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Changes in the global production of major crops are important drivers of food prices, food security and land use decisions. Average global yields for these commodities are determined by the performance of crops in millions of fields distributed across a range of management, soil and climate regimes. Despite the complexity of global food supply, here we show that simple measures of growing season temperatures and precipitation--spatial averages based on the locations of each crop--explain about 30% or more of year-to-year variations in global average yields for the world's six most widely grown crops. For wheat, maize, and barley, there is a clearly negative response of global yields to increased temperatures. Based on these sensitivities and observed climate trends, we estimate that warming since 1981 has resulted in annual combined losses of these three crops representing roughly 40 MT or $5 billion per year, as of 2002. While these impacts are small relative to the technological yield gains over the same period, the results demonstrate already occurring negative impacts of climate trends on crop yields at the global scale.

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Environmental Research Letters
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David Lobell
Christopher B. Field
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10,000 Shovels examines China's breakneck growth through a short documentary that integrates statistics, video footage, and satellite images. The documentary focuses on China's Pearl River Delta region while the accompanying teacher's guide takes a broader perspective, exploring many current national issues.
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The harmful environmental effects of livestock production are becoming increasingly serious at all levels-local, regional, national and global-and urgently need to be addressed, according to researchers from Stanford, the United Nations Food and Agriculture Organization (FAO) and other organizations. The researchers, representing five countries, presented their findings on Feb. 19 at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Francisco during a symposium titled "Livestock in a Changing Landscape: Drivers, Consequences and Responses."

Large-scale livestock operations provide most of the meat and meat products consumed around the world-consumption that is growing at a record pace and is projected to double by 2050, said symposium organizer Harold A. Mooney, professor of biological sciences. "We are seeing tremendous environmental problems with these operations, from land degradation and air and water pollution to loss of biodiversity," he said, noting that the developing world is especially vulnerable to the effects of these operations.

Intensive and extensive systems

Symposium co-organizer Henning Steinfeld of the FAO Livestock Environment and Development initiative emphasized that intensive and extensive forms of production are beset with a range of different problems. In "intensive systems," animals are contained and feed is brought to them. "Extensive systems" generally refer to grazing animals that live off the land.

"Extensive livestock production plays a critical role in land degradation, climate change, water and biodiversity loss," Steinfeld said. For example, grazing occupies 26 percent of the Earth's terrestrial surface, and feed-crop production requires about a third of all arable land, he said. Expansion of livestock grazing land is also a leading cause of deforestation, especially in Latin America, he added. In the Amazon basin alone, about 70 percent of previously forested land is used as pasture, while feed crops cover a large part of the remainder.

"We are seeing land once farmed locally being transformed to cropland for industrialized feed production, with grasslands and tropical forests being destroyed in these land use changes, with resources feeding livestock rather than the humans who previously depended on those lands," added Mooney, who co-chaired the scientific advisory panel for the United Nations-initiated Millennium Ecosystem Assessment.

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According to the FAO, when emissions from land use are factored in, the livestock sector accounts for 9 percent of all carbon dioxide emissions derived from human-related activities, as well as 37 percent of methane emissions-primarily gas from the digestive system of cattle and other domesticated ruminants-and 65 percent of nitrous oxide gases, mostly from manure.

The problems surrounding livestock production cannot be considered in isolation, nor are they limited to the environmental impact, Mooney said, noting that economic, social, health and environmental perspectives "will be critical to solving some of these problems. We hope to develop a greater understanding of these complex issues so that we may encourage policies and practices to reduce the adverse effects of livestock production, while ensuring that humans are fed and natural resources are preserved, today and in the future."

Kathy Neal is communications manager of the Woods Institute for the Environment.

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FSI senior fellow Lawrence H. Goulder has been named the vice-chair of the California Environmental Protection Agency's Market Advisory Committee. The 13-member committee, consisting of climate policy experts from around the world, is charged with developing a market-based plan for meeting the greenhouse gas emissions targets established under the California climate-change bill passed last September.
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In Boston Review's January/February 2007 issue, PESD Director David G. Victor and PESD researcher Danny Cullenward discuss why pursuing technologies that burn coal more cleanly is the "only practical approach" to stopping global warming. Their proposal is part of a larger forum on climate change led by MIT meteorology professor Kerry Emanuel.

Almost every facet of modern life - from driving to the grocery store to turning on a light - relies on inexpensive and abundant fossil fuels. When burned for power, these fuels yield emissions of carbon dioxide that accumulate in the atmosphere. They are the leading cause of global warming.

Assuring ample energy services for a growing world economy while protecting the climate will not be simple. The most critical task will be curtailing emissions from coal; it is the most abundant fossil fuel and stands above the others in its carbon effluent. Strong lobbies protect coal in every country where it is used in abundance, and they will block any strategy for protecting the climate that threatens the industry. The only practical approach is to pursue technologies that burn coal much more cleanly.

Such new technologies exist on the drawing board, but governments and regulators are failing to bring designs into practice with deliberate speed. Instead, most of the policy effort to tackle global warming has focused on creating global institutions, such as the Kyoto Protocol, to entice change. Although noble, these global efforts usually fall hostage to the interests of critical countries. After negotiating the Kyoto treaty, for example, the United States refused to sign when it found that it could not easily comply with the provisions. Australia did the same, and Canada is also poised to withdraw. Nor have treaties like Kyoto crafted a viable framework for engaging developing countries; these countries' share of world emissions is rising quickly, yet they are wary of policies that might crimp economic growth.

Breaking the deadlocks that have appeared in the Kyoto process requires, first and foremost, a serious plan by the United States to control its emissions. The United States has a strong historical responsibility for the greenhouse-gas pollution that has accumulated in the atmosphere, but little has been done at the federal level. (A few states are implementing some policies, and they, along with rising political pressure, might help to catalyze a more aggressive federal approach.) It will be difficult, however, for the United States (and other industrial countries) to sustain much effort in cutting emissions unless its economic competitors in China and the other developing countries make some effort as well. Without a strong policy framework to contain emissions throughout the world, levels of greenhouse-gas pollution will reflect only the vagaries in world energy markets. We need a proper strategy for moving away from harmful emissions.

A few years ago, many analysts thought that market forces were already shifting away from coal. They predicted the growth of natural gas, a fuel prized for its cleanliness and flexibility. That vision was good news for the climate because electricity made from natural gas leads to half of the carbon-dioxide emissions of electricity from coal. But natural-gas prices, which tend to track oil prices, have skyrocketed over the past few years, and, unsurprisingly, the vision for the growth of natural has dimmed. Natural-gas plants, which accounted for more than 90 percent of new plants built in the 1990s, are harder to justify in the boardroom. Most analysts now see a surge in the use of coal. One hundred new coal-fired plants are in the planning stages in the United States. Absent an unlikely plunge in gas prices, coal is here to stay.

Despite the challenges of handling coal responsibly, the potential of research and deployment of advanced technologies to help the United States and the major developing countries find common interest on the climate problem is great. In advanced industrialized countries, the vast majority of coal is burned for electricity in large plants managed by professionals - exactly the setting where such technology is usually best applied. In the United States, for example, coal accounts for more than four fifths of all greenhouse-gas emissions from the electricity sector.

Most of the innovative effort in coal is focused on making plants more efficient. Raising the temperature and pressure of steam to a "supercritical" point can yield improvements in efficiency that, all told, can reduce emissions about 20 to 25 percent. Boosting temperature and pressure still again, to "ultra-supercritical" levels, can deliver another slug of efficiency and lower emissions still further. Encouraging investments in this technology is not difficult: most countries and firms are already searching for gains in efficiency that can cut the cost of fuel; a sizeable fraction of new Chinese plants are supercritical; India is a few steps behind, in part because coal is generally cheaper in that country, but even there the first supercritical unit is expected soon. Across the advanced industrialized world, supercritical is the norm, at least for new plants. A few companies are taking further steps, investing in ultra-supercritical units. Two such plants are going up outside Shanghai, using mainly German technology, evidence that the concept of "technology transfer" is becoming meaningless in the parts of the world economy that are tightly integrated. Markets are spreading the best technologies worldwide where their application makes economic sense. In other countries, technologies to gasify coal - which also promise high efficiency - are also being tested.

But power-plant efficiency alone won't account for the necessary deep cuts in emissions. Already the growth in demand for electricity is outstripping the improvements in power plants such that the need for more plants and fuel is rising ever higher, as are emissions. This is spectacularly true in fast-growing China.

A radical redesign of coal plants will be needed if governments want to limit emissions of carbon dioxide. Here, the future is wide open. One track envisions gasifying the coal and collecting the concentrated wastes. Another would use more familiar technologies and separate carbon dioxide from other gases. All approaches require injecting the pollution underground where it is safe from the atmosphere. This is already done at scale in oil and gas production, where injection is used to pressurize fields and boost output. The consequences of injecting the massive quantities of pollution from power plants, however, are another matter. Regulatory systems are not in place or tested, and public acceptance is unknown.

While these technologies can work, they won't be used widely before they progress on two fronts. First, they must become commercially viable. Despite the huge potential of adopting them, it is striking how little money is being spent on advanced coal technologies. The U.S. government has created some financial incentives to build advanced coal plants, but much of that investment is slated for plants that are not actually designed to sequester CO2. In fact, the uncertainty of American policy gives investors in power plants an incentive to build conventional high-carbon technology, because it is more familiar to regulators and bankers. Worse yet, increased emissions today might actually improve a negotiating position in the future when targets for controlling emissions are ratcheted down from whatever is business as usual. Some private firms, such as BP and Xcel, are putting their own money into carbon-free power - but the totality of the private effort is small compared with the size of the problem. There are good mechanisms in place for encouraging public research and private investment in such technologies; the real shortcoming is in the paucity of the effort.

The second problem is that countries such as China, India, and other key developing nations won't spend the extra money to install carbon-free coal. Yet these countries' share of global coal consumption has soared almost 35 percent over the past ten years.

The inescapable conclusion is that the advanced industrialized countries must create a much larger program to test and apply advanced coal technologies. Electricity from plants with sequestration might eventually cost half more than from plants without the technology. That's not free, but it is affordable and is less than the changes in electric rates that many Americans already experience and accept.

State and federal regulators need to create direct incentives - such as a pool of subsidies - to pay the extra cost until the technology is proven and competitive with conventional alternatives. That subsidy, along with strict limits on emissions, will set a path for cutting the carbon from U.S. electricity without eliminating a future for coal. They must also extend the same incentives to the major developing countries, which have no interest in paying higher rates for electricity because their priorities do not rest on controlling CO2. Yet these countries' involvement now is essential. Averting emissions has a global benefit regardless of where the emissions are controlled. And developing countries are especially unlikely to shoulder more of the burden themselves, in the more distant future, unless they are first familiar with the technologies.

Solving the climate problem will be one of the hardest problems for societies to address - it entails complicated and uncertain choices with real costs today, and benefits in the distant future. Yet the stakes are high and the consequences of indecision severe. Serious action must contend with existing political constituencies and aim at existing resources that are most abundant. The technologies needed to make coal viable will not appear automatically. An active policy effort - pursued worldwide and initially financed by the industrialized world - is essential.

Originally published in the January/February 2007 issue of Boston Review.

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The Amazon Basin is one of the world's most important bioregions, harboring a rich array of plant and animal species and offering a wealth of goods and services to society. For years, ecological science has shown how large-scale forest clearings cause declines in biodiversity and the availability of forest products. Yet some important changes in the rainforests, and in the ecosystem services they provide, have been underappreciated until recently. Emerging research indicates that land use in the Amazon goes far beyond clearing large areas of forest; selective logging and other canopy damage is much more pervasive than once believed. Deforestation causes collateral damage to the surrounding forests - through enhanced drying of the forest floor, increased frequency of fires, and lowered productivity. The loss of healthy forests can degrade key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance and river flow, the modulation of regional climate patterns, and the amelioration of infectious diseases. We review these newly revealed changes in the Amazon rainforests and the ecosystem services that they provide.

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Frontiers in Ecology and the Environment
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Holly Gibbs

This project involves political scientists, economists, and medical researchers to address the question of whether hunger, poverty, disease and agricultural resource constraints foster civil conflict and international terrorism. Economists have elucidated the links between agricultural stagnation, poverty, and food insecurity, and political scientists have empirically analyzed the role of poverty in facilitating civil conflict.

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Most research on the agricultural impacts of climate change has focused on the major annual crops, yet perennial cropping systems are less adaptable and thus potentially more susceptible to damage. In regions where perennial crops are economically and culturally important, improved assessments of yield responses to future climate are needed to prioritize adaptation strategies. These impact assessments, in turn, must rely on climate and crop models that contain often poorly defined uncertainties. We evaluated the impact of climate change on six major perennial crops in California: wine grapes, almonds, table grapes, oranges, walnuts, and avocados. Outputs from multiple climate models were used to evaluate climate uncertainty, while multiple statistical crop models, derived by resampling historical databases, were used to address crop response uncertainties. We find that, despite these uncertainties, climate change in California is very likely to put downward pressure on yields of almonds, walnuts, avocados, and table grapes by 2050. Without CO2 fertilization or adaptation measures, projected losses range from 0 to >40% depending on the crop and the trajectory of climate change. Climate change uncertainty generally had a larger impact on projections than crop model uncertainty, although the latter was substantial for several crops. Opportunities for expansion into cooler regions were identified, but this adaptation would require substantial investments and may be limited by non-climatic constraints. Given the long time scales for growth and production of orchards and vineyards (30 years), climate change should be an important factor in selecting perennial varieties and deciding whether and where perennials should be planted.

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Agricultural and Forest Meteorology
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David Lobell
Christopher B. Field

Soybean production has become a significant force for economic development in Brazil, but has come at the cost of expansion into non-protected forests in the Amazon and native savanna in the Cerrado. Over the past fifty years, production has increased from 26 million to 260 million tons. Area planted to soybeans has increased from roughly 1 million hectares in 1970 to more than 23 million hectares in 2010, second only to the United States.

Orphan (or minor) crops are those crops which are typically not traded internationally but which can play an important role in regional food security. For various reasons, many of these crops have received little attention from crop breeders or other research institutions wishing to improve their productivity. This project produced an earlier paper on the role of orphan crops in regional food security, with implications for national and international breeding efforts.

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