Extreme heat likely to wipe out humans and mammals in ‘triple whammy’

A study predicts a mass extinction of mammals within 250 million years due to extreme heat resulting from the formation of a supercontinent. The research highlights the deadly combination of a hotter sun and increased carbon dioxide₂and continental influences, which underscores the importance of land mass mapping in assessing the habitability of exoplanets.

Unprecedented heat will likely trigger the next mass extinction since the extinction of the dinosaurs, wiping out almost all mammals within about 250 million years, according to a new study.

The research was published on September 25 in the journal Natural earth sciences Led by the University of Bristol, the book presents the first supercomputer climate models of the far future, and shows how extreme climate events will worsen dramatically when the world’s continents eventually merge to form a single hot, dry and largely uninhabitable supercontinent.

Factors that contribute to extreme temperatures

The results show how these higher temperatures are set to rise, as the sun becomes brighter, emits more energy and warms the Earth. Tectonic processes, which occur in the Earth’s crust and lead to the formation of a supercontinent, would also lead to more frequent volcanic eruptions, resulting in massive releases of carbon dioxide into the atmosphere, further warming the planet.

Mammals, including humans, have historically survived thanks to their ability to adapt to the vagaries of weather, particularly through adaptations such as fur and hibernation in the cold, as well as short periods of hibernation in warm weather.

While mammals have evolved to lower their threshold for cold-temperature survival, their upper-temperature tolerance has generally remained constant. This makes prolonged exposure to extreme heat difficult to overcome, and climate simulations, if achieved, will eventually prove unviable.

Implications for mammals

Lead author Dr. Alexander Farnsworth, senior research associate at University of Bristol“A newly emerging supercontinent would effectively create a triple whammy, involving a continental effect, a hotter sun, and more carbon dioxide,” he said.₂ in the atmosphere, leading to increased temperatures in most parts of the planet. The result is a mostly hostile environment devoid of food and water sources for mammals.

– Wide temperature range ranging from 40 to 50 degrees CelsiusEven larger daily extremes, exacerbated by high humidity levels, could ultimately determine our fate. Humans – along with many others Classify – They will expire due to their inability to get rid of this heat through sweat, and cool their bodies.

Although human-induced climate change and global warming are likely to be an increasing cause of heat stress and mortality in some regions, research suggests that the planet would have to remain largely habitable for seismic landmass to change in the distant future. But when the supercontinent forms, the results suggest that only between 8% and 16% of the land will be habitable for mammals.

Addressing the current climate crisis

Dr Eunice Lu, co-author and research fellow in climate change and health at the University of Bristol, said: “It is extremely important that we do not lose sight of the current climate crisis we face, which is a result of human emissions of greenhouse gases. While we expect the planet to become uninhabitable in 250 million years, today we are already witnessing extreme heat that is harmful to human health. That’s why it’s so important to reach net zero emissions as soon as possible.

Methodology and future forecasts

The international team of scientists applied climate models, simulating temperature, wind, rainfall and humidity trends for the next supercontinent – called Pangea Ultima – which is expected to form in the next 250 million years. To estimate the future level of carbon dioxide₂ The team used models of plate tectonics, ocean chemistry, and biology to map carbon dioxide inputs and outputs₂.

Future Company₂ The calculations were led by Professor Benjamin Mills from the University of Leeds, who said: “We believe that carbon dioxide₂ It could rise from about 400 parts per million (ppm) today to more than 600 ppm millions of years in the future. Of course, this assumes that humans will stop burning fossil fuels, otherwise we would see these numbers much sooner.

“The outlook for the distant future looks very bleak,” said Dr Farnsworth, who is also a visiting professor of the Tibetan Plateau Earth System, Environment and Resources (TPESER) at the Chinese Academy of Sciences Tibet Plateau Research Institute. Carbon dioxide levels could be double current levels. The Sun is also expected to emit about 2.5% additional radiation. The supercontinent is located mainly in the hot and humid tropics, and much of the planet may experience temperatures ranging from 40 to 70 degrees Celsius.

“This work also highlights that a world within the so-called ‘habitable zone’ of the solar system may not be the most hospitable for humans depending on whether the continents are scattered, as we have today, or in one large supercontinent.”

Relevance to exoplanet research

In addition, the research demonstrates the importance of continental tectonics and layout when conducting research on planets outside our solar system, called exoplanets. Although Earth will still be within the habitable zone in 250 million years, the formation of a supercontinent with high carbon dioxide content will make most of the world uninhabitable for mammals. The results suggest that mapping the land area of ​​a distant world could be a key factor when determining how habitable it is for humans.

Reference: “Climate extremes likely to drive extinction of terrestrial mammals during next supercontinent rally” by Alexander Farnsworth, Y. T. Eunice Lu, and Paul J. Valdes, and Jonathan R. Buzan, Benjamin J. W. Mills, and Andrew S. Meredith, and Christopher R. Scotties, and Hannah R. Wakeford, September 25, 2023, Natural earth sciences.
doi: 10.1038/s41561-023-01259-3

The research formed part of a project funded by the UK Natural Environment Research and Innovation Council (UKRI NERC) investigating the climate of supercontinents and mass extinctions.