***AT: Warming Good*** AT: CO2 Ag-Defense- Uniqueness

AT: CO2 Ag- Defense- Warming Outweighs

Warming outweighs CO2 – extreme weather offsets fertilization

Zero long-term solvency – carbon fertilization flattens out

Zabarenko, ‘7 – writer at Reuters [Deborah, 9/13/2007, Reuters, “Warming may hit world crop output,” Lexis, DS]
Global warming could send world agriculture into serious decline by 2080, with productivity collapsing in some developing countries while it improves in a few rich nations, a study reported yesterday. India, Pakistan, most of Africa and most of Latin America would be hit hardest, said economist William Cline, the study's author. The United States, most of Europe, Russia and Canada would probably see agricultural gains if climate change continues on its current course, the study found. Overall, the world's agricultural productivity was forecast to decline by between 3% and 16% by 2080, according to the study published by the Washington-based Center for Global Development and the Peterson Institute for International Economics. Among developed countries, Australia's outlook was bleakest, with predicted declines in crop yields ranging between 16% and 27%. In the developing world, fast-growing India's declines were forecast between 29% and 38%, while Sudan and Senegal both had predicted crop declines of more than 50%, essentially a collapse of agricultural productivity. The wide range between the low and high end of the forecast depends on how much carbon dioxide emissions actually spur some crops, Mr. Cline said. Plants absorb carbon dioxide, a climate-warming greenhouse gas emitted by coal-fired power plants, petroleum-fuelled vehicles and some natural processes. Some analysts maintain that global warming could actually be a boon to crops, making the impact of human-caused climate change negligible. They cite laboratory studies that have shown potential gains in crop yields of up to 30% when carbon dioxide emissions were increased. Mr. Cline disputed these contentions, saying that similar tests performed in farm fields have shown gains to be around 15%. He said the boost from so-called carbon fertilization tends to flatten out. For corn, there is already so much carbon dioxide in the atmosphere that putting more of this gas in the air would not help increase yields, Mr. Cline said. Wheat, rice and soybeans are continuing to benefit from increased carbon dioxide emissions, but that improvement is likely to taper off, he said. "It turns out that global yields for the major cereal [crops] have in fact slowed down, that the Green Revolution has slowed down," Mr. Cline said, referring to the global technological transformation of agriculture between the 1940s and 1960s. "There's already a sign that there is fatigue in the Green Revolution," he said, noting that the average annual growth in yields in the 1960s and 1970s was 2.6% per year, but by the 1980s and 1990s it had slowed to 1.8%. "The problem is that you need the technical change to keep up with demand for food," Mr. Cline said. "I estimate that the global demand for food after you take into account higher population, as well as higher incomes, would about triple from now to late in the century." Northern countries such as parts of the United States, Russia and Canada would have longer growing seasons due to global warming. But Mr. Cline said the world probably could not rely on increased crop yields in those areas. "By the end of the century, they're probably going to be earning so much money from their energy exports that their exchange rates are going to be very strong," he said. These strong currencies would make it prohibitively expensive for most other countries to buy Russian or Canadian agricultural goods.

CO2 doesn’t boost yields – their evidence is short-term and hypothetical

Jackson 9 – Research molecular biologist at USDA [Eric, 2009, “The international food system and the climate crisis,” The Panama News, Lexis]
A major weakness in the forecasts of the IPCC and others when it comes to agriculture is that their predictions accept a theory of “carbon fertilization,” which argues that higher levels CO2 in the atmosphere will enhance photosynthesis in many key crops, and boost their yields. Recent studies show that this is a mirage. Not only does any initial acceleration in growth slow down significantly after a few days or weeks, but the increase in CO2 reduces nitrogen and protein in the leaves by more than 12 percent. This means that, with climate change, there will be less protein for humans in major cereals such as wheat and rice. There will also be less nitrogen in the leaves for bugs, which means that bugs will eat more leaf, leading to important reductions in yield.

Long-term warming overtakes short-term benefits

Press Trust of India, ‘7 - Major newspaper, citing William Cline [9/13/2007, Press Trust of India, “Global warming may severely affect world agriculture,” Lexis, DS]
Global warming could send world agriculture into serious decline within this century, and the hardest hit will be developing countries like India and most of Africa and Latin America, a new study suggests. Developing countries, many with average temperatures that are already near or above crop tolerance levels, are predicted to suffer an average 10 to 25 per cent decline in agricultural productivity by the 2080s, said the study's author William Cline, a senior fellow at the Center for Global Development. India could see a drop of 30 to 40 per cent in its agricultural production, while poorer nations like Sudan and Senegal are projected to suffer by as much as a 56 per cent and 52 per cent respectively. On the other hand, rich countries in colder climes could experience an increase in productivity by up to eight per cent, according to the findings. Overall, agricultural productivity for the entire world is projected to decline by between 3 and 16 per cent by 2080s as a consequence of global warming. "Some analysts have suggested that a small amount of global warming could actually increase global agricultural productivity. My work shows that while productivity may increase in a minority of mostly northern countries, the global impact of climate change on agriculture will be negative by the second half of this century," Cline said. "There might be some initial overall benefit to warming for a decade or two but because future warming depends on greenhouse gas emissions today, if we delay action it would put global agriculture on an inexorable trajectory to serious damage," he said in a statement. Cline, who published his study in new book "Global Warming and Agriculture: Impact Estimates by Country", based his findings on climate models used by the Intergovernmental Panel on Climate Change (IPCC). Previous studies have provided regional estimates or country estimates for just a handful of countries.

Warming outweighs – droughts kill fertilization

Hansen, ’10 – writer at Space Daily [Kathryn, 8/26/2010, Space Daily, “Drought Drives Decade-Long Decline in Plant Growth,” Lexis, DS]
Earth has done an ecological about-face: Global plant productivity that once flourished under warming temperatures and a lengthened growing season is now on the decline, struck by the stress of drought. NASA-funded researchers Maosheng Zhao and Steven Running, of the University of Montana in Missoula, discovered the global shift during an analysis of NASA satellite data. Compared with a six-percent increase spanning two earlier decades, the recent ten-year decline is slight, just one percent. The shift, however, could impact food security, biofuels, and the global carbon cycle. "We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world," Running said. "These results are extraordinarily significant because they show that the global net effect of climatic warming on the productivity of terrestrial vegetation need not be positive, as was documented for the 1980's and 1990's," said Diane Wickland, of NASA Headquarters and manager of NASA's Terrestrial Ecology research program. Conventional wisdom based on previous research held that land plant productivity was on the rise. A 2003 paper in Science led by then University of Montana scientist Ramakrishna Nemani (now at NASA Ames Research Center, Moffett Field, Calif.) showed that global terrestrial plant productivity increased as much as six percent between 1982 and 1999. That's because for nearly two decades, temperature, solar radiation and water availability, influenced by climate change, were favorable for growth. Setting out to update that analysis, Zhao and Running expected to see similar results as global average temperatures have continued to climb. Instead, they found that the impact of regional drought overwhelmed the positive influence of a longer growing season, driving down global plant productivity between 2000 and 2009. The team published their findings Aug. 20 in Science. "This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth," Running said. The discovery comes from an analysis of plant productivity data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite, combined with growing season climate variables including temperature, solar radiation and water. The plant and climate data are factored into an algorithm that describes constraints on plant growth at different geographical locations. For example, growth is generally limited in high latitudes by temperature and in deserts by water. But regional limitations can very in their degree of impact on growth throughout the growing season. Zhao and Running's analysis showed that since 2000, high-latitude northern hemisphere ecosystems have continued to benefit from warmer temperatures and a longer growing season. But that effect was offset by warming-associated drought that limited growth in the southern hemisphere, resulting in a net global loss of land productivity. "This past decade's net decline in terrestrial productivity illustrates that a complex interplay between temperature, rainfall, cloudiness, and carbon dioxide, probably in combination with other factors such as nutrients and land management, will determine future patterns and trends in productivity," Wickland said. Researchers are keen on maintaining a record of the trends into the future. For one reason, plants act as a carbon dioxide "sink," and shifting plant productivity is linked to shifting levels of the greenhouse gas in the atmosphere. Also, stresses on plant growth could challenge food production. "The potential that future warming would cause additional declines does not bode well for the ability of the biosphere to support multiple societal demands for agricultural production, fiber needs, and increasingly, biofuel production," Zhao said. "Even if the declining trend of the past decade does not continue, managing forests and croplands for multiple benefits to include food production, biofuel harvest, and carbon storage may become exceedingly challenging in light of the possible impacts of such decadal-scale changes," Wickland said.

High-magnitude warming tanks any benefit of fertilization

Stern 7 – Chair of the London School of Economics and Poli Sci [Nicholas, “The Economics of Climate Change: The Stern Review”, The report of a team commissioned by the British Government to study the economics of climate change led by Siobhan Peters, Head of G8 and International Climate Change Policy Unit, Cambridge University Press, www.mccormack.umb.edu/centers/nejpp/articles/21_2/STERN.pdf]
Food production will be particularly sensitive to climate change, because crop yields depend in large part on prevailing climate conditions (temperature and rainfall patterns). Agriculture currently accounts for 24% of world output, employs 22% of the global population, and occupies 40% of the land area. 75% of the poorest people in the world (the one billion people who live on less than $1 a day) live in rural areas and rely on agriculture for their livelihood.29 Low levels of warming in mid to high latitudes (US, Europe, Australia, Siberia and some parts of China) may improve the conditions for crop growth by extending the growing season30 and/or opening up new areas for agriculture. Further warming will have increasingly negative impacts – the classic “hill function” (refer back to Box 3.1) - as damaging temperature thresholds are reached more often and water shortages limit growth in regions such as Southern Europe and Western USA.31 High temperature episodes can reduce yields by up to half if they coincide with a critical phase in the crop cycle like flowering (Figure 3.4).32 The impacts of climate change on agriculture depend crucially on the size of the “carbon fertilisation” effect (Box 3.4). Carbon dioxide is a basic building block for plant growth. Rising concentrations in the atmosphere may enhance the initial benefits of warming and even offset reductions in yield due to heat and water stress. Work based on the original predictions for the carbon fertilisation effect suggests that yields of several cereals (wheat and rice in particular) will increase for 2 or 3°C of warming globally, according to some models, but then start to fall once temperatures reach 3 or 4°C.33 Maize shows greater declines in yield with rising temperatures because its different physiology makes it less responsive to the direct effects of rising carbon dioxide. Correspondingly, world cereal production only falls marginally (1 – 2%) for warming up to 4°C (Box 3.4).34 But the latest analysis from crops grown in more realistic field conditions suggests that the effect is likely to be no more than half that typically included in crop models.35 When a weak carbon fertilisation effect is used, worldwide cereal production declines by 5% for a 2°C rise in temperature and 10% for a 4°C rise. By 4°C, entire regions may be too hot and dry to grow crops, including parts of Australia. Agricultural collapse across large areas of the world is possible at even higher temperatures (5 or 6°C) but clear empirical evidence is still limited.

Climate change decimates agriculture – kills key resource supplies

Wahlquist, ‘9 – Rural writer for the Weekend Australian [Asa, Weekend Australian, “Climate change will cause grave world food shortages,” Lexis, DS]
Climate change is forecast to reduce wheat and rice yields, increasing prices and resulting in an additional 25 million malnourished children by 2050. A report by the Washington-based International Food Policy Research Institute says climate change will reduce irrigated wheat yields by 30 per cent in developing countries by 2050, pushing prices up by as much as 121 per cent. Irrigated rice yields are forecast to fall by 15 per cent and rice prices are expected to rise by up to 150 per cent. Even without climate change, the world faces a big shortfall in food by 2050 due to the growing world population and declining agricultural productivity. Mark Rosegrant from the institute says it is the first report that looks at the effects of climate change on agriculture, food prices, demand and trade. He says it was prepared for the climate change conference to be held in Copenhagen in December. He says agriculture is uniquely vulnerable to climate change. ``It is reliant on natural resources, temperature and water for its production.'' The study says South Asia, ``particularly India and Pakistan, is going to be very hard hit in terms of production impacts, as much as possibly 40 per cent declines in wheat production in those areas. That translates into very significant negative impacts on malnutrition in the region.'' Rosegrant says the other area to suffer would be sub-Saharan Africa, ``where the impact isn't quite a high as in Southeast Asia, but they are starting from very high levels of poverty and vulnerability''. The report is based partly on information from the CSIRO. CSIRO chief executive Megan Clark this week told the National Press Club in Canberra that the world's farmers will need to produce as much food in the next 50 years as has been produced in human history. Clark says food production is going to become one of the world's biggest concerns and Australia has a huge role to play. ``Humans have met this challenge once before: from 1960 to 2000, world food production doubled through a combination of new technology and investment,'' she says. ``But this time, two things are different. We can no longer simply clear more forest and farm even more marginal land. And secondly, this is happening at a time when we are seeing the greatest migration of our species to urban centres.'' Rosegrant says demand for food from developed countries such as Australia will become much greater. Last year, reduced world supplies of wheat and rice led to price rises, food riots and a number of countries restricting food exports. He says Australia must maintain its leadership in the fight for free trade. ``It willbe absolutely essential to help the systembecome more resilient in the face of climate change.'' The report says an additional $US7billion ($7.9bn) a year must be invested in increased agricultural productivity, to help farmers in developing countries adapt to climate change. ``The developed countries have to live up to their pledges at the recent G8, and now the G20, to increase investments in developing countries,'' Rosegrant says. He wants to get agriculture into the agreement that will be forged in Copenhagen: ``It didn't have a big role in Kyoto.'' Rosegrant would like to see increased investment in agriculture, and for agriculture to become ``part of any carbon trading mechanisms to come out of Copenhagen. It wasn't in Kyoto at all,'' he says.

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