Earth’s Mysterious Heatwave 400,000 Years Ago: What Happened?
Scientists have unraveled the mystery behind the hottest period on Earth, which occurred around 400,000 years ago and had long puzzled researchers.
A recent study has finally shed light on how, despite weak solar radiation and moderate levels of greenhouse gases, massive ice melt and significant sea level rise took place.
The hottest period on Earth in the past million years occurred approximately 400,000 years ago. During this time, the Northern Hemisphere had even less ice than it does today, and sea levels were about 10 meters higher than current levels.
Surprisingly, solar radiation, a key factor in heat waves, was relatively weak, and greenhouse gas concentrations were lower than they are today. This seemingly inexplicable period in Earth’s history has been termed the “MIS 11c paradox.”
Hsun-Ming Hu, a scientist from National Taiwan University (NTU), along with an international team, believes they have finally solved this mystery.
According to the study’s lead author, the key to resolving the “MIS 11c paradox” lies in the complex interactions between Earth’s ice sheets, oceans, and atmosphere in response to solar radiation. This question has baffled scientists for years, largely due to the lack of precise dating in many oceanic and terrestrial records.
In this new study, the team extracted a 2-meter speleothem core sample from Basura Cave in northern Italy. Using advanced uranium-thorium dating technology, they reconstructed the environmental history of southern Europe from 480,000 to 360,000 years ago.
By comparing solar radiation intensity, sea level changes, and other climate data, the researchers made a breakthrough.
They found that the carbonate records from Basura Cave were closely linked to climate changes in the Atlantic and Mediterranean regions.
The findings revealed that the “MIS 11c paradox” was the result of a series of interconnected factors.
Around 426,000 years ago, extreme heat in the Middle Hemisphere led to unprecedented warming in the mid- and low-latitude regions of the Atlantic. At the same time, Earth’s axial tilt gradually increased, intensifying summer heat and maintaining elevated ocean temperatures for an extended period.
This prolonged transfer of heat to high latitudes via ocean currents caused an unusually extended melting of ice shelves, resulting in the hottest period on Earth in the past million years.
The researchers suggest that this paradox offers valuable insights into global warming. Just as in the past, the Earth today can experience significant ice shelf destruction and rising sea levels due to long-term ocean warming, even without exceptionally high solar radiation or record greenhouse gas concentrations.
Thus, the ocean plays a crucial role in global warming and the destruction of ice shelves.
