Human activity may delay the next ice age by 100,000 years, according to a new study.
Writing in the journal Nature, researchers from the Potsdam Institute for Climate Impact Research say that even “moderate human interference with the planet’s natural carbon balance” could cause us to skip an entire glacial cycle.
“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,” explains 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.”
The researchers write that the relation between insolation, the solar radiation that reaches the Earth's surface, and carbon dioxide concentration has allowed them to “explain” the last eight glacial cycles.
“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 system modeling that took into account atmosphere, ocean, ice sheets and global carbon cycle at the same time, the researchers analyzed ice volume in 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,” co-author Ricarda Winkelmann says. “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, and moderate future anthropogenic CO2-emissions of 1000 to 1500 Gigatons of Carbon are bound to postpone the next ice age by at least 100.000 years.”
The researchers said that at the beginning of a new ice age, there are periods of “very low solar radiation in the summer.” This, they say, is happening, but so far there is no indication of another ice age on the horizon.
“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 paper 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.”