The planet Earth is described by climatologists as currently being in an “interglacial” period. In other words, the planet Earth exited from an “Ice Age” around 10,000 years ago, a time when massive ice sheets covered all of what is now Canada and extended as far south as Ohio and Boston. A quick warming trend took hold and the ice shrank back toward the polar regions, melting into the world ocean and causing a massive sea level rise. The term “interglacial” also implies that the earth would expect to re-enter a cold period, another “Ice Age,” sometime in the future. But it now appears that this ice age may be pushed back considerably into the distance. If humans ask themselves “Could increased burning of fossil fuels and wood avert the coming ice age” they must now reply in the affirmative. But rather than celebrating the dodging of this bullet with dancing or tears of joy, the response should be concern and anxiety- because instead of an “Ice Age,” the future appears to hold a “Hot Age.”
The science of modern climatology has gradually formed a knowledge base regarding how the Earth’s global atmosphere functions to regulate the temperature of the planet. In the early 1800s a French scientist named Fourier discovered that carbon dioxide, a trace element in our skies, has a role to play out of proportion to its relatively tiny concentrations. While making up less than one thousandth of the gases humans breathe, carbon dioxide is vitally important not only by serving as a vital nutrient for plant life. It also serves, according to climatology, as a substance which traps heat from the sun by reflecting certain wavelengths of solar rays back down to the planetary surface instead of allowing them to bounce back out into space. As time has passed and a major effort of satellite observation has been undertaken over the past twenty years, understanding of temperature mechanisms in our atmosphere have advanced remarkably- but have only supported Fourier’s insight on carbon dioxide.
The word “albedo” expresses an essential truth about this planet. “Albedo” refers to the ability of planet Earth to reflect sunlight back into space- what people would call “earthshine” if they lived on the Moon. Parts of the Earth’s surface are white (ice and snow), and reflect most of the light that strikes them. Other portions are blue (seawater) or brown (earth) and absorb more heat. But above it all, carbon dioxide plays its vital role. CO2 is completely invisible and has no taste or smell, so it is easy for non-scientists to fail to understand how vital it is in holding onto the sun’s warmth. But this physical process is a two edged sword.
Over the past two centuries, as human populations have rocketed up to 7 billion and industrialization has taken hold of most human societies, humans have mined coal and oil and cut down large expanses of forest to manufacture products and generate energy. This process has boosted the concentrations of carbon dioxide in our skies from 260 parts per million to around 390 parts per million today. This is the highest concentration of carbon dioxide that the Earth’s atmosphere has contained in the past 650,000 years. As a result, planetary temperatures have increased by almost one degree Celsius. While this seems like a tiny change- many humans cannot really tell the difference- it is extremely rapid in geologic terms. Climate changes on a one degree scale usually take hundreds or even thousands of years, and this is talking about mere decades. The process also seems to be open-ended: as people continue to add CO2 and other greenhouse gases to the sky at the rate of some 30 billion tons per year, they expect temperatures to rise another 2 degrees Celsius by 2100. Such a change would be noticeable to everyone, and would probably begin to cause coastal sea flooding as ice sheets on Greenland and Antarctica would start to melt into warmer sea and air surrounding them. Scientists also expect the floating ice at the North Pole to almost totally disappear in the summertime within thirty years. This has never happened in human memory.
At 7 billion, the human race is in the unfortunate situation of needing a “Goldilocks” planet- not too hot and too cold. An ice age would gradually cover over vital land areas with ice, depriving humans of land for growing food. But unfortunately, a “hot age” is likely to be worse. For one thing, sea level rises of fifty to a hundred feet could destroy every major coastal city if all the ice on top of Greenland and Antarctica were to melt, chasing over a billion humans into homelessness. This would not be an overnight change- but many scientists expect a rise of three to five feet by the year 2100, enough to cause serious problems of flooding especially during storms. For another, the melting of most snow packs and mountain glaciers in the temperate zones of this planet along with increased air temperatures in agricultural regions promise to stress many crops with less reliable water and more heat. Additional dangers to the human race include the total destruction of coral reefs due to increasing levels of acid in the world ocean. Many millions of humans currently depend on the fisheries that are hosted by coral reefs for their survival. Finally, these changes are expected to happen with extreme rapidity, in decades or at most a couple of centuries. This time frame is totally inadequate for the human race to come to terms with the terrible consequences of changes on such a massive scale.
In conclusion, the human burning of fossil fuels has apparently pushed back the future Ice Age that would eventually have happened as part of a natural cycle. They have done so accidentally by driving the heat trapping characteristics of our atmosphere sharply upward through burning fossil fuels. But this process is rapid and extreme, promising to drive us into a Hot Age instead. That Hot Age promises to contain more misery and mortality for the human race in a shorter time frame than the Ice Age would have delivered in terms of damage to economics, food supplies, and infrastructure.