Ancient ‘magnetofossils’ from previous period of climate change could offer clue to future

Fifty-six million years ago, the Earth’s climate warmed by 5-8C – a global warming event similar to the one our planet is currently experiencing.

New land mammals evolved, tropical forests expanded, giant insects and reptiles appeared and the chemistry of the ocean changed.

Now analysis of "magnetic fossils" – traces of tiny magnetic particles left by bacteria in the ocean – is offering scientists a way to understand the effects of the rapid climate change we're facing.

Among other things, the results seem to show that the New Jersey coast rapidly declined in oxygen near the beginning of the ancient warming event – and then oxygen levels fluctuated thereafter.

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The "magnetofossils" offer information that is not available from other fossils, the University of Utah researchers say.

Associate professor Peter Lippert said: “We interpret the relative abundances of these different populations of magnetofossils based on shape and size, which are a function of bacteria species, to encode environmental changes that are not as apparent in other fossil data sets or geochemical proxies.”

Using "first-order reversal curves", the researchers analysed three subsets of magnetofossils from ancient coastal marine sediments.

University of Utah doctoral student Courtney Wagner said: "Each of the magnetofossil populations tells us something a little different about the environment.”

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One consists of "giant needle-shaped" magnetofossils, associated with increased iron and an expansion of a gradient between oxygenated and deoxygenated seawater.

Another contains "equant" magnetofossils, which may record more stable, long-term conditions in the ocean.

The last contains "elongated" magnetofossils, which may indicate seasonal conditions.

Wagner said: "All this has potential implications for understanding how climate change will affect these sensitive coastal ecosystems today and in the future.”

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Research earlier this year showed that scientists may already be closer to being able to predict which species will be able to adapt to our warming world – and which won’t.

Climate change has already pushed many species to the brink and wiped out others due to problems such as habitat loss and temperature swings, the researchers say.

Using genome sequencing, researchers have found that fish such as the threespine stickleback can adapt very rapidly to extreme seasonal changes.

Sticklebacks are known for their different shapes, sizes, and behaviours, and can live in both seawater and freshwater and under a wide range of temperatures.

Researchers found that sticklebacks genetically change to adapt to cold waters and warm summers.

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