According to a new study, Earth will become uninhabitable in about 250 million years due to extreme heat, volcanic activity, and the formation of a superheated supercontinent.
Human activities and greenhouse gas emissions are warming Earth’s climate in a way that hasn’t been seen for millions of years. This has serious effects on ecosystems. However, it’s unclear how this will specifically impact mammals, the dominant land species on Earth. We do not yet know if or when these species might encounter a climatic threshold that could endanger their predominance.
In a new study by the University of Bristol, researchers ran supercomputer simulations to predict Earth’s distant future. The team showed that climate extremes will drastically increase when the continents eventually merge into a hot, dry, and primarily uninhabitable supercontinent called Pangea Ultima.
According to their model, unprecedented heat will likely lead to the next mass extinction. High temperatures will likely wipe out humans and mammals in 250 million years.
The projections indicate a continued rise in high temperatures as the Sun’s brightness intensifies, emitting more energy and warming the Earth. Moreover, tectonic activities in Earth’s crust will lead to the formation of supercontinents, causing more frequent volcanic eruptions. This eruption’s large amounts of carbon dioxide further increase the planet’s temperature.
Historically, mammals, including humans, have demonstrated remarkable adaptability to weather extremes through various evolutionary traits, such as fur and hibernation during cold spells and brief periods of hibernation in warmer weather.
University of Bristol
While mammals have evolved to tolerate lower cold temperatures, their capacity to withstand higher temperatures has remained unchanged. Due to their fixed upper-temperature limit, mammals have a hard time coping with long periods of excessive heat. If the climate predictions come true, these conditions would become unsurvivable for them.
Lead author Dr Alexander Farnsworth, Senior Research Associate at the University of Bristol, said: “The newly-emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter Sun and more CO2 in the atmosphere, of increasing heat for much of the planet. The result is a mostly hostile environment devoid of food and water sources for mammals.”
“Widespread temperatures of between 40 to 50 degrees Celsius, and even greater daily extremes, compounded by high humidity levels, would ultimately seal our fate. Humans and many other species would expire due to their inability to shed this heat through sweat, cooling their bodies.”
Despite human-induced climate change and global warming posing increasing threats of heat stress and mortality in certain regions, research suggests that our planet will remain habitable until the profound shifts in landmass occur far in the future. However, when the following supercontinent forms, it is projected that only 8% to 16% of the land will be suitable for mammalian habitation.
Dr. Eunice Lo, a Research Fellow in Climate Change and Health at the University of Bristol, emphasized, “It is critical not to lose focus on our current Climate Crisis, which stems from human emissions of greenhouse gases. Although we foresee an uninhabitable planet in 250 million years, we have already witnessed extreme heat that adversely impacts human health. This underscores the urgency of achieving net-zero emissions as soon as possible.”
The global team of scientists utilized climate models to simulate future temperature, wind, precipitation, and humidity trends for the anticipated supercontinent, Pangea Ultima, expected to form within the next 250 million years. To estimate future CO2 levels, the team incorporated models of tectonic plate movements, ocean chemistry, and biology to map the inputs and outputs of CO2.
Professor Benjamin Mills at the University of Leeds led the future CO2 calculations, saying: “We think CO2 could rise from around 400 parts per million (ppm) today to more than 600 ppm many millions of years in the future. Of course, this assumes that humans will stop burning fossil fuels; otherwise, we will see those numbers much sooner.”
Dr Farnsworth, a visiting Professor at the Tibetan Plateau Earth System, Environment and Resources (TPESER) at the Chinese Academy of Sciences Institute of Tibetan Plateau Research, said: “The outlook in the distant future appears bleak. Carbon dioxide levels could be double current levels. With the Sun also anticipated to emit about 2.5% more radiation and the supercontinent being primarily in the hot, humid tropics, much of the planet could be facing temperatures between 40 to 70 °C.”
“This work also highlights that a world within the so-called ‘habitable zone’ of a solar system may not be the most hospitable for humans depending on whether the continents are dispersed, as we have today, or in one large supercontinent.”
While Earth will remain within the habitable zone 250 million years from now, forming a supercontinent with heightened carbon dioxide levels will render most of the planet uninhabitable for mammals. The research indicates that the arrangement of landmasses in the distant future could be crucial in determining the planet’s habitability for humans.
Journal Reference:
- Farnsworth, A., Lo, Y.T.E., Valdes, P.J. et al. Climate extremes are likely to drive land mammal extinction during the next supercontinent assembly. Nat. Geosci. 16, 901–908 (2023). DOI: 10.1038/s41561-023-01259-3
Source: Tech Explorist
