Friday, June 6, 2014, 09:45
Food for thought
By KARL WILSON in Sydney

Food for thought
An advertisement for a restaurant in Beijing shows a beef dish. As the region gets wealthier the demand for meat and poultry is increasing, but higher levels of grain and grass will be needed to feed animals if the nutritional value of cereals continues to drop, putting even more pressure on the world’s resources. (AFP)
The rising levels of carbon dioxide (CO2) in the atmosphere could have a devastating impact on food production, posing massive public health issues for billions of people around the world and with particularly worrying consequences for Asia.

As CO2 levels rise, the nutritional value of basic food crops such as rice and wheat is being slowly stripped away. Recent research has shown zinc, iron and protein levels fall significantly in rice and wheat grains as CO2 levels in the atmosphere increase.

In Asia, where 90 percent of the world’s rice is grown and consumed, the impact will be enormous.

It is estimated at least 2 billion people — mainly in the developing world — get most of their iron and zinc from eating rice or wheat, the same crops which are losing these micronutrients.

The lack of iron and zinc in diets is already a public health issue in many parts of Asia as it causes anemia, increased infant and maternal mortality, and lower IQ levels.

In May, the respected science journal Nature published the findings of a 12-year study carried out in Australia, Japan and the United States on the edible parts of 41 different varieties of rice, wheat, field peas, soybeans, maize and sorghum.

Called Increasing CO2 threatens human nutrition, the paper reported that the open field experiments over at least six growing seasons used the same amount of CO2 — about 550 parts per million (ppm) — that scientists predict will be in the atmosphere by the middle of the century.

In April, the amount of CO2 in the atmosphere reached a monthly average of 400 ppm — something which the United Nations described as being of “symbolic and scientific significance”.

To put this figure into perspective, prior to the industrial revolution the amount of CO2 in the atmosphere was 280 ppm, and less than a decade ago it was around 350 ppm.

Lead author of the paper, Samuel Myers of the Harvard School of Public Health, says the findings of the study are “possibly the most significant health threat that has been documented for climate change”.

In an exclusive interview with China Daily Asia Weekly from his office in Boston, Myers says: “The significance of the findings of the study should not be underestimated.”

“For years, scientists have been trying to figure out whether or not increasing levels of CO2 is impacting plant nutrients,” he explains. “This study has completely resolved that question.”

Global CO2 in the atmosphere is expected to reach 550 ppm in the next 40 to 60 years, even if further action is taken to decrease emissions, according to the study.

“At these concentrations, we find that the edible portions of many of the key crops for human nutrition have decreased nutritional value when compared with the same plant grown under identical conditions but at the present CO2 levels,” it said.

The study found that with higher CO2 levels (546 to 568 ppm), the zinc content of a grain of wheat is reduced by 9.3 percent, iron 5.1 percent and protein 6.3 percent. In rice, zinc is reduced by 3.3 percent, iron 5.2 percent and protein 7.8 percent.

With field peas, zinc is reduced by 6.8 percent, iron 4.1 percent and protein 2.1 percent; while in soybeans, zinc is cut by 5.1 percent, iron 4.1 percent and protein by 4.6 percent.

“The number of people in the world suffering from iron and zinc deficiencies is around 2 billion,” Myers says. “But if you look at the actual number of people getting the majority of their dietary iron and zinc from crops like these, it is probably between 2 and 3 billion.

“The problems this will pose for public health in the future could be very significant … especially for developing countries.”

Ros Gleadow, an associate professor at Monash University in Melbourne and one of Australia’s leading biologists, says rising CO2 levels in the atmosphere are having a “profound impact on the nutritional value of the plants and grains we eat”.

“This will have major consequences, not only on health, but on productivity in areas where people rely on certain foods such as rice and wheat for their main sources of protein,” she tells China Daily Asia Weekly.

“By 2050, people will have to get their protein from somewhere else as it will not be in the grains they eat.”

Gleadow explains that, based on some projections, by 2050 we will not be able to make bread with the current wheat varieties because there will not be enough protein in the grain to make bread.

“The point is, as the world grows richer and more urbanized, people want more meat and poultry. But if the grain you feed these animals is low in nutrients, then the animals will require more grains or grass to satisfy their own nutritional requirements.

“So there is a knock-on effect right throughout our food chain — or most of it anyway.”

The UN looks at 2050 as the tipping point for the planet. By then the population is expected to have grown from 7 billion today to 9.2 billion.

“At the same time, the world has to find ways of trying to double the amount of food it produces,” says Gleadow.

Experts are alarmed by the possible impact of increased levels of CO2 and the difficulty in arresting the rise. Myers explains that even if we cut CO2 emissions overnight, it would take probably 100 years to get the levels down to 350 ppm.

“The concentration of carbon dioxide in the atmosphere is now a function of how much we put into it … not what we take out,” he says.

“So in reality we have the option of giving up, knowing emissions are going to get higher, or start learning how to adapt.”

Scientists have been able to assess the amount of CO2 in the atmosphere going back thousands of years, and the results show that the levels have increased dramatically.

“We have a good idea how much CO2 was in the atmosphere going back 800,000 years by studying ice samples drilled in the South Pole. All this data is in the public domain for everyone to see,” Myers says.

“So a tiny pocket of air captured in a sample around the time of the industrial revolution will show us that the amount of CO2 in the atmosphere was 280 ppm.”

Myers explains that it is difficult to quantify the health impacts associated with climate change, but he is sure about one thing: “Is it the biggest public health issue we face? I think it is,” he asserts.

“You can do all sorts of complicated climate modeling to try and determine extreme weather conditions. What we don’t have a really clear picture of is how climate change is going to effect the distribution, for example, of infectious diseases, or how it will impact on crop yields,” he says.

But while predicting the impact of climate change is fairly complicated, Myers’ paper focuses on a single and clear-cut issue.

“What is nice about this study is that it is not about the effect of climate change but the direct effect of carbon dioxide,” he says.

“In fact, you can be a climate denier and not believe in a greenhouse effect at all, but you still have to be concerned that we know CO2 is rising in the atmosphere.

“No one is arguing about that, and we know CO2 is having a direct effect on the nutritional quality of food.”

With the CO2 level in the atmosphere now at 400 ppm, the highest it has ever been, World Meteorological Organization chief Michel Jarraud said: “Time is running out.”

“This should serve as yet another wake-up call about the constantly rising levels of greenhouse gases which are driving climate change,” he said in a statement in April.

The impact of carbon on nutrient levels is another blow to global food production.

According to the Intergovernmental Panel on Climate Change, crop yields are also set to suffer as a result of rising temperatures.

The organization’s recent summary on the impact of global warming stated that the production of maize, wheat and rice will go down over the course of this century.

“The public health problems are clearly quantified in the research … it really is going to be one of the great health and humanitarian challenges of this century,” Myers concludes.