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New Findings Illuminate Earth’s Temperature History Over 485 Million Years
Recent research has unveiled that over the last 485 million years, Earth’s climate has varied significantly, experiencing both extreme cold and heat beyond previous estimates.
A comprehensive timeline that merges geological data with advanced computational simulations paints an intricate picture of Earth’s temperature fluctuations throughout the majority of the Phanerozoic Eon. Researchers report that, as illustrated in their study published in the September 20 issue of Science, Earth’s average temperature has dropped to as low as 11° Celsius and spiked to a peak of 36° C.
Traditionally, earlier studies relying on computer simulations reported a narrower temperature range of approximately 14° C to 26° C during these periods. This new research establishes a broader and more dramatic scope of historical climate conditions.
Crucially, the significant shifts in temperature appear to align closely with variations in atmospheric carbon dioxide levels, a relationship that has proven more influential than changes in solar radiation and other factors historically considered impactful.
The timeline’s development began in 2018 by researchers at the Smithsonian National Museum of Natural History, intended to enhance the museum’s “Deep Time” fossil hall exhibit. However, the project soon faced a compelling challenge, as noted by Emily Judd, a paleoclimatologist formerly at the Smithsonian. Prior studies that combined various methods to estimate ancient greenhouse temperatures consistently reported higher temperatures than those derived from simulations alone. This realization indicated that past warm periods had been underestimated across the entire Phanerozoic Eon, particularly in Earth’s tropical regions, which were considerably warmer than previously acknowledged.
The reconstructed temperature data also sheds light on current warming trends. At present, the average temperature of our planet is about 15° C (59° Fahrenheit), categorizing it in a relatively icehouse state. However, Judd emphasizes that this does not diminish the urgency surrounding human-induced global warming. She expresses concern that this new information might be misconstrued by climate change skeptics to imply that little action is needed. Judd warns that such interpretations ignore a critical element of the climate crisis: the rate at which CO2 and temperature are changing.
In the past two thousand years, Earth has experienced a rapid temperature increase. While many organisms can adapt to gradual climate changes, the accelerated rise in CO2 levels and corresponding temperatures jeopardizes their survival, including our own. Judd points out that humans have adapted to cooler conditions and often settle near sea level, further complicating our ability to confront the challenges posed by accelerated climate change. “Earth’s resilience does not directly translate to our own ability to adapt and thrive in the face of human-caused climate change,” she concludes.
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