Humans have triggered an era of ‘de-glaciation’
The build-up of heat-trapping greenhouse gases in the atmosphere could delay onset of Earth’s next ice age by 100,000 years, scientists estimate in a new study published this week in Nature.
The researchers reached their findings after “cracking the code of glacial inception,” according to a statement from the Potsdam Institute for Climate Impact Research, who said the relationship between incoming solar radiation and CO2 levels are the key factors that explain the last eight glacial cycles in Earth history.
At the same time their results illustrate that even moderate human interference with the planet’s natural carbon balance might postpone the next glacial inception by 100.000 years.
The scientists explained their findings in a press release:
“Even without man-made climate change we would expect the beginning of a new ice age no earlier than in 50.000 years from now … which makes the Holocene as the present geological epoch an unusually long period in between ice ages,” said lead author Andrey Ganopolski.
“However, our study also shows that relatively moderate additional anthropogenic CO2-emissions from burning oil, coal and gas are already sufficient to postpone the next ice age for another 50.000 years. The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it,” Ganopolski said.
“Our results indicate a unique functional relationship between summer insolation and atmospheric CO2 for the beginning of a large-scale ice-sheet growth which does not only explain the past, but also enables us to anticipate future periods when glacial inception might occur again,” Ganopolski said.
Using an elaborate Earth system model simulating atmosphere, ocean, ice sheets and global carbon cycle at the same time, the scientists analyzed the effects of further human-made CO2-emissions on the ice volume on the Northern Hemisphere.
“Due to the extremely long life-time of anthropogenic CO2 in the atmosphere, past and future emissions have a significant impact on the timing of the next glacial inception,” said co-author Ricarda Winkelmann. “Our analysis shows that even small additional carbon emissions will most likely affect the evolution of the Northern Hemisphere ice sheets over tens of thousands of years.”
The quest for the drivers of glacial cycles remains one of the most fascinating questions of Earth system analysis and especially paleoclimatology, the study of climate changes throughout the entire history of our planet.
Usually, the beginning of a new ice age is marked by periods of very low solar radiation in the summer, like at current times. However, at present there is no evidence for the beginning of a new ice age:
“This is the motivation for our study. Unraveling the mystery of the mechanisms driving past glacial cycles also facilitates our ability to predict the next glacial inception,” Winkelmann says.
“Like no other force on the planet, ice ages have shaped the global environment and thereby determined the development of human civilization. For instance, we owe our fertile soil to the last ice age that also carved out today’s landscapes, leaving glaciers and rivers behind, forming fjords, moraines and lakes. However, today it is humankind with its emissions from burning fossil fuels that determines the future development of the planet,” said co-author and PIK-Director Hans Joachim Schellnhuber.
“This illustrates very clearly that we have long entered a new era, and that in the Anthropocene humanity itself has become a geological force. In fact, an epoch could be ushered in which might be dubbed the Deglacial.”