There's a point in life when you realize you're either a half-full or a half-empty kind of person. But there also comes a time when playing spot the silver lining, say, about midway through a terrorizing hurricane season, becomes a challenge even for global warming optimists. Over-warmed oceans aside, many scientists insist there is a positive side to the slow-motion explosion of greenhouse gases into the atmosphere. Their studies show that plants love carbon dioxide, and the more of it we pump into the world, the bigger our crops will grow, requiring less water and creating more bounty for all.
But there's a big "but" in here. Amidst the ongoing global warming scrap, a small but growing body of research is adding nutritional deficit to the negative side of the ledger. Those monster cabbages and broccoli forecast by greenhouse optimists may actually leave us starving.
And if a monumental new study from England is right, we might be living out the mass experiment much sooner than we'd hoped.
Science is full of contradictory messaging. We learn in grade school that humans exhale carbon dioxide with every breath. Plants inhale it during photosynthesis. And nature is happy. Then we learn in environmental studies that SUVs and lawn mowers also exhale the stuff, as do factories and coal-fired power plants. This time nature grimaces, temperatures rise and storms rage. Researchers, however, have discovered a bright side to pollution: crops exposed to twice the current levels of CO2 (which the world is expected to see by the end of the century) grow faster, can be harvested sooner and might even beat the heat of the sizzling summers to come. High-CO2 plants also drink less water, preparing them for the droughts that surely lie ahead. And, yes, high-CO2 greens grow bigger and, to the glee of heads of state around the globe, suck back more carbon dioxide, neutralizing a good chunk of the carbon our cars and industries spew into the air.
But in the midst of this celebration, scientists have failed to grasp the actual nutrient hit that CO2-drenched veggies would take. That's the view of Irakli Loladze, a mathematical biologist with the University of Nebraska who surveyed all the scientific lit on the topic. Of the few dozen projects that bothered to test for vitamin and mineral content in plants exposed to twice today's rates, Loladze says, "there was a very clear trend. Elemental content, like nitrogen, phosphorus, magnesium, zinc and calcium, drops. It drops significantly, as much as 30 per cent." These findings, he says, apply to a vast array of key crops like wheat and rice.
"We have never in the entire history of human agriculture grown plants over the globe with this high a level of CO2. We're experimenting with nature's food webs. Disregarding this effect would be simply ridiculous."
What kind of effect are we talking about? Well, so far, researchers have only studied the impact on insects and a few mammals. In studies Loladze points to, butterfly caterpillars that fed on leaves grown in twice the planet's current CO2 ate about 40 per cent more, but their growth was stunted. Leaf miners devoured 20 per cent extra but strangely died of starvation at twice normal rates.
Pesky crop-devouring aphids, on the other hand, thrived, reproducing 10 to 15 times faster. Not the kind of news farmers like to get. Listen closely and you'll hear the sound of pesticide guns being cocked.
While researchers aren't yet sure whether CO2 interferes with pesticide efficacy, scientists at the Alberta Research Council did forecast that more and stronger herbicides would be needed to fend off the mega-CO2 weeds of tomorrow.
Still, a majority of scientists will tell you that fretting about the impact of high CO2 on crops is a tad alarmist. The floods, droughts and Katrina-esque storms associated with climate change, they say, will be much more damaging to crops than a little extra gas in the air. Says Danny Harvey, a geography prof at U of T, "It could have some impact on how much grain you need to feed your cattle or how much range land they need in order to get enough nutrients." But humans, he says, have the technology to make sure our own food stocks are up to snuff. "You just increase fertilizer application if you need to."
While that might be the case, the question is whether there's any financial incentive for farmers to boost the nutrient content of crops if their tomatoes are nearly twice today's sizes and their apple trees bear 30 per cent more fruit. Rod MacRae, a food policy consultant and program coordinator of food security studies at Ryerson, thinks not. "The whole system, of course, rewards [the agriculture industry] for yield rather than for nutritional quality."
Synthetic fertilizers, adds MacRae, are partly behind the drop in calcium, vitamin C, iron and and other vital nutrients already detected in Canadian, British and American crops over the last 50 years. "It's known that synthetic fertilizers suppress a plant's normal tendency to take up micronutrients."
Even so, Sherwood Idso, president of the Arizona-based Center for the Study of Carbon Dioxide and Global Change, says any problems raised by high CO2 are minor and could easily be offset. "Let's say the protein is reduced a little bit - you just eat a little more. The percentage of yield increase is going to be far more than the percentage of protein decrease."
Adds Idso, "Most in the developed world are getting way more protein than the minimum daily requirement, so it becomes a moot point."
What of the vast majority on the planet who aren't so lucky? Idso, whose organization has been on Exxon Mobile's donor list a few times, says those are exactly the people who will benefit most from the water-efficient nature of high-CO2 plants. In fact, he says, letting levels of the greenhouse gas rise is the only answer to mounting global hunger issues.
Others say the whole scenario will only compound the problem of "hidden hunger," the condition in which a person gets enough calories but insufficient nutrients. Micronutrient deficiencies already affect half the world, slowing growth, depressing productivity and feeding countless forms of disease and illness.
"For the average middle- and upper-income earner, these things may not be a factor," says MacRae. "But they could be for people whose immune systems are compromised or whose income situation is so poor that they don't have the resources to acquire a proper diet."
Despite the potential health ramifications, Health Canada knows nothing about the issue and passed us off to Agriculture and Agri-Food Canada, where reps knew almost as little. But a handful of government scientists are doing some digging. Annick Bertrand, a plant physiologist with Agri-Food, says she and a few others are looking into ways to offset CO2's potential impact. The preliminary answer? Plant more alfalfa. According to Bertrand's research, "This is the best perennial crop for carbon sequestration. It's a way for agriculture to lower CO2 concentrations in the atmosphere."
Will the hippie sprouts suffice to offset the greenhouse gases streaming out of our SUVs, cement factories and soil beds at such alarming rates?
The unfolding experiment will be coming to a field near you faster than anyone imagined. Last month an English study revealed that the soil in temperate countries is releasing far more carbon dioxide than previously believed. Warmer temps, it seems, are seriously speeding up decomposition.
Why should we care? According to Guy Kirk, professor of soil systems at Cranfield University, it means we won't have to wait till the end of the century to reach doubled CO2 levels and put our theories to the test. "It's very difficult to predict, but maybe about 25 per cent [sooner]."
By the time we get there, our relationship with broccoli, beets and bananas might never be the same again. Says FoodShare's Debbie Field, "[We're] busy convincing people that eating more vegetables and fruits is going to make a difference to their health, but that's dependent on there being nutrients in the food."
If there aren't? "It's something we all have to worry about."