Human carbon emissions will defer the next ice age according to a scientist writing for Nature Geoscience. The next ice age ended 11,500 years ago and, currently, no-one knows when the next one will begin.
Scientists used data on the Earth’s orbit and other parameters to identify the closest matching warm interglacial period from history that looks most like the current one. In the journal they write that the next Ice Age should begin within 1,500 years – but with emissions so high it is believed that this will now not happen.
“At current levels of CO2, even if emissions stopped now we’d probably have a long interglacial duration determined by whatever long-term processes could kick in and bring [atmospheric] CO2 down,” said Luke Skinner from Cambridge University. Scientists from University College London, the University of Florida and Norway’s Bergen University calculated that the atmospheric concentration of CO2 would have to fall below about 240 parts per million (ppm) before the glaciation period could commence.
The root causes of the transitions from Ice Age to interglacial and back again are the subtle variations in the Earth’s orbit known as the Milankovitch cycles, after the Serbian scientist Milutin Milankovic who described the effect nearly 100 years ago. The variations include the eccentricity of the Earth’s orbit around the Sun, the degree to which its axis is inclined and the slow rotation of its axis.