No ice age for at least 100,000 years

Thursday 21st Jan 2016 by the Weather Club

Image: An artist's impression of ice-sheet covereage on Earth during previous ice ages (Source: Wiki)

The end of the most recent ice age, around 12,000 years ago, was different to previous episodes; it occurred around the time when humans had discovered fire. Fast-forward several thousand years, and we began burning fossil fuels, adding high amounts of CO2 to the atmosphere.

In a recently published Nature article, scientists from the Potsdam Institute for Climate Impact Research in Germany report that there will be no new ice age for at least the next 100,000 years.

Their work identifies two major factors that led to the onset of the past eight ice ages; 1) insolation and 2) carbon dioxide levels. So, “what is insolation?” It is the term used for how much energy the Earth receives from the sun. The exact amount of sunshine we get fluctuates over timescales of tens of thousands of years. This is because the earth orbits the sun in an elliptical shape, not a perfect circle. Another influence is the angle that the sun’s rays strike the surface of the earth. Carbon dioxide concentration is the second component. 200 years ago, CO2 levels were around 280ppm. As of 2015, levels are now at over 400ppm.

Therefore, if insolation is close to its lowest point, combined with atmospheric carbon dioxide concentrations not being too high, this enables vast ice sheets to start advancing over Europe, Asia and North America. Using climate simulation models, these two factors can be input, run based on past and current conditions, and then extrapolated forward, allowing scientists to make predictions of how ice ages in the future will evolve.

Their model reveals that we narrowly missed the initiation of another ice-age in the 19th century, because of the combined effect of relatively high CO2 concentrations and the low orbital eccentricity of the Earth. Even without anthropogenic CO2 emissions, their research shows that the next ice age would have begun in around 50,000 years time. However, additional anthropogenic CO2 emissions, has meant we will have to wait an extra 50,000 years on top of this, before ice-sheets begin to build-up again.

Supposing we significantly reduced the amount of fossil fuels used over the next 100 years, CO2 levels would still remain too high to send us back into an ice-age in the near-geological future. The fact that human actions seem to have steered us away from an ice age, further confirms the answer to an unnerving question - human’s now effectively control the climate of the planet.