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All species on Earth appear to thrive at an “optimal” 20°C, according to a new study, which suggests land species may struggle more to adapt to changing climate.
The review of studies confirmed that the temperature ranges of animals, plants as well as microbes living both in air and water overlap at 20°C.
Scientists say this temperature appears to be “pivotal” for biodiversity.
While many species have adapted to live in warmer and cooler regions, many still live at 20°C.
“We find evidence that temperatures above 20°C become increasingly suboptimal for all domains of life, including animals, plants, and prokaryotes,” researchers write.
They suspect this temperature is pivotal for the efficiency of biological processes due to the molecular properties of water in cells.
The efficiency of chemical processes inside cells increases as temperatures rise, reaches a maximum, and then declines rapidly when it gets too hot.
This means temperatures warmer than 20°C could result in several crucial changes among organisms, such as a reduction in tolerance to low oxygen levels among marine species, researchers explain.
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In a warming world, creatures unable to move to comfortable temperatures may struggle more to adapt.
While marine species can adapt by altering their geographical distribution, land species may not be able to shift so easily “due to landscapes modified by cities, farming, and other human infrastructures,” scientists write in The Conversation.
The research also means areas consistently experiencing temperatures above 20°C could lead to a decline in species richness of landscapes.
Scientists also found similar evidence of extinctions in fossil records when temperatures remained beyond this threshold for long periods.
The findings add to growing evidence that biodiversity already reducing above 20°C will be further compounded by global warming.
Researchers warn that this would lead to a “simplification” of ecosystems with fewer life forms existing in many places.
There will also be more competition among existing species that could restrict habitats even further, they say.
