Picturing our planet and its climate, 520 million years ago, when animals diversified throughout the oceans

Complex forms of animal life, including the ancestors of most of the major animal groups that we know today, diversified in the oceans around 520 million years ago, in an evolutionary event known as the “Cambrian explosion”. Researchers from Belgium, France, the UK and the USA¹ shed new light on the position of Earth’s continents, and on Earth’s climate, during this critical time. Results of the study are published in Nature Communications.

Most animal groups populating our planet today appeared during the early Cambrian (by about 520 million years ago), establishing the animal-rich biosphere we still have today. Despite the biological importance of this time, there are still substantial uncertainties about what Earth was actually like then, in particular the position of the continents and the nature of the climate. These uncertainties persist because most of the techniques used to reconstruct past climatic conditions and to determine the palaeo-positions of the continents are difficult to apply so far back in time. In particular, the further back in time we go, the less rock is preserved, and more likely it is that the physical and chemical properties of the preserved rock will have been altered by geological processes.

Figure 1: Early Cambrian continental arrangement and ocean temperatures, as deduced from the numerical comparison of our global climatic simulations with a database of climatically sensitive sedimentary rocks. White hexagons represent the sedimentary rocks formed during the early Cambrian and preserved today, which served as many “anchor points” to determine the extent to which simulated climate agreed with our current knowledge of early Cambrian climate. Continent names are typeset in bold.

Climatically sensitive rocks, such as sedimentary salt (evaporites) and tropical sea deposits (oolitic limestones), only form under certain climatic conditions and are an important source of climate data, independent of the commonly used geochemical methods. In particular, it is much harder to alter the climate signal of a whole rock type than it is to subtly change the climatically sensitive chemistry of that rock. As a result, climatically sensitive rock types provide a greater temporal and paleogeographic coverage of palaeoclimate data than can geochemical proxy data. An interdisciplinary team of researchers from Europe and the USA applied, for the first time in the Cambrian, a robust quantitative treatment to a database of climatically sensitive rock types to shed new light on what Earth looked like over 500 million years ago. By comparing global numerical simulations of early Cambrian climate with the database of sedimentary deposits, the researchers determined what combination of climate and continental arrangement best explained the geological database. This numerical approach provides a unique window on planet Earth at the time of the Cambrian explosion (Figure 1).

The numerical results indicate that the Cambrian animal radiation took place in a world with most continental land masses in the Southern Hemisphere and with a climate substantially warmer than today, with mean annual ocean surface temperatures of around 19°C at the poles and 38°C at tropical latitudes. These results show that integrating data and models in a quantitative analytical framework has the potential to substantially refine our understanding of what Earth looked like in the deep past, at least as far back as 500 million years ago.

¹Author affiliations

Department of Geology, Ghent University, 9000 Ghent, Belgium; School of Geography, Geology and the Environment, University of Leicester, Leicester, LE1 7RH, UK; Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA; Biogéosciences, UMR 6282, UBFC/CNRS, Université Bourgogne Franche-Comté, 6 boulevard Gabriel, F-21000 Dijon, France; Aix-Marseille Univ, CNRS, IRD, INRA, Coll. France, CEREGE, Aix-en-Provence, France; Department of Earth & Planetary Sciences, Northwestern University, Evanston, IL, USA; Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France ; INRAE, University of Bordeaux, BIOGECO, F-33610 Cestas, France ; Inria Bordeaux-Sud-Ouest, Pleiade, F-33405 Talence, France

Contact

Dr Thomas Wong Hearing – thomas.wonghearing@ugent.be +32 (0) 485 33 16 90
Professor Thijs Vandenbroucke – thijs.vandenbroucke@ugent.be +32 (0) 479 61 03 23

Note to editors regarding the treatment of this press release

This study does not show and cannot be used to state that the ongoing and future warming of our planet due to anthropogenic climate change will be beneficial to life or negate the deleterious environmental effects of anthropogenic climate change. This study does not look at modern climate or climate change. This study does not look at changing climates, only at constraining an ancient climate state. Fundamental climate parameters 500 million years ago were very different to those of today. The authors would be happy to explain further why this is the case.

Reference

Quantitative comparison of geological data and model simulations constrains early Cambrian geography and climate. Wong Hearing, T.W., Pohl, A., Williams, M., Donnadieu, Y., Harvey, T.H.P., Scotese, C.R., Sepulchre, P., Franc, A., Vandenbroucke, T.R.A. Nature Communications (2021)

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Picturing our planet and its climate, 520 million years ago, when animals diversified throughout the oceans

Complex forms of animal life, including the ancestors of most of the major animal groups that we know today, diversified in the oceans around 520 million years ago, in an evolutionary event known as the “Cambrian explosion”. Researchers from Belgium, France, the UK and the USA¹ shed new light on the position of Earth’s continents, and on Earth’s climate, during this critical time. Results of the study are published in Nature Communications.

 

Most animal groups populating our planet today appeared during the early Cambrian (by about 520 million years ago), establishing the animal-rich biosphere we still have today. Despite the biological importance of this time, there are still substantial uncertainties about what Earth was actually like then, in particular the position of the continents and the nature of the climate. These uncertainties persist because most of the techniques used to reconstruct past climatic conditions and to determine the palaeo-positions of the continents are difficult to apply so far back in time. In particular, the further back in time we go, the less rock is preserved, and more likely it is that the physical and chemical properties of the preserved rock will have been altered by geological processes.

[caption id="attachment_8072" align="alignright" width="600"] Figure 1: Early Cambrian continental arrangement and ocean temperatures, as deduced from the numerical comparison of our global climatic simulations with a database of climatically sensitive sedimentary rocks. White hexagons represent the sedimentary rocks formed during the early Cambrian and preserved today, which served as many “anchor points” to determine the extent to which simulated climate agreed with our current knowledge of early Cambrian climate. Continent names are typeset in bold.[/caption]

Climatically sensitive rocks, such as sedimentary salt (evaporites) and tropical sea deposits (oolitic limestones), only form under certain climatic conditions and are an important source of climate data, independent of the commonly used geochemical methods. In particular, it is much harder to alter the climate signal of a whole rock type than it is to subtly change the climatically sensitive chemistry of that rock. As a result, climatically sensitive rock types provide a greater temporal and paleogeographic coverage of palaeoclimate data than can geochemical proxy data. An interdisciplinary team of researchers from Europe and the USA applied, for the first time in the Cambrian, a robust quantitative treatment to a database of climatically sensitive rock types to shed new light on what Earth looked like over 500 million years ago. By comparing global numerical simulations of early Cambrian climate with the database of sedimentary deposits, the researchers determined what combination of climate and continental arrangement best explained the geological database. This numerical approach provides a unique window on planet Earth at the time of the Cambrian explosion (Figure 1).

The numerical results indicate that the Cambrian animal radiation took place in a world with most continental land masses in the Southern Hemisphere and with a climate substantially warmer than today, with mean annual ocean surface temperatures of around 19°C at the poles and 38°C at tropical latitudes. These results show that integrating data and models in a quantitative analytical framework has the potential to substantially refine our understanding of what Earth looked like in the deep past, at least as far back as 500 million years ago.

 

¹Author affiliations

Department of Geology, Ghent University, 9000 Ghent, Belgium; School of Geography, Geology and the Environment, University of Leicester, Leicester, LE1 7RH, UK; Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA; Biogéosciences, UMR 6282, UBFC/CNRS, Université Bourgogne Franche-Comté, 6 boulevard Gabriel, F-21000 Dijon, France; Aix-Marseille Univ, CNRS, IRD, INRA, Coll. France, CEREGE, Aix-en-Provence, France; Department of Earth & Planetary Sciences, Northwestern University, Evanston, IL, USA; Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France ; INRAE, University of Bordeaux, BIOGECO, F-33610 Cestas, France ; Inria Bordeaux-Sud-Ouest, Pleiade, F-33405 Talence, France

 

Contact

Dr Thomas Wong Hearing – thomas.wonghearing@ugent.be +32 (0) 485 33 16 90
Professor Thijs Vandenbroucke – thijs.vandenbroucke@ugent.be +32 (0) 479 61 03 23

 

Note to editors regarding the treatment of this press release

This study does not show and cannot be used to state that the ongoing and future warming of our planet due to anthropogenic climate change will be beneficial to life or negate the deleterious environmental effects of anthropogenic climate change. This study does not look at modern climate or climate change. This study does not look at changing climates, only at constraining an ancient climate state. Fundamental climate parameters 500 million years ago were very different to those of today. The authors would be happy to explain further why this is the case.

 

Reference

Quantitative comparison of geological data and model simulations constrains early Cambrian geography and climate. Wong Hearing, T.W., Pohl, A., Williams, M., Donnadieu, Y., Harvey, T.H.P., Scotese, C.R., Sepulchre, P., Franc, A., Vandenbroucke, T.R.A. Nature Communications (2021)