Earth is able to regulate and stabilize its own temperature across vast timescales – 100,000 years or so on average – even after dramatic shifts in climate caused by ice ages, solar radiation shifts, and intense volcanic activity, new research suggests.
According to the research team, this’stabilizing feedback is’ part of why Earth has been able to sustain life for the past 3.7billion years. This feedback has been HypothesizedThere was no direct evidence of this before.
Researchers dug into the existing paleoclimate records over the past 66,000,000 years and applied mathematical modeling to determine if swings in Earth’s average temperatures could be limited by one or several factors.
“You have a planet where the climate has been subjected so many drastic external changes.” says climate scientist Constantin Arnscheidt, from the Massachusetts Institute of Technology. “Why has life survived all these years?”
“One argument is we need some stabilizing mechanism to maintain temperature suitable for life. However, data has not shown that such a mechanism has ever consistently controlled Earth’s climate.
According to the team, silicate weathering is an important mechanism: silicate rocks weather over time and expose deeper layers of mineral to the atmosphere. Silicates and chemical reactions draw carbon dioxide out from the atmosphere, trapping it as rock and ocean sediment.
Increased atmospheric carbon dioxide levels can increase weathering activity and lead to more exposed silicates. This in turn reduces the atmospheric greenhouse gas, which limits future weathering.
The temperature stabilizations timescales are consistent with the timescales silicate weathering operates within, which can be up to 400,000 years. This weathering seems to be keeping temperatures under control, according to the record of fossils and ice-cores.
Researchers suggest that the planet would suffer from more extreme temperature fluctuations without this geological feedback mechanism. This is essential for understanding our planet’s past and its future.
“It’s almost like your car speeds down the street and then you brake, you slide for a while before you finally stop,” Daniel Rothman is a geophysicistMIT.
“Frictional resistance or stabilizing feedback kicks in after a certain time period. This is when the system returns back to a stable state.”
But there is more: The team looked at data over a longer time period, spanning over a million years. They found no stabilizing feedbacks. Chance may still play a significant role in the reason life continues to endure.
Researchers conclude that silicate weathering can provide stability in the short-term, but that it is not enough to stop temperature fluctuations over long periods.
The findings can also be used to predict the future of the planet. It’s likely that life on Earth is going to be able to weather whatever damage humans do to it – but we may not be here long enough to see it happen.
“On the other hand, it’s great because we know that todays global warming can be stopped by this stabilizing feedback.” says Arnscheidt.
“But it will take hundreds and thousands of years for it to happen, so it is not fast enough to fix our current-day problems.”
The research was published in Science Advances.
