Important climate change mystery solved

Illustration of Earth seen from space

Scientists find proof in the oceans that global temperatures today are the warmest for 10,000 years

The last ice age ended about 12,000 years ago. The warmer and more stable climate that followed allowed for the development of agriculture and the rise of human civilization, scientists call this the Holocene geological epoch, and we are still living in it.

Temperate forest scene
Image: Trevor Pye on Unsplash

There’s been a long-standing mystery surrounding this period because our climate models strongly suggest that global temperatures have risen steadily in parallel with rising carbon dioxide levels.

Some paleoclimatologists argue meanwhile, that there was a warm period from 7,000 to 5,000 years ago where earth was 1 to 2 degrees Celsius warmer than today. This debate is called the Holocene temperature conundrum and it’s important because because many climate sceptics argue that global warming predictions must be wrong because of it.

foraminifers under the microscope
Foraminifers under the microscope, the species studied by the team at Rutgers University

New research is attempting to obtain settle the argument. A scientific team* studied marine fossils from tiny single-celled organisms that lived at the ocean surface throughout the Holocene to reconstruct the temperature history of earth. They found that the first half of the Holocene was colder due to the cooling effects of remnant ice sheets from the previous glacial period, with a gradual warming through to modern times where carbon dioxide levels and temperatures increase dramatically because of human activity – as predicted by the modelling.

Infographic depicting Holocene Temperature Evolution

“The apparent discrepancy between climate models and data has cast doubts among sceptics about the role of greenhouse gases in climate change during the Holocene and possibly in the future,” said team leader Professor Yair Rosenthal of Rutgers University. “Our reconstructions demonstrate that the modern global temperature has exceeded annual levels over the past 12,000 years and probably approaches the warmth of the last interglacial period 128,000 to 115,000 years ago.”

The fossil samples were collected by a drilled core of bottom sediments near the Sepik River’s mouth off northern Papua New Guinea during the Rutgers-led Expedition 363 of the International Ocean Discovery Program.

*Yair Rosenthal, Co-author and Professor in the Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences at Rutgers University-New Brunswick. Shital P. Godard, a former Rutgers researcher now at National Taiwan University. Scientists at The Ohio State University and Nanjing Normal University also contributed to the study.

SOURCE 1, SOURCE 2, SOURCE 3, SOURCE 4, SOURCE 5

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