Global warming generates more extreme warming, Find a new study of ancient climate. Researchers note a ‘warming bias’ over the past 66 million years that may return if ice sheets disappear.
It has become clearer Prolonged drought conditions, unprecedented heat, persistent wildfires, and frequent and more intense storms in recent years are the direct result of rising global temperatures. Due to the addition of carbon dioxide to the atmosphere by humans. new study from the Massachusetts Institute of Technology on extreme weather events in Earth’s ancient history suggests that today’s planet may become more volatile as it continues to warm.
The study, which appears today in science progressAnd It examines the paleoclimate record for the past 66 million years, during the Cenozoic Era, which began shortly after the extinction of the dinosaurs. Scientists found that during this period, fluctuations in Earth’s climate experienced a sudden “warming bias”. In other words, There have been many more global warming events (periods of prolonged global warming, lasting from thousands to tens of thousands of years) than cooling events.. Moreover, warming events tend to be more extreme, with larger temperature changes, than cooling events.
Researchers say A possible explanation for this warming bias may lie in a ‘multiplier effect’., where a small degree of warming, for example, due to volcanoes releasing carbon dioxide into the atmosphere, naturally accelerates certain biological and chemical processes that enhance these fluctuations, leading, on average, to a greater warming.
curiously, The team noted that this global warming bias disappeared about 5 million years ago, When ice sheets began to form in the northern hemisphere. It is unclear what effect ice has on Earth’s response to climate change. But as current Arctic ice recedes, the new study suggests a ripple effect may be emerging. The result could be a further amplification of human-caused global warming.
“The ice sheets in the northern hemisphere are shrinking and could disappear as a long-term consequence of human actions,” says the study’s lead author. Constantine Arnschedt, Graduate student in the Department of Earth, Atmospheric, and Planetary Sciences at MIT. “Our research suggests that this may fundamentally make Earth’s climate more vulnerable to long-term extreme global warming events, such as those seen in the geological past.” Arnscheidt study co-author Daniel Rothman, professor of geophysics at MIT and co-founder and co-director of the MIT Lorenz Center.
for your analysis, The team consulted large databases of sediments containing benthic foraminifera in the deep sea, single-celled organisms that have been around for hundreds of millions of years and whose hard shells are preserved in the sediments.. The formation of these shells is influenced by ocean temperatures as organisms grow; Therefore, shells are considered a reliable proxy for ancient Earth temperatures. For decades, scientists have analyzed the composition of these shells, collected from around the world and dated at different time periods, to track how Earth’s temperature has fluctuated over millions of years.
“When using this data to study extreme weather events, most studies have focused on large individual increases in temperature, typically a few degrees Celsius of warming,” says Arnscheidt. “Instead, we’re trying to look at the general stats and look at all the relevant fluctuations, rather than picking the big ones.”
The team first performed a statistical analysis of the data and found that over the past 66 million years, the distribution of global temperature fluctuations did not resemble a standard bell curve, With symmetrical tails representing equal potential for extreme heat and extreme cold. Instead, the curve was noticeably skewed, leaning toward warmer events rather than cold ones. The curve also showed a significantly longer tail, representing warm events that were either more intense or warmer than cooler ones.
“This suggests there is some kind of amplification relative to what I would have otherwise expected,” Arnscheidt says. “Everything points to something fundamental that is causing this push or bias towards warming events. It is fair to say that the Earth system is becoming more volatile, in the sense of warming.“.
The team wondered if this global warming bias might be the result of “double noise” in the climate carbon cycle. Scientists have long recognized that higher temperatures, to some extent, tend to speed up biological and chemical processes. Since the carbon cycle, which is a major driver of long-term climate fluctuations, itself consists of such processes, increases in temperature can lead to larger fluctuations, skewing the system toward extreme warming events.
In mathematics, there is a set of equations that describe these general inflationary or doubling effects. The researchers applied this multiplier theory to their analysis to see if the equations could predict skewed distribution, including the degree of bias and the length of their tails.
In the end, they found it The data and the observed bias towards warming can be explained by the multiplier theory. In other words, it is very likely that over the past 66 million years, periods of moderate warming on average have been enhanced by multiplier effects, such as in response to biological and chemical processes that have warmed the planet.
As part of the study, The researchers also analyzed the relationship between previous warming events and changes in Earth’s orbit.. Over hundreds of thousands of years, the Earth’s orbit around the Sun regularly becomes more or less elliptical. But scientists have questioned why so many past warming events have coincided with these changes, and why these events show such a dramatic rise in temperatures that what might be causing the change in Earth’s orbit alone.
Therefore, Arnscheidt and Rothman incorporated Earth’s orbital changes into the multiplier model and their analysis of Earth’s temperature changes, and found that multiplier effects can amplify, on average, modest increases in temperature due to changes in Earth’s orbit.
Rothman continues: “The climate is warming and cooling in conjunction with tropical changes, but the tropical cycles themselves will only predict modest changes in climate.” “But if we consider a multiplier model, the modest warming, combined with this multiplier effect, It can lead to extreme events that tend to occur at the same time as these orbital changes“Humans impose order in a new way,” adds Arnscheidt. “And this study shows that when we raise the temperature, we are likely to interact with these natural amplification effects.”
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