Plants tend to accumulate
in areas where a benign environment is encountered. When humans were small bands of
hunter-gatherers, they could follow the plants and animals to find their
food. They eventually discovered that
some plants could be raised under controlled conditions and produce a more
reliable source of nourishment. They
also discovered that selective breeding of plants would produce more productive
crops. As food security increased,
population could grow, and as the density of people increased, more complex
societal organizations would develop.
This was the beginning of civilization as we now know it.
As time went on science
provided more options for producing greater agricultural productivity. Tremendous improvements in recent generations
has allowed the world population to surge during that period. There are now about 7 billion people on Earth
and that population is on track to reach about 11 billion in this century. If that is to happen, food production must
increase even more than proportionately.
This is because people will begin to consume more food and more
crop-intensive types of food as their lot in life improves. The question is whether or not the food
supply can continue to be delivered to our current population, let alone one of
11 billion people.
Malthusian predictions have
thus far been proved wrong, but that does not mean that will always be the
case. Lester R. Brown provides a survey
of all the issues involved in continuing to provide our food supply in Full Planet, Empty Plates: The New Geopolitics of Food Scarcity (2012). He is not optimistic about the future.
“While
the decline of early civilizations can be traced to one or possibly two
environmental trends such as deforestation and soil erosion that undermined
their food supply, we are now dealing with several. In addition to some of the most severe soil
erosion in human history, we are also facing newer trends such as depletion of
aquifers, the plateauing of grain yields in the more agriculturally advanced
countries, and rising temperatures.”
Our civilization has
developed crops, and techniques for growing them, best suited to the soil,
water, and temperature conditions of the past few generations. The current generation is seeing changes in
basic conditions. Soil and water
availability are currently well-understood issues. Rising temperatures have been added to that
list of concerns and are becoming ever more a threat.
“Agriculture
as it exists today developed over 11,000 years of remarkable climate
stability. It has evolved to maximize
production within that climate system.
Now, suddenly, the climate is changing.
With each passing year, the agricultural system is becoming more out of
sync with the climate system.”
We are concerned here with
the effects of climate change. Perspective
will be gained from Brown’s book and one by David Wallace-Wells: The Uninhabitable Earth: Life After Warming.
Since the beginning of the
industrial revolution human activities have raised the global temperature
almost 1.0 degree Celsius (Centigrade).
The Paris Accord indicated 2.0 degrees as a point which must not be
reached. At current rates of carbon
emissions, we will reach 4.0-5.0 degrees.
These changes may not seem like much to some, but the consequences are
enormous. A few plants are the basis of
our food supply either as a direct consumable or as food for providing the
animal products we consume.
Unfortunately, the plants we depend on are highly sensitive to
temperature. This from Wallace-Wells.
“Globally,
grain [mostly wheat and rice] accounts for about 40 percent of the human diet;
when you add soybeans and corn [animal feed], you get up to two-thirds of all
human calories. Overall, the United Nations
estimates that the planet will need nearly twice as much food in 2050 as it
does today—and although this is a speculative figure, it’s not a bad one.”
The needed increase in food
supply is hindered by the fact that crop yields decline as the temperature
rises. This from Brown.
“Crop ecologists
in several countries have been focusing on the precise relationship between
temperatures and crop yields. Their
findings suggest a rule of thumb that a 1-degree-Celsius rise in temperature
above the norm during the growing season lowers wheat, rice, and corn yields by
10 percent.”
Temperature plays a critical
role in the processes of photosynthesis and pollination, partly explaining the
decline in yield as the climate warms.
“…as
temperature rises, photosynthetic activity in plants increases until the
temperature reaches 68 degrees Fahrenheit.
The rate of photosynthesis then plateaus until the temperature reaches
95 degrees Fahrenheit. Beyond this point
it declines, until at 104 degrees Fahrenheit, photosynthesis ceases entirely.”
“The
most vulnerable part of a plant’s life cycle is the pollination period. Of the world’s three food staples—corn,
wheat, and rice—corn is particularly vulnerable. In order for corn to reproduce, pollen must
fall from the tassel to the strands of silk that emerge from the end of each
ear. Each of these silk strands is
attached to a kernel site on the cob. If
the kernel is to develop, a grain of pollen must fall on the silk strand and
then journey to the kernel site where fertilization takes place. When temperatures are uncommonly high, the
silk strands quickly dry out and turn brown, unable to play their role in the
fertilization process.”
“When
it comes to rice, the effects of temperature on pollination have been studied
in detail in the Philippines. Scientists
there report that the pollination of rice falls from 100 percent at 93 degrees
Fahrenheit (34 degrees Celsius) to near zero at 104 degrees, leading to crop
failure.”
There are already vast areas too
warm to grow grain, and the extent of these regions will increase in the
future. It is often claimed that rising
temperatures are not such a severe problem since the crop-growing regions will
just drift north. Life is not so
simple. This from Wallace-Wells.
“…the
tropics are already too hot to efficiently grow grain, and those places where
grain is produced today are already at optimal growing temperature—which means
even a small warming will push them down a slope of declining
productivity. The same, broadly
speaking, is true for corn. At four
degrees of warming, corn yields in the United States, the world’s top producer
of maize, are expected to drop by almost half.”
“The
world’s natural wheatbelt is moving poleward by about 160 miles each decade,
but you can’t easily move croplands north a few hundred miles, and not just
because it is difficult to suddenly clear the land occupied now by towns,
highways, office parks, and industrial institutions. Yields in remote areas of Canada and Russia,
even if they warmed by a few degrees, would be limited by the quality of soil
there, since it takes many centuries for the planet to produce optimally
fertile dirt. The lands that are fertile
are the ones we are already using, and the climate is changing much too fast to
wait for the northern soil to catch up. That
soil, believe it or not, is literally disappearing—75 billion tons of soil lost
each year. In the United States, the
rate of erosion is ten times as high as the natural replenishment rate; in China
and India, it is thirty to forty times as fast.”
There will be collateral effects
that will arrive with climate change that will also hinder crop
production. Rising temperatures will
encourage crop pests and diseases from hotter regions to move further north
into regions where they were not previously active. Climate change will also affect rainfall and
its distribution. Too little rain can
make vegetation more susceptible to pests and diseases and allow it to become
fuel for wildfires. It will be the
change in precipitation at warmer temperatures that will lead to both more
intense flooding and more severe droughts.
“Precipitation
is notoriously hard to model in detail, yet predictions for later this century
are basically unanimous: both unprecedented droughts and unprecedented
flood-producing rains.”
“Drought
may be an even bigger problem for food production than heat, with some of the
world’s most arable land turning quickly to desert. At 2 degrees of worming, droughts will wallop
the Mediterranean and much of India, and corn and sorghum all around the world
will suffer, straining global food supply.
At 2.5 degrees, thanks mostly to drought, the world would enter a global
food deficit—needing more calories than the planet can produce. At 3 degrees, there would be further
drought—in Central America, Pakistan, the Western United States, and Australia. At 5 degrees, the whole earth would be
wrapped in what the environmentalist Mark Lynas calls “two globe-girdling belts
of perennial drought.”
Recently, yet another threat to our food supply has been
discovered. It was long thought that
carbon dioxide acted as a plant nutrient and an elevated level in the
atmosphere would provide a net benefit in terms of plant growth. It was true that plants did grow bigger, but
the net effect was to replace needed nutrients like proteins, vitamins, and
minerals with carbohydrates. This effect
has been referred to as “nutrient collapse.”
In Wallace-Wells’ words:
“Everything is becoming more
like junk food.”
If the protein content of
our foods has declined by 5-10 percent over the last 50 years, tracking the
rise in atmospheric carbon dioxide, we in the developed nations get our
nourishment but may be getting a little fatter as a result. Food is a relatively small portion of
expenses for most of us. But there are
many millions of people in the world who must spend half or more of their
income on food—assuming it is available.
Diminished nutrient content for them is equivalent to a loss of food
supply. And the nutrient content will
continue to fall.
“Recently,
researchers have estimated that by 2050 as many as 150 million people in the
developing world will be at risk of protein deficiency as the result of
nutrient collapse, since so many of the world’s poor depend on crops, rather
than animal meat, for protein; 138 million could suffer from a deficiency of
zinc, essential to healthy pregnancies; and 1,4 billion could face a dramatic
decline in dietary iron—pointing to a possible epidemic of anemia. In 2018, a team led by Chunwu Zhu looked at
the protein content of eighteen different strains of rice, the staple crop for
more than 2 billion people, and found that more carbon dioxide in the air
produced nutritional declines across the board—drops in protein content, as
well as in iron, zinc, and vitamins B1, B2, B5, and B9. Really everything but vitamin E. Overall, the researchers found that, acting
just through that single crop, rice, carbon emissions could imperil the health
of 600 million people.”
The outlook for food
production does not look promising—and the future is already upon us. A consequence of global warming that is often
overlooked is that the regions of the Earth where political unrest and violence
are endemic are mostly regions where the food supply is unreliable. As the Earth’s temperature continues to rise
the regions of food insecurity will grow and break out in new areas. The world will become a nastier, more brutal
place.
As with other threats from
climate change, the wealthy will initially be able to escape its consequences,
but the poor will not. For them it is an
existential threat already. The rest of
us will have a few more years to figure out what to do about it—if anything.
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