PBS Space Time Season 2016 Episode 21 Is an Ice Age Coming?

In PBS Space Time's 2016 season, the 21st episode asks the question on whether an Ice Age is coming or not. Throughout the episode, the show's host and experts explore the factors and contributing elements behind global climate change and the Earth's many ice ages throughout history.

Viewers are first taken on a journey through the complex, interwoven systems of our planet's climate. The focus is on the Milankovitch cycles. These cycles are the collective name given to the variations in Earth's eccentricity, axial tilt, and precession that affect the amount of sunlight per square meter the planet receives. These fluctuations happen across timescales that are well beyond human lifetimes, with the shortest cycle lasting around 20,000 years and the longest cycle taking around 400,000 years.

By examining the Milankovitch cycles, the episode begins to show the complicated factors behind whether an Ice Age is coming or not. While these cycles have played a significant role in bringing about ice ages in the past, there is still much debate about how they will contribute to shaping Earth's climate in the future. Some researchers believe that the changes in the Milankovitch cycles may have been impacted by human activity that affects the levels of greenhouse gases in the atmosphere. It raises the question, will human activities override natural cycles that have existed for millions of years, or will they play a part in bringing about what scientist predict the start of a new Ice Age?

The host moves on and explores one contributing aspect that could lead to an Ice Age: volcanic eruptions. How is that connected to an Ice Age? The answer lies in the way volcanoes impact the Earth's atmosphere. When a volcanic eruption occurs, it releases massive amounts of sulfur dioxide and other compounds that absorb a portion of the Sun's energy and reflect it back into space, lowering global temperatures. There are indications that a dramatic reduction in temperature due to volcanic eruption could trigger an Ice Age. However, scientists do not believe that a single individual eruption can lead to an Ice Age.

While volcanic eruptions are a possibility, the show also discusses the elephant in the room - human activity. Fossil fuel use, the cutting down of trees, and other human activities are leading to an increase in the concentration of greenhouse gases in the Earth's atmosphere. These gases trap heat in our atmosphere, which leads to increased Earth temperatures. The evidence is mounting, with clear and broad-scale changes in Earth's climate, including more extreme weather patterns, longer droughts, and melting polar ice caps. The show discusses climate models based on various scenarios of future greenhouse gas concentrations. One model predicts a new Ice Age in about 1,500 years, whereas another model predicts a continuation of the present-day warming.

Near the end of the episode, PBS Space Time explores the possibilities of whether humanity has any power to stop an impending Ice Age. By examining the factors that have led to slowing down and increasing the ice ages of history, scientists suggest that it may be possible to impact the coming of a new Ice Age. However, it would need a shift in climate between double the speed of previous climate shifts, along with more substantial volcanic activity to occur within the next couple of centuries. Therefore, the episode concludes that the likelihood of humanity being able to stop or slow down an Ice Age is low.

In summary, the episode "Is an Ice Age Coming?" of PBS Space Time's 2016 season explores the natural and human-made factors behind the possibility of a new Ice Age in the future. The host and experts explore the intricate systems that dictate our planet's climate and raise the question of human's role in altering them. While there is much debate about the impact humans may play in the Earth's future, one thing is evident; the planet's climate is a vast and complex system that is rapidly changing due to natural and human factors.