Former farmers have prevented another ice age, study finds

A new study suggests that former farmers may have had a significant impact on the Earth's climate. By burning forests to pave the way for livestock farming and grazing, early humans increased atmospheric emissions of heat-capture gases and fundamentally altered the Earth's temperature. These activities associated with farming have probably played a key role in the warmer climate we are experiencing today.

The researchers suggest that the first farmers helped keep the Earth warm. Without their influence, our planet would probably have moved to another ice age. The last ice age ended around 12,000 years ago. Since then, we have been in an interglacial period or a warmer global temperature period.

"Without early agriculture, the Earth's climate would be significantly cooler today," said lead author Stephen Vavrus of the University of Wisconsin-Madison. "The ancient roots of agriculture produced enough carbon dioxide and methane to influence the environment."

To reach their conclusion, the researchers used a sophisticated climate model. The model allowed them to compare the current geological period, called the Holocene, to a similar period 800,000 years ago. He showed that the first period, called MIS19, was already 2.3 degrees Fahrenheit colder than the equivalent time in the Holocene. MIS19 and the Holocene have both started with similar concentrations of carbon dioxide and methane, but greenhouse gas levels have gradually decreased in MIS19. The era of the Holocene, by contrast, has seen a sharp increase in greenhouse gases.

"I noticed that methane concentrations began to decrease about 10,000 years ago and that 5,000 years ago, and that carbon dioxide began to decrease about 10 years ago. 000 years ago, about 7000 years ago, "said William Ruddiman. , Paleoclimatologist Emeritus at the University of Virginia: "This interglaciation has alerted me to the fact that early agriculture, which injects greenhouse gases into the atmosphere, was the starting point. "

The widespread deforestation in Europe began around 6000 years ago. Large agricultural settlements appeared in China 7000 years ago and spread throughout Northeast Asia 5000 years ago. The data show a link between clearing and increasing levels of carbon and methane.

To test their hypothesis, the researchers used the community climate system model 4 to simulate what would have happened in the Holocene without agriculture. The simulations provided a new insight into the natural cooling process and how greenhouse gases have diverted a new ice age.

"The climate community agrees that we have stopped the next glaciation in the near future and predictably, because even if we stop putting carbon dioxide in the atmosphere, what we have now will persist." said Ruddiman. "The phenomenal fact is that we may have stopped the Earth's major climate cycle and we are stuck in a warmer, warmer interglacial."