The recent global warming-induced drought has given us a taste of possible future impacts to world food supply resulting from climate change. But a drying out of the US’s breadbasket is just one of many affects climate change will have on world food supply as it continues to intensify in coming years.
First Impact: Damage to Transportation Infrastructure
To a lesser degree, we’ve already experienced the increased fires, floods, violent storms, and droughts caused by climate change. But, over time, these impacts worsen. And as they do they present increased harm to national and international infrastructures. Damage to waterways, roads, runways, and electricity grids all present challenges and slow food distribution in an age of ‘just in time’ delivery. Violent storms constrain air and sea traffic. And fires, floods, and tornadoes may damage, destroy, or block key transportation nodes.
The affects of the recent drought on the Mississippi river is a good example of one of these impacts. Glacial floods washing out roads and bridges in Greenland this summer is another example. Taken alone, any of these impacts would be easy to deal with. But it is the pace and frequency of these events that present a primary challenge to the world’s ability to distribute food and other key resources. Over time, the tempo and scope of these events will increase, causing further difficulty.
Second Impact: The Drying Out of the World’s Breadbaskets
According to climate models, global warming will result in increasing heat and dryness in the hearts of continents and across broad sections of the world. Europe, the US, Brazil, Mexico, large swaths of Asia and Africa all experience ongoing heat and drought unlike anything experienced before. In many areas, it may no longer be practical to plant crops. And overall productivity of these regions will suffer.
Though some areas do receive additional moisture, these areas are confined to the northern reaches of the globe. The land masses of the areas drying out, however, greatly exceed the land masses of the areas gaining new moisture. So, overall, the impact will be an increasingly strenuous challenge to world food production where, in the past, agricultural output was plentiful.
Third Impact: Coastlines Begin to Destabilize
As the Arctic loses more and more of its protective coating of sea ice, Greenland will become increasingly vulnerable to periods of rapid melt. Rates of deposition of water and glaciers into the ocean will increase. Some of these pulses are likely to be very powerful and dramatic. In addition, as the world continues to warm, the oceans gain heat and thermally expand. Melt from other glaciers contributes to sea level rise as well. Finally, the West Antarctic Ice Sheet begins to feel effects similar to those impacting Greenland.
The result will be that sea levels rise at ever-increasing rates as the years and decades pass. And this rise destabilizes many of the world’s coastlines. The band of coastal shallow water, the shore itself, and the wetlands surrounding the coast are some of the world’s most productive food zones. They take decades, even centuries, of stable water level to establish. Once these coastal zones start to move, a substantial element of world food production will be damaged and/or removed.
Fourth Impact: Ocean Heating, Acidification, Oxygen Loss
The fourth impact encompasses the many threats to the world’s oceans due to global warming. First, the warming oceans pose a threat to the highly productive coral reefs. Extreme heating can cause numerous and widespread instances of coral bleaching, which can damage or kill many reef systems. Coral reefs support at least a million species including fish and crustaceans that feed hundreds of millions of people around the world.
The impact of hot seas begins near the equator and expands north and south as global warming intensifies. Near the poles, the second and third impacts begin to take hold.
Ocean acidification begins in the northern and southern regions and expands towards the equator. Acidification is caused by increased levels of CO2 in the atmosphere being absorbed by the world’s oceans. The increasing levels of CO2 cause rising levels of ocean acidity. Many ocean creatures build their shells and exoskeletons from calcium carbonate. But as acidity levels rise, these creatures begin to lose the ability to build these structures. The result is that all life forms in the ocean which depend on shells made from calcium carbonate fall under an extreme stress. This includes many shellfish, corals, and crustaceans. Animals who feed on these creatures will also be impacted.
Expanding heat from the south and growing acidification from the north inflict a one-two punch on the world’s ocean systems. But the third punch is a general blow to all sea life. And it comes from oxygen depletion in the northern seas. As the ocean heats up, large areas of seabed methane begin to destabilize. These zones leech methane into the water column. As the methane rises, it chemically reacts with the water, binding oxygen to form CO2. If large areas of methane begin welling up from the water, large zones of oxygen depleted water are produced. These zones begin circulating around the globe, driven by wind and currents. These roving anoxic regions kill off any oxygen-dependent, water-breathing life so unfortunate to blunder into them.
In all, more than a billion people are fed from the bounty provided by the world’s oceans. So losses in productivity will have strong consequences for both world poverty and world hunger if policy measures do not prevent the more extreme cases of global warming. Current ocean impacts at 400 ppm CO2 are growing, but still somewhat moderate. By 600 ppm CO2, very severe impacts are prevalent. The current IEA projection based on business as usual fossil fuel consumption is 1000 ppm by end of century. It is doubtful that the oceans would survive such a blow in any form not resembling a most horrific science fiction.
All Impacts Operating In Concert
So what we will see as global warming intensifies is a combination of drying productive agricultural regions, a loss of productive coastal zones, increasing damage to the world’s ocean food supplies, and increasing levels of damage to the systems currently used to transport food around the world. These combined impacts, at their ramp up and peak, will be difficult or impossible for even the most advanced civilizations to adapt to. Under such a scenario, the difficulties imposed would almost certainly result in expanding hunger, poverty, and political destabilization over very large regions of the world.
Generally, there has been a tendency to emphasize one impact and ignore the others (just as there has been a tendency to emphasize the benefits or short comings of one solution while ignoring the others). This is an unhealthy and myopic response. All impacts must be taken together if we are to have a clear understanding of the situation and what must be done. And, though daunting, these combined impacts should serve as a call to action to do our best to prevent the ramping up of these impacts which, should we permit it, will have truly devastating consequences.