A recent study by international researchers suggests that life on Earth may have benefited from a brief weakening of our planet’s protective magnetic field. This phenomenon is thought to have occurred between 591 and 565 million years ago, coinciding with a significant increase in oxygen levels in Earth’s atmosphere and oceans.
Boom of life
There are approximately 575 to 565 million years ago, the Earth has experienced a period of major biological upheavals which have radically transformed the landscape of life on our planet. This period, known as the Ediacaran, witnessed a remarkable phenomenon: the emergence of more complex life forms. Before this period, life on Earth was mainly represented by simple single-celled organisms.
Fossils from this period demonstrate an astonishing diversity of organisms, from soft-bodied jellyfish-like animals to strange shapes and complex body structures. These first animals, although very different from the forms of life we know today, will have laid the foundations for the subsequent evolution of biodiversity on Earth.
That being said, despite advances in our understanding of the evolution of life on Earth, the precise mechanisms behind this emergence of more complex life forms during the Ediacaran remain a matter of debate among scientists.
However, several theories have been put forward to explain this crucial transition period in the history of life on our planet. One of the most discussed hypotheses is increasing oxygen levels in Earth’s atmosphere and oceans. Indeed, oxygen is an essential element for the respiration of aerobic organisms and it provides a Source of energy necessary for complex life. Thus, increased oxygen levels could have provided the environmental conditions conducive to the emergence and diversification of multicellular life forms.
Near collapse of the magnetic field
This hypothesis of increasing oxygen levels as a catalyst for the evolution towards multicellular life forms finds new light in light of recent discoveries concerning a brief weakening of the magnetic field terrestrial about 591 to 565 million years ago (about thirty times weaker than it is now).
The researchers were able to determine this period of weak magnetic field by carefully examining the magnetic properties of crystals of plagioclase, a common mineral in the Earth’s crust. These crystals were extracted from rock formations located in Brazil. By studying them, scientists were able to go back in time and reconstruct the history of the intensity of the Earth’s magnetic field.
How could an ultra-weak magnetic field cause increased oxygen levels? By modeling the evolution of the solar wind, scientists suggest that this weakening of the magnetic field could have allowed more hydrogen ions from escaping from Earth’s atmosphere into space, which could have led to higher oxygen levels in the seas and atmosphere.
The study suggests that this weakening would have lasted approximately 26 million yearsthus providing a window of time during which life on Earth could have thrived with higher oxygen levels.
Naturally, it has long been thought that an extremely weak magnetic field would be harmful to emerging life, because it shields life from solar winds. However, not everyone agrees with this view. As early as 1965, planetary scientist Carl Sagan asserted that the Earth’s atmosphere and oceans could have served as a protective cover for the first forms of life, even if the planet’s magnetic field diminished. This new work also goes in the same direction.
Details of the study are published in the journal Communications Earth. & Environment.
