Climate Conversations: It’s just a matter of time

Our Climate Conversations series continues with John Cooper, Geologist and Keeper Emeritus of the Booth Museum of Natural History. John explains how fossils from the Booth Museum’s chalk fossil collection show us how most of the UK was once covered by warm shallow seas filled with marine giants and schools of fish.

The Booth Museum houses a significant collection of fossils collected from local Sussex rocks. It includes dinosaurs and insects from rocks in the Weald, shellfish, fish and reptiles from the Chalk and ice age mammals from various cliffs, pits and quarries in the county. Scientists have been studying these collections since 1850, when the first of our fossil specimens were published in science journals. Similar collections are housed in museums and universities around the world and over the last two centuries the complex jigsaw of the history of our planet, its life, its geography, and its climate have been unearthed.

Unravelling 100 million year old mysteries

Our collection of chalk fossils from the Chalk cliffs and quarries of Sussex have helped to unravel the mysteries of the planet from 100 million years ago during the Late Cretaceous Period and are still studied by experts today.

Fossil Ctenothrissa radians, fish species found by Charles Potter in the Lewes area in the 19th century. Photo by Bob Foreman

During the Late Cretaceous period, much of Europe was covered by a shallow sea, and was a very different place from today. There were no icecaps and as a result, sea levels were up to 300 metres higher than now. Only the tops of the Scottish mountains would have been visible.There was intense volcanic activity around the world which would have produced enormous amounts of carbon dioxide (1000ppm compared to 280ppm pre-industrial). This pushed average global temperatures up to 35 degrees C in the oceans. The continents were in very different positions compared to those we see now, with a much greater area of shallow shelf seas.

Late Cretaceous World Map, Mannion, P. D. (2013). “The latitudinal biodiversity gradient through deep time”. Trends in Ecology and Evolution 29 (1). DOI:10.1016/j.tree.2013.09.012. / CC BY-SA 3.0

But life, despite the extreme climate, had time to adapt, evolve and thrive in the seas over millions of years. A huge amount of biodiversity including Ammonites, ichthyosaurs and plesiosaurs swam in the seas, and on land, birds and pterosaurs flew, and the dinosaurs still roamed. The mammals were few, being only small scurrying creatures.

Chalk Lobster: Palaeastacus dixoni Lower Chalk, Clayton, East Sussex. Photo by Bob Foreman

A Cataclysmic Collision

This plethora of life came to a dramatic pause when an enormous chunk of asteroid collided with the Earth 66 million years ago, impacting near the Caribbean sea, plunging the planet into a lockdown which changed everything. Clouds of dust filled the skies, blotting out the sun perhaps for years, causing the death of plants, and setting off a chain of extinctions. Most famously, the dinosaurs, marine reptiles and the ammonites all disappeared. And yet, again, the planet survived, life adapted and evolved. Flowering plants blossomed, the mammals evolved, and the seas and continents teemed with life. Humankind appeared.

Life goes on?

And so when we look at climate change that we know is affecting the Earth today, we can use what we know about climates from the past to help us understand and put into perspective the changes we now observe. As human beings we can be rightfully saddened at the loss of species through the eradication of so many important habitats. We bemoan our stupidity at poisoning the oceans with our waste, the atmosphere with our greenhouse gases, and spreading ourselves so thickly across the land that we are exhausting our own food and mineral wealth causing starvation and disease.

Here today, gone tomorrow…

Yet with a geological perspective, especially looking at the Cretaceous world, the Earth has seen it all before, only more extreme. The fossils tell us so. But the planet survived and grew. We as mere humans may struggle to survive the changes that are yet to come, with rising sea-levels and intensifying climate. We will mourn the loss of biodiversity and the destruction of our coastal cities and populations, to say nothing of our ancient cultures. But modern peoples have only inhabited the Earth for the last 300,000 years; and our more ancient ancestors only for a few million years, a small fraction of time in Earth history: we are here today and gone tomorrow. Will Homo sapiens survive? The Earth will carry on, with us or without us.

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Read more from our Climate Conversations series 

John Cooper, Keeper Emeritus, Booth Museum of Natural History

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