The average temperature over 500 million years ranged from 11 to 36 degrees

September 20 () –

The Earth’s average global temperature has varied much more than previously thought over the past 500 million years, ranging between 11 and 36 degrees Celsius.

Periods of extreme heat were, in most cases, linked to elevated levels of carbon dioxide, the main greenhouse gas, in the atmosphere.

These are the main conclusions drawn from a new temperature curve based on a method called data assimilation, which allowed researchers to combine data from the geological record and climate models to create a more coherent understanding of ancient climates. The study is published in Science.

“This research clearly illustrates that carbon dioxide is the dominant factor controlling global temperatures over geological time,” he said. in a statement Jessica Tierney, a paleoclimatologist at the University of Arizona and lead author of the study.When CO2 is low, the temperature is cold; when CO2 is high, the temperature is warm.”

The findings also reveal that Earth’s current global temperature, At 15 degrees, it is colder than the Earth has been for much of the Phanerozoic, the eon under study. But greenhouse gas emissions resulting from human-caused climate change are currently warming the planet at a much faster rate than even the most rapid warming events of the Phanerozoic, the researchers say.

The speed of warming is endangering species and ecosystems around the world and is causing rapid sea level rise. Several other episodes of rapid climate change during the Phanerozoic have led to mass extinctions.

Rapid advance towards a warmer climate could pose a danger to humanswho have mostly lived in a range of global temperatures of 5 degrees Celsiuscompared with a temperature range of 24 degrees over the past 485 million years, the researchers say.

“Our entire species evolved towards a climate of ‘icehouse’, “It’s not reflective of most of geologic history,” Tierney adds. “We’re changing the climate to a place that’s really out of context for humans. The planet has been and can be warmer, but humans and animals can’t adapt that quickly.”

Tierney and the Smithsonian began working in 2018 to provide museum visitors with a curve that charts Earth’s global temperature throughout the Phanerozoic, which began about 540 million years ago and continues to the present day.

The team collected more than 150,000 estimates of ancient temperature calculated from five different chemical indicators of temperature preserved in fossilized shells and other types of ancient organic matter.

Their colleagues at the University of Bristol created more than 850 model simulations of what Earth’s climate might have been like at different periods in the distant past based on continental position and atmospheric composition. The researchers then combined these two lines of research evidence to create the most accurate curve of how the Earth’s temperature has varied over the past 485 million years.

Another finding of the study concerns climate sensitivity, a metric of how much the climate warms when carbon dioxide doubles. “We found that carbon dioxide and temperature are not only closely related, but they are related in the same way over 485 million years. We don’t see the climate being more sensitive when it’s hot or cold,” Tierney concludes.