The Earth has had a 4,000-7,000 ppm CO2 concentration in the atmosphere before and it hasn't led to Venusification. We've only gone from ~250 to ~420 ppm so far, so we're a long way off, and hopefully we'll stop before we dump another 20+ "industrial revolution units" of CO2 into the atmosphere.

Of course long before then we melt Antarctica and the Earth's climate looks a lot different, but it won't be Venus.

Found this from April 2023:

>How a Stable Greenhouse Effect on Earth Is Maintained Under Global Warming

>Plain Language Summary: Observations and model simulations have shown that Earth maintains a stable longwave radiative feedback process. When the surface warms by 1 K, Earth allows for 1.7 to 2.0 Wm−2 of extra thermal cooling to escape to space in cloud-free conditions. Recent studies have claimed that this enhanced thermal cooling to space can be explained by emissions from the surface passing through the atmosphere's infrared window. However, we find that a large portion of the stability actually results from enhanced atmospheric emission during global warming, which arises from the weakening of spectral lines broadening by radiatively inert gases (N2, O2, Ar) as the Earth warms. It is a well-understood phenomenon in spectral physics but has been largely ignored in the feedback literature. As a result, the feedback responses from the thermal radiative effects of greenhouse gases tend to stabilize the climate, rather than initializing a runaway of thermal radiative energy. This study further proposes a simple theory for accurately predicting the clear-sky longwave feedback from climate base states.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2022...