Dr. Mark Maslin opined in 2016 that geoscientists have realized over the years that there were limitations and challenges of their research into climate – many of which remain today. In particular, they recognized that variations in the Earth’s orbit did not cause the ice age cycles per se – they rather paced them. A certain orbit of the Earth can be associated with many different climates. The one we have today is in fact similar to the one we had during the most intense part of the last ice age.
Small changes in insolation driven by changes in the Earth’s orbit can push the planet into or out of an ice age through the planet’s “climate feedback” mechanisms. For example when summer solar radiation in reduced it allows some ice to remain after the winter. This white ice reflects more sunlight, which cools the area further and allows more ice to build up, which reflects even more sunlight and so forth. Therefore, the researchers’ next step was to understand the relative importance of ice sheet, ocean and atmospheric feedbacks. They discovered that greenhouse gases had an important role in controlling climate. In particular atmospheric carbon dioxide had to be low enough for the planet to start cooling before it could tip into an ice age.
So how can all this help us understand future climate? One idea is that small increases in greenhouse gases due to the expansion of agriculture that started 8,000 years ago have in fact delayed the next ice age. What’s more, if we continue emitting greenhouse gases at the same rate, we might have put off the next ice age for at least half a million years. If we have merely delayed the next ice age, we will still be in the Quaternary Period – the last 2.58 million years defined by the ice age cycles. But if we have stopped the ice ages, humans will have caused a much greater change and so have entered the Anthropocene period as some argue. If I had to put money on it, I’d say the Earth has experienced its last ice age for a very, very long time.
Managed & Built by I2M Consulting, LLC | © 2010-
