by Humans aren’t just making the Earth warmer, they’re making the climate chaotic, a grim new study suggests.
The new research, posted to the preprint database on April 21 arXiv (opens in new tab), paints a broad and general picture of the full potential impact of human activities on the climate. And the picture is not pretty.
While the study doesn’t present a full simulation of a climate model, it does outline a rough outline of where we’re going if we don’t curtail climate change and our uncontrolled use of fossil fuels, according to the study authors, scientists from the Department of Physics and Astronomy at the University of Porto in Portugal.
“The implications of climate change are well known (drought, heat waves, extreme phenomena, etc.),” study researcher Orfeu Bertolami told Live Science in an email. “If the Earth system gets into the realm of chaotic behavior, we lose all hope of solving the problem one way or another.”
Related: It’s ‘now or never’ to stop climate disasters, UN scientists say
Climate changes
The Earth periodically experiences massive changes in climate patterns, going from one stable equilibrium to another. These shifts are usually caused by external factors such as changes in the Earth’s orbit or a massive increase in volcanic activity. But past research suggests that we are now entering a new phase, one driven by human activity. As people pump more carbon (opens in new tab) in the atmosphere, we are creating a new Anthropocene era, a period of human-influenced climate systems, something our planet has never experienced before.
In the new study, researchers modeled the introduction of the Anthropocene as a phase transition. Most people are familiar with phase transitions in materials, for example when an ice cube changes phase from a solid to a liquid by melting in water, or when water evaporates to a gas. But phase transitions also occur in other systems. In this case, the system is the Earth’s climate. A certain climate ensures regular and predictable seasons and weather, and a phase transition in climate leads to a new pattern of seasons and weather. When the climate goes through a phase transition, it means that the Earth experiences a sudden and rapid change in patterns.
Logistic problems
If human activity is causing a phase transition in Earth’s climate, it means we’re causing the planet to develop a new set of weather patterns. What those patterns will look like is one of the most pressing problems of climate science.
Where is the Earth’s climate heading? That strongly depends on what exactly our activity will be in the coming decades. For example, drastically reducing CO2 emissions would lead to different results than changing nothing at all, the researchers wrote in the study.
To account for the different trajectories and choices humanity might make, the researchers used a mathematician… (opens in new tab) tool called a logistics map. The logistics map is great at describing situations where a variable — such as the amount of carbon in the atmosphere — can grow, but naturally reaches a limit. For example, scientists often use the logistic map to describe animal populations: Animals can continue to give birth, increasing their numbers, but they reach a limit when they consume all the food in their environment (or their predators get too hungry and consume them).
Related: The 5 Mass Extinction Events That Shaped Earth’s History (opens in new tab)
Our impact on the environment is certainly increasing, and has been for more than a century. But it will of course reach a limit, the researchers say. For example, the human population can only grow so large and have only so many carbon-emitting activities; and pollution will eventually affect the environment. At some point in the future, carbon output will reach a maximum limit, and the researchers found that a logistics map can very well capture the future trajectory of that carbon output.
everything is chaos
The researchers examined different ways the human logistics map could evolve, depending on a variety of factors such as our population, introduction of carbon reduction strategies and better, more efficient technologies. Once they discovered how human carbon output would evolve over time, they used it to study how Earth’s climate would evolve through the human-driven phase transition.
In the best cases, once humanity reaches the limit of carbon output, the Earth’s climate stabilizes at a new, higher average temperature. This higher temperature is generally bad for humans, as it still leads to higher sea levels and more extreme weather events. But at least it’s stable: The Anthropocene is similar to previous climate eras, only warmer, and it will still have regular and repeatable weather patterns.
But worst-case scenario, the researchers found that Earth’s climate leads to chaos. Real, mathematical chaos. In a chaotic system there is no equilibrium and no repeatable patterns. A chaotic climate would have seasons that change dramatically from decade to decade (or even year to year). Some years would experience sudden flashes of extreme weather, while others would be completely silent. Even the average temperature on Earth can fluctuate wildly, swinging from cooler to warmer periods in relatively short periods of time. It would become completely impossible to determine in which direction the Earth’s climate is heading.
“Chaotic behavior means that it will be impossible to predict the behavior of the Earth System in the future, even if we know with great certainty its current state,” Bertolami said. “It will mean that any ability to control the Earth system and bring it to a state of equilibrium that favors the habitability of the biosphere will be lost.”
Most disturbingly, the researchers found that above a certain critical threshold temperature for Earth’s atmosphere, a feedback cycle can occur where a chaotic result would become inevitable. There are some signs that we may already have passed that tipping point, but it’s not too late to prevent a climate catastrophe.
Originally published on Live Science†
