OT- The Food, the Bad, and the Ugly

[Guest guest]

& gt; The Food, the Bad, and the Ugly

& gt; In a warmed world, even food won't be as good for you

& gt; By Glenn Scherer

& gt; 12 Jul 2005

& gt;

& gt;

& gt; Humanity is on the threshold of a century of extraordinary bounty,

& gt; courtesy of global climate change. That's the opinion of

& gt; Balling, former scientific adviser to the Greening Earth Society, a

& gt; lobbying arm of the power industry founded by the Western Fuels

& gt; Association. In a world where atmospheric carbon dioxide levels soar

& gt; from the burning of fossil fuels, he says, " crops will grow faster,

& gt; larger, more water-use efficient, and more resistant to stress. "

& gt; Quoting study after study, he invokes visions of massive melon yields,

& gt; heftier potatoes, and " pumped-up pastureland. " Bumper crops of wheat

& gt; and rice, he says, will benefit the world's farmers and the hungry.

& gt;

& gt; Balling's assertions are backed by solid science: Gaseous CO2

& gt; fertilization does cause remarkable growth spurts in many plants, and

& gt; could create a greener planet with beefier tomatoes and

& gt; faster-growing, bigger trees. But there's a catch: The insects,

& gt; mammals, and impoverished people in developing countries who feed on

& gt; this bounty may end up malnourished, or even starving.

& gt;

& gt; A small but growing body of research is finding that elevated levels

& gt; of atmospheric carbon dioxide, while increasing crop yield, decrease

& gt; the nutritional value of plants. More than a hundred studies, for

& gt; example, have found that when CO2 from fossil-fuel burning builds up

& gt; in plant tissues, nitrogen (essential for making protein) declines. A

& gt; smaller number of studies hint at another troubling impact: As

& gt; atmospheric CO2 levels go up, trace elements in plants (such as zinc

& gt; and iron, which are vital to animal and human life) go down,

& gt; potentially malnourishing all those that subsist on the plants. This

& gt; preliminary research has given scientists reason to worry about bigger

& gt; unknowns: Virtually no studies have been done on the effects of

& gt; elevated CO2 on other essential trace elements, such as selenium, an

& gt; important antioxidant, or chromium, which is believed to regulate

& gt; blood-sugar levels.

& gt;

& gt; The less-nutritious plants of a CO2-enriched world will likely not

& gt; be a problem for rich nations, where " super-sized " meals and vitamin

& gt; supplements are a dietary mainstay. But things could be very different

& gt; in the developing world, where millions already live on the edge of

& gt; starvation, and where the micronutrient deficit, known as " hidden

& gt; hunger, " is already considered one of the world's leading health

& gt; problems by the United Nations.

& gt;

& gt; The problem of hidden hunger grew out of the 1960s " green

& gt; revolution. " That boom in agriculture relied on new varieties of

& gt; high-yield crops and chemical fertilizers to staunch world hunger by

& gt; upping caloric intake in the developing world. Unfortunately, those

& gt; high-yield crops are typically low in micronutrients, and eating them

& gt; has resulted in an epidemic of hidden hunger. At least a third of the

& gt; world is already lacking in some chemical element, according to the

& gt; U.N., and the problem is due in part to a steady diet of

& gt; micronutrient-deficient green-revolution plants. Iron deficiency

& gt; alone, which can cause cognitive impairment in children and increase

& gt; the rate of stillbirths, affects some 4.5 billion people. Lack of

& gt; iodine, another micronutrient, can result in brain damage and is a

& gt; serious problem in 130 countries. According to the World Bank, hidden

& gt; hunger is one of the most important causes of slowed economic

& gt; development in the Third World.

& gt;

& gt; Enter rising CO2 levels, which could exacerbate hidden hunger in

& gt; this century. Current concentrations of atmospheric CO2 now exceed

& gt; anything seen in the last 420,000 years -- and likely in the last 20

& gt; million years, according to the U.N. Intergovernmental Panel on

& gt; Climate Change. And forecasts call for CO2 levels to rise

& gt; dramatically, from today's 378 parts per million to 560 parts per

& gt; million or more by as early as 2050. The micronutrient decline brought

& gt; by these ballooning CO2 levels could collide dangerously with the

& gt; developing world's nutrient-poor green-revolution crops and its

& gt; exploding population. Scientists also worry about how plant nutrient

& gt; deficiencies might destabilize the world's wild ecosystems in

& gt; unexpected ways.

& gt;

& gt; " This is one of those slow-motion effects that does not hit us like

& gt; a hammer, so we don't notice it, " says Irakli Loladze, an assistant

& gt; professor at the University of Nebraska. But, he says, failing to

& gt; notice the hidden hunger fueled by changing CO2 levels does not lessen

& gt; its potential impact: " The structure of the whole food web could

& gt; change. "

& gt;

& gt; Early carbon-dioxide enrichment experiments were relatively simple:

& gt; All kinds of wild and cultivated plants were exposed in field or lab

& gt; to current, doubled, and tripled levels of CO2, and scientists watched

& gt; what happened. In more than 2,700 studies, plant growth typically

& gt; exploded. Doubled CO2 levels resulted in an average increase in

& gt; agricultural yield of over 40 percent.

& gt;

& gt; But after about 1993, some scientists began to question this

& gt; approach. While the early studies looked at overall growth, they

& gt; ignored the nutritional quality of the bigger, faster-growing plants,

& gt; according to Loladze. When researchers began measuring the nutritive

& gt; value of CO2-enriched plants and feeding the vegetation to insects and

& gt; livestock, they started getting discomforting data.

& gt;

& gt; Those data reveal a clear pattern for the macronutrient nitrogen,

& gt; the only dietary chemical element that has been extensively studied to

& gt; date. Curtis, a professor of plant ecology at Ohio State

& gt; University, gathered 159 papers addressing the nitrogen-depletion

& gt; problem and found a " reduction of nitrogen in seeds in both wild and

& gt; crop species, " he says. Some species, like soybeans, showed no change,

& gt; while barley and wheat showed a 20 percent reduction.

& gt;

& gt; Though Curtis doesn't see this nitrogen shortage as a crisis for

& gt; industrial agriculture, where chemical fertilizers can make up

& gt; nutritional shortfalls, he wonders how protein declines might affect

& gt; " wildlife that rely on plant seeds -- insects, seed-eating birds, or

& gt; mammals, for example. For them, the nitrogen levels are really quite

& gt; important. "

& gt;

& gt; CO2-induced nitrogen deficiency in plants has already been shown to

& gt; affect herbivorous insects and the carnivores that eat them. To make

& gt; up for the plunge in plant protein, some plant-eating insects must

& gt; dramatically increase their intake of vegetation. But unable to keep

& gt; up with the need to eat enough food, some bugs suffer increased

& gt; malnutrition, starvation, predation, and mortality, writes

& gt; evolutionary biologist Seaborg in a recent issue of Earth Island

& gt; Journal.

& gt;

& gt; When Western Michigan University entomologist Karowe fed

& gt; cabbage white butterfly caterpillars leaves grown in an atmosphere

& gt; with double the earth's current CO2 levels, the insects ate about 40

& gt; percent more plant matter than under current atmospheric conditions.

& gt; But they still couldn't meet their dietary needs. Their growth rate

& gt; slowed by about 10 percent and their adult size was smaller.

& gt; Stiling at the University of South Florida made similar findings for

& gt; leaf miners, insects that eat out tiny caverns in leaves where they

& gt; live. When they took up housekeeping in CO2-enriched leaves, the

& gt; insects had to eat out 20 percent larger leaf homes. But the bugs were

& gt; still twice as likely to die of starvation as insects living at

& gt; today's CO2 levels.

& gt;

& gt; As serious as these results seem, no one should jump to conclusions,

& gt; says Mattson, chief insect ecologist with the U.S. Forest

& gt; Service in Rhinelander, Wis. He has spent the past five years

& gt; monitoring 10 insect species and found they react differently to

& gt; raised CO2 levels and lowered nitrogen levels, with some showing no

& gt; change and others harmed, and no clear pattern yet in sight. He

& gt; worries, though, that CO2 fertilization and nitrogen depletion could

& gt; combine to alter insect balances in unexpected ways. For example, the

& gt; leaf miners described above were also four times more likely to be

& gt; killed by parasitic wasps -- bad news for the miners but good news for

& gt; the wasps. In another study, aphids reproduced 10 to 15 percent faster

& gt; in enriched CO2 atmospheres -- good for the aphids, but bad for the

& gt; crops they infest.

& gt;

& gt; Sorting out CO2 winners and losers ultimately depends on your point

& gt; of view. To most people, " good insects " pollinate our crops, provide

& gt; food for fish and birds, and regulate wild and domestic plant growth,

& gt; and their decline would be problematic. However, farmers would likely

& gt; herald a population crash in " bad bugs " -- that is, crop-eating pests.

& gt; Unfortunately, no one can guess what CO2-altered natural and

& gt; cultivated systems might look like.

& gt;

& gt; The problem gets more complex with bigger animals. Clenton Owensby of

& gt; Kansas State University has conducted one of the most extensive CO2

& gt; experiments involving mammals -- specifically, sheep. " We got around a

& gt; 22 percent increase in yield of forage grasses over an eight-year

& gt; period in an enriched CO2 environment, " Owensby says -- but, " over

& gt; that same time period, we also saw an 8 to 12 percent reduction in

& gt; nitrogen concentration in the grasses, with a 5 to 10 percent

& gt; reduction in ruminant animal productivity. " That, he says, could

& gt; translate into longer times spent raising sheep and cattle in the

& gt; future, shaving already thin profit margins from financially strapped

& gt; ranches. The problem, Owensby says, is that sheep and cattle cannot

& gt; digest forage directly; they rely on microbes in their guts to break

& gt; down cellulose. But reduced nitrogen decreases the microbial

& gt; population, which slows the rate at which the forage can be digested,

& gt; which in turn slows the rate at which forage can be eaten, and

& gt; ultimately the rate at which the animals grow.

& gt;

& gt; Owensby assumes it will be easy for industrialized nations to

& gt; compensate. They can add nitrogen supplements to livestock diets,

& gt; though that will still add some cost to meat production. But this

& gt; would not be so easy in the developing world, where livestock

& gt; productivity is often already marginal. And it would be nearly

& gt; impossible with wild ruminants, such as browsing deer, elk, and

& gt; gazelles, among which nitrogen deficiency remains unstudied.

& gt;

& gt; Oddly, air pollution from fossil fuels may help offset the negative

& gt; impacts of increased CO2 in plants. Auto exhaust and coal-burning

& gt; emissions have increased nitrogen deposits in soils in the farm

& gt; country of industrial nations by up to 50 times natural levels,

& gt; according to Christian Korner of the Institute of Botany at the

& gt; University of Basel, Switzerland. While this brings with it other

& gt; serious problems such as acid rain, it could help ease or even solve

& gt; nitrogen and protein deficiencies. But not without other

& gt; repercussions, says Curtis: " The bottom line is that the combination

& gt; of high CO2 and high nitrogen favors typical human-camp followers,

& gt; mostly weedy species, " such as Canadian thistle, spotted knapweed,

& gt; leafy spurge, and kudzu, all of which seriously damage croplands and

& gt; ecosystems and compete with native plants. " That could lead to an

& gt; acceleration in the decline of biodiversity, " he says.

& gt;

& gt; What about the other 24 elements known to be vital to the human

& gt; diet? Precious few studies have been conducted on these

& gt; micronutrients, but the University of Nebraska's Loladze surveyed the

& gt; entire available scientific literature. He found that an overwhelming

& gt; number of the three-dozen-plus experiments conducted to date showed

& gt; that CO2 enrichment caused a significant decline in one or more

& gt; micronutrients, which include zinc and magnesium.

& gt;

& gt; " It is obviously known that carbon dioxide boosts plant growth; it is

& gt; after all a 'greenhouse' gas, " says Loladze. " Even a high-school

& gt; student in New Zealand growing plants with high amounts of CO2 was

& gt; able to grow huge tomatoes. But when she investigated their quality,

& gt; it turned out that the tomatoes had lower levels of micronutrients,

& gt; and less nutrition in them. "

& gt;

& gt; Loladze, to his dismay, found just two studies on rice, the world's

& gt; most important crop, and four on wheat, the second most important. One

& gt; rice study found that four out of five elements decreased when grown

& gt; in CO2-enriched air, with nitrogen dropping 14 percent, phosphorus 5

& gt; percent, iron 17 percent, and zinc 28 percent. Only calcium showed an

& gt; increase, of 32 percent. The other rice study showed no significant

& gt; change in micronutrient levels. In wheat, on average, every measured

& gt; element except potassium declined in three studies. A just-published

& gt; study by Chinese researchers led by Dong-Xiu Wu found that while high

& gt; CO2 levels significantly increased grain yield, they severely

& gt; decreased nutrient quality: nitrogen concentrations fell by 15

& gt; percent, phosphorus by 36 percent, potassium by 23 percent, and zinc

& gt; by 32 percent.

& gt;

& gt; Mattson points to still another problem with CO2. " Something else

& gt; that may exacerbate micronutrient deficiency is that added CO2 tends

& gt; to drive up [the production of] many plant non-nutrients " -- poisons

& gt; that enhance plant defenses against their would-be consumers. " The sum

& gt; total of lowered nitrogen, lowered essential micronutrients, and

& gt; heightened [plant poisons such as] tannins and other phenolics could

& gt; be the worst kind of soup, " he says. What we're doing, he believes, is

& gt; running an unregulated and probably irrevocable chemical experiment on

& gt; earth's ecosystems.

& gt;

& gt; Now that researchers have detected CO2-induced nutrient

& gt; deficiencies, they are seeking to understand why they happen. And they

& gt; think they have found some relatively simple underlying causes --

& gt; simple to scientists, that is, although perhaps not to those of us who

& gt; glazed over in high-school biology.

& gt;

& gt; We live in a carbon world, scientists explain: All life on earth,

& gt; from oranges to orangutans, is carbon-based. Most of this carbon comes

& gt; from our atmosphere, which is absorbed by plants, which pass it on to

& gt; grazing animals, which in turn pass it on to their predators. Change

& gt; the levels of atmospheric carbon, and all plants and animals along the

& gt; chain may be affected.

& gt;

& gt; Here's how: Plants create much of their biomass out of thin air,

& gt; from a steady diet of CO2 sucked through small leaf openings called

& gt; stomata. Then, via the miraculous sleight-of-hand known as

& gt; photosynthesis, the plants combine CO2 and water in the presence of

& gt; chlorophyll and sunlight to make carbohydrates, simple sugars, and

& gt; complex starches, which provide energy for plant growth. Much of the

& gt; remainder of what plants need -- nitrogen and trace elements --

& gt; doesn't come from the air, but is pulled up through the root system

& gt; from the soil.

& gt;

& gt; Scientists have isolated two mechanisms that potentially explain how

& gt; elevated CO2 levels reduce plant nutrients. The first is a " biomass

& gt; dilution " effect. As plants absorb more airborne carbon, they produce

& gt; higher-than-normal levels of carbohydrates but are unable to boost

& gt; their relative intake of soil nutrients. The result of this dilution

& gt; effect is increased yields of carbohydrate-rich fruits, vegetables,

& gt; and grains that contain lower levels of macro- and micronutrients. Put

& gt; simply, a bite of bread in our current CO2 atmosphere ends up being

& gt; more nutritious than one in the CO2-enriched atmosphere of the future.

& gt;

& gt; A second problem: Plants exposed to increased CO2 levels start to

& gt; narrow the stomata through which they inhale CO2 and exhale water

& gt; vapor via transpiration. This benefits plants by making them more

& gt; drought resistant, but it also means that fewer waterborne nutrients

& gt; flow into the roots. According to Loladze, if carbon-dioxide levels

& gt; are doubled, transpiration decreases by about 23 percent.

& gt;

& gt; A particularly disturbing study suggests that the mechanisms of CO2

& gt; nutrient depletion may already be causing a decline in the quality of

& gt; our food supply. p Penuelas of the Center for Ecological Research

& gt; and Forestry Applications in Barcelona, Spain, compared historical

& gt; plant samples grown at preindustrial levels of atmospheric CO2 with

& gt; modern equivalents. He found that today's plants had the lowest levels

& gt; of calcium, copper, iron, potassium, magnesium, sodium, sulfur, and

& gt; zinc than at any time in the last three centuries.

& gt;

& gt; Research for Tomorrow

& gt;

& gt; The obvious way to reduce the risk of declining food quality is to

& gt; cut fossil-fuel emissions, thereby reducing atmospheric CO2

& gt; concentrations. But political resistance in the U.S. and the global

& gt; failure to effectively curtail emissions means that CO2 levels will

& gt; rise far higher in coming decades. Therefore, scientists say, we need

& gt; to quickly embark on a crash program to research the biochemical

& gt; impacts of CO2 and prepare for the potential nutritional harm.

& gt;

& gt; " Nobody really knows how serious the changing chemical composition

& gt; of plants caused by heightened CO2 will be, " warns Mattson. " We are

& gt; just scratching the surface here. ... It is a wide-open question about

& gt; what impact this will have on the nutritional physiology or

& gt; reproductive success of animals. "

& gt;

& gt; Loladze agrees that three dozen studies, or even 200, prove nothing

& gt; conclusively. Curtis suggests a novel fast-track strategy for quickly

& gt; expanding that database: He says that data may not need to come from

& gt; new experiments, but may already exist " as archived seeds " and other

& gt; stored vegetative matter left over from the 2,700 CO2 plant

& gt; experiments already completed. Korner, however, calls for an

& gt; aggressive new round of nutrient experiments conducted on a global

& gt; scale.

& gt;

& gt; Such massive research would require major funding, something the

& gt; Bush administration seems unlikely to provide. Still, throw more money

& gt; at the problem, agrees Mattson, and, " you'll get more people working,

& gt; and you'll accrue the knowledge faster. Whether it can influence

& gt; policy, that's difficult to say. We have an administration that has

& gt; its mind set on what the policy should be. And it's always possible

& gt; for them to say we just don't know enough yet to act. It's a [faulty]

& gt; defense anyone can employ: to say, 'there is so much unknown; let's

& gt; not do anything.' "

& gt;

& gt; At some point, though, there will be a tipping point, which is what

& gt; most worries scientists like Mattson. He looks at the vast array of

& gt; harm caused by increased greenhouse-gas levels -- melting ice caps,

& gt; extreme weather, the altering of wildlife habitat, and the biochemical

& gt; impacts of rising CO2 levels -- and concludes, " You push something a

& gt; little bit every year over the long term, and you see little or

& gt; nothing changing. And all of a sudden ... one of those nonlinear

& gt; changes occurs, where you push everything just far enough, and you're

& gt; over a cliff. "

_______________________________________________

Join Excite! - http://www.excite.com

The most personalized portal on the Web!