According to the study, the next Ice Age is due between 10,000 and 100,000 years from now - but global warming may step in to prevent it.
Credit: iStockphoto
The chill would likely induce a long, stable period of glaciation in the mid-latitudes, smothering Europe, Asia and North America to about 45 to 50º latitude with a thick sheet of ice.
However, there is now so much CO2 in the air, as a result of fossil-fuel burning and deforestation, that this adds a heat-trapping greenhouse effect that will offset the cooling impacts of orbital shift, said Crowley.
Critical state
"Even the level that we have there now is more than sufficient to reach that critical state seen in the model," he said. "If we cut back [on CO2] some, that would probably still be enough."
In September, a scientific research consortium called the Global Carbon Project (GCP) said that atmospheric concentrations of CO2 reached 383 parts per million (ppm) in 2007, or 37 per cent above pre-industrial levels.
Present concentrations are "the highest during the last 650,000 years and probably during the last 20 million years," the report said.
"No justification"
Crowley cautioned those who would seize on the new study to say "'carbon dioxide is now good, it prevents us from walking the plank into this deep glaciation'."
"We don't want to give people that impression," he said. "You can't use this argument to justify [man-made] global warming."
Last year, the U.N.'s Nobel-winning Intergovernmental Panel on Climate Change (IPCC) said that greenhouse-gas emissions were already inflicting visible changes to the climate system, especially on ice and snow.
Left unchecked, climate change could inflict widespread drought and flooding by the end of the century, translating into hunger, homelessness and other stresses for millions of people.
Global Warming
Amazing that these two scientists have discovered what Milankovitch wrote about 80 years ago.