If an ice age is coming soon, how will our lives be affected? In my first blog post in this series, I described the latest scientific research that demonstrates how continued global warming will bring on the next ice age and approximately when we can expect its onset. In this post I will describe the consequences the onset of the next ice age will create for modern civilization. In the final post in this series I will briefly summarize our options for delaying the dawn of the next ice age and review what preparations we should make ahead of its arrival.
Ice Age Consequence #1: Too Much Ice
Right now, only about 10 percent of Earth’s surface is covered by ice. At the height of the last ice age, about 23 percent of Earth’s surface was covered by ice. Figure 1 shows the regions of the northern hemisphere that were covered by at least 3 kilometers’ thickness of ice. In the southern hemisphere, New Zealand, Tasmania, and the southern part of Chile were covered with similarly thick layers of ice.
Figure 1: Maximum Extent of Thick Ice Cover of the Northern Hemisphere during the Last Ice Age. The turquoise-colored parts of the map indicate those regions covered by at least a 3-kilometer (2-mile) thickness of ice. Winter sea ice extended as far south as Mexico in the Pacific and North Carolina and Spain in the Atlantic. Image credit: John S. Schlee, United States Geological Survey and Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research.
In addition to those parts of Earth covered by ice 3 kilometers thick, there were many other regions covered by tens or hundreds of meters of ice. For example, in North America ice cover sufficient to prevent agriculture and the building of cities and transportation arteries extended south to Southern California.
Ice Age Consequence #2: Too Little River Water Flow
Regions of the world not covered by ice fields also would suffer. People there would find the water flow from rivers that they depend on to grow food largely locked up in ice that is not melting.
Ice Age Consequence #3: Depletion of Atmospheric Carbon Dioxide
Growing food would be a huge challenge for another reason—the depletion of carbon dioxide from the atmosphere. The greater the percentage of Earth’s surface covered by ice, the less concentration of carbon dioxide in Earth’s atmosphere.
This consequence occurs because greater ice coverage and lower global mean temperatures alter ocean currents. As a carbon isotope study revealed, these altered ocean currents remove carbon dioxide from the atmosphere and transport it to the deep ocean where it remains stored until ice coverage recedes and global mean temperatures rise.1
During the last ice age, the atmospheric carbon dioxide concentration dropped down to 180–190 parts per million.2 The minimum requirement for plants to make any food at all through photosynthesis is 150 parts per million at sea level, 167 parts per million at 3,000 feet elevation, 187 parts per million at 6,000 feet elevation, and 210 parts per million at 9,000 feet elevation.3 At levels of 150–500 parts per million of carbon dioxide in the atmosphere, there is a direct correlation between that CO2 level in the atmosphere and the amount of food plants can produce through photosynthesis. Thus, it would be impossible to grow enough food to feed more than a billion humans under ice age conditions.
Ice Age Consequence #4: Extreme Climate Instability
It would be impossible to feed that many humans under ice age conditions for yet another reason. Only for the last 2.59 million years of Earth’s 4.566-billion-year history has there been an ice age cycle. Except for the past 0.009 million years, the ice age cycle has been characterized by extreme climate instability (see figure 2).
Figure 2: Temperature Variability during the Last Ice Age. The blue and purple tracings portray the global mean temperature indicated by the GRIP and NGRIP Greenland ice cores, respectively. Image credit: Leland McInnes/Wikipedia Commons, CC-by-3.0.
This climate instability was characterized by unpredictable global mean temperature swings of up to 20°Fahrenheit (11°Celsius) on time scales of 2–3 centuries. Such radical climate instability explains why humans living during the last ice age were unable to launch and sustain any kind of large-scale civilization or sustain a large population.
Ice Age Consequence #5: Species Extinction
Because the Himalayas and the Tibetan Plateau are continuing to rise to higher elevations as a consequence of the ongoing tectonic collision between the Indian subcontinent and Asia, geophysicists confidently predict that the next ice age will be more catastrophic to life than the previous one. Specifically, they demonstrate that very likely the next ice age will result in even greater ice coverage, lower global mean temperatures, and lower atmospheric carbon dioxide levels than the previous ice age.
Most species of life presently on Earth, with appropriate human assistance, are capable of surviving these more dire consequences. However, many are not. The probable extinction of hundreds, if not thousands, of species of life will inevitably disturb ecosystems and eco-balances. Such disturbances will then impact human civilization.
Today, we possess the technology to ameliorate some of the more dire consequences brought on by the next ice age. For example, we could build glass-enclosed greenhouses on top of the more stable ice fields. We could heat these greenhouses and, at appropriate time intervals, augment the carbon dioxide concentration inside them. Since soil would be in much shorter supply and difficult to transport, we could employ hydroponic technology to grow crops inside greenhouses. Since fresh liquid water also would be in short supply, we could use a variety of energy sources to melt the abundant ice. However, no matter how much technology we marshal toward food production, it is highly unlikely that we could produce as much food as we do today.
In my third blog post, I will discuss other possible technological fixes aimed at ameliorating the consequences the next ice age is bound to bring. I will also briefly summarize to what degree we can use technology to delay its onset and review the preparations we should undertake right now in anticipation of the arrival of the life-altering event.
- Jochen Schmidt et al, “Carbon Isotope Constraints on the Deglacial CO2 Rise from Ice Cores,” Science 336 (May 11, 2012): 711–714, https://doi:10.1126/science.1217161.
- Schmidt et al., “Carbon Isotope Constraints,” 711; J. R. Petit et al., “Climate and Atmospheric History of the Past 420,000 Years from the Vostok Ice Core, Antarctica,” Nature 399 (June 3, 1999): 433, https://doi:10.1038/20859.
- King-Fai Li et al., “Atmospheric Pressure as a Natural Climate Regulator for a Terrestrial Planet with a Biosphere,” Proceedings of the National Academy of Sciences USA 106 (June 16, 2009): 9576–79, https://doi:10.1073/pnas.0809436106.