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November 14, 2017


Arshad M. Khan

The UN has announced record average levels of CO2. So states the annual flagship
report released October 30 by its World Meteorological Organization. The average
levels measured using ships, aircraft and land stations have reached over 400 parts
per million (ppm), prompting the authors and other scientists to urge strong action.  At
the 23rd Conference of the Parties (COP23) of the United Nations Framework
Convention on Climate Change (UNFCCC) taking place Nov 6-17 at UNFCCC
headquarters in Bonn, local and regional leaders have signed the Bonn-Fiji
Commitment for faster climate action to help deliver the Paris Accords.  Such efforts
are increasingly urgent.

That climate change will affect food production is intuitive. Rising global temperatures
and the consequent extreme weather events and changes in climate patterns impact
production, distribution and potential for spoilage. Some of the worst hurt will be
people in a broad tropical belt of countries in Africa, Asia and the Americas. And ever
more severe hurricanes and typhoons due to rising ocean temperatures will do their
damage to coastal areas.

But there is another effect related to rising CO2 levels: Higher CO2 concentration
stimulates plant growth. Plants are larger, producing more carbohydrates, but this fast
growth lowers the concentration of protein and essential minerals. As this also affects
food crops like rice, wheat, potatoes and vegetables, it is likely to impact negatively on
nutrition and health.

As CO2 rises, plant stomata (pores that facilitate gas exchange) close up. Less water
transpiring through the stomata results in less water from the roots, and less minerals
brought up to build the proteins and vitamins.

A Harvard study reports that under elevated concentrations of CO2 (eCO2) as
projected for 2050-2100, protein content decreased as follows: rice (7.6 percent),
wheat (7.8 percent), barley (14.1 percent) and potatoes (6 .4 percent). It estimated an
additional 148 million of the world's population could risk protein deficiency.
Plant-based diets (such as those prevalent in India) increase vulnerability in the
population. The study also projects that a billion-plus mothers and 354 million children
could be affected by a dietary drop in iron and subsequent anemia.

The levels of CO2 have been rising steadily since the industrial revolution. In the
nearly 60 years since 1958, they have increased from 316 ppm to the latest figure of
406.58 ppm measured on January 22, 2017. It is the highest figure in human history.
The Harvard study noted above predicts CO2 to increase in the range 500-700 ppm
for 2050-2100. Meanwhile, the US Global Change Research Program projects CO2
levels to reach anywhere from 540-958 ppm by 2100 -- the latter figure a truly
disconcerting scenario.

Vegetables too, are not immune. The United States Department of Agriculture
(USDA), in studying the food content of 43 garden crops, found significant decline in
nutrients. They found statistically reliable declines in protein, calcium, phosphorous,
iron, riboflavin and ascorbic acid, ranging from 6 percent for protein to 38 percent for
riboflavin. To maintain health, humans will have to supplement their diet with vitamins
and minerals. It is a prospect not very feasible in the less developed countries,
leaving those populations exposed to malnutrition and early death.

Irakli Loladze noted the effects of speeded up growth on plant nutrients while pursuing
a Ph.D. at Arizona State University. The subject was green algae, and how, when they
were bombarded with light, they grew faster. Yet the plankton that fed on it, and had
now more than enough to eat, began to struggle to survive. The cause was soon
evident. Speeded up growth had so reduced the nutritional content that the plankton
could not eat enough to thrive.

Another way growth speeds up is through increased levels of atmospheric CO2, and
that also increases levels of carbohydrates through plant sugars, thereby diluting
other nutrients. Loladze had moved to a post-doctorate position at Princeton, and
while there, published his findings as "Rising CO2 and Human Nutrition: Towards
Globally Imbalanced Plant Stoichiometry." It was the first to propose that rising CO2
levels cause a change in plant quality, reducing essential minerals and protein, thus
affecting human nutrition. A later article backed up his assertions with solid research.

Many researchers are now involved in the area. Thus, a paper by Swedish and
German academics published this year examined wheat crops under elevated levels
of CO2. Its findings confirm increasing yields but decreasing nutrients, including
significant reductions in the dietary important elements N, Fe, S, Zn and Mg.

If humans are impacted, then surely other species are as well. Lewis Ziska, a noted
researcher with the USDA, planned an experiment to allay another concern: that of
plant breeding and its effect on nutrients. He chose the goldenrod, a wild flower for
which there is a long history. The Smithsonian has in its archive samples dating back
as far as 1842. Since no human plant breeding is involved in the goldenrod, it
afforded the Ziska team a clear path to look at environmental effects. They
discovered the protein content had reduced by a third through increasing CO2.  

It also happens the goldenrod is critical to bees. It flowers late and the protein in its
pollen is an important source of nutrition for bees as they build themselves up to
weather the winter. Thus, a drastic drop like a third of protein content could easily
contribute to the serious decline in bee populations around the globe. Now with its
own acronym, CCD for Colony Collapse Disorder, it continues, although thankfully has
declined from a high of 60 percent in 2008 to 31.1 percent in 2013, as reported by
beekeepers to the Environmental Protection Agency. Moreover, strenuous
replenishment efforts by beekeepers have helped to stabilize somewhat these
domesticated colonies. Of course, wild bee losses are another matter.  Bees are
critically important as they pollinate over 80 percent of cultivated fruit, vegetable and
grain crops, not to mention nuts, herbs, oils, forage for dairy and beef cattle, and
medicinal plants.

One final sobering thought: The nutrient content of food is expected to continue to fall
as CO2 levels increase this century. There is no doubt that this decline will impact a
wide range of species, including us.

Author's Note:  This article's original version appeared first on