The earth reveals a species distribution in a chilly local weather – watts with that?

Guest contribution by Eric Worrall

Scientists Emma Dunne and Bethany Allen believe we are heading for a new climate-induced mass extinction – but they admit that the earth still has polar ice caps and that global biodiversity shows an “ice house” pattern that peaks in warm tropical latitudes reached.

Prehistoric creatures flocked to different latitudes to survive climate change – the same thing is happening today

June 28, 2021 7:37 PM AEST

Emma Dunne
Postdoctoral Researcher, School of Geography, Earth and Environmental Sciences, University of Birmingham
Bethany Allen
PhD student, School of Earth and Environment, University of Leeds

Life on earth is most diverse at the equator. This pattern of increasing biodiversity as we move through the tropics towards the equator can be seen on land and in the oceans and has been documented for a wide range of animal and plant groups, from mammals and birds to ants to trees.

Although this pattern is so striking today, the distribution of biodiversity across latitudes – the so-called latitude gradient of biodiversity – has not always been this way. Studies looking at the evolution of biodiversity by latitude have shown that for some time periods in the earth’s history, species diversity was indeed highest at latitudes far from the equator.

Modern biodiversity peaks in equatorial regions of lower latitudes, such as the tropical rainforests of the Amazon and Central Africa. This pattern is more likely to be recorded during “ice house” times, when ice sheets are present at both poles at the same time – like today.

Bimodal peaks were recorded during warmer intervals, known as “greenhouse” or “greenhouse” earth states. This means that there were two bands where biodiversity was highest, and these wrapped around the earth in mid-latitudes or regions between 25 ° and 65 ° north and south of the equator.

As a possible “sixth mass extinction” is looming or is already underway, a long-term perspective will be crucial in order to understand how the earth’s biodiversity can also be preserved in the future.

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The part that Bethany and Emma left out was that CO2 levels were much higher than they are today (420 ppm) for most of Earth’s history, including previous cool periods like Carboniferous (800 ppm). The Cretaceous Period, the age of the dinosaurs, was only 4 ° C warmer than today, but had an incredible 1700 ppm CO2.

What I’m saying is, even if CO2 is the main driver of climate change to achieve something like the species redistribution that Bethany and Emma are talking about, at our current pace you would be burning fossil fuels for about seven hundred years. That just won’t happen – we will run out of recoverable fossil fuel reserves long before we have any geologically noticeable impact on the world’s climate.


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