What this means in a warming world

Have you ever wondered about the optimum temperature for life on Earth? For humans, 20 °C is comfortable. Any warm and we Work less efficiently Because energy is required to release heat.

We know that many species can live in extreme cold. Hot temperature compared to humans. But our Systematic review According to published research, the thermal ranges of animals, plants and microbes living in air and water overlap at 20°C. Could this be a coincidence?

For all species, the relationship with temperature is an asymmetric bell-shaped curve. It means Biological process Increase according to temperaturereach a maximum, and then drop rapidly when very hot.

Recently, a New Zealand research group looked at their numbers Marine species Did not ascend to the equator., as is generally assumed. Rather, numbers declined, with peaks in the subtropics.

Follow up the study The dip appears to have been deepening since the last ice age, about 20,000 years ago. And it’s getting deeper because of global ocean warming.

When species numbers were plotted against mean annual temperature, there was a decline above 20°C. Another coincidence?

Biological processes and biodiversity

Research in Tasmania Modeled the growth rate of microbes and multicellular organisms and found that the most stable temperature for their biological processes was also 20 °C.

It is built on the “Corkary Model”. Other studies 20 °C was the most stable temperature for biological molecules. The third coincidence?

We worked with colleagues from Canada, Scotland, Germany, Hong Kong and Taiwan to explore general patterns of how temperature affects life. To our surprise, everywhere we looked we kept seeing that indeed, 20°C is a critical temperature for many measures of biodiversity, and not just for marine species.

Examples show temperatures over about 20 °C warmer resulting in a decrease in various key measures:

• Low oxygen tolerance of marine and freshwater species
• Marine pelagic (living in open water) and benthic (living on the sea floor) algal productivity and fish predation rates on bait.
• Global species richness in pelagic fishes, plankton, benthic invertebrates and fossil molluscs
• and genetic diversity.

Extinctions in the fossil record also increased when temperatures exceeded 20°C.

Increase in species richness

Globally, the temperature at which reef fish and invertebrates live is the lowest among species whose geographic distributions are centered at 20 °C. The same effect is observed in microbes.

Although many species have evolved to live at warm and cold temperatures, most species survive at 20 °C. Also, extinctions in the fossil record—including sponges, lampreys, molluscs, sea mats (bryozoans), starfish and sea urchins, insects and crustaceans were lower at 20°C.

As species evolve to survive at temperatures above and below 20°C, their thermal range widens. This means that most can still survive at 20°C whether they live in hot or cold places.

The mathematical Corkray model predicts that thermal expansion should be minimized, and biological processes most stable and efficient, at 20 °C. This, in turn, maximizes species richness in all walks of life, from bacteria to multicellular plants and animals. The model therefore provides a theoretical explanation for this “20°C effect”.

Forecasting the effects of climate change

That life appears to be centered around 20°C implies fundamental constraints that compromise the ability of tropical species to adapt to higher temperatures.

As long as species can adapt their ranges to global warming, the 20°C effect means that there will be a spatial increase in species richness up to an annual average of 20°C. Beyond this, the wealth will decrease.

This means many marine species can adapt. Global Warming By transferring them Geographical distribution Extinction is unlikely due to climate change.

However, terrestrial species cannot change their geographic distributions as easily because of landscapes altered by cities, agriculture, and other human infrastructure.

The 20°C effect is the simplest explanation for the above phenomena, including: trends Species richness and genetic diversity with temperature; Extinction rate in The fossil record; biological productivity; maximum growth rate; and marine predation rates.

Despite the complexity of multicellular species, it is notable that the utility of cellular surface temperature is reflected in these other aspects of biodiversity.

Precisely why 20°C is important and energy-efficient for cellular processes may be due to the molecular properties of water associated with cells. These features may also be why ~42°C appears to be an absolute limit for most species.

Greater awareness of this 20°C effect may lead to new insights into how temperature controls ecosystem processes, species abundance and distribution, and the evolution of life.

This article has been republished. Conversation Under Creative Commons License. read Original article.