We’re Still in the Ice Age
We usually talk about the “Ice Age” as though it were an ancient event that ended more than 10,000 years ago. But that's wrong.
Here’s a fact not many people know: For the vast majority of its history, Earth had no polar ice caps. The presence of ice sheets in the Arctic and Antarctic is not normal.
We usually talk about the “Ice Age” as though it were an ancient event that ended more than 10,000 years ago. That’s because there was a period, from around 2.5 million years ago to around 10,000 years ago, when global temperatures were as much as 6°C lower than they are today. During this period, Arctic ice sheets extended as far south as central England and the continental United States. This period ended with the Younger Dryas, a final cold snap before the planet warmed up somewhat, and the ice retreated to form the polar caps as we know them today.
But that was just the coldest part of the Ice Age. The full Ice Age actually began 34 million years ago, when global temperatures were 5-6°C warmer than today—and it hasn’t ended. Before it began, there was no ice at the poles. With the exception of the current ice age and another that occurred around 300 million years ago, Earth’s temperature has been higher than it is today for the entire time that large-scale multicellular life has existed (more than 500 million years).
Even factoring in the approximately 1°C rise in global temperatures since human industrialization, global temperatures are still 5°C lower than they were before the Ice Age began.
Carbon dioxide levels are also lower today than they were for the majority of the time that complex life has existed on Earth. Although today’s levels are far higher than they have been for hundreds of thousands of years, they are far lower than they were before the Ice Age began.
At some point in the future, this Ice Age will end, and Earth will return to its normal temperature range. Rising atmospheric carbon dioxide levels and changes in the chemical composition of the oceans will go hand-in-hand with this. Species will go extinct as the temperature rises, and new species will evolve to thrive in the new environment. That is how periods of global warming have always played out. But it is typically a slow process. If the current ice age lasts as long as the one 300 million years ago did, it should still have several million more years to go.
Is it a problem if human activity accelerates the end of the Ice Age?
As far as nature is concerned, probably not. Species dying and evolving is part of Earth’s natural evolution—including sudden changes in the climate, such as those following asteroid impacts. Changing atmospheric and oceanic chemistry is also a normal part of Earth’s life cycle. Further, the existence of human beings and the things we create is itself part of Earth’s natural evolution (just as other life forms have impacted the climate in ages past, such as when plants reduced the CO2 content of the atmosphere). In short, the climate will change, and the biosphere will change, but life will go on in a new form.
But the acceleration could present a problem for humans. A huge proportion of the human race lives in low-lying coastal cities such as New York, London, Hong Kong, Amsterdam, Los Angeles, and Sydney. These are at risk of permanent flooding when the polar ice caps melt (just as the sites of human settlements from before the Younger Dryas are submerged today). With a natural warming process, we might have thousands of years to build up coastal defenses to protect these cities. With accelerated warming, we may need to mount a more rapid response.
As the ecosystem changes, we may also need to take measures to protect our food supplies and the chain on which they depend. We may need to intervene to protect certain species on which we depend, develop ways of synthesizing foods that become unavailable naturally, or create indoor habitats or vertical farms to replace traditional agriculture.
These, fortunately, are the kind of things human beings excel at. We are not tied to a particular environment; we can adapt to change, and we can adapt the environment to suit our needs. But we will not be able to do these things if we restrict innovation and reverse our technological progress by trying to limit our energy use and protect the Earth’s environment as it happens to exist right now from human activity. Surviving climate change (which will happen whether we pollute or not) requires energy and technology.
We should not try to make the Ice Age last forever. That is what attempts to “stop global warming” amount to. Instead, we should continue innovating new solutions to ensure human life continues, and continues to improve, through whatever comes next as Earth recovers back to its normal, pre-Ice-Age temperatures.