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SciAm: Experts Warn Climate Change Is Beginning to Disrupt Agriculture
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06/17/2010 04:15 PM
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Every nation -- developed and otherwise -- is dependent upon a stable agricultural sector, and climate change threatens that stability, a panel of experts said yesterday.
World population is expected to swell by 50 percent by 2050. This alone is a challenge for the world's supply of vital grains, said Gerald Nelson, an agricultural economist and fellow at the International Food Policy Research Institute. But then you have to tack on the impacts of climate change.
The price of major grains like rice and wheat were already projected to also increase by roughly 50 percent by 2050, Nelson said. With the added environmental stresses expected of climate change, prices could instead double, according to IFPRI.
Global agriculture, he said, could adapt to climate change for about $7 billion annually, with most of the resources being devoted to research, new irrigation techniques and training small farmers for rises in sea level.
Agricultural management directly affects how the three major greenhouse gases -- carbon dioxide, methane and nitrous oxide -- are cycled through the environment. According to United Nations Environment Programme, "Agriculture, deforestation and other forms of land use account for nearly one-third of global greenhouse gas emissions."
The four-member panel was organized by the American Association for the Advancement of Science with support, the host noted, from Sen. Tom Harkin (D-Iowa). Panelists stressed the need for funding aimed at mitigating the damage to agricultural resources around the world potentially affected by climate change.
Accelerating cycles of drought and rain
Climate variability has already affected rains, droughts and temperatures in several parts of the United States, said Cynthia Rosenzweig, a senior research scientist with NASA's Goddard Institute for Space Studies. "We are already seeing climate change."
"We are seeing the expansion of drying," said Rosenzweig, as she brought up a slide showing precipitation measurements across the United States. The measurements, comparing values from 1958 through 2008, showed significant reductions in rainfall across large portions of the Northwest and Southeast. Idaho, Washington, Montana, Georgia and Florida had some of the most drastic changes in rainfall on the map.
However, the opposite is not good either, she said, adding that increased soil moisture in some areas could potentially harbor insects and other pests. And, in general, "crops do not like to have their feet wet."
Aside from concerns about rainfall, local temperature is also extremely important for crop performance.
The reproductive development in many important grains is a process sensitive to temperature, said Paul Gepts, a professor of agronomy at the University of California, Davis.
Some plants need cold winters
One of the potential side effects of climate change is a trend toward milder winters in some regions. Vital plants, Gepts said, require a cold winter in order to properly develop their seeds for the next season.
Rosenzweig agreed. Heat waves, at odd times of the year, affect the proper development of proteins within corn kernels, she said. "It is like scrambling eggs."
[link to www.scientificamerican.com]