The climes they are a changing
By Joel Preston Smith
“The fact that the entire home was lifted off its foundation is almost certainly evidence of inadequate attachment of the home to its foundation ... This evidence is bolstered by a number of flying objects during the event, including a certain Ms. Gulch, who was to be the tornado’s only fatality.”
- Charles A. Doswell III and Harold E. Brooks of the National Oceanic and Atmospheric Administration’s Severe Storms Laboratory, commenting to the American Meteorological Society in 1996 on the twister that extracted Dorothy Gale’s clapboard shack from Clyde, Kansas and set it down in the Land of Oz, crushing taxpayer Ms. Gulch—the Wicked Witch of the West.
Sans dead witches or drowed Gulf Coast denizens, it’s getting harder to believe the U.S. Government is more than vaguely interested in addressing global warming in terms that don’t just add more hot air to the problem. Reading accounts of the Bush Administration’s resistance to cut greenhouse emissions, and how the White House oscillates between scientific fact and cinematic fantasy, one gets the impression of a government that wishes its troubles would melt like lemon drops. Meanwhile, NASA scientists keep throwing back the curtain and presenting the Administration with revelatory satellite photos of the mushy, receding Patagonia Icefields of Chile and Argentina.
Separating the Administration’s facts from fiction is like sorting wind from whispers. The conflicting doomsday reports are particularly troubling for farmers, who’d like someone to just come out and tell them if their fields are going to fry, or if it’s going to rain frogs from here to Leviticus.
What does global warming mean for those who feed us? The most comprehensive and accessible field guide to the presumed apocalypse is a 250-page report published last May by the U.S. Climate Change Science Program, a task force composed of 15 agencies charged with integrating federal research on climate change. The projected impacts to U.S. agriculture outlined in The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States are often just as vague—with good reason—as they are grim.
Jerry L. Hatfield, lead author of the report’s chapter on climate change and agriculture, says research to date has largely overlooked the question of food security for 300 million U.S. residents.
“The government is finally beginning to realize that there are very real impacts associated with climate change,” says Hatfield, director of the USDA’s National Soil Tilth Laboratory in Ames, Iowa. “That a 1.8 degree Celsius rise in annual temperature may lead to a seven to eight percent decline in corn yields.”
Calculating the projected yield of even one of the USDA’s 116 economically significant “plant commodity groups,” is a nightmare unto itself. Hatfield notes that in order to estimate how climate might affect production, researchers must consider impacts on precipitation, nitrogen cycling, soil permeability and water-storage capacity. They might also consider growth rates and life cycles of individual crops, and pollen viability under a variety of weather and climate conditions. A 2-to-3 degree spike during pollen production for some crops, Hatfield notes, “can mean the difference between a fertile plant and an infertile one.”
Complicated as they are, statistical projections often don’t take into account such variables as the impact of changing technologies, the impact of various forestry or agricultural practices, competing demands for water resources among industry, agriculture and the private sector, pest versus host interactions … or other interrelated (but perhaps underrated) variables. Nevertheless, the Climate Change Science Program looked at the dominant variables—at historical climate patterns, crop yields and “constituent biota and processes”—and at the existing body of scientific literature in drawing what is an unquestionably bleak picture (save for rangelands) for U.S. agriculture (and therefore the U.S. environment and economy) through the year 2050.
Here’s a brief summary of their projections
- Increased incidence of disturbances such as forest fires, insect outbreaks, severe storms, and drought will command public attention and place increasing demands on management resources;
- Increased intensity of rainfall; One economic consequence of excessive rainfall is delayed spring planting, which jeopardizes profits for farmers paid a premium for early season production of high value horticultural crops such as melon, sweet corn, and tomatoes;
- Warmer winters will increase the overwintering of pest species, the range of some pests, and increase the occurrence of some pathogens (and chemical controls on pests); studies conducted in Western Europe and other regions have already documented changes in spring arrival and/or geographic range of many insect and animal species due to climate change; warmer winters will likely increase populations of insect species that are currently marginally over-wintering in high latitude regions;
- Increased atmospheric CO2 may lead to intensified pest behavior; the frequently observed higher carbon-to-nitrogen ratio of leaves of plants grown at high CO2 can require increased insect feeding to meet nitrogen (protein) requirements;
- Physiologic and metabolic changes to crops; smaller grain size (affecting both grain cattle producers) or lower test weight from heat stress, more failures of pollination associated with heat stress, and greater variability in crop production; however, elevated CO2 will have a helpful effect via reduced water consumption;
- Expanded ranges for weeds, and more of them, and Monsanto can’t help; many weeds respond more positively to increasing CO2 than most cash crops, particularly “invasive” weeds that reproduce by vegetative means; recent research also suggests that glyphosate, the most widely used her-bicide in the United States, loses its efficacy on weeds grown at CO2 levels that likely will occur in the coming decades;
- Diminished yields; the anticipated 1.2ºC rise in temperature over the next 30 years is projected to decrease maize, wheat, sorghum, and dry bean yields by 4.0, 6.7, 9.4, and 8.6 percent, respectively, in their major production regions;
- Rangelands are likely to experience increased productivity, but may undergo shifts in species; by stimulating both photosynthesis and water use efficiency, rising CO2 has likely enhanced plant productivity on most rangelands over the past 150 years, and will likely continue to do so over the next 30 years;
- Diminished water quality, potential loss of some species, expanded ranges of warm-water species; warmer temperatures will also enhance algal production and most likely the growth of nuisance species, such as blue-green algae; modeling results suggest that increased temperatures associated with climate warming will increase the abundance of bluegreen algae and thus reduce water quality; stream temperature increases have already begun to be detected across some of the United States, although a comprehensive analysis … has yet to be conducted.
Adding another element of uncertainty, the report notes that “irrigated crops can easily be 10°C cooler than air temperature …” In other words, in order to accurately predict yields, scientists may also need to factor in the impact of irrigation, crop by crop. The report also concedes that for horticultural crops, fruits and vegetables—40 percent of the U.S. agricultural market in 2002, according to the USDA—very little is known about the relationship between climate change, plant physiology and projected yields.
But the question remains: What does it all mean to a specific farmer in a specific place? To assess climate change on a local scale, Washington State University is running computer models of how changes in temperature might affect growing seasons on parcels of land (in some cases) as small as a few hundred acres. Chad Kruger, Interim Director of the university’s Center for Sustaining Agriculture and Natural Resources, says the Climate Impact Assessment Project is the first small-scale study to look at the backyard dynamics of a global phenomenon.
Kruger’s team is calculating regional shifts in temperature on the life-cycle of the codling moth Cydia pomonella—the world’s most resilient and ubiquitous apple pest. The moth, whose larval form bores its way through apple cores to feed on seeds, produces two full generations annually in Washington, requiring two insecticide treatments. But over the past five years or so, Kruger observes, rising temperatures, an earlier onset of the growing season and a longer summer have led to a partial third generation of the moth. Kruger says his team’s study, due out December first, projects that current climate trends indicate that by 2040, the moth is likely to produce three full generations annually, outbreeding the methods used to control it.
“That’s a significant concern to us,” Kruger adds, “because if we’re going to be spraying three times a year instead of two, the moth is going to develop resistance to the insecticide even more quickly.”
Kruger points out that while there’s been much talk of how farmers can combat global warming trends by sequestering CO2 in soil and in crops, few reports have considered the negative impacts of nitrogen fertilizer in agriculture. “Nitrogen management,” Kruger says, “may become the single greatest issue we need to be concerned with. What we’re doing, ultimately, is creating nitrous oxide, which is an extremely potent greenhouse gas.”
There doesn’t seem to be much good news in climatic projections for organic farmers, but at least there’s some recognition that insecticides and industrial fertilizers may contribute to the problem. Kruger says WSU is looking at low-energy, non-industrial solutions. “Anything we can do to reduce energy use, and our nitrogen use is going to have a major impact on climate. We’re going to have to start finding biological substitutes for nitrogen.”
Environmentalists have struggled for more than a quarter century to find an ear in Washington, but now both Federal and State governments are coming to terms (at least in principal) with the need to manage resources for potential climate shifts. In its 2007 list of “Top 20 Issues Facing the Industry,” The Oregon Department of Agriculture ranked climate change as an attribute of the “availability, storage and distribution of water.” The department ranked climate change as the state’s fourth highest concern, behind labor availability, Farm bill legislation and plant protection.
In May of 2006, Oregon Governor Ted Kulongoski founded a Climate Change Integration Group and populated it with scientists, and government and industry officials, but has yet to provide funding for a single paid staff member.
The Climate Change Science Program report can be downloaded at: www.usda.gov/oce/global_change/files/CCSPFinalReport.pdf.
Doswell, Charles A. III and Harold E. Brooks: Case Analysis Of A Historic Killer Tornado Event In Kansas On June 10, 1938. NOAA/ERL National Severe Storms Laboratory. Appears in Preprints, 18th AMS Conf. Severe Local Storms (San Francisco, CA), 19-23 February 1996, Amer. Meteor. Soc., 471-473.
Oregon Governor establishes climate change panel: www.oregon.gov/ENERGY/GBLWRM/CCIG.shtml.
Joel Preston Smith’s work can be found at www.joelprestonsmith.com.