Worldwide increases in population and affluence have created a disparity between supply and demand of food in recent years. This in turn has caused grain prices to rise, and poor people to go hungry. The New York Times reports that these issues are worsened by climate change which is currently impeding food production, and promises to become an increasing problem over time:
Many of the failed harvests of the past decade were a consequence of weather disasters, like floods in the United States, drought in Australia and blistering heat waves in Europe and Russia. Scientists believe some, though not all, of those events were caused or worsened by human-induced global warming.
Temperatures are rising rapidly during the growing season in some of the most important agricultural countries, and a paper published several weeks ago found that this had shaved several percentage points off potential yields, adding to the price gyrations.
Scientist have been slow to produce responses to the negative effects climate change has on agricultural production. This is partially due to the wide held belief that the problems caused by human use of fossil fuels will be offset by the resultant increase in carbon dioxide.
Carbon dioxide, the main gas released by combustion, is also the primary fuel for the growth of plants. They draw it out of the air and, using the energy from sunlight, convert the carbon into energy-dense compounds like glucose. All human and animal life runs on these compounds.
Humans have already raised the level of carbon dioxide in the atmosphere by 40 percent since the Industrial Revolution, and are on course to double or triple it over the coming century. Studies have long suggested that the extra gas would supercharge the world’s food crops, and might be especially helpful in years when the weather is difficult.
Unfortunately, recent research has indicated that crops may not respond as well as hypothesized to increased carbon dioxide levels.
They started by planting soybeans in a field, then sprayed extra carbon dioxide from a giant tank. Based on the earlier research, they hoped the gas might bump yields as much as 30 percent under optimal growing conditions.
But when they harvested their soybeans, they got a rude surprise: the bump was only half as large. “When we measured the yields, it was like, wait a minute — this is not what we expected,” said Elizabeth A. Ainsworth, a Department of Agriculture researcher who played a leading role in the work.
When they grew the soybeans in the sort of conditions expected to prevail in a future climate, with high temperatures or low water, the extra carbon dioxide could not fully offset the yield decline caused by those factors.
They also ran tests using corn, America’s single most valuable crop and the basis for its meat production and its biofuel industry. While that crop was already known to be less responsive to carbon dioxide, a yield bump was still expected — especially during droughts. The Illinois researchers got no bump.
Some measures have been taken to counter the damage caused by climate change, though. For instance, new crop varieties have been produced that are designed to withstand flooding and increased temperatures. But it’s clear that more action is needed in order to meet the food shortage that threatens our world’s future.
The United Nations recently projected that global population would hit 10 billion by the end of the century, 3 billion more than today. Coupled with the demand for diets richer in protein, the projections mean that food production may need to double by later in the century.
Unlike in the past, that demand must somehow be met on a planet where little new land is available for farming, where water supplies are tightening, where the temperature is rising, where the weather has become erratic and where the food system is already showing serious signs of instability.