share of a community garden in 2009, up from 36 million in 2008. That’s quite a few home gardeners who — given the popularity of the humble tomato — probably planted a starter or two this summer. Here’s the unhappy twist: the explosion of home gardeners — the very people most conscious of buying local food and opting out of the conventional food chain — has paradoxically set the stage for the worst local tomato harvest in memory.”

Barber goes on to explain a few things that home gardeners and the government can to to help stop the kind of perfect storm that hit the tomato industry this year. One of the things he recommends is for all new growers to take advantage of local expertise. He continues:

“What does the resilient farm of the future look like? I saw it the other day. The farmer was growing 30 or so different crops, with several varieties of the same vegetable. Some were heirloom varieties, many weren’t. He showed me where he had pulled out his late blight-infected tomato plants and replaced them with beans and an extra crop of Brussels sprouts for the fall. He won’t make the same profit as he would have from the tomato harvest, but he wasn’t complaining, either. Sometimes giving in to nature can be the biggest victory of all.”

Resilient farms are going to be important according The Economist, which claims that “global warming will make it harder to feed the world in 2050” [“Seasonally adjusted,” 3 October 2009 print issue]. The Bible declares there is a time and a season for all things, but global warming is eliminating seasons in some areas of the world.

“Since time immemorial, farmers have planted their crops according to the seasons. ‘That is what my forefathers have been doing,’ says Mohammad Ilisasuddin in Shibganj, in northern Bangladesh, but now ‘the weather does not seem right for what we have done traditionally.’ Seasonal planting is ‘useless’, agrees Florence Madamu, a smallholder in Bulirehe, in western Uganda. ‘The sun is prolonged until the end of September and whenever it rains, it rains so heavily it destroys all our crops.’ Oxfam, a British charity, has compiled a litany of laments by poor farmers. John Magrath, a researcher, says they all say similar things: ‘moderate, temperate seasons are shrinking … rainy seasons are shorter and more violent … making it more difficult to grow crops [and] difficult for them to know when best to plant.’ As the earth warms up, many have feared that farmers will pay a high price. But working out who will pay, how, and where is tricky. Higher temperatures might turn arid shrub lands into deserts while improving the growing season in colder steppes. Global warming could produce more evaporation from plants, and more rain, which would benefit some places, while hurting others. In theory extra carbon dioxide in the atmosphere should help plants grow faster, though whether this actually happens may also depend on the amount of nitrogen in the soil.”

The article reports that to help sort out this conundrum a comprehensive study was undertaken by the International Food Policy Research Institute, a Washington, D.C., think tank. It reports that the study “reached some sobering conclusions.”

“In parts of the developing world some crop yields in 2050 could be only half of their 2000 levels. Irrigation may not help: climate change will hit irrigated systems harder than rain-fed ones. And the hope that gainers from climate change will outweigh losers looks vain: the damage from higher temperatures and erratic rainfall will be too big.”

The study made use of climate-change models, “one run by America’s National Centre for Atmospheric Research (NCAR), the other by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO).”

“These gave different descriptions of the world in 2050. NCAR thinks the climate would be hotter and wetter, with rainfall about 10% heavier than now. The CSIRO forecasts that there would be 2% more rain. There were big regional disparities, too: CSIRO forecast the sharpest increases in temperature in southern Africa; NCAR sees Russia and Canada heating up more. To take account of the differences IFPRI fed both forecasts into its own computer, which describes how every agricultural region and, in some places, practically every farm, responds to changes in temperature and rainfall. The results varied less than the assumptions. In developing countries, IFPRI found, irrigated wheat in 2050 would yield 34% less than in 2000, using NCAR data; and 28% less going by CSIRO figures. For irrigated rice, the declines would be 19% and 14% (see chart below — click to enlarge). These falls are large but not unlikely: scientists in South Africa recently said the region could see a 50% fall in cereals productivity by 2080. Bad though they are, the average declines hide even more disturbing variations. Latin America comes out of the exercise relatively well: the yields of its main crops are expected to fall by only a few percent. China’s farming may also be more resilient than it sometimes appears. But South Asia, the world’s most heavily populated region, looks vulnerable: IFPRI forecasts a possible 50% fall in its wheat yield in 2050 (one-sixth of all the world’s wheat grows on the north Indian plain). In the Middle East the institute predicts yield declines of 47% for maize and 30% for rice.”


The lead author of the report, Jerry Nelson, believes that agricultural trade liberalization — I assume like that envisioned by the Doha Round of trade talks — is important in mitigating potential effects of global warming. He also argues that “yield declines are so great that only another round of technological change — a new Green Revolution — would be enough to offset them.” Food security is going to be a concern for generations to come and we owe it to them to start thinking about the future now. Farming may be an old profession, but it remains crucial for humanity’s survival.

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