Researchers decode years of studies to find the optimal temperature for life. Find it out here

What is the optimal temperature for life? A systematic review of published research has now identified that 20°C is the comfortable temperature that allows life to thrive on Earth. Here's why.

Why 20°C?

As per a team of specialists from institutes around the globe — Norway, Tasmania, Canada, Scotland, Germany, Hong Kong and Taiwan — 20°C is comfortable for humans and other species. Anything warmer than that affects productivity and efficiency, because releasing heat requires energy.

This is also true for various animals, plants, and microbes living in air and water. 

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It was earlier assumed that the number of marine species peaks at the warm waters of the equator. However, a research group from New Zealand recently observed that this was not true. Rather, the number of species dipped, and this dip as per an article in The Conversation, "has been getting deeper since the last ice age about 20,000 years ago."

This is because of global ocean warming.

Not only this, researchers found that even though many species have evolved to live at temperatures lower or higher than 20°C, fossil records also show that extinctions were lower at around this temperature.

Climate change

With climate change driving global warming, researchers said, "Our findings suggest that the pace of climate change is too fast for new species to evolve to replace those lost within the lowest latitudes."

This data is based on the systematic review of a total of 54 papers published in peer-reviewed journals.

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As per the researchers, temperatures higher than 20°C deplete genetic diversity; marine and freshwater species' tolerance of low oxygen; marine pelagic (open water living) and benthic (seabed living) algal productivity and fish predation rates on bait; and global species richness in pelagic fishes, plankton, benthic invertebrates and fossil molluscs.

The Corkrey Model

A mathematical Corkrey model predicts that "thermal breadth should be minimised, and biological processes most stable and efficient, at 20°C."

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Here, thermal breadth refers to the temperature range at which survival was equal to or above 50 per cent of its peak.

Scientists argue that while many marine species still may be able to adapt to global warming by simply shifting their geographic distribution, land species could suffer. This is because a shift in their geographical distributions won't be easy "due to landscapes modified by cities, farming and other human infrastructures."

(With inputs from agencies)