Key Takeaways on the Hothouse Earth Scenario
- The idea of the greenhouse or hothouse effect originated in 1824 and was proven in 1896.
- The Hothouse effect is raising global temperatures and driving climate change, which could lead to detrimental impacts to our planet and the species that live on it.
- Though it may seem hopeless, not all is lost. We can still work together to lower our climate impact.
In 1824 — yes, that long ago — French mathematician Joseph Fourier first described what we now call “the greenhouse effect” to explain why the Earth does not lose more heat after the sun goes down. Then, in 1896, Swedish scientist Svante Arrhenius developed the first model showing how carbon dioxide influences climate, building up heat in what he called a hot-house theory.
Since then, climate science has been piling up. And so has the heat. According to the most recent Intergovernmental Panel on Climate Change (IPCC) report, global temperatures are warmer than they’ve been in the last 125,000 years, and carbon dioxide levels are higher than they’ve been in at least two million years.
And the pace of warming is picking up. The rate of increase was roughly 0.05 degrees Celsius per decade in the mid-twentieth century. Now it’s at roughly 0.31 degrees per decade. What’s more, in both 2023 and 2024 global temperatures overshot the target set by the Paris Climate Accords — no more than 1.5 degrees Celsius above preindustrial levels — a target considered essential if we are to avoid the worst outcomes of climate change.
The problem, however, is more complex than simple increases in global temperatures. In recent years, scientists have learned about the many complex, interacting systems that play a role in Earth’s climate. But it is precisely the disruption of these interconnected systems that poses the greatest threat.
Read More: Climate Change May Be Making Our Days A Little Longer — Here’s How We Know
The Hothouse Earth Tipping Point
A 2018 paper in the journal PNAS found that, owing to self-reinforcing feedbacks in these systems, we may be headed toward a threshold beyond which the trajectory of Earth’s climate would lead inexorably to what the researchers call Hothouse Earth, a state in which we have tipped the climate into a point of no return, a point beyond which, even if emissions are later reduced, temperatures will remain substantially higher for a very long time.
A paper published in February 2026 in the journal One Earth builds on this work, identifying 16 potential tipping points, including collapsing ice sheets, thawing permafrost, loss of rainforest, and die-off of coral reefs.
“The concern is that once some tipping elements are triggered, they can begin to reinforce each other, creating a cascade of changes in the Earth system,” William J. Ripple, senior author of the One Earth paper and professor of ecology at Oregon State University, told Discover. “For example, large-scale melting of the Greenland Ice Sheet adds freshwater to the North Atlantic, which could weaken major ocean circulation patterns that influence climate across the globe.”
Though it is not known exactly how close we are to those tipping points, accumulating data suggests we may be much closer than previously thought. Going beyond the 1.5-degree target only increases the probability that we will reach those tipping points. In short, time is running out.
Hot House Earth Is Not a Point of Despair, but a Call to Action
Frightening as this is, it’s not a reason for despair, but rather a call to action.
“The choices we make in the coming years will strongly influence how much warming occurs and how many tipping risks we face,” Ripple said. “Preventing even a tenth of a degree of warming could reduce the likelihood of crossing critical thresholds and potentially save many [millions of] lives.”
If, like many people, your optimism is wearing a bit thin, you might take some inspiration from Ripple, who is director of the Alliance of World Scientists, an international assembly of scientists committed to the health of life on the planet. Ripple has been sounding alarms for much of his career. He’s the lead author of more than one “World Scientists’ Warning” published in BioScience about the climate crisis, the latest of which begins with the words, “We are now at ‘code red’ on planet Earth.”
But even now, Ripple does not despair.
“I try to focus on the progress that has been made. Public awareness of climate change has grown dramatically, renewable energy is expanding quickly, and more people are recognizing the importance of protecting nature,” he said. “History shows that societies can change direction surprisingly quickly when the risks become widely understood.”
If ever there were a time to change direction quickly, it is now.
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