We Would Have Delayed the Next Ice Age by Hundreds of Thousands of Years

Earth has been in a global glacial era for 34 million years, as evidenced by the thick ice sheets at its poles. According to a new study, the current warming trend will significantly push back its next cold phase.

A Cold Phase Stalled by Climate Warming

At such time scales, it is not a continuous and homogeneous glaciation: it is punctuated by markedly warmer periods, called interglacials. If the most recent one began about 11,700 years ago, recent work locates the start of a new cooling phase two millennia ago.

To reach this conclusion, climatologists from Columbia and Colorado Universities studied rock samples as well as preserved plant remains beneath the Barnes Ice Cap. Located on Canada’s Baffin Island, it represents the last vestige of the Laurentide Ice Sheet, which stretched from the polar circle to Illinois between 95,000 and 20,000 years ago.

Revealing the duration of exposure of the rock substrate to cosmic radiation, the concentrations of beryllium-10 indicate that the Barnes Ice Cap reached its minimal extent about 3,600 years ago, before beginning a new phase of expansion around the first century CE, which was halted during the second half of the 20th century.

The team attributes its interruption to the rapid rise in global temperatures observed over the past sixty years, a direct consequence of greenhouse gas emissions linked to human activities. “It’s a striking example of how we have disrupted this planetary mechanism,” says geochemist Nicolás Young.

Glaciation on Hold

According to the calculations of the authors of the new study, published in the journal Science, anthropogenic climate change should significantly delay the next glaciation.

“Humans are now geological agents capable of disrupting millions of years of natural glacial cycles and altering the Earth’s climate for hundreds of thousands to come,” they write. ” This postponement marks a major rupture in the geological history of the last two million years, with repercussions for ecosystems and the physical processes that have evolved in step with glaciations. “

For Professor Shaun Marcott, its duration will closely depend on the measures taken to reduce greenhouse gas levels.

Previously, scientists had looked into the causes of Earth’s “snowball” state, about 700 million years ago.