Scientists do not currently have a single, universally agreed upon number for a threshold that would trigger a runaway greenhouse effect. While the term is often used in discussions about climate change, it refers to a specific theoretical scenario where a planet's temperature rises uncontrollably because its feedback loops become self sustaining.
In such a scenario, warming causes more water vapor or other gases to enter the atmosphere, which in turn traps even more heat. This creates a cycle that cannot be stopped by natural or human processes. Most climate models suggest that while Earth is currently experiencing significant warming, we are not currently at the doorstep of a true runaway greenhouse effect like the one seen on Venus.
Instead, scientists focus on tipping points. These are critical thresholds where small changes can lead to large and irreversible shifts in the climate system, such as the melting of permafrost or the collapse of ice sheets. Preventing these shifts requires keeping global warming well below 2 degrees Celsius above pre-industrial levels. To stay informed about the latest climate research, you can visit the official website of the Intergovernmental Panel on Climate Change (IPCC) at https://www.ipcc.ch.
